Merge remote-tracking branch 'apache/trunk' into HDFS-7285

Conflicts:
	hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java
	hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java
	hadoop-hdfs-project/hadoop-hdfs-client/src/main/proto/hdfs.proto
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSConfigKeys.java
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSUtil.java
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/PBHelper.java
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
	hadoop-hdfs-project/hadoop-hdfs/src/main/proto/DatanodeProtocol.proto
	hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockTokenWithDFS.java
	hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFsck.java

Change-Id: Ic7946c4ea35bed587fe879ce58b959b25ecc0823

dev-support/test-patch.sh

@@ -599,6 +599,8 @@ function hadoop_usage
   echo "--run-tests            Run all relevant tests below the base directory"
   echo "--skip-system-plugins  Do not load plugins from ${BINDIR}/test-patch.d"
   echo "--testlist=<list>      Specify which subsystem tests to use (comma delimited)"
+  echo "--test-parallel=<bool> Run multiple tests in parallel (default false in developer mode, true in Jenkins mode)"
+  echo "--test-threads=<int>   Number of tests to run in parallel (default defined in ${PROJECT_NAME} build)"
 
   echo "Shell binary overrides:"
   echo "--awk-cmd=<cmd>        The 'awk' command to use (default 'awk')"
@@ -691,6 +693,7 @@ function parse_args
       ;;
       --jenkins)
         JENKINS=true
+        TEST_PARALLEL=${TEST_PARALLEL:-true}
       ;;
       --jira-cmd=*)
         JIRACLI=${i#*=}
@@ -749,6 +752,12 @@ function parse_args
           add_test "${j}"
         done
       ;;
+      --test-parallel=*)
+        TEST_PARALLEL=${i#*=}
+      ;;
+      --test-threads=*)
+        TEST_THREADS=${i#*=}
+      ;;
       --wget-cmd=*)
         WGET=${i#*=}
       ;;
@@ -811,6 +820,13 @@ function parse_args
   PATCH_DIR=$(cd -P -- "${PATCH_DIR}" >/dev/null && pwd -P)
 
   GITDIFFLINES=${PATCH_DIR}/gitdifflines.txt
+
+  if [[ ${TEST_PARALLEL} == "true" ]] ; then
+    PARALLEL_TESTS_PROFILE=-Pparallel-tests
+    if [[ -n ${TEST_THREADS:-} ]]; then
+      TESTS_THREAD_COUNT="-DtestsThreadCount=$TEST_THREADS"
+    fi
+  fi
 }
 
 ## @description  Locate the pom.xml file for a given directory
@@ -2245,13 +2261,22 @@ function check_unittests
 
     test_logfile=${PATCH_DIR}/testrun_${module_suffix}.txt
     echo "  Running tests in ${module_suffix}"
-    echo_and_redirect "${test_logfile}" "${MVN}" "${MAVEN_ARGS[@]}" clean install -fae ${NATIVE_PROFILE} ${REQUIRE_TEST_LIB_HADOOP} -D${PROJECT_NAME}PatchProcess
+    # Temporary hack to run the parallel tests profile only for hadoop-common.
+    # This code will be removed once hadoop-hdfs is ready for parallel test
+    # execution.
+    if [[ ${module} == "hadoop-common-project/hadoop-common" ]] ; then
+      OPTIONAL_PARALLEL_TESTS_PROFILE=${PARALLEL_TESTS_PROFILE}
+    else
+      unset OPTIONAL_PARALLEL_TESTS_PROFILE
+    fi
+    # shellcheck disable=2086
+    echo_and_redirect "${test_logfile}" "${MVN}" "${MAVEN_ARGS[@]}" clean install -fae ${NATIVE_PROFILE} ${REQUIRE_TEST_LIB_HADOOP} ${OPTIONAL_PARALLEL_TESTS_PROFILE} ${TESTS_THREAD_COUNT} -D${PROJECT_NAME}PatchProcess
     test_build_result=$?
 
     add_jira_footer "${module_suffix} test log" "@@BASE@@/testrun_${module_suffix}.txt"
 
     # shellcheck disable=2016
-    module_test_timeouts=$(${AWK} '/^Running / { if (last) { print last } last=$2 } /^Tests run: / { last="" }' "${test_logfile}")
+    module_test_timeouts=$(${AWK} '/^Running / { array[$NF] = 1 } /^Tests run: .* in / { delete array[$NF] } END { for (x in array) { print x } }' "${test_logfile}")
     if [[ -n "${module_test_timeouts}" ]] ; then
       test_timeouts="${test_timeouts} ${module_test_timeouts}"
       result=1

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -348,10 +348,6 @@ Trunk (Unreleased)
     HADOOP-8813. Add InterfaceAudience and InterfaceStability annotations
     to RPC Server and Client classes. (Brandon Li via suresh)
 
-    HADOOP-8436. NPE In getLocalPathForWrite ( path, conf ) when the
-    required context item is not configured
-    (Brahma Reddy Battula via harsh)
-
     HADOOP-8386. hadoop script doesn't work if 'cd' prints to stdout
     (default behavior in some bash setups (esp. Ubuntu))
     (Chiristopher Berner and Andy Isaacson via harsh)
@@ -791,6 +787,8 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12428. Fix inconsistency between log-level guards and statements.
     (Jagadesh Kiran N and Jackie Chang via ozawa)
 
+    HADOOP-12446. Undeprecate createNonRecursive() (Ted Yu via kihwal)
+
   OPTIMIZATIONS
 
     HADOOP-11785. Reduce the number of listStatus operation in distcp
@@ -826,6 +824,9 @@ Release 2.8.0 - UNRELEASED
     HADOOP-11878. FileContext#fixRelativePart should check for not null for a
     more informative exception. (Brahma Reddy Battula via kasha)
 
+    HADOOP-11984. Enable parallel JUnit tests in pre-commit.
+    (Chris Nauroth via vinayakumarb)
+
   BUG FIXES
 
     HADOOP-12374. Updated expunge command description.
@@ -1084,6 +1085,19 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12386. RetryPolicies.RETRY_FOREVER should be able to specify a 
     retry interval. (Sunil G via wangda)
 
+    HADOOP-8436. NPE In getLocalPathForWrite ( path, conf ) when the
+    required context item is not configured
+    (Brahma Reddy Battula via harsh)
+
+    HADOOP-12252. LocalDirAllocator should not throw NPE with empty string
+    configuration. (Zhihai Xu)
+
+    HADOOP-11918. Listing an empty s3a root directory throws FileNotFound.
+    (Lei (Eddy) Xu via cnauroth)
+
+    HADOOP-12440. TestRPC#testRPCServerShutdown did not produce the desired
+    thread states before shutting down. (Xiao Chen via mingma)
+
   OPTIMIZATIONS
 
     HADOOP-12051. ProtobufRpcEngine.invoke() should use Exception.toString()
@@ -1144,6 +1158,15 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12417. TestWebDelegationToken failing with port in use.
     (Mingliang Liu via wheat9)
 
+    HADOOP-12438. Reset RawLocalFileSystem.useDeprecatedFileStatus in
+    TestLocalFileSystem. (Chris Nauroth via wheat9)
+
+    HADOOP-12437. Allow SecurityUtil to lookup alternate hostnames.
+    (Arpit Agarwal)
+
+    HADOOP-12442. Display help if the command option to 'hdfs dfs' is not valid
+    (nijel via vinayakumarb)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES
@@ -1924,7 +1947,7 @@ Release 2.6.2 - UNRELEASED
 
   BUG FIXES
 
-Release 2.6.1 - 2015-09-09
+Release 2.6.1 - 2015-09-23
 
   INCOMPATIBLE CHANGES
 

hadoop-common-project/hadoop-common/pom.xml

@@ -246,7 +246,7 @@
 
     <dependency>
       <groupId>org.apache.htrace</groupId>
-      <artifactId>htrace-core</artifactId>
+      <artifactId>htrace-core4</artifactId>
     </dependency>
     <dependency>
       <groupId>org.apache.zookeeper</groupId>
@@ -878,12 +878,53 @@
       <id>parallel-tests</id>
       <build>
         <plugins>
+          <plugin>
+            <artifactId>maven-antrun-plugin</artifactId>
+            <executions>
+              <execution>
+                <id>create-parallel-tests-dirs</id>
+                <phase>test-compile</phase>
+                <configuration>
+                  <target>
+                    <script language="javascript"><![CDATA[
+                      var baseDirs = [
+                          "${test.build.data}",
+                          "${test.build.dir}",
+                          "${hadoop.tmp.dir}" ];
+                      for (var i in baseDirs) {
+                        for (var j = 1; j <= ${testsThreadCount}; ++j) {
+                          var mkdir = project.createTask("mkdir");
+                          mkdir.setDir(new java.io.File(baseDirs[i], j));
+                          mkdir.perform();
+                        }
+                      }
+                    ]]></script>
+                  </target>
+                </configuration>
+                <goals>
+                  <goal>run</goal>
+                </goals>
+              </execution>
+            </executions>
+          </plugin>
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-surefire-plugin</artifactId>
             <configuration>
               <forkCount>${testsThreadCount}</forkCount>
-              <argLine>-Xmx1024m -XX:+HeapDumpOnOutOfMemoryError -DminiClusterDedicatedDirs=true</argLine>
+              <reuseForks>false</reuseForks>
+              <argLine>${maven-surefire-plugin.argLine} -DminiClusterDedicatedDirs=true</argLine>
+              <systemPropertyVariables>
+                <test.build.data>${test.build.data}/${surefire.forkNumber}</test.build.data>
+                <test.build.dir>${test.build.dir}/${surefire.forkNumber}</test.build.dir>
+                <hadoop.tmp.dir>${hadoop.tmp.dir}/${surefire.forkNumber}</hadoop.tmp.dir>
+
+                <!-- Due to a Maven quirk, setting this to just -->
+                <!-- surefire.forkNumber won't do the parameter substitution. -->
+                <!-- Putting a prefix in front of it like "fork-" makes it -->
+                <!-- work. -->
+                <test.unique.fork.id>fork-${surefire.forkNumber}</test.unique.fork.id>
+              </systemPropertyVariables>
             </configuration>
           </plugin>
         </plugins>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeys.java

@@ -310,4 +310,7 @@ public class CommonConfigurationKeys extends CommonConfigurationKeysPublic {
   public static final String NFS_EXPORTS_ALLOWED_HOSTS_SEPARATOR = ";";
   public static final String NFS_EXPORTS_ALLOWED_HOSTS_KEY = "nfs.exports.allowed.hosts";
   public static final String NFS_EXPORTS_ALLOWED_HOSTS_KEY_DEFAULT = "* rw";
+
+  // HDFS client HTrace configuration.
+  public static final String  FS_CLIENT_HTRACE_PREFIX = "fs.client.htrace.";
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeysPublic.java

@@ -294,6 +294,12 @@ public class CommonConfigurationKeysPublic {
   /** See <a href="{@docRoot}/../core-default.html">core-default.xml</a> */
   public static final String  HADOOP_SECURITY_AUTH_TO_LOCAL =
     "hadoop.security.auth_to_local";
+  /** See <a href="{@docRoot}/../core-default.html">core-default.xml</a> */
+  public static final String HADOOP_SECURITY_DNS_INTERFACE_KEY =
+    "hadoop.security.dns.interface";
+  /** See <a href="{@docRoot}/../core-default.html">core-default.xml</a> */
+  public static final String HADOOP_SECURITY_DNS_NAMESERVER_KEY =
+    "hadoop.security.dns.nameserver";
 
   /** See <a href="{@docRoot}/../core-default.html">core-default.xml</a> */
   public static final String HADOOP_KERBEROS_MIN_SECONDS_BEFORE_RELOGIN =

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSOutputSummer.java

@@ -21,8 +21,8 @@ package org.apache.hadoop.fs;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.NullScope;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 import java.io.IOException;
 import java.io.OutputStream;
@@ -43,6 +43,8 @@ abstract public class FSOutputSummer extends OutputStream {
   private byte checksum[];
   // The number of valid bytes in the buffer.
   private int count;
+  // The HTrace tracer to use
+  private Tracer tracer;
   
   // We want this value to be a multiple of 3 because the native code checksums
   // 3 chunks simultaneously. The chosen value of 9 strikes a balance between
@@ -201,7 +203,7 @@ abstract public class FSOutputSummer extends OutputStream {
   }
 
   protected TraceScope createWriteTraceScope() {
-    return NullScope.INSTANCE;
+    return null;
   }
 
   /** Generate checksums for the given data chunks and output chunks & checksums
@@ -219,9 +221,11 @@ abstract public class FSOutputSummer extends OutputStream {
             getChecksumSize());
       }
     } finally {
+      if (scope != null) {
         scope.close();
       }
     }
+  }
 
   /**
    * Converts a checksum integer value to a byte stream

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileContext.java

@@ -61,6 +61,7 @@ import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.ShutdownHookManager;
 
 import com.google.common.base.Preconditions;
+import org.apache.htrace.core.Tracer;
 
 /**
  * The FileContext class provides an interface for users of the Hadoop
@@ -222,12 +223,14 @@ public class FileContext {
   private final Configuration conf;
   private final UserGroupInformation ugi;
   final boolean resolveSymlinks;
+  private final Tracer tracer;
 
   private FileContext(final AbstractFileSystem defFs,
     final FsPermission theUmask, final Configuration aConf) {
     defaultFS = defFs;
     umask = FsPermission.getUMask(aConf);
     conf = aConf;
+    tracer = FsTracer.get(aConf);
     try {
       ugi = UserGroupInformation.getCurrentUser();
     } catch (IOException e) {
@@ -2721,4 +2724,8 @@ public class FileContext {
       throws IOException {
     return defaultFS.getAllStoragePolicies();
   }
+
+  Tracer getTracer() {
+    return tracer;
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileSystem.java

@@ -67,9 +67,8 @@ import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.apache.hadoop.util.ShutdownHookManager;
 import org.apache.hadoop.util.StringUtils;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 
@@ -129,6 +128,13 @@ public abstract class FileSystem extends Configured implements Closeable {
   private Set<Path> deleteOnExit = new TreeSet<Path>();
   
   boolean resolveSymlinks;
+
+  private Tracer tracer;
+
+  protected final Tracer getTracer() {
+    return tracer;
+  }
+
   /**
    * This method adds a file system for testing so that we can find it later. It
    * is only for testing.
@@ -1083,9 +1089,7 @@ public abstract class FileSystem extends Configured implements Closeable {
    * @param progress
    * @throws IOException
    * @see #setPermission(Path, FsPermission)
-   * @deprecated API only for 0.20-append
    */
-  @Deprecated
   public FSDataOutputStream createNonRecursive(Path f,
       boolean overwrite,
       int bufferSize, short replication, long blockSize,
@@ -1108,9 +1112,7 @@ public abstract class FileSystem extends Configured implements Closeable {
    * @param progress
    * @throws IOException
    * @see #setPermission(Path, FsPermission)
-   * @deprecated API only for 0.20-append
    */
-   @Deprecated
    public FSDataOutputStream createNonRecursive(Path f, FsPermission permission,
        boolean overwrite, int bufferSize, short replication, long blockSize,
        Progressable progress) throws IOException {
@@ -1133,9 +1135,7 @@ public abstract class FileSystem extends Configured implements Closeable {
     * @param progress
     * @throws IOException
     * @see #setPermission(Path, FsPermission)
-    * @deprecated API only for 0.20-append
     */
-    @Deprecated
     public FSDataOutputStream createNonRecursive(Path f, FsPermission permission,
         EnumSet<CreateFlag> flags, int bufferSize, short replication, long blockSize,
         Progressable progress) throws IOException {
@@ -2706,14 +2706,13 @@ public abstract class FileSystem extends Configured implements Closeable {
 
   private static FileSystem createFileSystem(URI uri, Configuration conf
       ) throws IOException {
-    TraceScope scope = Trace.startSpan("FileSystem#createFileSystem");
+    Tracer tracer = FsTracer.get(conf);
-    Span span = scope.getSpan();
+    TraceScope scope = tracer.newScope("FileSystem#createFileSystem");
-    if (span != null) {
+    scope.addKVAnnotation("scheme", uri.getScheme());
-      span.addKVAnnotation("scheme", uri.getScheme());
-    }
     try {
       Class<?> clazz = getFileSystemClass(uri.getScheme(), conf);
       FileSystem fs = (FileSystem)ReflectionUtils.newInstance(clazz, conf);
+      fs.tracer = tracer;
       fs.initialize(uri, conf);
       return fs;
     } finally {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FilterFileSystem.java

@@ -203,7 +203,6 @@ public class FilterFileSystem extends FileSystem {
 
 
   @Override
-  @Deprecated
   public FSDataOutputStream createNonRecursive(Path f, FsPermission permission,
       EnumSet<CreateFlag> flags, int bufferSize, short replication, long blockSize,
       Progressable progress) throws IOException {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsShell.java

@@ -32,16 +32,13 @@ import org.apache.hadoop.conf.Configured;
 import org.apache.hadoop.fs.shell.Command;
 import org.apache.hadoop.fs.shell.CommandFactory;
 import org.apache.hadoop.fs.shell.FsCommand;
-import org.apache.hadoop.tracing.SpanReceiverHost;
 import org.apache.hadoop.tools.TableListing;
 import org.apache.hadoop.tracing.TraceUtils;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Tool;
 import org.apache.hadoop.util.ToolRunner;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.SamplerBuilder;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 
 /** Provide command line access to a FileSystem. */
 @InterfaceAudience.Private
@@ -54,13 +51,12 @@ public class FsShell extends Configured implements Tool {
   private FileSystem fs;
   private Trash trash;
   protected CommandFactory commandFactory;
-  private Sampler traceSampler;
 
   private final String usagePrefix =
     "Usage: hadoop fs [generic options]";
 
-  private SpanReceiverHost spanReceiverHost;
+  private Tracer tracer;
-  static final String SEHLL_HTRACE_PREFIX = "dfs.shell.htrace.";
+  static final String SHELL_HTRACE_PREFIX = "fs.shell.htrace.";
 
   /**
    * Default ctor with no configuration.  Be sure to invoke
@@ -102,8 +98,9 @@ public class FsShell extends Configured implements Tool {
       commandFactory.addObject(new Usage(), "-usage");
       registerCommands(commandFactory);
     }
-    this.spanReceiverHost =
+    this.tracer = new Tracer.Builder("FsShell").
-        SpanReceiverHost.get(getConf(), SEHLL_HTRACE_PREFIX);
+        conf(TraceUtils.wrapHadoopConf(SHELL_HTRACE_PREFIX, getConf())).
+        build();
   }
 
   protected void registerCommands(CommandFactory factory) {
@@ -289,8 +286,6 @@ public class FsShell extends Configured implements Tool {
   public int run(String argv[]) throws Exception {
     // initialize FsShell
     init();
-    traceSampler = new SamplerBuilder(TraceUtils.
-        wrapHadoopConf(SEHLL_HTRACE_PREFIX, getConf())).build();
     int exitCode = -1;
     if (argv.length < 1) {
       printUsage(System.err);
@@ -302,7 +297,7 @@ public class FsShell extends Configured implements Tool {
         if (instance == null) {
           throw new UnknownCommandException();
         }
-        TraceScope scope = Trace.startSpan(instance.getCommandName(), traceSampler);
+        TraceScope scope = tracer.newScope(instance.getCommandName());
         if (scope.getSpan() != null) {
           String args = StringUtils.join(" ", argv);
           if (args.length() > 2048) {
@@ -317,6 +312,7 @@ public class FsShell extends Configured implements Tool {
         }
       } catch (IllegalArgumentException e) {
         displayError(cmd, e.getLocalizedMessage());
+        printUsage(System.err);
         if (instance != null) {
           printInstanceUsage(System.err, instance);
         }
@@ -327,6 +323,7 @@ public class FsShell extends Configured implements Tool {
         e.printStackTrace(System.err);
       }
     }
+    tracer.close();
     return exitCode;
   }
   
@@ -353,9 +350,6 @@ public class FsShell extends Configured implements Tool {
       fs.close();
       fs = null;
     }
-    if (this.spanReceiverHost != null) {
-      this.spanReceiverHost.closeReceivers();
-    }
   }
 
   /**

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsTracer.java

@@ -0,0 +1,64 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.fs;
+
+import com.google.common.annotations.VisibleForTesting;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.tracing.TraceUtils;
+import org.apache.htrace.core.Tracer;
+
+/**
+ * Holds the HTrace Tracer used for FileSystem operations.
+ *
+ * Ideally, this would be owned by the DFSClient, rather than global.  However,
+ * the FileContext API may create a new DFSClient for each operation in some
+ * cases.  Because of this, we cannot store this Tracer inside DFSClient.  See
+ * HADOOP-6356 for details.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+public final class FsTracer {
+  private static Tracer instance;
+
+  public static synchronized Tracer get(Configuration conf) {
+    if (instance == null) {
+      instance = new Tracer.Builder("FSClient").
+          conf(TraceUtils.wrapHadoopConf(CommonConfigurationKeys.
+              FS_CLIENT_HTRACE_PREFIX, conf)).
+          build();
+    }
+    return instance;
+  }
+
+  @VisibleForTesting
+  public static synchronized void clear() {
+    if (instance == null) {
+      return;
+    }
+    try {
+      instance.close();
+    } finally {
+      instance = null;
+    }
+  }
+
+  private FsTracer() {
+  }
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/Globber.java

@@ -28,9 +28,8 @@ import org.apache.commons.logging.Log;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 
-import org.apache.htrace.Span;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 
 @InterfaceAudience.Private
 @InterfaceStability.Unstable
@@ -41,12 +40,14 @@ class Globber {
   private final FileContext fc;
   private final Path pathPattern;
   private final PathFilter filter;
+  private final Tracer tracer;
   
   public Globber(FileSystem fs, Path pathPattern, PathFilter filter) {
     this.fs = fs;
     this.fc = null;
     this.pathPattern = pathPattern;
     this.filter = filter;
+    this.tracer = fs.getTracer();
   }
 
   public Globber(FileContext fc, Path pathPattern, PathFilter filter) {
@@ -54,6 +55,7 @@ class Globber {
     this.fc = fc;
     this.pathPattern = pathPattern;
     this.filter = filter;
+    this.tracer = fc.getTracer();
   }
 
   private FileStatus getFileStatus(Path path) throws IOException {
@@ -140,11 +142,8 @@ class Globber {
   }
 
   public FileStatus[] glob() throws IOException {
-    TraceScope scope = Trace.startSpan("Globber#glob");
+    TraceScope scope = tracer.newScope("Globber#glob");
-    Span span = scope.getSpan();
+    scope.addKVAnnotation("pattern", pathPattern.toUri().getPath());
-    if (span != null) {
-      span.addKVAnnotation("pattern", pathPattern.toUri().getPath());
-    }
     try {
       return doGlob();
     } finally {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/HarFileSystem.java

@@ -713,7 +713,6 @@ public class HarFileSystem extends FileSystem {
     throw new IOException("Har: create not allowed.");
   }
 
-  @SuppressWarnings("deprecation")
   @Override
   public FSDataOutputStream createNonRecursive(Path f, boolean overwrite,
       int bufferSize, short replication, long blockSize, Progressable progress)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/LocalDirAllocator.java

@@ -250,9 +250,9 @@ public class LocalDirAllocator {
     private int dirNumLastAccessed;
     private Random dirIndexRandomizer = new Random();
     private FileSystem localFS;
-    private DF[] dirDF;
+    private DF[] dirDF = new DF[0];
     private String contextCfgItemName;
-    private String[] localDirs;
+    private String[] localDirs = new String[0];
     private String savedLocalDirs = "";
 
     public AllocatorPerContext(String contextCfgItemName) {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/RawLocalFileSystem.java

@@ -319,7 +319,6 @@ public class RawLocalFileSystem extends FileSystem {
   }
   
   @Override
-  @Deprecated
   public FSDataOutputStream createNonRecursive(Path f, FsPermission permission,
       EnumSet<CreateFlag> flags, int bufferSize, short replication, long blockSize,
       Progressable progress) throws IOException {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/shell/CommandWithDestination.java

@@ -238,7 +238,13 @@ abstract class CommandWithDestination extends FsCommand {
         e.setTargetPath(dstPath.toString());
         throw e;
       }
-      if (dstPath.startsWith(srcPath+Path.SEPARATOR)) {
+      // When a path is normalized, all trailing slashes are removed
+      // except for the root
+      if(!srcPath.endsWith(Path.SEPARATOR)) {
+        srcPath += Path.SEPARATOR;
+      }
+
+      if(dstPath.startsWith(srcPath)) {
         PathIOException e = new PathIOException(src.toString(),
             "is a subdirectory of itself");
         e.setTargetPath(target.toString());

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/ChRootedFileSystem.java

@@ -185,7 +185,6 @@ class ChRootedFileSystem extends FilterFileSystem {
   }
   
   @Override
-  @Deprecated
   public FSDataOutputStream createNonRecursive(Path f, FsPermission permission,
       EnumSet<CreateFlag> flags, int bufferSize, short replication, long blockSize,
       Progressable progress) throws IOException {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

@@ -92,7 +92,8 @@ import org.apache.hadoop.util.ProtoUtil;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Span;
+import org.apache.htrace.core.Tracer;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
@@ -722,8 +723,9 @@ public class Client {
         if (LOG.isDebugEnabled()) {
           LOG.debug("Connecting to "+server);
         }
-        if (Trace.isTracing()) {
+        Span span = Tracer.getCurrentSpan();
-          Trace.addTimelineAnnotation("IPC client connecting to " + server);
+        if (span != null) {
+          span.addTimelineAnnotation("IPC client connecting to " + server);
         }
         short numRetries = 0;
         Random rand = null;
@@ -796,8 +798,9 @@ public class Client {
           // update last activity time
           touch();
 
-          if (Trace.isTracing()) {
+          span = Tracer.getCurrentSpan();
-            Trace.addTimelineAnnotation("IPC client connected to " + server);
+          if (span != null) {
+            span.addTimelineAnnotation("IPC client connected to " + server);
           }
 
           // start the receiver thread after the socket connection has been set

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/ProtobufRpcEngine.java

@@ -49,8 +49,8 @@ import org.apache.hadoop.security.token.SecretManager;
 import org.apache.hadoop.security.token.TokenIdentifier;
 import org.apache.hadoop.util.ProtoUtil;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.protobuf.BlockingService;
@@ -206,12 +206,13 @@ public class ProtobufRpcEngine implements RpcEngine {
             + method.getName() + "]");
       }
 
-      TraceScope traceScope = null;
       // if Tracing is on then start a new span for this rpc.
       // guard it in the if statement to make sure there isn't
       // any extra string manipulation.
-      if (Trace.isTracing()) {
+      Tracer tracer = Tracer.curThreadTracer();
-        traceScope = Trace.startSpan(RpcClientUtil.methodToTraceString(method));
+      TraceScope traceScope = null;
+      if (tracer != null) {
+        traceScope = tracer.newScope(RpcClientUtil.methodToTraceString(method));
       }
 
       RequestHeaderProto rpcRequestHeader = constructRpcRequestHeader(method);
@@ -236,9 +237,9 @@ public class ProtobufRpcEngine implements RpcEngine {
               remoteId + ": " + method.getName() +
                 " {" + e + "}");
         }
-        if (Trace.isTracing()) {
+        if (traceScope != null) {
-          traceScope.getSpan().addTimelineAnnotation(
+          traceScope.addTimelineAnnotation("Call got exception: " +
-              "Call got exception: " + e.toString());
+              e.toString());
         }
         throw new ServiceException(e);
       } finally {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Server.java

@@ -117,10 +117,9 @@ import org.apache.hadoop.util.ProtoUtil;
 import org.apache.hadoop.util.ReflectionUtils;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.SpanId;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceInfo;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.protobuf.ByteString;
@@ -141,6 +140,7 @@ public abstract class Server {
   private List<AuthMethod> enabledAuthMethods;
   private RpcSaslProto negotiateResponse;
   private ExceptionsHandler exceptionsHandler = new ExceptionsHandler();
+  private Tracer tracer;
   
   public void addTerseExceptions(Class<?>... exceptionClass) {
     exceptionsHandler.addTerseExceptions(exceptionClass);
@@ -581,7 +581,7 @@ public abstract class Server {
     private ByteBuffer rpcResponse;       // the response for this call
     private final RPC.RpcKind rpcKind;
     private final byte[] clientId;
-    private final Span traceSpan; // the tracing span on the server side
+    private final TraceScope traceScope; // the HTrace scope on the server side
 
     public Call(int id, int retryCount, Writable param, 
         Connection connection) {
@@ -595,7 +595,7 @@ public abstract class Server {
     }
 
     public Call(int id, int retryCount, Writable param, Connection connection,
-        RPC.RpcKind kind, byte[] clientId, Span span) {
+        RPC.RpcKind kind, byte[] clientId, TraceScope traceScope) {
       this.callId = id;
       this.retryCount = retryCount;
       this.rpcRequest = param;
@@ -604,7 +604,7 @@ public abstract class Server {
       this.rpcResponse = null;
       this.rpcKind = kind;
       this.clientId = clientId;
-      this.traceSpan = span;
+      this.traceScope = traceScope;
     }
     
     @Override
@@ -2014,19 +2014,24 @@ public abstract class Server {
             RpcErrorCodeProto.FATAL_DESERIALIZING_REQUEST, err);
       }
         
-      Span traceSpan = null;
+      TraceScope traceScope = null;
       if (header.hasTraceInfo()) {
-        // If the incoming RPC included tracing info, always continue the trace
+        if (tracer != null) {
-        TraceInfo parentSpan = new TraceInfo(header.getTraceInfo().getTraceId(),
+          // If the incoming RPC included tracing info, always continue the
+          // trace
+          SpanId parentSpanId = new SpanId(
+              header.getTraceInfo().getTraceId(),
               header.getTraceInfo().getParentId());
-        traceSpan = Trace.startSpan(
+          traceScope = tracer.newScope(
               RpcClientUtil.toTraceName(rpcRequest.toString()),
-            parentSpan).detach();
+              parentSpanId);
+          traceScope.detach();
+        }
       }
 
       Call call = new Call(header.getCallId(), header.getRetryCount(),
           rpcRequest, this, ProtoUtil.convert(header.getRpcKind()),
-          header.getClientId().toByteArray(), traceSpan);
+          header.getClientId().toByteArray(), traceScope);
 
       if (callQueue.isClientBackoffEnabled()) {
         // if RPC queue is full, we will ask the RPC client to back off by
@@ -2209,8 +2214,9 @@ public abstract class Server {
           Writable value = null;
 
           CurCall.set(call);
-          if (call.traceSpan != null) {
+          if (call.traceScope != null) {
-            traceScope = Trace.continueSpan(call.traceSpan);
+            call.traceScope.reattach();
+            traceScope = call.traceScope;
             traceScope.getSpan().addTimelineAnnotation("called");
           }
 
@@ -2287,21 +2293,18 @@ public abstract class Server {
         } catch (InterruptedException e) {
           if (running) {                          // unexpected -- log it
             LOG.info(Thread.currentThread().getName() + " unexpectedly interrupted", e);
-            if (Trace.isTracing()) {
+            if (traceScope != null) {
               traceScope.getSpan().addTimelineAnnotation("unexpectedly interrupted: " +
                   StringUtils.stringifyException(e));
             }
           }
         } catch (Exception e) {
           LOG.info(Thread.currentThread().getName() + " caught an exception", e);
-          if (Trace.isTracing()) {
+          if (traceScope != null) {
             traceScope.getSpan().addTimelineAnnotation("Exception: " +
                 StringUtils.stringifyException(e));
           }
         } finally {
-          if (traceScope != null) {
-            traceScope.close();
-          }
           IOUtils.cleanup(LOG, traceScope);
         }
       }
@@ -2615,6 +2618,10 @@ public abstract class Server {
   /** Sets the socket buffer size used for responding to RPCs */
   public void setSocketSendBufSize(int size) { this.socketSendBufferSize = size; }
 
+  public void setTracer(Tracer t) {
+    this.tracer = t;
+  }
+
   /** Starts the service.  Must be called before any calls will be handled. */
   public synchronized void start() {
     responder.start();

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/WritableRpcEngine.java

@@ -42,8 +42,8 @@ import org.apache.hadoop.util.Time;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.*;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 /** An RpcEngine implementation for Writable data. */
 @InterfaceStability.Evolving
@@ -233,9 +233,14 @@ public class WritableRpcEngine implements RpcEngine {
       if (LOG.isDebugEnabled()) {
         startTime = Time.now();
       }
+
+      // if Tracing is on then start a new span for this rpc.
+      // guard it in the if statement to make sure there isn't
+      // any extra string manipulation.
+      Tracer tracer = Tracer.curThreadTracer();
       TraceScope traceScope = null;
-      if (Trace.isTracing()) {
+      if (tracer != null) {
-        traceScope = Trace.startSpan(RpcClientUtil.methodToTraceString(method));
+        traceScope = tracer.newScope(RpcClientUtil.methodToTraceString(method));
       }
       ObjectWritable value;
       try {

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/DNS.java

@@ -18,6 +18,8 @@
 
 package org.apache.hadoop.net;
 
+import com.google.common.net.InetAddresses;
+import com.sun.istack.Nullable;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -27,9 +29,11 @@ import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
 import java.net.UnknownHostException;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Vector;
 
 import javax.naming.NamingException;
@@ -68,7 +72,7 @@ public class DNS {
    * @return The host name associated with the provided IP
    * @throws NamingException If a NamingException is encountered
    */
-  public static String reverseDns(InetAddress hostIp, String ns)
+  public static String reverseDns(InetAddress hostIp, @Nullable String ns)
     throws NamingException {
     //
     // Builds the reverse IP lookup form
@@ -228,29 +232,45 @@ public class DNS {
    *            (e.g. eth0 or eth0:0)
    * @param nameserver
    *            The DNS host name
+   * @param tryfallbackResolution
+   *            if true and if reverse DNS resolution fails then attempt to
+   *            resolve the hostname with
+   *            {@link InetAddress#getCanonicalHostName()} which includes
+   *            hosts file resolution.
    * @return A string vector of all host names associated with the IPs tied to
    *         the specified interface
    * @throws UnknownHostException if the given interface is invalid
    */
-  public static String[] getHosts(String strInterface, String nameserver)
+  public static String[] getHosts(String strInterface,
+                                  @Nullable String nameserver,
+                                  boolean tryfallbackResolution)
       throws UnknownHostException {
-    String[] ips = getIPs(strInterface);
+    final List<String> hosts = new Vector<String>();
-    Vector<String> hosts = new Vector<String>();
+    final List<InetAddress> addresses =
-    for (int ctr = 0; ctr < ips.length; ctr++) {
+        getIPsAsInetAddressList(strInterface, true);
+    for (InetAddress address : addresses) {
       try {
-        hosts.add(reverseDns(InetAddress.getByName(ips[ctr]),
+        hosts.add(reverseDns(address, nameserver));
-                             nameserver));
-      } catch (UnknownHostException ignored) {
       } catch (NamingException ignored) {
       }
     }
-    if (hosts.isEmpty()) {
+    if (hosts.isEmpty() && tryfallbackResolution) {
-      LOG.warn("Unable to determine hostname for interface " + strInterface);
+      for (InetAddress address : addresses) {
-      return new String[] { cachedHostname };
+        final String canonicalHostName = address.getCanonicalHostName();
-    } else {
+        // Don't use the result if it looks like an IP address.
-      return hosts.toArray(new String[hosts.size()]);
+        if (!InetAddresses.isInetAddress(canonicalHostName)) {
+          hosts.add(canonicalHostName);
         }
       }
+    }
+
+    if (hosts.isEmpty()) {
+      LOG.warn("Unable to determine hostname for interface " +
+          strInterface);
+      hosts.add(cachedHostname);
+    }
+    return hosts.toArray(new String[hosts.size()]);
+  }
 
 
   /**
@@ -315,7 +335,7 @@ public class DNS {
    */
   public static String[] getHosts(String strInterface)
     throws UnknownHostException {
-    return getHosts(strInterface, null);
+    return getHosts(strInterface, null, false);
   }
 
   /**
@@ -331,17 +351,19 @@ public class DNS {
    * @throws UnknownHostException
    *             If one is encountered while querying the default interface
    */
-  public static String getDefaultHost(String strInterface, String nameserver)
+  public static String getDefaultHost(@Nullable String strInterface,
+                                      @Nullable String nameserver,
+                                      boolean tryfallbackResolution)
     throws UnknownHostException {
-    if ("default".equals(strInterface)) {
+    if (strInterface == null || "default".equals(strInterface)) {
       return cachedHostname;
     }
 
-    if ("default".equals(nameserver)) {
+    if (nameserver != null && "default".equals(nameserver)) {
-      return getDefaultHost(strInterface);
+      nameserver = null;
     }
 
-    String[] hosts = getHosts(strInterface, nameserver);
+    String[] hosts = getHosts(strInterface, nameserver, tryfallbackResolution);
     return hosts[0];
   }
 
@@ -357,9 +379,74 @@ public class DNS {
    * @throws UnknownHostException
    *             If one is encountered while querying the default interface
    */
-  public static String getDefaultHost(String strInterface)
+  public static String getDefaultHost(@Nullable String strInterface)
     throws UnknownHostException {
-    return getDefaultHost(strInterface, null);
+    return getDefaultHost(strInterface, null, false);
   }
 
+  /**
+   * Returns the default (first) host name associated by the provided
+   * nameserver with the address bound to the specified network interface.
+   *
+   * @param strInterface
+   *            The name of the network interface to query (e.g. eth0)
+   * @param nameserver
+   *            The DNS host name
+   * @throws UnknownHostException
+   *             If one is encountered while querying the default interface
+   */
+  public static String getDefaultHost(@Nullable String strInterface,
+                                      @Nullable String nameserver)
+      throws UnknownHostException {
+    return getDefaultHost(strInterface, nameserver, false);
+  }
+
+  /**
+   * Returns all the IPs associated with the provided interface, if any, as
+   * a list of InetAddress objects.
+   *
+   * @param strInterface
+   *            The name of the network interface or sub-interface to query
+   *            (eg eth0 or eth0:0) or the string "default"
+   * @param returnSubinterfaces
+   *            Whether to return IPs associated with subinterfaces of
+   *            the given interface
+   * @return A list of all the IPs associated with the provided
+   *         interface. The local host IP is returned if the interface
+   *         name "default" is specified or there is an I/O error looking
+   *         for the given interface.
+   * @throws UnknownHostException
+   *             If the given interface is invalid
+   *
+   */
+  public static List<InetAddress> getIPsAsInetAddressList(String strInterface,
+      boolean returnSubinterfaces) throws UnknownHostException {
+    if ("default".equals(strInterface)) {
+      return Arrays.asList(InetAddress.getByName(cachedHostAddress));
+    }
+    NetworkInterface netIf;
+    try {
+      netIf = NetworkInterface.getByName(strInterface);
+      if (netIf == null) {
+        netIf = getSubinterface(strInterface);
+      }
+    } catch (SocketException e) {
+      LOG.warn("I/O error finding interface " + strInterface +
+          ": " + e.getMessage());
+      return Arrays.asList(InetAddress.getByName(cachedHostAddress));
+    }
+    if (netIf == null) {
+      throw new UnknownHostException("No such interface " + strInterface);
+    }
+
+    // NB: Using a LinkedHashSet to preserve the order for callers
+    // that depend on a particular element being 1st in the array.
+    // For example, getDefaultIP always returns the first element.
+    LinkedHashSet<InetAddress> allAddrs = new LinkedHashSet<InetAddress>();
+    allAddrs.addAll(Collections.list(netIf.getInetAddresses()));
+    if (!returnSubinterfaces) {
+      allAddrs.removeAll(getSubinterfaceInetAddrs(netIf));
+    }
+    return new Vector<InetAddress>(allAddrs);
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/SecurityUtil.java

@@ -17,6 +17,8 @@
 package org.apache.hadoop.security;
 
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_AUTHENTICATION;
+import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_DNS_INTERFACE_KEY;
+import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.HADOOP_SECURITY_DNS_NAMESERVER_KEY;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -29,6 +31,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.ServiceLoader;
 
+import javax.annotation.Nullable;
 import javax.security.auth.kerberos.KerberosPrincipal;
 import javax.security.auth.kerberos.KerberosTicket;
 
@@ -39,6 +42,7 @@ import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.net.DNS;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;
 import org.apache.hadoop.security.token.Token;
@@ -180,13 +184,38 @@ public class SecurityUtil {
       throws IOException {
     String fqdn = hostname;
     if (fqdn == null || fqdn.isEmpty() || fqdn.equals("0.0.0.0")) {
-      fqdn = getLocalHostName();
+      fqdn = getLocalHostName(null);
     }
     return components[0] + "/" +
         StringUtils.toLowerCase(fqdn) + "@" + components[2];
   }
 
-  static String getLocalHostName() throws UnknownHostException {
+  /**
+   * Retrieve the name of the current host. Multihomed hosts may restrict the
+   * hostname lookup to a specific interface and nameserver with {@link
+   * org.apache.hadoop.fs.CommonConfigurationKeysPublic#HADOOP_SECURITY_DNS_INTERFACE_KEY}
+   * and {@link org.apache.hadoop.fs.CommonConfigurationKeysPublic#HADOOP_SECURITY_DNS_NAMESERVER_KEY}
+   *
+   * @param conf Configuration object. May be null.
+   * @return
+   * @throws UnknownHostException
+   */
+  static String getLocalHostName(@Nullable Configuration conf)
+      throws UnknownHostException {
+    if (conf != null) {
+      String dnsInterface = conf.get(HADOOP_SECURITY_DNS_INTERFACE_KEY);
+      String nameServer = conf.get(HADOOP_SECURITY_DNS_NAMESERVER_KEY);
+
+      if (dnsInterface != null) {
+        return DNS.getDefaultHost(dnsInterface, nameServer, true);
+      } else if (nameServer != null) {
+        throw new IllegalArgumentException(HADOOP_SECURITY_DNS_NAMESERVER_KEY +
+            " requires " + HADOOP_SECURITY_DNS_INTERFACE_KEY + ". Check your" +
+            "configuration.");
+      }
+    }
+
+    // Fallback to querying the default hostname as we did before.
     return InetAddress.getLocalHost().getCanonicalHostName();
   }
 
@@ -207,7 +236,7 @@ public class SecurityUtil {
   @InterfaceStability.Evolving
   public static void login(final Configuration conf,
       final String keytabFileKey, final String userNameKey) throws IOException {
-    login(conf, keytabFileKey, userNameKey, getLocalHostName());
+    login(conf, keytabFileKey, userNameKey, getLocalHostName(conf));
   }
 
   /**

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/SpanReceiverHost.java

@@ -1,208 +0,0 @@
-/**
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.apache.hadoop.tracing;
-
-import java.io.IOException;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.TreeMap;
-
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-import org.apache.hadoop.classification.InterfaceAudience;
-import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.tracing.SpanReceiverInfo.ConfigurationPair;
-import org.apache.hadoop.util.ShutdownHookManager;
-import org.apache.htrace.SpanReceiver;
-import org.apache.htrace.SpanReceiverBuilder;
-import org.apache.htrace.Trace;
-import org.apache.htrace.impl.LocalFileSpanReceiver;
-
-/**
- * This class provides functions for reading the names of SpanReceivers from
- * the Hadoop configuration, adding those SpanReceivers to the Tracer,
- * and closing those SpanReceivers when appropriate.
- * This class does nothing If no SpanReceiver is configured.
- */
-@InterfaceAudience.Private
-public class SpanReceiverHost implements TraceAdminProtocol {
-  public static final String SPAN_RECEIVERS_CONF_SUFFIX =
-      "spanreceiver.classes";
-  private static final Log LOG = LogFactory.getLog(SpanReceiverHost.class);
-  private static final HashMap<String, SpanReceiverHost> hosts =
-      new HashMap<String, SpanReceiverHost>(1);
-  private final TreeMap<Long, SpanReceiver> receivers =
-      new TreeMap<Long, SpanReceiver>();
-  private final String confPrefix;
-  private Configuration config;
-  private boolean closed = false;
-  private long highestId = 1;
-
-  private final static String LOCAL_FILE_SPAN_RECEIVER_PATH_SUFFIX =
-      "local-file-span-receiver.path";
-
-  public static SpanReceiverHost get(Configuration conf, String confPrefix) {
-    synchronized (SpanReceiverHost.class) {
-      SpanReceiverHost host = hosts.get(confPrefix);
-      if (host != null) {
-        return host;
-      }
-      final SpanReceiverHost newHost = new SpanReceiverHost(confPrefix);
-      newHost.loadSpanReceivers(conf);
-      ShutdownHookManager.get().addShutdownHook(new Runnable() {
-          public void run() {
-            newHost.closeReceivers();
-          }
-        }, 0);
-      hosts.put(confPrefix, newHost);
-      return newHost;
-    }
-  }
-
-  private static List<ConfigurationPair> EMPTY = Collections.emptyList();
-
-  private SpanReceiverHost(String confPrefix) {
-    this.confPrefix = confPrefix;
-  }
-
-  /**
-   * Reads the names of classes specified in the
-   * "hadoop.htrace.spanreceiver.classes" property and instantiates and registers
-   * them with the Tracer as SpanReceiver's.
-   *
-   * The nullary constructor is called during construction, but if the classes
-   * specified implement the Configurable interface, setConfiguration() will be
-   * called on them. This allows SpanReceivers to use values from the Hadoop
-   * configuration.
-   */
-  public synchronized void loadSpanReceivers(Configuration conf) {
-    config = new Configuration(conf);
-    String receiverKey = confPrefix + SPAN_RECEIVERS_CONF_SUFFIX;
-    String[] receiverNames = config.getTrimmedStrings(receiverKey);
-    if (receiverNames == null || receiverNames.length == 0) {
-      if (LOG.isTraceEnabled()) {
-        LOG.trace("No span receiver names found in " + receiverKey + ".");
-      }
-      return;
-    }
-    // It's convenient to have each daemon log to a random trace file when
-    // testing.
-    String pathKey = confPrefix + LOCAL_FILE_SPAN_RECEIVER_PATH_SUFFIX;
-    if (config.get(pathKey) == null) {
-      String uniqueFile = LocalFileSpanReceiver.getUniqueLocalTraceFileName();
-      config.set(pathKey, uniqueFile);
-      if (LOG.isTraceEnabled()) {
-        LOG.trace("Set " + pathKey + " to " + uniqueFile);
-      }
-    }
-    for (String className : receiverNames) {
-      try {
-        SpanReceiver rcvr = loadInstance(className, EMPTY);
-        Trace.addReceiver(rcvr);
-        receivers.put(highestId++, rcvr);
-        LOG.info("Loaded SpanReceiver " + className + " successfully.");
-      } catch (IOException e) {
-        LOG.error("Failed to load SpanReceiver", e);
-      }
-    }
-  }
-
-  private synchronized SpanReceiver loadInstance(String className,
-      List<ConfigurationPair> extraConfig) throws IOException {
-    SpanReceiverBuilder builder =
-        new SpanReceiverBuilder(TraceUtils.
-            wrapHadoopConf(confPrefix, config, extraConfig));
-    SpanReceiver rcvr = builder.spanReceiverClass(className.trim()).build();
-    if (rcvr == null) {
-      throw new IOException("Failed to load SpanReceiver " + className);
-    }
-    return rcvr;
-  }
-
-  /**
-   * Calls close() on all SpanReceivers created by this SpanReceiverHost.
-   */
-  public synchronized void closeReceivers() {
-    if (closed) return;
-    closed = true;
-    for (SpanReceiver rcvr : receivers.values()) {
-      try {
-        rcvr.close();
-      } catch (IOException e) {
-        LOG.warn("Unable to close SpanReceiver correctly: " + e.getMessage(), e);
-      }
-    }
-    receivers.clear();
-  }
-
-  public synchronized SpanReceiverInfo[] listSpanReceivers()
-      throws IOException {
-    SpanReceiverInfo[] info = new SpanReceiverInfo[receivers.size()];
-    int i = 0;
-
-    for(Map.Entry<Long, SpanReceiver> entry : receivers.entrySet()) {
-      info[i] = new SpanReceiverInfo(entry.getKey(),
-          entry.getValue().getClass().getName());
-      i++;
-    }
-    return info;
-  }
-
-  public synchronized long addSpanReceiver(SpanReceiverInfo info)
-      throws IOException {
-    StringBuilder configStringBuilder = new StringBuilder();
-    String prefix = "";
-    for (ConfigurationPair pair : info.configPairs) {
-      configStringBuilder.append(prefix).append(pair.getKey()).
-          append(" = ").append(pair.getValue());
-      prefix = ", ";
-    }
-    SpanReceiver rcvr = null;
-    try {
-      rcvr = loadInstance(info.getClassName(), info.configPairs);
-    } catch (IOException e) {
-      LOG.info("Failed to add SpanReceiver " + info.getClassName() +
-          " with configuration " + configStringBuilder.toString(), e);
-      throw e;
-    } catch (RuntimeException e) {
-      LOG.info("Failed to add SpanReceiver " + info.getClassName() +
-          " with configuration " + configStringBuilder.toString(), e);
-      throw e;
-    }
-    Trace.addReceiver(rcvr);
-    long newId = highestId++;
-    receivers.put(newId, rcvr);
-    LOG.info("Successfully added SpanReceiver " + info.getClassName() +
-        " with configuration " + configStringBuilder.toString());
-    return newId;
-  }
-
-  public synchronized void removeSpanReceiver(long spanReceiverId)
-      throws IOException {
-    SpanReceiver rcvr = receivers.remove(spanReceiverId);
-    if (rcvr == null) {
-      throw new IOException("There is no span receiver with id " + spanReceiverId);
-    }
-    Trace.removeReceiver(rcvr);
-    rcvr.close();
-    LOG.info("Successfully removed SpanReceiver " + spanReceiverId +
-        " with class " + rcvr.getClass().getName());
-  }
-}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/TraceUtils.java

@@ -24,7 +24,7 @@ import java.util.List;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.tracing.SpanReceiverInfo.ConfigurationPair;
-import org.apache.htrace.HTraceConfiguration;
+import org.apache.htrace.core.HTraceConfiguration;
 
 /**
  * This class provides utility functions for tracing.
@@ -32,6 +32,7 @@ import org.apache.htrace.HTraceConfiguration;
 @InterfaceAudience.Private
 public class TraceUtils {
   private static List<ConfigurationPair> EMPTY = Collections.emptyList();
+  static final String DEFAULT_HADOOP_PREFIX = "hadoop.htrace.";
 
   public static HTraceConfiguration wrapHadoopConf(final String prefix,
         final Configuration conf) {
@@ -47,16 +48,27 @@ public class TraceUtils {
     return new HTraceConfiguration() {
       @Override
       public String get(String key) {
-        return get(key, "");
+        String ret = getInternal(prefix + key);
+        if (ret != null) {
+          return ret;
+        }
+        return getInternal(DEFAULT_HADOOP_PREFIX  + key);
       }
 
       @Override
       public String get(String key, String defaultValue) {
-        String prefixedKey = prefix + key;
+        String ret = get(key);
-        if (extraMap.containsKey(prefixedKey)) {
+        if (ret != null) {
-          return extraMap.get(prefixedKey);
+          return ret;
         }
-        return conf.get(prefixedKey, defaultValue);
+        return defaultValue;
+      }
+
+      private String getInternal(String key) {
+        if (extraMap.containsKey(key)) {
+          return extraMap.get(key);
+        }
+        return conf.get(key);
       }
     };
   }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/tracing/TracerConfigurationManager.java

@@ -0,0 +1,100 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.tracing;
+
+import java.io.IOException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.tracing.SpanReceiverInfo.ConfigurationPair;
+import org.apache.htrace.core.SpanReceiver;
+import org.apache.htrace.core.TracerPool;
+
+/**
+ * This class provides functions for managing the tracer configuration at
+ * runtime via an RPC protocol.
+ */
+@InterfaceAudience.Private
+public class TracerConfigurationManager implements TraceAdminProtocol {
+  private static final Log LOG =
+      LogFactory.getLog(TracerConfigurationManager.class);
+
+  private final String confPrefix;
+  private final Configuration conf;
+
+  public TracerConfigurationManager(String confPrefix, Configuration conf) {
+    this.confPrefix = confPrefix;
+    this.conf = conf;
+  }
+
+  public synchronized SpanReceiverInfo[] listSpanReceivers()
+      throws IOException {
+    TracerPool pool = TracerPool.getGlobalTracerPool();
+    SpanReceiver[] receivers = pool.getReceivers();
+    SpanReceiverInfo[] info = new SpanReceiverInfo[receivers.length];
+    for (int i = 0; i < receivers.length; i++) {
+      SpanReceiver receiver = receivers[i];
+      info[i] = new SpanReceiverInfo(receiver.getId(),
+          receiver.getClass().getName());
+    }
+    return info;
+  }
+
+  public synchronized long addSpanReceiver(SpanReceiverInfo info)
+      throws IOException {
+    StringBuilder configStringBuilder = new StringBuilder();
+    String prefix = "";
+    for (ConfigurationPair pair : info.configPairs) {
+      configStringBuilder.append(prefix).append(pair.getKey()).
+          append(" = ").append(pair.getValue());
+      prefix = ", ";
+    }
+    SpanReceiver rcvr = null;
+    try {
+      rcvr = new SpanReceiver.Builder(TraceUtils.wrapHadoopConf(
+              confPrefix, conf, info.configPairs)).
+          className(info.getClassName().trim()).
+          build();
+    } catch (RuntimeException e) {
+      LOG.info("Failed to add SpanReceiver " + info.getClassName() +
+          " with configuration " + configStringBuilder.toString(), e);
+      throw e;
+    }
+    TracerPool.getGlobalTracerPool().addReceiver(rcvr);
+    LOG.info("Successfully added SpanReceiver " + info.getClassName() +
+        " with configuration " + configStringBuilder.toString());
+    return rcvr.getId();
+  }
+
+  public synchronized void removeSpanReceiver(long spanReceiverId)
+      throws IOException {
+    SpanReceiver[] receivers =
+        TracerPool.getGlobalTracerPool().getReceivers();
+    for (SpanReceiver receiver : receivers) {
+      if (receiver.getId() == spanReceiverId) {
+        TracerPool.getGlobalTracerPool().removeAndCloseReceiver(receiver);
+        LOG.info("Successfully removed SpanReceiver " + spanReceiverId +
+            " with class " + receiver.getClass().getName());
+        return;
+      }
+    }
+    throw new IOException("There is no span receiver with id " + spanReceiverId);
+  }
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/ProtoUtil.java

@@ -27,8 +27,8 @@ import org.apache.hadoop.ipc.protobuf.IpcConnectionContextProtos.UserInformation
 import org.apache.hadoop.ipc.protobuf.RpcHeaderProtos.*;
 import org.apache.hadoop.security.SaslRpcServer.AuthMethod;
 import org.apache.hadoop.security.UserGroupInformation;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.Span;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
 
 import com.google.protobuf.ByteString;
 
@@ -169,11 +169,12 @@ public abstract class ProtoUtil {
         .setRetryCount(retryCount).setClientId(ByteString.copyFrom(uuid));
 
     // Add tracing info if we are currently tracing.
-    if (Trace.isTracing()) {
+    Span span = Tracer.getCurrentSpan();
-      Span s = Trace.currentSpan();
+    if (span != null) {
       result.setTraceInfo(RPCTraceInfoProto.newBuilder()
-          .setParentId(s.getSpanId())
+          .setTraceId(span.getSpanId().getHigh())
-          .setTraceId(s.getTraceId()).build());
+          .setParentId(span.getSpanId().getLow())
+            .build());
     }
 
     return result.build();

hadoop-common-project/hadoop-common/src/main/proto/RpcHeader.proto

@@ -61,8 +61,9 @@ enum RpcKindProto {
  * what span caused the new span we will create when this message is received.
  */
 message RPCTraceInfoProto {
-  optional int64 traceId = 1;
+    optional int64 traceId = 1; // parentIdHigh
-  optional int64 parentId = 2;
+    optional int64 parentId = 2; // parentIdLow
+
 }
 
 message RpcRequestHeaderProto { // the header for the RpcRequest

hadoop-common-project/hadoop-common/src/main/resources/core-default.xml

@@ -88,6 +88,31 @@
   </description>
 </property>
 
+<property>
+  <name>hadoop.security.dns.interface</name>
+  <description>
+    The name of the Network Interface from which the service should determine
+    its host name for Kerberos login. e.g. eth2. In a multi-homed environment,
+    the setting can be used to affect the _HOST subsitution in the service
+    Kerberos principal. If this configuration value is not set, the service
+    will use its default hostname as returned by
+    InetAddress.getLocalHost().getCanonicalHostName().
+
+    Most clusters will not require this setting.
+  </description>
+</property>
+
+<property>
+  <name>hadoop.security.dns.nameserver</name>
+  <description>
+    The host name or IP address of the name server (DNS) which a service Node
+    should use to determine its own host name for Kerberos Login. Requires
+    hadoop.security.dns.interface.
+
+    Most clusters will not require this setting.
+  </description>
+</property>
+
 <!-- 
 === Multiple group mapping providers configuration sample === 
   This sample illustrates a typical use case for CompositeGroupsMapping where
@@ -1973,4 +1998,19 @@ for ldap providers in the same way as above does.
       the limit is 0 or the -safely is not specified in -rm command.
     </description>
   </property>
+
+  <property>
+    <name>fs.client.htrace.sampler.classes</name>
+    <value></value>
+    <description>The class names of the HTrace Samplers to use for Hadoop
+      filesystem clients.
+    </description>
+  </property>
+
+  <property>
+    <name>hadoop.htrace.span.receiver.classes</name>
+    <value></value>
+    <description>The class names of the Span Receivers to use for Hadoop.
+    </description>
+  </property>
 </configuration>

hadoop-common-project/hadoop-common/src/site/markdown/Metrics.md

@@ -192,7 +192,6 @@ Each metrics record contains tags such as ProcessName, SessionId, and Hostname a
 | `PutImageNumOps` | Total number of fsimage uploads to SecondaryNameNode |
 | `PutImageAvgTime` | Average fsimage upload time in milliseconds |
 | `TotalFileOps`| Total number of file operations performed |
-| `NNStarted`| NameNode start time |
 | `NNStartedTimeInMillis`| NameNode start time in milliseconds |
 
 FSNamesystem

hadoop-common-project/hadoop-common/src/site/markdown/Tracing.md

@@ -49,37 +49,14 @@ interface bundled with HTrace or implementing it by yourself.
 * HTracedRESTReceiver
 * ZipkinSpanReceiver
 
-In order to set up SpanReceivers for HDFS servers,
+See core-default.xml for a description of HTrace configuration keys.  In some
-configure what SpanReceivers you'd like to use
+cases, you will also need to add the jar containing the SpanReceiver that you
-by putting a comma separated list of the fully-qualified class name of classes implementing SpanReceiver
+are using to the classpath of Hadoop on each node. (In the example above,
-in `hdfs-site.xml` property: `dfs.htrace.spanreceiver.classes`.
+LocalFileSpanReceiver is included in the htrace-core4 jar which is bundled
-
+with Hadoop.)
-```xml
-      <property>
-        <name>dfs.htrace.spanreceiver.classes</name>
-        <value>org.apache.htrace.impl.LocalFileSpanReceiver</value>
-      </property>
-      <property>
-        <name>dfs.htrace.local-file-span-receiver.path</name>
-        <value>/var/log/hadoop/htrace.out</value>
-      </property>
-```
-
-You can omit package name prefix if you use span receiver bundled with HTrace.
-
-```xml
-      <property>
-        <name>dfs.htrace.spanreceiver.classes</name>
-        <value>LocalFileSpanReceiver</value>
-      </property>
-```
-
-You also need to add the jar bundling SpanReceiver to the classpath of Hadoop
-on each node. (LocalFileSpanReceiver in the example above is included in the
-jar of htrace-core which is bundled with Hadoop.)
 
 ```
-    $ cp htrace-htraced/target/htrace-htraced-3.2.0-incubating.jar $HADOOP_HOME/share/hadoop/common/lib/
+    $ cp htrace-htraced/target/htrace-htraced-4.0.1-incubating.jar $HADOOP_HOME/share/hadoop/common/lib/
 ```
 
 ### Dynamic update of tracing configuration
@@ -92,11 +69,11 @@ You need to run the command against all servers if you want to update the config
 
       $ hadoop trace -list -host 192.168.56.2:9000
       ID  CLASS
-      1   org.apache.htrace.impl.LocalFileSpanReceiver
+      1   org.apache.htrace.core.LocalFileSpanReceiver
 
       $ hadoop trace -list -host 192.168.56.2:50020
       ID  CLASS
-      1   org.apache.htrace.impl.LocalFileSpanReceiver
+      1   org.apache.htrace.core.LocalFileSpanReceiver
 
 `hadoop trace -remove` removes span receiver from server.
 `-remove` options takes id of span receiver as argument.
@@ -113,7 +90,7 @@ You can specify the configuration associated with span receiver by `-Ckey=value`
 
       $ hadoop trace -list -host 192.168.56.2:9000
       ID  CLASS
-      2   org.apache.htrace.impl.LocalFileSpanReceiver
+      2   org.apache.htrace.core.LocalFileSpanReceiver
 
 ### Starting tracing spans by HTrace API
 
@@ -121,26 +98,21 @@ In order to trace, you will need to wrap the traced logic with **tracing span**
 When there is running tracing spans,
 the tracing information is propagated to servers along with RPC requests.
 
-In addition, you need to initialize `SpanReceiverHost` once per process.
-
 ```java
     import org.apache.hadoop.hdfs.HdfsConfiguration;
-    import org.apache.hadoop.tracing.SpanReceiverHost;
+    import org.apache.htrace.core.Tracer;
-    import org.apache.htrace.Sampler;
+    import org.apache.htrace.core.TraceScope;
-    import org.apache.htrace.Trace;
-    import org.apache.htrace.TraceScope;
 
     ...
 
-        SpanReceiverHost.getInstance(new HdfsConfiguration());
 
     ...
 
-        TraceScope ts = Trace.startSpan("Gets", Sampler.ALWAYS);
+        TraceScope ts = tracer.newScope("Gets");
         try {
           ... // traced logic
         } finally {
-          if (ts != null) ts.close();
+          ts.close();
         }
 ```
 
@@ -154,11 +126,10 @@ which start tracing span before invoking HDFS shell command.
     import org.apache.hadoop.fs.FsShell;
     import org.apache.hadoop.hdfs.DFSConfigKeys;
     import org.apache.hadoop.hdfs.HdfsConfiguration;
-    import org.apache.hadoop.tracing.SpanReceiverHost;
+    import org.apache.hadoop.tracing.TraceUtils;
     import org.apache.hadoop.util.ToolRunner;
-    import org.apache.htrace.Sampler;
+    import org.apache.htrace.core.Trace;
-    import org.apache.htrace.Trace;
+    import org.apache.htrace.core.TraceScope;
-    import org.apache.htrace.TraceScope;
 
     public class TracingFsShell {
       public static void main(String argv[]) throws Exception {
@@ -166,13 +137,19 @@ which start tracing span before invoking HDFS shell command.
         FsShell shell = new FsShell();
         conf.setQuietMode(false);
         shell.setConf(conf);
-        SpanReceiverHost.get(conf, DFSConfigKeys.DFS_SERVER_HTRACE_PREFIX);
+        Tracer tracer = new Tracer.Builder().
+            name("TracingFsShell).
+            conf(TraceUtils.wrapHadoopConf("tracing.fs.shell.htrace.", conf)).
+            build();
         int res = 0;
-        try (TraceScope ts = Trace.startSpan("FsShell", Sampler.ALWAYS)) {
+        TraceScope scope = tracer.newScope("FsShell");
+        try {
           res = ToolRunner.run(shell, argv);
         } finally {
+          scope.close();
           shell.close();
         }
+        tracer.close();
         System.exit(res);
       }
     }
@@ -189,16 +166,15 @@ The DFSClient can enable tracing internally. This allows you to use HTrace with
 your client without modifying the client source code.
 
 Configure the span receivers and samplers in `hdfs-site.xml`
-by properties `dfs.client.htrace.sampler` and `dfs.client.htrace.sampler`.
+by properties `fs.client.htrace.sampler.classes` and
-The value of `dfs.client.htrace.sampler` can be NeverSampler, AlwaysSampler or ProbabilitySampler.
+`fs.client.htrace.spanreceiver.classes`.  The value of
+`fs.client.htrace.sampler.classes` can be NeverSampler, AlwaysSampler or
+ProbabilitySampler.
 
 * NeverSampler: HTrace is OFF for all requests to namenodes and datanodes;
 * AlwaysSampler: HTrace is ON for all requests to namenodes and datanodes;
 * ProbabilitySampler: HTrace is ON for some percentage% of  requests to namenodes and datanodes
 
-You do not need to enable this if your client program has been modified
-to use HTrace.
-
 ```xml
       <property>
         <name>dfs.client.htrace.spanreceiver.classes</name>

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/conf/TestConfiguration.java

@@ -1493,7 +1493,7 @@ public class TestConfiguration extends TestCase {
 
       @Override
       public void run() {
-        for (int i = 0; i < 100000; i++) {
+        for (int i = 0; i < 10000; i++) {
           config.set("some.config.value-" + prefix + i, "value");
         }
       }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestFsShell.java

@@ -17,13 +17,16 @@
  */
 package org.apache.hadoop.fs;
 
+import java.io.ByteArrayOutputStream;
+import java.io.PrintStream;
+
 import junit.framework.AssertionFailedError;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.tracing.SetSpanReceiver;
-import org.apache.hadoop.tracing.SpanReceiverHost;
 import org.apache.hadoop.util.ToolRunner;
-import org.apache.htrace.SamplerBuilder;
+import org.apache.htrace.core.AlwaysSampler;
-import org.apache.htrace.impl.AlwaysSampler;
+import org.apache.htrace.core.Tracer;
 import org.junit.Assert;
 import org.junit.Test;
 
@@ -49,10 +52,10 @@ public class TestFsShell {
   @Test
   public void testTracing() throws Throwable {
     Configuration conf = new Configuration();
-    String prefix = FsShell.SEHLL_HTRACE_PREFIX;
+    String prefix = "fs.shell.htrace.";
-    conf.set(prefix + SpanReceiverHost.SPAN_RECEIVERS_CONF_SUFFIX,
+    conf.set(prefix + Tracer.SPAN_RECEIVER_CLASSES_KEY,
         SetSpanReceiver.class.getName());
-    conf.set(prefix + SamplerBuilder.SAMPLER_CONF_KEY,
+    conf.set(prefix + Tracer.SAMPLER_CLASSES_KEY,
         AlwaysSampler.class.getName());
     conf.setQuietMode(false);
     FsShell shell = new FsShell(conf);
@@ -67,4 +70,33 @@ public class TestFsShell {
         SetSpanReceiver.getMap()
             .get("help").get(0).getKVAnnotations().get("args"));
   }
+
+  @Test
+  public void testDFSWithInvalidCommmand() throws Throwable {
+    Configuration conf = new Configuration();
+    FsShell shell = new FsShell(conf);
+    String[] args = new String[1];
+    args[0] = "dfs -mkdirs";
+    final ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+    final PrintStream out = new PrintStream(bytes);
+    final PrintStream oldErr = System.err;
+    try {
+      System.setErr(out);
+      ToolRunner.run(shell, args);
+      String errorValue=new String(bytes.toString());
+      Assert
+      .assertTrue(
+          "FSShell dfs command did not print the error " +
+          "message when invalid command is passed",
+          errorValue.contains("-mkdirs: Unknown command"));
+      Assert
+          .assertTrue(
+              "FSShell dfs command did not print help " +
+              "message when invalid command is passed",
+          errorValue.contains("Usage: hadoop fs [generic options]"));
+    } finally {
+      IOUtils.closeStream(out);
+      System.setErr(oldErr);
+    }
+  }
 }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestHarFileSystem.java

@@ -55,7 +55,6 @@ public class TestHarFileSystem {
    * {@link HarFileSystem}. Either because there is a default implementation
    * already available or because it is not relevant.
    */
-  @SuppressWarnings("deprecation")
   private interface MustNotImplement {
     public BlockLocation[] getFileBlockLocations(Path p, long start, long len);
     public long getLength(Path f);

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestLocalDirAllocator.java

@@ -26,6 +26,7 @@ import java.util.Iterator;
 import java.util.NoSuchElementException;
 
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.util.DiskChecker.DiskErrorException;
 import org.apache.hadoop.util.Shell;
 
 import org.junit.runner.RunWith;
@@ -312,7 +313,30 @@ public class TestLocalDirAllocator {
     } catch (IOException e) {
       assertEquals(CONTEXT + " not configured", e.getMessage());
     } catch (NullPointerException e) {
-      fail("Lack of configuration should not have thrown an NPE.");
+      fail("Lack of configuration should not have thrown a NPE.");
+    }
+
+    String  NEW_CONTEXT = CONTEXT + ".new";
+    conf1.set(NEW_CONTEXT, "");
+    LocalDirAllocator newDirAllocator = new LocalDirAllocator(NEW_CONTEXT);
+    try {
+      newDirAllocator.getLocalPathForWrite("/test", conf1);
+      fail("Exception not thrown when " + NEW_CONTEXT +
+          " is set to empty string");
+    } catch (IOException e) {
+      assertTrue(e instanceof DiskErrorException);
+    } catch (NullPointerException e) {
+      fail("Wrong configuration should not have thrown a NPE.");
+    }
+
+    try {
+      newDirAllocator.getLocalPathToRead("/test", conf1);
+      fail("Exception not thrown when " + NEW_CONTEXT +
+          " is set to empty string");
+    } catch (IOException e) {
+      assertTrue(e instanceof DiskErrorException);
+    } catch (NullPointerException e) {
+      fail("Wrong configuration should not have thrown a NPE.");
     }
   }
 

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/TestLocalFileSystem.java

@@ -72,6 +72,7 @@ public class TestLocalFileSystem {
     FileUtil.setWritable(base, true);
     FileUtil.fullyDelete(base);
     assertTrue(!base.exists());
+    RawLocalFileSystem.useStatIfAvailable();
   }
 
   /**

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/contract/AbstractContractRootDirectoryTest.java

@@ -25,6 +25,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import org.apache.hadoop.fs.FileStatus;
 
 import static org.apache.hadoop.fs.contract.ContractTestUtils.createFile;
 import static org.apache.hadoop.fs.contract.ContractTestUtils.dataset;
@@ -120,4 +121,17 @@ public abstract class AbstractContractRootDirectoryTest extends AbstractFSContra
     assertIsDirectory(root);
   }
 
+  @Test
+  public void testListEmptyRootDirectory() throws IOException {
+    //extra sanity checks here to avoid support calls about complete loss of data
+    skipIfUnsupported(TEST_ROOT_TESTS_ENABLED);
+    FileSystem fs = getFileSystem();
+    Path root = new Path("/");
+    FileStatus[] statuses = fs.listStatus(root);
+    for (FileStatus status : statuses) {
+      ContractTestUtils.assertDeleted(fs, status.getPath(), true);
+    }
+    assertEquals("listStatus on empty root-directory returned a non-empty list",
+        0, fs.listStatus(root).length);
+  }
 }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ha/ClientBaseWithFixes.java

@@ -23,10 +23,7 @@ import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
-import java.io.RandomAccessFile;
 import java.net.Socket;
-import java.nio.channels.FileLock;
-import java.nio.channels.OverlappingFileLockException;
 import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
@@ -34,8 +31,8 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
+import org.apache.hadoop.net.ServerSocketUtil;
 import org.apache.hadoop.util.Time;
-import org.apache.zookeeper.PortAssignment;
 import org.apache.zookeeper.TestableZooKeeper;
 import org.apache.zookeeper.WatchedEvent;
 import org.apache.zookeeper.Watcher;
@@ -167,10 +164,6 @@ public abstract class ClientBaseWithFixes extends ZKTestCase {
     private LinkedList<ZooKeeper> allClients;
     private boolean allClientsSetup = false;
 
-    private RandomAccessFile portNumLockFile;
-
-    private File portNumFile;
-
     protected TestableZooKeeper createClient(CountdownWatcher watcher, String hp)
         throws IOException, InterruptedException
     {
@@ -413,30 +406,12 @@ public abstract class ClientBaseWithFixes extends ZKTestCase {
 
     private String initHostPort() {
         BASETEST.mkdirs();
-        int port;
+        int port = 0;
-        for (;;) {
-            port = PortAssignment.unique();
-            FileLock lock = null;
-            portNumLockFile = null;
         try {
-                try {
+           port = ServerSocketUtil.getPort(port, 100);
-                    portNumFile = new File(BASETEST, port + ".lock");
-                    portNumLockFile = new RandomAccessFile(portNumFile, "rw");
-                    try {
-                        lock = portNumLockFile.getChannel().tryLock();
-                    } catch (OverlappingFileLockException e) {
-                        continue;
-                    }
-                } finally {
-                    if (lock != null)
-                        break;
-                    if (portNumLockFile != null)
-                        portNumLockFile.close();
-                }
         } catch (IOException e) {
            throw new RuntimeException(e);
         }
-        }
         return "127.0.0.1:" + port;
     }
 
@@ -480,9 +455,6 @@ public abstract class ClientBaseWithFixes extends ZKTestCase {
 
         stopServer();
 
-        portNumLockFile.close();
-        portNumFile.delete();
-        
         if (tmpDir != null) {
             Assert.assertTrue("delete " + tmpDir.toString(), recursiveDelete(tmpDir));
         }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/http/TestAuthenticationSessionCookie.java

@@ -113,10 +113,7 @@ public class TestAuthenticationSessionCookie {
     sslConfDir = KeyStoreTestUtil.getClasspathDir(TestSSLHttpServer.class);
 
     KeyStoreTestUtil.setupSSLConfig(keystoresDir, sslConfDir, conf, false);
-    Configuration sslConf = new Configuration(false);
+    Configuration sslConf = KeyStoreTestUtil.getSslConfig();
-    sslConf.addResource("ssl-server.xml");
-    sslConf.addResource("ssl-client.xml");
-
 
     server = new HttpServer2.Builder()
             .setName("test")

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/http/TestHttpCookieFlag.java

@@ -17,7 +17,6 @@ import org.junit.Assert;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.net.NetUtils;
-import org.apache.hadoop.security.authentication.client.AuthenticatedURL;
 import org.apache.hadoop.security.authentication.server.AuthenticationFilter;
 import org.apache.hadoop.security.ssl.KeyStoreTestUtil;
 import org.apache.hadoop.security.ssl.SSLFactory;
@@ -27,12 +26,10 @@ import org.junit.Test;
 
 import javax.net.ssl.HttpsURLConnection;
 import javax.servlet.*;
-import javax.servlet.http.Cookie;
 import javax.servlet.http.HttpServletResponse;
 import java.io.File;
 import java.io.IOException;
 import java.net.HttpURLConnection;
-import java.net.MalformedURLException;
 import java.net.URI;
 import java.net.URL;
 import java.security.GeneralSecurityException;
@@ -89,9 +86,7 @@ public class TestHttpCookieFlag {
     sslConfDir = KeyStoreTestUtil.getClasspathDir(TestSSLHttpServer.class);
 
     KeyStoreTestUtil.setupSSLConfig(keystoresDir, sslConfDir, conf, false);
-    Configuration sslConf = new Configuration(false);
+    Configuration sslConf = KeyStoreTestUtil.getSslConfig();
-    sslConf.addResource("ssl-server.xml");
-    sslConf.addResource("ssl-client.xml");
 
     clientSslFactory = new SSLFactory(SSLFactory.Mode.CLIENT, sslConf);
     clientSslFactory.init();

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/http/TestSSLHttpServer.java

@@ -65,9 +65,7 @@ public class TestSSLHttpServer extends HttpServerFunctionalTest {
     sslConfDir = KeyStoreTestUtil.getClasspathDir(TestSSLHttpServer.class);
 
     KeyStoreTestUtil.setupSSLConfig(keystoresDir, sslConfDir, conf, false);
-    Configuration sslConf = new Configuration(false);
+    Configuration sslConf = KeyStoreTestUtil.getSslConfig();
-    sslConf.addResource("ssl-server.xml");
-    sslConf.addResource("ssl-client.xml");
 
     clientSslFactory = new SSLFactory(SSLFactory.Mode.CLIENT, sslConf);
     clientSslFactory.init();

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/TestRPC.java

@@ -1060,8 +1060,8 @@ public class TestRPC {
             }));
       }
       while (server.getCallQueueLen() != 1
-          && countThreads(CallQueueManager.class.getName()) != 1
+          || countThreads(CallQueueManager.class.getName()) != 1
-          && countThreads(TestProtocol.class.getName()) != 1) {
+          || countThreads(TestImpl.class.getName()) != 1) {
         Thread.sleep(100);
       }
     } finally {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/net/ServerSocketUtil.java

@@ -28,6 +28,7 @@ import org.apache.commons.logging.LogFactory;
 public class ServerSocketUtil {
 
   private static final Log LOG = LogFactory.getLog(ServerSocketUtil.class);
+  private static Random rand = new Random();
 
   /**
    * Port scan & allocate is how most other apps find ports
@@ -38,13 +39,15 @@ public class ServerSocketUtil {
    * @throws IOException
    */
   public static int getPort(int port, int retries) throws IOException {
-    Random rand = new Random();
     int tryPort = port;
     int tries = 0;
     while (true) {
-      if (tries > 0) {
+      if (tries > 0 || tryPort == 0) {
         tryPort = port + rand.nextInt(65535 - port);
       }
+      if (tryPort == 0) {
+        continue;
+      }
       LOG.info("Using port " + tryPort);
       try (ServerSocket s = new ServerSocket(tryPort)) {
         return tryPort;

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/net/TestDNS.java

@@ -18,6 +18,10 @@
 
 package org.apache.hadoop.net;
 
+import java.lang.reflect.Field;
+import java.lang.reflect.Modifier;
+import java.net.NetworkInterface;
+import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.net.InetAddress;
 
@@ -28,6 +32,9 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.util.Time;
 
 import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.*;
 
 /**
@@ -38,6 +45,11 @@ public class TestDNS {
   private static final Log LOG = LogFactory.getLog(TestDNS.class);
   private static final String DEFAULT = "default";
 
+  // This is not a legal hostname (starts with a hyphen). It will never
+  // be returned on any test machine.
+  private static final String DUMMY_HOSTNAME = "-DUMMY_HOSTNAME";
+  private static final String INVALID_DNS_SERVER = "0.0.0.0";
+
   /**
    * Test that asking for the default hostname works
    * @throws Exception if hostname lookups fail
@@ -89,12 +101,8 @@ public class TestDNS {
    */
   @Test
   public void testNullInterface() throws Exception {
-    try {
+    String host = DNS.getDefaultHost(null);  // should work.
-      String host = DNS.getDefaultHost(null);
+    assertThat(host, is(DNS.getDefaultHost(DEFAULT)));
-      fail("Expected a NullPointerException, got " + host);
-    } catch (NullPointerException npe) {
-      // Expected
-    }
     try {
       String ip = DNS.getDefaultIP(null);
       fail("Expected a NullPointerException, got " + ip);
@@ -103,6 +111,26 @@ public class TestDNS {
     }
   }
 
+  /**
+   * Test that 'null' DNS server gives the same result as if no DNS
+   * server was passed.
+   */
+  @Test
+  public void testNullDnsServer() throws Exception {
+    String host = DNS.getDefaultHost(getLoopbackInterface(), null);
+    assertThat(host, is(DNS.getDefaultHost(getLoopbackInterface())));
+  }
+
+  /**
+   * Test that "default" DNS server gives the same result as if no DNS
+   * server was passed.
+   */
+  @Test
+  public void testDefaultDnsServer() throws Exception {
+    String host = DNS.getDefaultHost(getLoopbackInterface(), DEFAULT);
+    assertThat(host, is(DNS.getDefaultHost(getLoopbackInterface())));
+  }
+
   /**
    * Get the IP addresses of an unknown interface
    */
@@ -147,10 +175,80 @@ public class TestDNS {
                 + " Loopback=" + localhost.isLoopbackAddress()
                 + " Linklocal=" + localhost.isLinkLocalAddress());
       }
-
     }
   }
 
+  /**
+   * Test that when using an invalid DNS server with hosts file fallback,
+   * we are able to get the hostname from the hosts file.
+   *
+   * This test may fail on some misconfigured test machines that don't have
+   * an entry for "localhost" in their hosts file. This entry is correctly
+   * configured out of the box on common Linux distributions, OS X and
+   * Windows.
+   *
+   * @throws Exception
+   */
+  @Test (timeout=60000)
+  public void testLookupWithHostsFallback() throws Exception {
+    final String oldHostname = changeDnsCachedHostname(DUMMY_HOSTNAME);
+
+    try {
+      String hostname = DNS.getDefaultHost(
+          getLoopbackInterface(), INVALID_DNS_SERVER, true);
+
+      // Expect to get back something other than the cached host name.
+      assertThat(hostname, not(DUMMY_HOSTNAME));
+    } finally {
+      // Restore DNS#cachedHostname for subsequent tests.
+      changeDnsCachedHostname(oldHostname);
+    }
+  }
+
+  /**
+   * Test that when using an invalid DNS server without hosts file
+   * fallback, we get back the cached host name.
+   *
+   * @throws Exception
+   */
+  @Test(timeout=60000)
+  public void testLookupWithoutHostsFallback() throws Exception {
+    final String oldHostname = changeDnsCachedHostname(DUMMY_HOSTNAME);
+
+    try {
+      String hostname = DNS.getDefaultHost(
+          getLoopbackInterface(), INVALID_DNS_SERVER, false);
+
+      // Expect to get back the cached host name since there was no hosts
+      // file lookup.
+      assertThat(hostname, is(DUMMY_HOSTNAME));
+    } finally {
+      // Restore DNS#cachedHostname for subsequent tests.
+      changeDnsCachedHostname(oldHostname);
+    }
+  }
+
+  private String getLoopbackInterface() throws SocketException {
+    return NetworkInterface.getByInetAddress(
+        InetAddress.getLoopbackAddress()).getDisplayName();
+  }
+
+  /**
+   * Change DNS#cachedHostName to something which cannot be a real
+   * host name. Uses reflection since it is a 'private final' field.
+   */
+  private String changeDnsCachedHostname(final String newHostname)
+      throws Exception {
+    final String oldCachedHostname = DNS.getDefaultHost(DEFAULT);
+    Field field = DNS.class.getDeclaredField("cachedHostname");
+    field.setAccessible(true);
+    Field modifiersField = Field.class.getDeclaredField("modifiers");
+    modifiersField.setAccessible(true);
+    modifiersField.set(field, field.getModifiers() & ~Modifier.FINAL);
+    field.set(null, newHostname);
+    return oldCachedHostname;
+  }
+
   /**
    * Test that the name "localhost" resolves to something.
    *

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/TestSecurityUtil.java

@@ -111,7 +111,7 @@ public class TestSecurityUtil {
 
   @Test
   public void testLocalHostNameForNullOrWild() throws Exception {
-    String local = StringUtils.toLowerCase(SecurityUtil.getLocalHostName());
+    String local = StringUtils.toLowerCase(SecurityUtil.getLocalHostName(null));
     assertEquals("hdfs/" + local + "@REALM",
                  SecurityUtil.getServerPrincipal("hdfs/_HOST@REALM", (String)null));
     assertEquals("hdfs/" + local + "@REALM",

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/security/ssl/KeyStoreTestUtil.java

@@ -37,7 +37,6 @@ import java.security.KeyPair;
 import java.security.KeyPairGenerator;
 import java.security.KeyStore;
 import java.security.NoSuchAlgorithmException;
-import java.security.PrivateKey;
 import java.security.SecureRandom;
 import java.security.cert.Certificate;
 import java.security.cert.X509Certificate;
@@ -49,8 +48,6 @@ import java.security.InvalidKeyException;
 import java.security.NoSuchProviderException;
 import java.security.SignatureException;
 import java.security.cert.CertificateEncodingException;
-import java.security.cert.CertificateException;
-import java.security.cert.CertificateFactory;
 import javax.security.auth.x500.X500Principal;
 import org.bouncycastle.x509.X509V1CertificateGenerator;
 
@@ -233,8 +230,8 @@ public class KeyStoreTestUtil {
     String trustKS = null;
     String trustPassword = "trustP";
 
-    File sslClientConfFile = new File(sslConfDir + "/ssl-client.xml");
+    File sslClientConfFile = new File(sslConfDir, getClientSSLConfigFileName());
-    File sslServerConfFile = new File(sslConfDir + "/ssl-server.xml");
+    File sslServerConfFile = new File(sslConfDir, getServerSSLConfigFileName());
 
     Map<String, X509Certificate> certs = new HashMap<String, X509Certificate>();
 
@@ -311,6 +308,42 @@ public class KeyStoreTestUtil {
     return serverSSLConf;
   }
 
+  /**
+   * Returns the client SSL configuration file name.  Under parallel test
+   * execution, this file name is parameterized by a unique ID to ensure that
+   * concurrent tests don't collide on an SSL configuration file.
+   *
+   * @return client SSL configuration file name
+   */
+  public static String getClientSSLConfigFileName() {
+    return getSSLConfigFileName("ssl-client");
+  }
+
+  /**
+   * Returns the server SSL configuration file name.  Under parallel test
+   * execution, this file name is parameterized by a unique ID to ensure that
+   * concurrent tests don't collide on an SSL configuration file.
+   *
+   * @return client SSL configuration file name
+   */
+  public static String getServerSSLConfigFileName() {
+    return getSSLConfigFileName("ssl-server");
+  }
+
+  /**
+   * Returns an SSL configuration file name.  Under parallel test
+   * execution, this file name is parameterized by a unique ID to ensure that
+   * concurrent tests don't collide on an SSL configuration file.
+   *
+   * @param base the base of the file name
+   * @return SSL configuration file name for base
+   */
+  private static String getSSLConfigFileName(String base) {
+    String testUniqueForkId = System.getProperty("test.unique.fork.id");
+    String fileSuffix = testUniqueForkId != null ? "-" + testUniqueForkId : "";
+    return base + fileSuffix + ".xml";
+  }
+
   /**
    * Creates SSL configuration.
    *
@@ -410,4 +443,19 @@ public class KeyStoreTestUtil {
       throw e;
     }
   }
+
+  /**
+   * Get the SSL configuration
+   * @return {@link Configuration} instance with ssl configs loaded
+   */
+  public static Configuration getSslConfig(){
+    Configuration sslConf = new Configuration(false);
+    String sslServerConfFile = KeyStoreTestUtil.getServerSSLConfigFileName();
+    String sslClientConfFile = KeyStoreTestUtil.getClientSSLConfigFileName();
+    sslConf.addResource(sslServerConfFile);
+    sslConf.addResource(sslClientConfFile);
+    sslConf.set(SSLFactory.SSL_SERVER_CONF_KEY, sslServerConfFile);
+    sslConf.set(SSLFactory.SSL_CLIENT_CONF_KEY, sslClientConfFile);
+    return sslConf;
+  }
 }

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/tracing/SetSpanReceiver.java

@@ -19,9 +19,10 @@ package org.apache.hadoop.tracing;
 
 import com.google.common.base.Supplier;
 import org.apache.hadoop.test.GenericTestUtils;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.Span;
-import org.apache.htrace.SpanReceiver;
+import org.apache.htrace.core.SpanId;
-import org.apache.htrace.HTraceConfiguration;
+import org.apache.htrace.core.SpanReceiver;
+import org.apache.htrace.core.HTraceConfiguration;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.LinkedList;
@@ -39,7 +40,7 @@ import org.junit.Assert;
  * push all the metrics to a static place, and would make testing
  * SpanReceiverHost harder.
  */
-public class SetSpanReceiver implements SpanReceiver {
+public class SetSpanReceiver extends SpanReceiver {
 
   public SetSpanReceiver(HTraceConfiguration conf) {
   }
@@ -68,8 +69,8 @@ public class SetSpanReceiver implements SpanReceiver {
   }
 
   public static class SetHolder {
-    public static ConcurrentHashMap<Long, Span> spans =
+    public static ConcurrentHashMap<SpanId, Span> spans =
-        new ConcurrentHashMap<Long, Span>();
+        new ConcurrentHashMap<SpanId, Span>();
 
     public static Map<String, List<Span>> getMap() {
       Map<String, List<Span>> map = new HashMap<String, List<Span>>();

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/tracing/TestTraceUtils.java

@@ -21,7 +21,7 @@ import static org.junit.Assert.assertEquals;
 import java.util.LinkedList;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.tracing.SpanReceiverInfo.ConfigurationPair;
-import org.apache.htrace.HTraceConfiguration;
+import org.apache.htrace.core.HTraceConfiguration;
 import org.junit.Test;
 
 public class TestTraceUtils {

hadoop-hdfs-project/hadoop-hdfs-client/dev-support/findbugsExcludeFile.xml

@@ -32,4 +32,28 @@
     <Method name="allocSlot" />
     <Bug pattern="UL_UNRELEASED_LOCK" />
   </Match>
+  <Match>
+    <Class name="org.apache.hadoop.hdfs.DFSInputStream"/>
+    <Field name="tcpReadsDisabledForTesting"/>
+    <Bug pattern="MS_SHOULD_BE_FINAL"/>
+  </Match>
+
+  <!--
+    ResponseProccessor is thread that is designed to catch RuntimeException.
+  -->
+  <Match>
+    <Class name="org.apache.hadoop.hdfs.DataStreamer$ResponseProcessor" />
+    <Method name="run" />
+    <Bug pattern="REC_CATCH_EXCEPTION" />
+  </Match>
+
+  <!--
+    We use a separate lock to guard cachingStrategy in order to separate
+    locks for p-reads from seek + read invocations.
+  -->
+  <Match>
+    <Class name="org.apache.hadoop.hdfs.DFSInputStream" />
+    <Field name="cachingStrategy" />
+    <Bug pattern="IS2_INCONSISTENT_SYNC" />
+  </Match>
 </FindBugsFilter>

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/BlockReaderFactory.java

@@ -31,8 +31,6 @@ import java.util.List;
 import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 import org.apache.commons.lang.mutable.MutableBoolean;
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.StorageType;
@@ -56,7 +54,7 @@ import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitReplica;
 import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitReplicaInfo;
 import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitShm.Slot;
 import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitShm.SlotId;
-import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.hdfs.util.IOUtilsClient;
 import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.net.unix.DomainSocket;
 import org.apache.hadoop.security.AccessControlException;
@@ -68,6 +66,10 @@ import org.apache.hadoop.util.Time;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
+import org.apache.htrace.core.Tracer;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 
 /** 
@@ -75,7 +77,7 @@ import com.google.common.base.Preconditions;
  */
 @InterfaceAudience.Private
 public class BlockReaderFactory implements ShortCircuitReplicaCreator {
-  static final Log LOG = LogFactory.getLog(BlockReaderFactory.class);
+  static final Logger LOG = LoggerFactory.getLogger(BlockReaderFactory.class);
 
   public static class FailureInjector {
     public void injectRequestFileDescriptorsFailure() throws IOException {
@@ -177,6 +179,11 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
    */
   private Configuration configuration;
 
+  /**
+   * The HTrace tracer to use.
+   */
+  private Tracer tracer;
+
   /**
    * Information about the domain socket path we should use to connect to the
    * local peer-- or null if we haven't examined the local domain socket.
@@ -281,6 +288,11 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
     return this;
   }
 
+  public BlockReaderFactory setTracer(Tracer tracer) {
+    this.tracer = tracer;
+    return this;
+  }
+
   @VisibleForTesting
   public static void setFailureInjectorForTesting(FailureInjector injector) {
     failureInjector = injector;
@@ -380,15 +392,17 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
         Constructor<? extends ReplicaAccessorBuilder> ctor =
             cls.getConstructor();
         ReplicaAccessorBuilder builder = ctor.newInstance();
+        long visibleLength = startOffset + length;
         ReplicaAccessor accessor = builder.
             setAllowShortCircuitReads(allowShortCircuitLocalReads).
             setBlock(block.getBlockId(), block.getBlockPoolId()).
+            setGenerationStamp(block.getGenerationStamp()).
             setBlockAccessToken(tokenBytes).
             setClientName(clientName).
             setConfiguration(configuration).
             setFileName(fileName).
             setVerifyChecksum(verifyChecksum).
-            setVisibleLength(length).
+            setVisibleLength(visibleLength).
             build();
         if (accessor == null) {
           if (LOG.isTraceEnabled()) {
@@ -396,7 +410,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
                 cls.getName());
           }
         } else {
-          return new ExternalBlockReader(accessor, length, startOffset);
+          return new ExternalBlockReader(accessor, visibleLength, startOffset);
         }
       } catch (Throwable t) {
         LOG.warn("Failed to construct new object of type " +
@@ -433,7 +447,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
     try {
       return BlockReaderLocalLegacy.newBlockReader(conf,
           userGroupInformation, configuration, fileName, block, token,
-          datanode, startOffset, length, storageType);
+          datanode, startOffset, length, storageType, tracer);
     } catch (RemoteException remoteException) {
       ioe = remoteException.unwrapRemoteException(
                 InvalidToken.class, AccessControlException.class);
@@ -494,6 +508,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
         setVerifyChecksum(verifyChecksum).
         setCachingStrategy(cachingStrategy).
         setStorageType(storageType).
+        setTracer(tracer).
         build();
   }
 
@@ -550,14 +565,14 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
           if (LOG.isDebugEnabled()) {
             LOG.debug(this + ": closing stale domain peer " + peer, e);
           }
-          IOUtils.cleanup(LOG, peer);
+          IOUtilsClient.cleanup(LOG, peer);
         } else {
           // Handle an I/O error we got when using a newly created socket.
           // We temporarily disable the domain socket path for a few minutes in
           // this case, to prevent wasting more time on it.
           LOG.warn(this + ": I/O error requesting file descriptors.  " + 
               "Disabling domain socket " + peer.getDomainSocket(), e);
-          IOUtils.cleanup(LOG, peer);
+          IOUtilsClient.cleanup(LOG, peer);
           clientContext.getDomainSocketFactory()
               .disableDomainSocketPath(pathInfo.getPath());
           return null;
@@ -616,7 +631,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
         return null;
       } finally {
         if (replica == null) {
-          IOUtils.cleanup(DFSClient.LOG, fis[0], fis[1]);
+          IOUtilsClient.cleanup(DFSClient.LOG, fis[0], fis[1]);
         }
       }
     case ERROR_UNSUPPORTED:
@@ -684,7 +699,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
         blockReader = getRemoteBlockReader(peer);
         return blockReader;
       } catch (IOException ioe) {
-        IOUtils.cleanup(LOG, peer);
+        IOUtilsClient.cleanup(LOG, peer);
         if (isSecurityException(ioe)) {
           if (LOG.isTraceEnabled()) {
             LOG.trace(this + ": got security exception while constructing " +
@@ -711,7 +726,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
         }
       } finally {
         if (blockReader == null) {
-          IOUtils.cleanup(LOG, peer);
+          IOUtilsClient.cleanup(LOG, peer);
         }
       }
     }
@@ -768,7 +783,7 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
         }
       } finally {
         if (blockReader == null) {
-          IOUtils.cleanup(LOG, peer);
+          IOUtilsClient.cleanup(LOG, peer);
         }
       }
     }
@@ -863,12 +878,12 @@ public class BlockReaderFactory implements ShortCircuitReplicaCreator {
       return RemoteBlockReader.newBlockReader(fileName,
           block, token, startOffset, length, conf.getIoBufferSize(),
           verifyChecksum, clientName, peer, datanode,
-          clientContext.getPeerCache(), cachingStrategy);
+          clientContext.getPeerCache(), cachingStrategy, tracer);
     } else {
       return RemoteBlockReader2.newBlockReader(
           fileName, block, token, startOffset, length,
           verifyChecksum, clientName, peer, datanode,
-          clientContext.getPeerCache(), cachingStrategy);
+          clientContext.getPeerCache(), cachingStrategy, tracer);
     }
   }
 

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/BlockReaderLocal.java

@@ -34,9 +34,8 @@ import org.apache.hadoop.hdfs.shortcircuit.ClientMmap;
 import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitReplica;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DirectBufferPool;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
@@ -75,6 +74,7 @@ class BlockReaderLocal implements BlockReader {
     private long dataPos;
     private ExtendedBlock block;
     private StorageType storageType;
+    private Tracer tracer;
 
     public Builder(ShortCircuitConf conf) {
       this.maxReadahead = Integer.MAX_VALUE;
@@ -120,6 +120,11 @@ class BlockReaderLocal implements BlockReader {
       return this;
     }
 
+    public Builder setTracer(Tracer tracer) {
+      this.tracer = tracer;
+      return this;
+    }
+
     public BlockReaderLocal build() {
       Preconditions.checkNotNull(replica);
       return new BlockReaderLocal(this);
@@ -228,6 +233,11 @@ class BlockReaderLocal implements BlockReader {
    */
   private StorageType storageType;
 
+  /**
+   * The Tracer to use.
+   */
+  private final Tracer tracer;
+
   private BlockReaderLocal(Builder builder) {
     this.replica = builder.replica;
     this.dataIn = replica.getDataStream().getChannel();
@@ -257,6 +267,7 @@ class BlockReaderLocal implements BlockReader {
     }
     this.maxReadaheadLength = maxReadaheadChunks * bytesPerChecksum;
     this.storageType = builder.storageType;
+    this.tracer = builder.tracer;
   }
 
   private synchronized void createDataBufIfNeeded() {
@@ -324,8 +335,8 @@ class BlockReaderLocal implements BlockReader {
    */
   private synchronized int fillBuffer(ByteBuffer buf, boolean canSkipChecksum)
       throws IOException {
-    TraceScope scope = Trace.startSpan("BlockReaderLocal#fillBuffer(" +
+    TraceScope scope = tracer.newScope(
-        block.getBlockId() + ")", Sampler.NEVER);
+        "BlockReaderLocal#fillBuffer(" + block.getBlockId() + ")");
     try {
       int total = 0;
       long startDataPos = dataPos;

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/BlockReaderLocalLegacy.java

@@ -50,10 +50,8 @@ import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DirectBufferPool;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
-
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -182,6 +180,7 @@ class BlockReaderLocalLegacy implements BlockReader {
   private long startOffset;
   private final String filename;
   private long blockId;
+  private final Tracer tracer;
 
   /**
    * The only way this object can be instantiated.
@@ -190,8 +189,8 @@ class BlockReaderLocalLegacy implements BlockReader {
       UserGroupInformation userGroupInformation,
       Configuration configuration, String file, ExtendedBlock blk,
       Token<BlockTokenIdentifier> token, DatanodeInfo node, 
-      long startOffset, long length, StorageType storageType)
+      long startOffset, long length, StorageType storageType,
-      throws IOException {
+      Tracer tracer) throws IOException {
     final ShortCircuitConf scConf = conf.getShortCircuitConf();
     LocalDatanodeInfo localDatanodeInfo = getLocalDatanodeInfo(node
         .getIpcPort());
@@ -239,10 +238,10 @@ class BlockReaderLocalLegacy implements BlockReader {
             - (startOffset % checksum.getBytesPerChecksum());
         localBlockReader = new BlockReaderLocalLegacy(scConf, file, blk, token,
             startOffset, length, pathinfo, checksum, true, dataIn,
-            firstChunkOffset, checksumIn);
+            firstChunkOffset, checksumIn, tracer);
       } else {
         localBlockReader = new BlockReaderLocalLegacy(scConf, file, blk, token,
-            startOffset, length, pathinfo, dataIn);
+            startOffset, length, pathinfo, dataIn, tracer);
       }
     } catch (IOException e) {
       // remove from cache
@@ -321,18 +320,18 @@ class BlockReaderLocalLegacy implements BlockReader {
 
   private BlockReaderLocalLegacy(ShortCircuitConf conf, String hdfsfile,
       ExtendedBlock block, Token<BlockTokenIdentifier> token, long startOffset,
-      long length, BlockLocalPathInfo pathinfo, FileInputStream dataIn)
+      long length, BlockLocalPathInfo pathinfo, FileInputStream dataIn,
-      throws IOException {
+      Tracer tracer) throws IOException {
     this(conf, hdfsfile, block, token, startOffset, length, pathinfo,
         DataChecksum.newDataChecksum(DataChecksum.Type.NULL, 4), false,
-        dataIn, startOffset, null);
+        dataIn, startOffset, null, tracer);
   }
 
   private BlockReaderLocalLegacy(ShortCircuitConf conf, String hdfsfile,
       ExtendedBlock block, Token<BlockTokenIdentifier> token, long startOffset,
       long length, BlockLocalPathInfo pathinfo, DataChecksum checksum,
       boolean verifyChecksum, FileInputStream dataIn, long firstChunkOffset,
-      FileInputStream checksumIn) throws IOException {
+      FileInputStream checksumIn, Tracer tracer) throws IOException {
     this.filename = hdfsfile;
     this.checksum = checksum;
     this.verifyChecksum = verifyChecksum;
@@ -368,6 +367,7 @@ class BlockReaderLocalLegacy implements BlockReader {
         bufferPool.returnBuffer(checksumBuff);
       }
     }
+    this.tracer = tracer;
   }
 
   /**
@@ -375,8 +375,8 @@ class BlockReaderLocalLegacy implements BlockReader {
    */
   private int fillBuffer(FileInputStream stream, ByteBuffer buf)
       throws IOException {
-    TraceScope scope = Trace.startSpan("BlockReaderLocalLegacy#fillBuffer(" +
+    TraceScope scope = tracer.
-        blockId + ")", Sampler.NEVER);
+        newScope("BlockReaderLocalLegacy#fillBuffer(" + blockId + ")");
     try {
       int bytesRead = stream.getChannel().read(buf);
       if (bytesRead < 0) {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClient.java

@@ -53,8 +53,6 @@ import java.util.concurrent.atomic.AtomicInteger;
 
 import javax.net.SocketFactory;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
@@ -76,6 +74,7 @@ import org.apache.hadoop.fs.FileEncryptionInfo;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.FsServerDefaults;
 import org.apache.hadoop.fs.FsStatus;
+import org.apache.hadoop.fs.FsTracer;
 import org.apache.hadoop.fs.HdfsBlockLocation;
 import org.apache.hadoop.fs.InvalidPathException;
 import org.apache.hadoop.fs.MD5MD5CRC32CastagnoliFileChecksum;
@@ -94,6 +93,8 @@ import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsAction;
 import org.apache.hadoop.fs.permission.FsPermission;
+import org.apache.hadoop.hdfs.NameNodeProxiesClient.ProxyAndInfo;
+import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.client.HdfsDataInputStream;
 import org.apache.hadoop.hdfs.client.HdfsDataOutputStream;
 import org.apache.hadoop.hdfs.client.impl.DfsClientConf;
@@ -147,10 +148,10 @@ import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.block.DataEncryptionKey;
 import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
-import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
 import org.apache.hadoop.hdfs.server.datanode.CachingStrategy;
 import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeStorageReport;
+import org.apache.hadoop.hdfs.util.IOUtilsClient;
 import org.apache.hadoop.io.DataOutputBuffer;
 import org.apache.hadoop.io.EnumSetWritable;
 import org.apache.hadoop.io.IOUtils;
@@ -167,24 +168,22 @@ import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.SecretManager.InvalidToken;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenRenewer;
-import org.apache.hadoop.tracing.SpanReceiverHost;
-import org.apache.hadoop.tracing.TraceUtils;
 import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DataChecksum.Type;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.SamplerBuilder;
-import org.apache.htrace.Span;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.net.InetAddresses;
+import org.apache.htrace.core.Tracer;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /********************************************************
  * DFSClient can connect to a Hadoop Filesystem and 
@@ -200,10 +199,11 @@ import com.google.common.net.InetAddresses;
 @InterfaceAudience.Private
 public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     DataEncryptionKeyFactory {
-  public static final Log LOG = LogFactory.getLog(DFSClient.class);
+  public static final Logger LOG = LoggerFactory.getLogger(DFSClient.class);
   public static final long SERVER_DEFAULTS_VALIDITY_PERIOD = 60 * 60 * 1000L; // 1 hour
 
   private final Configuration conf;
+  private final Tracer tracer;
   private final DfsClientConf dfsClientConf;
   final ClientProtocol namenode;
   /* The service used for delegation tokens */
@@ -231,7 +231,6 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       new DFSHedgedReadMetrics();
   private static ThreadPoolExecutor HEDGED_READ_THREAD_POOL;
   private static volatile ThreadPoolExecutor STRIPED_READ_THREAD_POOL;
-  private final Sampler<?> traceSampler;
   private final int smallBufferSize;
 
   public DfsClientConf getConf() {
@@ -286,25 +285,23 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   /** 
    * Create a new DFSClient connected to the given nameNodeUri or rpcNamenode.
    * If HA is enabled and a positive value is set for
-   * {@link DFSConfigKeys#DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY} in the
+   * {@link HdfsClientConfigKeys#DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY}
-   * configuration, the DFSClient will use {@link LossyRetryInvocationHandler}
+   * in the configuration, the DFSClient will use
-   * as its RetryInvocationHandler. Otherwise one of nameNodeUri or rpcNamenode 
+   * {@link LossyRetryInvocationHandler} as its RetryInvocationHandler.
-   * must be null.
+   * Otherwise one of nameNodeUri or rpcNamenode must be null.
    */
   @VisibleForTesting
   public DFSClient(URI nameNodeUri, ClientProtocol rpcNamenode,
       Configuration conf, FileSystem.Statistics stats)
     throws IOException {
-    SpanReceiverHost.get(conf, DFSConfigKeys.DFS_CLIENT_HTRACE_PREFIX);
-    traceSampler = new SamplerBuilder(TraceUtils.
-        wrapHadoopConf(DFSConfigKeys.DFS_CLIENT_HTRACE_PREFIX, conf)).build();
     // Copy only the required DFSClient configuration
+    this.tracer = FsTracer.get(conf);
     this.dfsClientConf = new DfsClientConf(conf);
     this.conf = conf;
     this.stats = stats;
     this.socketFactory = NetUtils.getSocketFactory(conf, ClientProtocol.class);
     this.dtpReplaceDatanodeOnFailure = ReplaceDatanodeOnFailure.get(conf);
-    this.smallBufferSize = DFSUtil.getSmallBufferSize(conf);
+    this.smallBufferSize = DFSUtilClient.getSmallBufferSize(conf);
 
     this.ugi = UserGroupInformation.getCurrentUser();
     
@@ -313,16 +310,17 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
         ThreadLocalRandom.current().nextInt()  + "_" +
         Thread.currentThread().getId();
     int numResponseToDrop = conf.getInt(
-        DFSConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY,
+        HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY,
-        DFSConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT);
+        HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT);
-    NameNodeProxies.ProxyAndInfo<ClientProtocol> proxyInfo = null;
+    ProxyAndInfo<ClientProtocol> proxyInfo = null;
     AtomicBoolean nnFallbackToSimpleAuth = new AtomicBoolean(false);
+
     if (numResponseToDrop > 0) {
       // This case is used for testing.
-      LOG.warn(DFSConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY
+      LOG.warn(HdfsClientConfigKeys.DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY
           + " is set to " + numResponseToDrop
           + ", this hacked client will proactively drop responses");
-      proxyInfo = NameNodeProxies.createProxyWithLossyRetryHandler(conf,
+      proxyInfo = NameNodeProxiesClient.createProxyWithLossyRetryHandler(conf,
           nameNodeUri, ClientProtocol.class, numResponseToDrop,
           nnFallbackToSimpleAuth);
     }
@@ -338,14 +336,14 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     } else {
       Preconditions.checkArgument(nameNodeUri != null,
           "null URI");
-      proxyInfo = NameNodeProxies.createProxy(conf, nameNodeUri,
+      proxyInfo = NameNodeProxiesClient.createProxyWithClientProtocol(conf,
-          ClientProtocol.class, nnFallbackToSimpleAuth);
+          nameNodeUri, nnFallbackToSimpleAuth);
       this.dtService = proxyInfo.getDelegationTokenService();
       this.namenode = proxyInfo.getProxy();
     }
 
     String localInterfaces[] =
-      conf.getTrimmedStrings(DFSConfigKeys.DFS_CLIENT_LOCAL_INTERFACES);
+      conf.getTrimmedStrings(HdfsClientConfigKeys.DFS_CLIENT_LOCAL_INTERFACES);
     localInterfaceAddrs = getLocalInterfaceAddrs(localInterfaces);
     if (LOG.isDebugEnabled() && 0 != localInterfaces.length) {
       LOG.debug("Using local interfaces [" +
@@ -544,10 +542,10 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       } catch (IOException e) {
         // Abort if the lease has already expired. 
         final long elapsed = Time.monotonicNow() - getLastLeaseRenewal();
-        if (elapsed > HdfsServerConstants.LEASE_HARDLIMIT_PERIOD) {
+        if (elapsed > HdfsConstants.LEASE_HARDLIMIT_PERIOD) {
           LOG.warn("Failed to renew lease for " + clientName + " for "
               + (elapsed/1000) + " seconds (>= hard-limit ="
-              + (HdfsServerConstants.LEASE_HARDLIMIT_PERIOD/1000) + " seconds.) "
+              + (HdfsConstants.LEASE_HARDLIMIT_PERIOD / 1000) + " seconds.) "
               + "Closing all files being written ...", e);
           closeAllFilesBeingWritten(true);
         } else {
@@ -586,8 +584,8 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
             out.close();
           }
         } catch(IOException ie) {
-          LOG.error("Failed to " + (abort? "abort": "close") +
+          LOG.error("Failed to " + (abort ? "abort" : "close") + " file: "
-                  " inode " + inodeId, ie);
+              + out.getSrc() + " with inode: " + inodeId, ie);
         }
       }
     }
@@ -624,7 +622,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public long getBlockSize(String f) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getBlockSize", f);
+    TraceScope scope = newPathTraceScope("getBlockSize", f);
     try {
       return namenode.getPreferredBlockSize(f);
     } catch (IOException ie) {
@@ -667,7 +665,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public Token<DelegationTokenIdentifier> getDelegationToken(Text renewer)
       throws IOException {
     assert dtService != null;
-    TraceScope scope = Trace.startSpan("getDelegationToken", traceSampler);
+    TraceScope scope = tracer.newScope("getDelegationToken");
     try {
       Token<DelegationTokenIdentifier> token =
         namenode.getDelegationToken(renewer);
@@ -732,7 +730,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     static {
       //Ensure that HDFS Configuration files are loaded before trying to use
       // the renewer.
-      HdfsConfiguration.init();
+      HdfsConfigurationLoader.init();
     }
     
     @Override
@@ -786,8 +784,8 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
             "a failover proxy provider configured.");
       }
       
-      NameNodeProxies.ProxyAndInfo<ClientProtocol> info =
+      ProxyAndInfo<ClientProtocol> info =
-        NameNodeProxies.createProxy(conf, uri, ClientProtocol.class);
+        NameNodeProxiesClient.createProxyWithClientProtocol(conf, uri, null);
       assert info.getDelegationTokenService().equals(token.getService()) :
         "Returned service '" + info.getDelegationTokenService().toString() +
         "' doesn't match expected service '" +
@@ -824,7 +822,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   @VisibleForTesting
   public LocatedBlocks getLocatedBlocks(String src, long start, long length)
       throws IOException {
-    TraceScope scope = getPathTraceScope("getBlockLocations", src);
+    TraceScope scope = newPathTraceScope("getBlockLocations", src);
     try {
       return callGetBlockLocations(namenode, src, start, length);
     } finally {
@@ -856,7 +854,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   boolean recoverLease(String src) throws IOException {
     checkOpen();
 
-    TraceScope scope = getPathTraceScope("recoverLease", src);
+    TraceScope scope = newPathTraceScope("recoverLease", src);
     try {
       return namenode.recoverLease(src, clientName);
     } catch (RemoteException re) {
@@ -883,7 +881,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public BlockLocation[] getBlockLocations(String src, long start, 
         long length) throws IOException, UnresolvedLinkException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getBlockLocations", src);
+    TraceScope scope = newPathTraceScope("getBlockLocations", src);
     try {
       LocatedBlocks blocks = getLocatedBlocks(src, start, length);
       BlockLocation[] locations =  DFSUtilClient.locatedBlocks2Locations(blocks);
@@ -902,7 +900,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   private KeyVersion decryptEncryptedDataEncryptionKey(FileEncryptionInfo
       feInfo) throws IOException {
-    TraceScope scope = Trace.startSpan("decryptEDEK", traceSampler);
+    TraceScope scope = tracer.newScope("decryptEDEK");
     try {
       KeyProvider provider = getKeyProvider();
       if (provider == null) {
@@ -1058,7 +1056,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       throws IOException, UnresolvedLinkException {
     checkOpen();
     //    Get block info from namenode
-    TraceScope scope = getPathTraceScope("newDFSInputStream", src);
+    TraceScope scope = newPathTraceScope("newDFSInputStream", src);
     try {
       LocatedBlocks locatedBlocks = getLocatedBlocks(src, 0);
       if (locatedBlocks != null) {
@@ -1314,7 +1312,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void createSymlink(String target, String link, boolean createParent)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("createSymlink", target);
+    TraceScope scope = newPathTraceScope("createSymlink", target);
     try {
       final FsPermission dirPerm = applyUMask(null);
       namenode.createSymlink(target, link, dirPerm, createParent);
@@ -1340,7 +1338,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public String getLinkTarget(String path) throws IOException { 
     checkOpen();
-    TraceScope scope = getPathTraceScope("getLinkTarget", path);
+    TraceScope scope = newPathTraceScope("getLinkTarget", path);
     try {
       return namenode.getLinkTarget(path);
     } catch (RemoteException re) {
@@ -1437,7 +1435,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public boolean setReplication(String src, short replication)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setReplication", src);
+    TraceScope scope = newPathTraceScope("setReplication", src);
     try {
       return namenode.setReplication(src, replication);
     } catch(RemoteException re) {
@@ -1461,7 +1459,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void setStoragePolicy(String src, String policyName)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setStoragePolicy", src);
+    TraceScope scope = newPathTraceScope("setStoragePolicy", src);
     try {
       namenode.setStoragePolicy(src, policyName);
     } catch (RemoteException e) {
@@ -1482,7 +1480,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public BlockStoragePolicy getStoragePolicy(String path) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getStoragePolicy", path);
+    TraceScope scope = newPathTraceScope("getStoragePolicy", path);
     try {
       return namenode.getStoragePolicy(path);
     } catch (RemoteException e) {
@@ -1500,7 +1498,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public BlockStoragePolicy[] getStoragePolicies() throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getStoragePolicies", traceSampler);
+    TraceScope scope = tracer.newScope("getStoragePolicies");
     try {
       return namenode.getStoragePolicies();
     } finally {
@@ -1516,7 +1514,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   @Deprecated
   public boolean rename(String src, String dst) throws IOException {
     checkOpen();
-    TraceScope scope = getSrcDstTraceScope("rename", src, dst);
+    TraceScope scope = newSrcDstTraceScope("rename", src, dst);
     try {
       return namenode.rename(src, dst);
     } catch(RemoteException re) {
@@ -1537,7 +1535,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void concat(String trg, String [] srcs) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("concat", traceSampler);
+    TraceScope scope = tracer.newScope("concat");
     try {
       namenode.concat(trg, srcs);
     } catch(RemoteException re) {
@@ -1555,7 +1553,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void rename(String src, String dst, Options.Rename... options)
       throws IOException {
     checkOpen();
-    TraceScope scope = getSrcDstTraceScope("rename2", src, dst);
+    TraceScope scope = newSrcDstTraceScope("rename2", src, dst);
     try {
       namenode.rename2(src, dst, options);
     } catch(RemoteException re) {
@@ -1584,7 +1582,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       throw new HadoopIllegalArgumentException(
           "Cannot truncate to a negative file size: " + newLength + ".");
     }
-    TraceScope scope = getPathTraceScope("truncate", src);
+    TraceScope scope = newPathTraceScope("truncate", src);
     try {
       return namenode.truncate(src, newLength, clientName);
     } catch (RemoteException re) {
@@ -1614,7 +1612,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean delete(String src, boolean recursive) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("delete", src);
+    TraceScope scope = newPathTraceScope("delete", src);
     try {
       return namenode.delete(src, recursive);
     } catch(RemoteException re) {
@@ -1656,7 +1654,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public DirectoryListing listPaths(String src,  byte[] startAfter,
       boolean needLocation) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("listPaths", src);
+    TraceScope scope = newPathTraceScope("listPaths", src);
     try {
       return namenode.getListing(src, startAfter, needLocation);
     } catch(RemoteException re) {
@@ -1678,7 +1676,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public HdfsFileStatus getFileInfo(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getFileInfo", src);
+    TraceScope scope = newPathTraceScope("getFileInfo", src);
     try {
       return namenode.getFileInfo(src);
     } catch(RemoteException re) {
@@ -1696,7 +1694,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean isFileClosed(String src) throws IOException{
     checkOpen();
-    TraceScope scope = getPathTraceScope("isFileClosed", src);
+    TraceScope scope = newPathTraceScope("isFileClosed", src);
     try {
       return namenode.isFileClosed(src);
     } catch(RemoteException re) {
@@ -1718,7 +1716,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public HdfsFileStatus getFileLinkInfo(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getFileLinkInfo", src);
+    TraceScope scope = newPathTraceScope("getFileLinkInfo", src);
     try {
       return namenode.getFileLinkInfo(src);
     } catch(RemoteException re) {
@@ -2007,7 +2005,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
       return PBHelperClient.convert(reply.getReadOpChecksumInfo().getChecksum().getType());
     } finally {
-      IOUtils.cleanup(null, pair.in, pair.out);
+      IOUtilsClient.cleanup(null, pair.in, pair.out);
     }
   }
 
@@ -2021,7 +2019,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void setPermission(String src, FsPermission permission)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setPermission", src);
+    TraceScope scope = newPathTraceScope("setPermission", src);
     try {
       namenode.setPermission(src, permission);
     } catch(RemoteException re) {
@@ -2046,7 +2044,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void setOwner(String src, String username, String groupname)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setOwner", src);
+    TraceScope scope = newPathTraceScope("setOwner", src);
     try {
       namenode.setOwner(src, username, groupname);
     } catch(RemoteException re) {
@@ -2062,7 +2060,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   private long[] callGetStats() throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getStats", traceSampler);
+    TraceScope scope = tracer.newScope("getStats");
     try {
       return namenode.getStats();
     } finally {
@@ -2121,7 +2119,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
                                                  String cookie)
         throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("listCorruptFileBlocks", path);
+    TraceScope scope = newPathTraceScope("listCorruptFileBlocks", path);
     try {
       return namenode.listCorruptFileBlocks(path, cookie);
     } finally {
@@ -2132,7 +2130,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public DatanodeInfo[] datanodeReport(DatanodeReportType type)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("datanodeReport", traceSampler);
+    TraceScope scope = tracer.newScope("datanodeReport");
     try {
       return namenode.getDatanodeReport(type);
     } finally {
@@ -2144,7 +2142,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       DatanodeReportType type) throws IOException {
     checkOpen();
     TraceScope scope =
-        Trace.startSpan("datanodeStorageReport", traceSampler);
+        tracer.newScope("datanodeStorageReport");
     try {
       return namenode.getDatanodeStorageReport(type);
     } finally {
@@ -2175,7 +2173,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public boolean setSafeMode(SafeModeAction action, boolean isChecked) throws IOException{
     TraceScope scope =
-        Trace.startSpan("setSafeMode", traceSampler);
+        tracer.newScope("setSafeMode");
     try {
       return namenode.setSafeMode(action, isChecked);
     } finally {
@@ -2194,7 +2192,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public String createSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("createSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("createSnapshot");
     try {
       return namenode.createSnapshot(snapshotRoot, snapshotName);
     } catch(RemoteException re) {
@@ -2216,7 +2214,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void deleteSnapshot(String snapshotRoot, String snapshotName)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("deleteSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("deleteSnapshot");
     try {
       namenode.deleteSnapshot(snapshotRoot, snapshotName);
     } catch(RemoteException re) {
@@ -2237,7 +2235,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void renameSnapshot(String snapshotDir, String snapshotOldName,
       String snapshotNewName) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("renameSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("renameSnapshot");
     try {
       namenode.renameSnapshot(snapshotDir, snapshotOldName, snapshotNewName);
     } catch(RemoteException re) {
@@ -2256,8 +2254,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getSnapshottableDirListing",
+    TraceScope scope = tracer.newScope("getSnapshottableDirListing");
-        traceSampler);
     try {
       return namenode.getSnapshottableDirListing();
     } catch(RemoteException re) {
@@ -2274,7 +2271,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void allowSnapshot(String snapshotRoot) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("allowSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("allowSnapshot");
     try {
       namenode.allowSnapshot(snapshotRoot);
     } catch (RemoteException re) {
@@ -2291,7 +2288,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void disallowSnapshot(String snapshotRoot) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("disallowSnapshot", traceSampler);
+    TraceScope scope = tracer.newScope("disallowSnapshot");
     try {
       namenode.disallowSnapshot(snapshotRoot);
     } catch (RemoteException re) {
@@ -2309,7 +2306,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public SnapshotDiffReport getSnapshotDiffReport(String snapshotDir,
       String fromSnapshot, String toSnapshot) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getSnapshotDiffReport", traceSampler);
+    TraceScope scope = tracer.newScope("getSnapshotDiffReport");
     try {
       return namenode.getSnapshotDiffReport(snapshotDir,
           fromSnapshot, toSnapshot);
@@ -2323,7 +2320,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public long addCacheDirective(
       CacheDirectiveInfo info, EnumSet<CacheFlag> flags) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("addCacheDirective", traceSampler);
+    TraceScope scope = tracer.newScope("addCacheDirective");
     try {
       return namenode.addCacheDirective(info, flags);
     } catch (RemoteException re) {
@@ -2336,7 +2333,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void modifyCacheDirective(
       CacheDirectiveInfo info, EnumSet<CacheFlag> flags) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("modifyCacheDirective", traceSampler);
+    TraceScope scope = tracer.newScope("modifyCacheDirective");
     try {
       namenode.modifyCacheDirective(info, flags);
     } catch (RemoteException re) {
@@ -2349,7 +2346,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void removeCacheDirective(long id)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeCacheDirective", traceSampler);
+    TraceScope scope = tracer.newScope("removeCacheDirective");
     try {
       namenode.removeCacheDirective(id);
     } catch (RemoteException re) {
@@ -2362,12 +2359,12 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public RemoteIterator<CacheDirectiveEntry> listCacheDirectives(
       CacheDirectiveInfo filter) throws IOException {
     checkOpen();
-    return new CacheDirectiveIterator(namenode, filter, traceSampler);
+    return new CacheDirectiveIterator(namenode, filter, tracer);
   }
 
   public void addCachePool(CachePoolInfo info) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("addCachePool", traceSampler);
+    TraceScope scope = tracer.newScope("addCachePool");
     try {
       namenode.addCachePool(info);
     } catch (RemoteException re) {
@@ -2379,7 +2376,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void modifyCachePool(CachePoolInfo info) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("modifyCachePool", traceSampler);
+    TraceScope scope = tracer.newScope("modifyCachePool");
     try {
       namenode.modifyCachePool(info);
     } catch (RemoteException re) {
@@ -2391,7 +2388,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeCachePool(String poolName) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeCachePool", traceSampler);
+    TraceScope scope = tracer.newScope("removeCachePool");
     try {
       namenode.removeCachePool(poolName);
     } catch (RemoteException re) {
@@ -2403,7 +2400,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public RemoteIterator<CachePoolEntry> listCachePools() throws IOException {
     checkOpen();
-    return new CachePoolIterator(namenode, traceSampler);
+    return new CachePoolIterator(namenode, tracer);
   }
 
   /**
@@ -2413,7 +2410,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   boolean saveNamespace(long timeWindow, long txGap) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("saveNamespace", traceSampler);
+    TraceScope scope = tracer.newScope("saveNamespace");
     try {
       return namenode.saveNamespace(timeWindow, txGap);
     } catch(RemoteException re) {
@@ -2431,7 +2428,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   long rollEdits() throws AccessControlException, IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("rollEdits", traceSampler);
+    TraceScope scope = tracer.newScope("rollEdits");
     try {
       return namenode.rollEdits();
     } catch(RemoteException re) {
@@ -2454,7 +2451,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   boolean restoreFailedStorage(String arg)
       throws AccessControlException, IOException{
     checkOpen();
-    TraceScope scope = Trace.startSpan("restoreFailedStorage", traceSampler);
+    TraceScope scope = tracer.newScope("restoreFailedStorage");
     try {
       return namenode.restoreFailedStorage(arg);
     } finally {
@@ -2471,7 +2468,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void refreshNodes() throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("refreshNodes", traceSampler);
+    TraceScope scope = tracer.newScope("refreshNodes");
     try {
       namenode.refreshNodes();
     } finally {
@@ -2486,7 +2483,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void metaSave(String pathname) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("metaSave", traceSampler);
+    TraceScope scope = tracer.newScope("metaSave");
     try {
       namenode.metaSave(pathname);
     } finally {
@@ -2504,7 +2501,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void setBalancerBandwidth(long bandwidth) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("setBalancerBandwidth", traceSampler);
+    TraceScope scope = tracer.newScope("setBalancerBandwidth");
     try {
       namenode.setBalancerBandwidth(bandwidth);
     } finally {
@@ -2517,7 +2514,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void finalizeUpgrade() throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("finalizeUpgrade", traceSampler);
+    TraceScope scope = tracer.newScope("finalizeUpgrade");
     try {
       namenode.finalizeUpgrade();
     } finally {
@@ -2527,7 +2524,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   RollingUpgradeInfo rollingUpgrade(RollingUpgradeAction action) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("rollingUpgrade", traceSampler);
+    TraceScope scope = tracer.newScope("rollingUpgrade");
     try {
       return namenode.rollingUpgrade(action);
     } finally {
@@ -2585,7 +2582,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     if(LOG.isDebugEnabled()) {
       LOG.debug(src + ": masked=" + absPermission);
     }
-    TraceScope scope = Trace.startSpan("mkdir", traceSampler);
+    TraceScope scope = tracer.newScope("mkdir");
     try {
       return namenode.mkdirs(src, absPermission, createParent);
     } catch(RemoteException re) {
@@ -2613,7 +2610,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   ContentSummary getContentSummary(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getContentSummary", src);
+    TraceScope scope = newPathTraceScope("getContentSummary", src);
     try {
       return namenode.getContentSummary(src);
     } catch(RemoteException re) {
@@ -2642,7 +2639,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
                                          storagespaceQuota);
                                          
     }
-    TraceScope scope = getPathTraceScope("setQuota", src);
+    TraceScope scope = newPathTraceScope("setQuota", src);
     try {
       // Pass null as storage type for traditional namespace/storagespace quota.
       namenode.setQuota(src, namespaceQuota, storagespaceQuota, null);
@@ -2678,7 +2675,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       throw new IllegalArgumentException("Don't support Quota for storage type : "
         + type.toString());
     }
-    TraceScope scope = getPathTraceScope("setQuotaByStorageType", src);
+    TraceScope scope = newPathTraceScope("setQuotaByStorageType", src);
     try {
       namenode.setQuota(src, HdfsConstants.QUOTA_DONT_SET, quota, type);
     } catch (RemoteException re) {
@@ -2698,7 +2695,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
    */
   public void setTimes(String src, long mtime, long atime) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setTimes", src);
+    TraceScope scope = newPathTraceScope("setTimes", src);
     try {
       namenode.setTimes(src, mtime, atime);
     } catch(RemoteException re) {
@@ -2759,7 +2756,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void modifyAclEntries(String src, List<AclEntry> aclSpec)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("modifyAclEntries", src);
+    TraceScope scope = newPathTraceScope("modifyAclEntries", src);
     try {
       namenode.modifyAclEntries(src, aclSpec);
     } catch(RemoteException re) {
@@ -2778,7 +2775,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void removeAclEntries(String src, List<AclEntry> aclSpec)
       throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeAclEntries", traceSampler);
+    TraceScope scope = tracer.newScope("removeAclEntries");
     try {
       namenode.removeAclEntries(src, aclSpec);
     } catch(RemoteException re) {
@@ -2796,7 +2793,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeDefaultAcl(String src) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeDefaultAcl", traceSampler);
+    TraceScope scope = tracer.newScope("removeDefaultAcl");
     try {
       namenode.removeDefaultAcl(src);
     } catch(RemoteException re) {
@@ -2814,7 +2811,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeAcl(String src) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("removeAcl", traceSampler);
+    TraceScope scope = tracer.newScope("removeAcl");
     try {
       namenode.removeAcl(src);
     } catch(RemoteException re) {
@@ -2832,7 +2829,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void setAcl(String src, List<AclEntry> aclSpec) throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("setAcl", traceSampler);
+    TraceScope scope = tracer.newScope("setAcl");
     try {
       namenode.setAcl(src, aclSpec);
     } catch(RemoteException re) {
@@ -2850,7 +2847,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public AclStatus getAclStatus(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getAclStatus", src);
+    TraceScope scope = newPathTraceScope("getAclStatus", src);
     try {
       return namenode.getAclStatus(src);
     } catch(RemoteException re) {
@@ -2866,7 +2863,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void createEncryptionZone(String src, String keyName)
     throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("createEncryptionZone", src);
+    TraceScope scope = newPathTraceScope("createEncryptionZone", src);
     try {
       namenode.createEncryptionZone(src, keyName);
     } catch (RemoteException re) {
@@ -2881,7 +2878,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public EncryptionZone getEZForPath(String src)
           throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getEZForPath", src);
+    TraceScope scope = newPathTraceScope("getEZForPath", src);
     try {
       return namenode.getEZForPath(src);
     } catch (RemoteException re) {
@@ -2895,14 +2892,14 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public RemoteIterator<EncryptionZone> listEncryptionZones()
       throws IOException {
     checkOpen();
-    return new EncryptionZoneIterator(namenode, traceSampler);
+    return new EncryptionZoneIterator(namenode, tracer);
   }
 
 
   public void setErasureCodingPolicy(String src, ErasureCodingPolicy ecPolicy)
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setErasureCodingPolicy", src);
+    TraceScope scope = newPathTraceScope("setErasureCodingPolicy", src);
     try {
       namenode.setErasureCodingPolicy(src, ecPolicy);
     } catch (RemoteException re) {
@@ -2917,7 +2914,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public void setXAttr(String src, String name, byte[] value, 
       EnumSet<XAttrSetFlag> flag) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("setXAttr", src);
+    TraceScope scope = newPathTraceScope("setXAttr", src);
     try {
       namenode.setXAttr(src, XAttrHelper.buildXAttr(name, value), flag);
     } catch (RemoteException re) {
@@ -2934,7 +2931,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   
   public byte[] getXAttr(String src, String name) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getXAttr", src);
+    TraceScope scope = newPathTraceScope("getXAttr", src);
     try {
       final List<XAttr> xAttrs = XAttrHelper.buildXAttrAsList(name);
       final List<XAttr> result = namenode.getXAttrs(src, xAttrs);
@@ -2950,7 +2947,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   
   public Map<String, byte[]> getXAttrs(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getXAttrs", src);
+    TraceScope scope = newPathTraceScope("getXAttrs", src);
     try {
       return XAttrHelper.buildXAttrMap(namenode.getXAttrs(src, null));
     } catch(RemoteException re) {
@@ -2965,7 +2962,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public Map<String, byte[]> getXAttrs(String src, List<String> names) 
       throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getXAttrs", src);
+    TraceScope scope = newPathTraceScope("getXAttrs", src);
     try {
       return XAttrHelper.buildXAttrMap(namenode.getXAttrs(
           src, XAttrHelper.buildXAttrs(names)));
@@ -2981,7 +2978,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
   public List<String> listXAttrs(String src)
           throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("listXAttrs", src);
+    TraceScope scope = newPathTraceScope("listXAttrs", src);
     try {
       final Map<String, byte[]> xattrs =
         XAttrHelper.buildXAttrMap(namenode.listXAttrs(src));
@@ -2997,7 +2994,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void removeXAttr(String src, String name) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("removeXAttr", src);
+    TraceScope scope = newPathTraceScope("removeXAttr", src);
     try {
       namenode.removeXAttr(src, XAttrHelper.buildXAttr(name));
     } catch(RemoteException re) {
@@ -3014,7 +3011,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public void checkAccess(String src, FsAction mode) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("checkAccess", src);
+    TraceScope scope = newPathTraceScope("checkAccess", src);
     try {
       namenode.checkAccess(src, mode);
     } catch (RemoteException re) {
@@ -3028,7 +3025,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public ErasureCodingPolicy[] getErasureCodingPolicies() throws IOException {
     checkOpen();
-    TraceScope scope = Trace.startSpan("getErasureCodingPolicies", traceSampler);
+    TraceScope scope = tracer.newScope("getErasureCodingPolicies");
     try {
       return namenode.getErasureCodingPolicies();
     } finally {
@@ -3038,13 +3035,14 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public DFSInotifyEventInputStream getInotifyEventStream() throws IOException {
     checkOpen();
-    return new DFSInotifyEventInputStream(traceSampler, namenode);
+    return new DFSInotifyEventInputStream(namenode, tracer);
   }
 
   public DFSInotifyEventInputStream getInotifyEventStream(long lastReadTxid)
       throws IOException {
     checkOpen();
-    return new DFSInotifyEventInputStream(traceSampler, namenode, lastReadTxid);
+    return new DFSInotifyEventInputStream(namenode, tracer,
+          lastReadTxid);
   }
 
   @Override // RemotePeerFactory
@@ -3066,7 +3064,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       return peer;
     } finally {
       if (!success) {
-        IOUtils.cleanup(LOG, peer);
+        IOUtilsClient.cleanup(LOG, peer);
         IOUtils.closeSocket(sock);
       }
     }
@@ -3179,11 +3177,11 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   /**
    * Probe for encryption enabled on this filesystem.
-   * See {@link DFSUtil#isHDFSEncryptionEnabled(Configuration)}
+   * See {@link DFSUtilClient#isHDFSEncryptionEnabled(Configuration)}
    * @return true if encryption is enabled
    */
   public boolean isHDFSEncryptionEnabled() {
-    return DFSUtil.isHDFSEncryptionEnabled(this.conf);
+    return DFSUtilClient.isHDFSEncryptionEnabled(this.conf);
   }
 
   /**
@@ -3195,27 +3193,21 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
     return saslClient;
   }
 
-  TraceScope getPathTraceScope(String description, String path) {
+  TraceScope newPathTraceScope(String description, String path) {
-    TraceScope scope = Trace.startSpan(description, traceSampler);
+    TraceScope scope = tracer.newScope(description);
-    Span span = scope.getSpan();
-    if (span != null) {
     if (path != null) {
-        span.addKVAnnotation("path", path);
+      scope.addKVAnnotation("path", path);
-      }
     }
     return scope;
   }
 
-  TraceScope getSrcDstTraceScope(String description, String src, String dst) {
+  TraceScope newSrcDstTraceScope(String description, String src, String dst) {
-    TraceScope scope = Trace.startSpan(description, traceSampler);
+    TraceScope scope = tracer.newScope(description);
-    Span span = scope.getSpan();
-    if (span != null) {
     if (src != null) {
-        span.addKVAnnotation("src", src);
+      scope.addKVAnnotation("src", src);
     }
     if (dst != null) {
-        span.addKVAnnotation("dst", dst);
+      scope.addKVAnnotation("dst", dst);
-      }
     }
     return scope;
   }
@@ -3231,7 +3223,7 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
 
   public ErasureCodingPolicy getErasureCodingPolicy(String src) throws IOException {
     checkOpen();
-    TraceScope scope = getPathTraceScope("getErasureCodingPolicy", src);
+    TraceScope scope = newPathTraceScope("getErasureCodingPolicy", src);
     try {
       return namenode.getErasureCodingPolicy(src);
     } catch (RemoteException re) {
@@ -3241,4 +3233,8 @@ public class DFSClient implements java.io.Closeable, RemotePeerFactory,
       scope.close();
     }
   }
+
+  Tracer getTracer() {
+    return tracer;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSClientFaultInjector.java

@@ -30,12 +30,15 @@ import org.apache.hadoop.classification.InterfaceAudience;
 @VisibleForTesting
 @InterfaceAudience.Private
 public class DFSClientFaultInjector {
-  public static DFSClientFaultInjector instance = new DFSClientFaultInjector();
+  private static DFSClientFaultInjector instance = new DFSClientFaultInjector();
   public static AtomicLong exceptionNum = new AtomicLong(0);
 
   public static DFSClientFaultInjector get() {
     return instance;
   }
+  public static void set(DFSClientFaultInjector instance) {
+    DFSClientFaultInjector.instance = instance;
+  }
 
   public boolean corruptPacket() {
     return false;

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInotifyEventInputStream.java

@@ -26,9 +26,8 @@ import org.apache.hadoop.hdfs.inotify.EventBatchList;
 import org.apache.hadoop.hdfs.inotify.MissingEventsException;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -44,13 +43,8 @@ import java.util.concurrent.TimeUnit;
 @InterfaceAudience.Public
 @InterfaceStability.Unstable
 public class DFSInotifyEventInputStream {
-  public static Logger LOG = LoggerFactory.getLogger(DFSInotifyEventInputStream
+  public static final Logger LOG = LoggerFactory.getLogger(
-      .class);
+      DFSInotifyEventInputStream.class);
-
-  /**
-   * The trace sampler to use when making RPCs to the NameNode.
-   */
-  private final Sampler<?> traceSampler;
 
   private final ClientProtocol namenode;
   private Iterator<EventBatch> it;
@@ -65,20 +59,22 @@ public class DFSInotifyEventInputStream {
    */
   private Random rng = new Random();
 
+  private final Tracer tracer;
+
   private static final int INITIAL_WAIT_MS = 10;
 
-  DFSInotifyEventInputStream(Sampler<?> traceSampler, ClientProtocol namenode)
+  DFSInotifyEventInputStream(ClientProtocol namenode, Tracer tracer)
         throws IOException {
     // Only consider new transaction IDs.
-    this(traceSampler, namenode, namenode.getCurrentEditLogTxid());
+    this(namenode, tracer, namenode.getCurrentEditLogTxid());
   }
 
-  DFSInotifyEventInputStream(Sampler traceSampler, ClientProtocol namenode,
+  DFSInotifyEventInputStream(ClientProtocol namenode,
-        long lastReadTxid) throws IOException {
+        Tracer tracer, long lastReadTxid) throws IOException {
-    this.traceSampler = traceSampler;
     this.namenode = namenode;
     this.it = Iterators.emptyIterator();
     this.lastReadTxid = lastReadTxid;
+    this.tracer = tracer;
   }
 
   /**
@@ -98,8 +94,7 @@ public class DFSInotifyEventInputStream {
    * The next available batch of events will be returned.
    */
   public EventBatch poll() throws IOException, MissingEventsException {
-    TraceScope scope =
+    TraceScope scope = tracer.newScope("inotifyPoll");
-        Trace.startSpan("inotifyPoll", traceSampler);
     try {
       // need to keep retrying until the NN sends us the latest committed txid
       if (lastReadTxid == -1) {
@@ -180,7 +175,7 @@ public class DFSInotifyEventInputStream {
    */
   public EventBatch poll(long time, TimeUnit tu) throws IOException,
       InterruptedException, MissingEventsException {
-    TraceScope scope = Trace.startSpan("inotifyPollWithTimeout", traceSampler);
+    TraceScope scope = tracer.newScope("inotifyPollWithTimeout");
     EventBatch next = null;
     try {
       long initialTime = Time.monotonicNow();
@@ -217,7 +212,7 @@ public class DFSInotifyEventInputStream {
    */
   public EventBatch take() throws IOException, InterruptedException,
       MissingEventsException {
-    TraceScope scope = Trace.startSpan("inotifyTake", traceSampler);
+    TraceScope scope = tracer.newScope("inotifyTake");
     EventBatch next = null;
     try {
       int nextWaitMin = INITIAL_WAIT_MS;

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java

@@ -54,6 +54,7 @@ import org.apache.hadoop.fs.CanUnbuffer;
 import org.apache.hadoop.fs.ChecksumException;
 import org.apache.hadoop.fs.FSInputStream;
 import org.apache.hadoop.fs.FileEncryptionInfo;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.HasEnhancedByteBufferAccess;
 import org.apache.hadoop.fs.ReadOption;
 import org.apache.hadoop.fs.StorageType;
@@ -77,9 +78,9 @@ import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.token.SecretManager.InvalidToken;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.IdentityHashStore;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.SpanId;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 import com.google.common.annotations.VisibleForTesting;
 
@@ -677,6 +678,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
         setClientCacheContext(dfsClient.getClientContext()).
         setUserGroupInformation(dfsClient.ugi).
         setConfiguration(dfsClient.getConfiguration()).
+        setTracer(dfsClient.getTracer()).
         build();
   }
 
@@ -940,7 +942,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   public synchronized int read(final byte buf[], int off, int len) throws IOException {
     ReaderStrategy byteArrayReader = new ByteArrayStrategy(buf);
     TraceScope scope =
-        dfsClient.getPathTraceScope("DFSInputStream#byteArrayRead", src);
+        dfsClient.newPathTraceScope("DFSInputStream#byteArrayRead", src);
     try {
       return readWithStrategy(byteArrayReader, off, len);
     } finally {
@@ -952,7 +954,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   public synchronized int read(final ByteBuffer buf) throws IOException {
     ReaderStrategy byteBufferReader = new ByteBufferStrategy(buf);
     TraceScope scope =
-        dfsClient.getPathTraceScope("DFSInputStream#byteBufferRead", src);
+        dfsClient.newPathTraceScope("DFSInputStream#byteBufferRead", src);
     try {
       return readWithStrategy(byteBufferReader, 0, buf.remaining());
     } finally {
@@ -1128,14 +1130,14 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
       final ByteBuffer bb,
       final Map<ExtendedBlock, Set<DatanodeInfo>> corruptedBlockMap,
       final int hedgedReadId) {
-    final Span parentSpan = Trace.currentSpan();
+    final SpanId parentSpanId = Tracer.getCurrentSpanId();
     return new Callable<ByteBuffer>() {
       @Override
       public ByteBuffer call() throws Exception {
         byte[] buf = bb.array();
         int offset = bb.position();
-        TraceScope scope =
+        TraceScope scope = dfsClient.getTracer().
-            Trace.startSpan("hedgedRead" + hedgedReadId, parentSpan);
+            newScope("hedgedRead" + hedgedReadId, parentSpanId);
         try {
           actualGetFromOneDataNode(datanode, block, start, end, buf,
               offset, corruptedBlockMap);
@@ -1421,8 +1423,8 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   @Override
   public int read(long position, byte[] buffer, int offset, int length)
       throws IOException {
-    TraceScope scope =
+    TraceScope scope = dfsClient.
-        dfsClient.getPathTraceScope("DFSInputStream#byteArrayPread", src);
+        newPathTraceScope("DFSInputStream#byteArrayPread", src);
     try {
       return pread(position, buffer, offset, length);
     } finally {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSOutputStream.java

@@ -32,6 +32,7 @@ import org.apache.hadoop.fs.CreateFlag;
 import org.apache.hadoop.fs.FSOutputSummer;
 import org.apache.hadoop.fs.FileAlreadyExistsException;
 import org.apache.hadoop.fs.FileEncryptionInfo;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.ParentNotDirectoryException;
 import org.apache.hadoop.fs.Syncable;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -63,9 +64,7 @@ import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.DataChecksum.Type;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -231,7 +230,7 @@ public class DFSOutputStream extends FSOutputSummer
       short replication, long blockSize, Progressable progress, int buffersize,
       DataChecksum checksum, String[] favoredNodes) throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("newStreamForCreate", src);
+        dfsClient.newPathTraceScope("newStreamForCreate", src);
     try {
       HdfsFileStatus stat = null;
 
@@ -360,7 +359,7 @@ public class DFSOutputStream extends FSOutputSummer
       LocatedBlock lastBlock, HdfsFileStatus stat, DataChecksum checksum,
       String[] favoredNodes) throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("newStreamForAppend", src);
+        dfsClient.newPathTraceScope("newStreamForAppend", src);
     if(stat.getErasureCodingPolicy() != null) {
       throw new IOException("Not support appending to a striping layout file yet.");
     }
@@ -388,7 +387,7 @@ public class DFSOutputStream extends FSOutputSummer
   }
 
   protected TraceScope createWriteTraceScope() {
-    return dfsClient.getPathTraceScope("DFSOutputStream#write", src);
+    return dfsClient.newPathTraceScope("DFSOutputStream#write", src);
   }
 
   // @see FSOutputSummer#writeChunk()
@@ -502,7 +501,7 @@ public class DFSOutputStream extends FSOutputSummer
   @Override
   public void hflush() throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("hflush", src);
+        dfsClient.newPathTraceScope("hflush", src);
     try {
       flushOrSync(false, EnumSet.noneOf(SyncFlag.class));
     } finally {
@@ -513,7 +512,7 @@ public class DFSOutputStream extends FSOutputSummer
   @Override
   public void hsync() throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("hsync", src);
+        dfsClient.newPathTraceScope("hsync", src);
     try {
       flushOrSync(true, EnumSet.noneOf(SyncFlag.class));
     } finally {
@@ -536,7 +535,7 @@ public class DFSOutputStream extends FSOutputSummer
    */
   public void hsync(EnumSet<SyncFlag> syncFlags) throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("hsync", src);
+        dfsClient.newPathTraceScope("hsync", src);
     try {
       flushOrSync(true, syncFlags);
     } finally {
@@ -777,7 +776,7 @@ public class DFSOutputStream extends FSOutputSummer
   @Override
   public synchronized void close() throws IOException {
     TraceScope scope =
-        dfsClient.getPathTraceScope("DFSOutputStream#close", src);
+        dfsClient.newPathTraceScope("DFSOutputStream#close", src);
     try {
       closeImpl();
     } finally {
@@ -806,7 +805,7 @@ public class DFSOutputStream extends FSOutputSummer
       // get last block before destroying the streamer
       ExtendedBlock lastBlock = getStreamer().getBlock();
       closeThreads(false);
-      TraceScope scope = Trace.startSpan("completeFile", Sampler.NEVER);
+      TraceScope scope = dfsClient.getTracer().newScope("completeFile");
       try {
         completeFile(lastBlock);
       } finally {
@@ -914,6 +913,13 @@ public class DFSOutputStream extends FSOutputSummer
     return fileId;
   }
 
+  /**
+   * Return the source of stream.
+   */
+  String getSrc() {
+    return src;
+  }
+
   /**
    * Returns the data streamer object.
    */

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSPacket.java

@@ -28,7 +28,9 @@ import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.datatransfer.PacketHeader;
 import org.apache.hadoop.hdfs.util.ByteArrayManager;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.Span;
+import org.apache.htrace.core.SpanId;
+import org.apache.htrace.core.TraceScope;
 
 /****************************************************************
  * DFSPacket is used by DataStreamer and DFSOutputStream.
@@ -39,7 +41,7 @@ import org.apache.htrace.Span;
 @InterfaceAudience.Private
 public class DFSPacket {
   public static final long HEART_BEAT_SEQNO = -1L;
-  private static long[] EMPTY = new long[0];
+  private static SpanId[] EMPTY = new SpanId[0];
   private final long seqno; // sequence number of buffer in block
   private final long offsetInBlock; // offset in block
   private boolean syncBlock; // this packet forces the current block to disk
@@ -66,9 +68,9 @@ public class DFSPacket {
   private int checksumPos;
   private final int dataStart;
   private int dataPos;
-  private long[] traceParents = EMPTY;
+  private SpanId[] traceParents = EMPTY;
   private int traceParentsUsed;
-  private Span span;
+  private TraceScope scope;
 
   /**
    * Create a new packet.
@@ -307,7 +309,10 @@ public class DFSPacket {
     addTraceParent(span.getSpanId());
   }
 
-  public void addTraceParent(long id) {
+  public void addTraceParent(SpanId id) {
+    if (!id.isValid()) {
+      return;
+    }
     if (traceParentsUsed == traceParents.length) {
       int newLength = (traceParents.length == 0) ? 8 :
           traceParents.length * 2;
@@ -324,18 +329,18 @@ public class DFSPacket {
    *
    * Protected by the DFSOutputStream dataQueue lock.
    */
-  public long[] getTraceParents() {
+  public SpanId[] getTraceParents() {
     // Remove duplicates from the array.
     int len = traceParentsUsed;
     Arrays.sort(traceParents, 0, len);
     int i = 0, j = 0;
-    long prevVal = 0; // 0 is not a valid span id
+    SpanId prevVal = SpanId.INVALID;
     while (true) {
       if (i == len) {
         break;
       }
-      long val = traceParents[i];
+      SpanId val = traceParents[i];
-      if (val != prevVal) {
+      if (!val.equals(prevVal)) {
         traceParents[j] = val;
         j++;
         prevVal = val;
@@ -349,11 +354,11 @@ public class DFSPacket {
     return traceParents;
   }
 
-  public void setTraceSpan(Span span) {
+  public void setTraceScope(TraceScope scope) {
-    this.span = span;
+    this.scope = scope;
   }
 
-  public Span getTraceSpan() {
+  public TraceScope getTraceScope() {
-    return span;
+    return scope;
   }
 }

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedInputStream.java

@@ -26,7 +26,6 @@ import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.protocol.LocatedStripedBlock;
 import org.apache.hadoop.hdfs.protocol.datatransfer.InvalidEncryptionKeyException;
-import org.apache.hadoop.hdfs.server.blockmanagement.BlockIdManager;
 import org.apache.hadoop.hdfs.util.StripedBlockUtil;
 import org.apache.hadoop.io.ByteBufferPool;
 
@@ -260,7 +259,7 @@ public class DFSStripedInputStream extends DFSInputStream {
 
   private void closeReader(BlockReaderInfo readerInfo) {
     if (readerInfo != null) {
-      IOUtils.cleanup(DFSClient.LOG, readerInfo.reader);
+//      IOUtils.cleanup(null, readerInfo.reader);
       readerInfo.skip();
     }
   }
@@ -483,7 +482,7 @@ public class DFSStripedInputStream extends DFSInputStream {
   @Override
   protected LocatedBlock refreshLocatedBlock(LocatedBlock block)
       throws IOException {
-    int idx = BlockIdManager.getBlockIndex(block.getBlock().getLocalBlock());
+    int idx = StripedBlockUtil.getBlockIndex(block.getBlock().getLocalBlock());
     LocatedBlock lb = getBlockGroupAt(block.getStartOffset());
     // If indexing information is returned, iterate through the index array
     // to find the entry for position idx in the group

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSStripedOutputStream.java

@@ -37,6 +37,7 @@ import java.util.concurrent.TimeUnit;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.fs.CreateFlag;
+import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
@@ -53,11 +54,9 @@ import org.apache.hadoop.io.erasurecode.rawcoder.RawErasureEncoder;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.base.Preconditions;
+import org.apache.htrace.core.TraceScope;
 
 
 /**
@@ -87,7 +86,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
       try {
         return queues.get(i).take();
       } catch(InterruptedException ie) {
-        throw DFSUtil.toInterruptedIOException("take interrupted, i=" + i, ie);
+        throw DFSUtilClient.toInterruptedIOException("take interrupted, i=" + i, ie);
       }
     }
 
@@ -95,7 +94,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
       try {
         return queues.get(i).poll(100, TimeUnit.MILLISECONDS);
       } catch (InterruptedException e) {
-        throw DFSUtil.toInterruptedIOException("take interrupted, i=" + i, e);
+        throw DFSUtilClient.toInterruptedIOException("take interrupted, i=" + i, e);
       }
     }
 
@@ -187,7 +186,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
     CellBuffers(int numParityBlocks) throws InterruptedException{
       if (cellSize % bytesPerChecksum != 0) {
         throw new HadoopIllegalArgumentException("Invalid values: "
-            + DFSConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY + " (="
+            + HdfsClientConfigKeys.DFS_BYTES_PER_CHECKSUM_KEY + " (="
             + bytesPerChecksum + ") must divide cell size (=" + cellSize + ").");
       }
 
@@ -280,7 +279,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
     try {
       cellBuffers = new CellBuffers(numParityBlocks);
     } catch (InterruptedException ie) {
-      throw DFSUtil.toInterruptedIOException(
+      throw DFSUtilClient.toInterruptedIOException(
           "Failed to create cell buffers", ie);
     }
 
@@ -621,7 +620,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
           coordinator.wait(waitInterval);
           remaingTime -= Time.monotonicNow() - start;
         } catch (InterruptedException e) {
-          throw DFSUtil.toInterruptedIOException("Interrupted when waiting" +
+          throw DFSUtilClient.toInterruptedIOException("Interrupted when waiting" +
               " for results of updating striped streamers", e);
         }
       }
@@ -893,7 +892,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
       }
 
       closeThreads(false);
-      TraceScope scope = Trace.startSpan("completeFile", Sampler.NEVER);
+      TraceScope scope = dfsClient.getTracer().newScope("completeFile");
       try {
         completeFile(currentBlockGroup);
       } finally {
@@ -942,7 +941,7 @@ public class DFSStripedOutputStream extends DFSOutputStream {
     try {
       Thread.sleep(ms);
     } catch(InterruptedException ie) {
-      throw DFSUtil.toInterruptedIOException(
+      throw DFSUtilClient.toInterruptedIOException(
           "Sleep interrupted during " + op, ie);
     }
   }

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DFSUtilClient.java

@@ -25,6 +25,7 @@ import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.crypto.key.KeyProvider;
 import org.apache.hadoop.crypto.key.KeyProviderFactory;
 import org.apache.hadoop.fs.BlockLocation;
+import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
@@ -53,6 +54,7 @@ import org.slf4j.LoggerFactory;
 
 import javax.net.SocketFactory;
 import java.io.IOException;
+import java.io.InterruptedIOException;
 import java.io.UnsupportedEncodingException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
@@ -590,6 +592,29 @@ public class DFSUtilClient {
     }
   }
 
+  public static int getIoFileBufferSize(Configuration conf) {
+    return conf.getInt(
+        CommonConfigurationKeysPublic.IO_FILE_BUFFER_SIZE_KEY,
+        CommonConfigurationKeysPublic.IO_FILE_BUFFER_SIZE_DEFAULT);
+  }
+
+  public static int getSmallBufferSize(Configuration conf) {
+    return Math.min(getIoFileBufferSize(conf) / 2, 512);
+  }
+
+  /**
+   * Probe for HDFS Encryption being enabled; this uses the value of
+   * the option {@link HdfsClientConfigKeys#DFS_ENCRYPTION_KEY_PROVIDER_URI},
+   * returning true if that property contains a non-empty, non-whitespace
+   * string.
+   * @param conf configuration to probe
+   * @return true if encryption is considered enabled.
+   */
+  public static boolean isHDFSEncryptionEnabled(Configuration conf) {
+    return !conf.getTrimmed(
+        HdfsClientConfigKeys.DFS_ENCRYPTION_KEY_PROVIDER_URI, "").isEmpty();
+  }
+
   public static InetSocketAddress getNNAddress(String address) {
     return NetUtils.createSocketAddr(address,
         HdfsClientConfigKeys.DFS_NAMENODE_RPC_PORT_DEFAULT);
@@ -628,4 +653,11 @@ public class DFSUtilClient {
     return URI.create(HdfsConstants.HDFS_URI_SCHEME + "://"
         + namenode.getHostName() + portString);
   }
+
+  public static InterruptedIOException toInterruptedIOException(String message,
+      InterruptedException e) {
+    final InterruptedIOException iioe = new InterruptedIOException(message);
+    iioe.initCause(e);
+    return iioe;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java

@@ -39,9 +39,8 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.StorageType;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys.BlockWrite;
 import org.apache.hadoop.hdfs.client.impl.DfsClientConf;
@@ -73,12 +72,11 @@ import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.hadoop.util.Progressable;
 import org.apache.hadoop.util.Time;
-import org.apache.htrace.NullScope;
+import org.apache.htrace.core.Sampler;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.Span;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.SpanId;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.TraceInfo;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
@@ -86,6 +84,9 @@ import com.google.common.cache.LoadingCache;
 import com.google.common.cache.RemovalListener;
 import com.google.common.cache.RemovalNotification;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /*********************************************************************
  *
  * The DataStreamer class is responsible for sending data packets to the
@@ -109,7 +110,7 @@ import com.google.common.cache.RemovalNotification;
 
 @InterfaceAudience.Private
 class DataStreamer extends Daemon {
-  static final Log LOG = LogFactory.getLog(DataStreamer.class);
+  static final Logger LOG = LoggerFactory.getLogger(DataStreamer.class);
 
   /**
    * Create a socket for a write pipeline
@@ -528,7 +529,7 @@ class DataStreamer extends Daemon {
   @Override
   public void run() {
     long lastPacket = Time.monotonicNow();
-    TraceScope scope = NullScope.INSTANCE;
+    TraceScope scope = null;
     while (!streamerClosed && dfsClient.clientRunning) {
       // if the Responder encountered an error, shutdown Responder
       if (errorState.hasError() && response != null) {
@@ -579,12 +580,11 @@ class DataStreamer extends Daemon {
               LOG.warn("Caught exception", e);
             }
             one = dataQueue.getFirst(); // regular data packet
-            long parents[] = one.getTraceParents();
+            SpanId[] parents = one.getTraceParents();
             if (parents.length > 0) {
-              scope = Trace.startSpan("dataStreamer", new TraceInfo(0, parents[0]));
+              scope = dfsClient.getTracer().
-              // TODO: use setParents API once it's available from HTrace 3.2
+                  newScope("dataStreamer", parents[0]);
-              // scope = Trace.startSpan("dataStreamer", Sampler.ALWAYS);
+              scope.getSpan().setParents(parents);
-              // scope.getSpan().setParents(parents);
             }
           }
         }
@@ -629,12 +629,16 @@ class DataStreamer extends Daemon {
         }
 
         // send the packet
-        Span span = null;
+        SpanId spanId = SpanId.INVALID;
         synchronized (dataQueue) {
           // move packet from dataQueue to ackQueue
           if (!one.isHeartbeatPacket()) {
-            span = scope.detach();
+            if (scope != null) {
-            one.setTraceSpan(span);
+              spanId = scope.getSpanId();
+              scope.detach();
+              one.setTraceScope(scope);
+            }
+            scope = null;
             dataQueue.removeFirst();
             ackQueue.addLast(one);
             dataQueue.notifyAll();
@@ -646,7 +650,8 @@ class DataStreamer extends Daemon {
         }
 
         // write out data to remote datanode
-        TraceScope writeScope = Trace.startSpan("writeTo", span);
+        TraceScope writeScope = dfsClient.getTracer().
+            newScope("DataStreamer#writeTo", spanId);
         try {
           one.writeTo(blockStream);
           blockStream.flush();
@@ -713,7 +718,10 @@ class DataStreamer extends Daemon {
           streamerClosed = true;
         }
       } finally {
+        if (scope != null) {
           scope.close();
+          scope = null;
+        }
       }
     }
     closeInternal();
@@ -747,7 +755,8 @@ class DataStreamer extends Daemon {
    * @throws IOException
    */
   void waitForAckedSeqno(long seqno) throws IOException {
-    TraceScope scope = Trace.startSpan("waitForAckedSeqno", Sampler.NEVER);
+    TraceScope scope = dfsClient.getTracer().
+        newScope("waitForAckedSeqno");
     try {
       if (LOG.isDebugEnabled()) {
         LOG.debug("Waiting for ack for: " + seqno);
@@ -797,7 +806,7 @@ class DataStreamer extends Daemon {
           while (!streamerClosed && dataQueue.size() + ackQueue.size() >
               dfsClient.getConf().getWriteMaxPackets()) {
             if (firstWait) {
-              Span span = Trace.currentSpan();
+              Span span = Tracer.getCurrentSpan();
               if (span != null) {
                 span.addTimelineAnnotation("dataQueue.wait");
               }
@@ -818,7 +827,7 @@ class DataStreamer extends Daemon {
             }
           }
         } finally {
-          Span span = Trace.currentSpan();
+          Span span = Tracer.getCurrentSpan();
           if ((span != null) && (!firstWait)) {
             span.addTimelineAnnotation("end.wait");
           }
@@ -953,7 +962,7 @@ class DataStreamer extends Daemon {
       setName("ResponseProcessor for block " + block);
       PipelineAck ack = new PipelineAck();
 
-      TraceScope scope = NullScope.INSTANCE;
+      TraceScope scope = null;
       while (!responderClosed && dfsClient.clientRunning && !isLastPacketInBlock) {
         // process responses from datanodes.
         try {
@@ -1040,8 +1049,11 @@ class DataStreamer extends Daemon {
           block.setNumBytes(one.getLastByteOffsetBlock());
 
           synchronized (dataQueue) {
-            scope = Trace.continueSpan(one.getTraceSpan());
+            scope = one.getTraceScope();
-            one.setTraceSpan(null);
+            if (scope != null) {
+              scope.reattach();
+              one.setTraceScope(null);
+            }
             lastAckedSeqno = seqno;
             ackQueue.removeFirst();
             dataQueue.notifyAll();
@@ -1062,8 +1074,11 @@ class DataStreamer extends Daemon {
             responderClosed = true;
           }
         } finally {
+          if (scope != null) {
             scope.close();
           }
+          scope = null;
+        }
       }
     }
 
@@ -1133,11 +1148,12 @@ class DataStreamer extends Daemon {
         // a client waiting on close() will be aware that the flush finished.
         synchronized (dataQueue) {
           DFSPacket endOfBlockPacket = dataQueue.remove();  // remove the end of block packet
-          Span span = endOfBlockPacket.getTraceSpan();
-          if (span != null) {
           // Close any trace span associated with this Packet
-            TraceScope scope = Trace.continueSpan(span);
+          TraceScope scope = endOfBlockPacket.getTraceScope();
+          if (scope != null) {
+            scope.reattach();
             scope.close();
+            endOfBlockPacket.setTraceScope(null);
           }
           assert endOfBlockPacket.isLastPacketInBlock();
           assert lastAckedSeqno == endOfBlockPacket.getSeqno() - 1;
@@ -1217,22 +1233,46 @@ class DataStreamer extends Daemon {
       return;
     }
 
-    //get a new datanode
+    int tried = 0;
     final DatanodeInfo[] original = nodes;
-    final LocatedBlock lb = dfsClient.namenode.getAdditionalDatanode(
+    final StorageType[] originalTypes = storageTypes;
+    final String[] originalIDs = storageIDs;
+    IOException caughtException = null;
+    ArrayList<DatanodeInfo> exclude = new ArrayList<DatanodeInfo>(failed);
+    while (tried < 3) {
+      LocatedBlock lb;
+      //get a new datanode
+      lb = dfsClient.namenode.getAdditionalDatanode(
           src, stat.getFileId(), block, nodes, storageIDs,
-        failed.toArray(new DatanodeInfo[failed.size()]),
+          exclude.toArray(new DatanodeInfo[exclude.size()]),
           1, dfsClient.clientName);
+      // a new node was allocated by the namenode. Update nodes.
       setPipeline(lb);
 
       //find the new datanode
       final int d = findNewDatanode(original);
-
+      //transfer replica. pick a source from the original nodes
-    //transfer replica
+      final DatanodeInfo src = original[tried % original.length];
-    final DatanodeInfo src = d == 0? nodes[1]: nodes[d - 1];
       final DatanodeInfo[] targets = {nodes[d]};
       final StorageType[] targetStorageTypes = {storageTypes[d]};
+
+      try {
         transfer(src, targets, targetStorageTypes, lb.getBlockToken());
+      } catch (IOException ioe) {
+        DFSClient.LOG.warn("Error transferring data from " + src + " to " +
+            nodes[d] + ": " + ioe.getMessage());
+        caughtException = ioe;
+        // add the allocated node to the exclude list.
+        exclude.add(nodes[d]);
+        setPipeline(original, originalTypes, originalIDs);
+        tried++;
+        continue;
+      }
+      return; // finished successfully
+    }
+    // All retries failed
+    throw (caughtException != null) ? caughtException :
+        new IOException("Failed to add a node");
   }
 
   private void transfer(final DatanodeInfo src, final DatanodeInfo[] targets,
@@ -1245,7 +1285,11 @@ class DataStreamer extends Daemon {
     try {
       sock = createSocketForPipeline(src, 2, dfsClient);
       final long writeTimeout = dfsClient.getDatanodeWriteTimeout(2);
-      final long readTimeout = dfsClient.getDatanodeReadTimeout(2);
+
+      // transfer timeout multiplier based on the transfer size
+      // One per 200 packets = 12.8MB. Minimum is 2.
+      int multi = 2 + (int)(bytesSent/dfsClient.getConf().getWritePacketSize())/200;
+      final long readTimeout = dfsClient.getDatanodeReadTimeout(multi);
 
       OutputStream unbufOut = NetUtils.getOutputStream(sock, writeTimeout);
       InputStream unbufIn = NetUtils.getInputStream(sock, readTimeout);
@@ -1254,7 +1298,7 @@ class DataStreamer extends Daemon {
       unbufOut = saslStreams.out;
       unbufIn = saslStreams.in;
       out = new DataOutputStream(new BufferedOutputStream(unbufOut,
-          DFSUtil.getSmallBufferSize(dfsClient.getConfiguration())));
+          DFSUtilClient.getSmallBufferSize(dfsClient.getConfiguration())));
       in = new DataInputStream(unbufIn);
 
       //send the TRANSFER_BLOCK request
@@ -1528,7 +1572,7 @@ class DataStreamer extends Daemon {
         unbufOut = saslStreams.out;
         unbufIn = saslStreams.in;
         out = new DataOutputStream(new BufferedOutputStream(unbufOut,
-            DFSUtil.getSmallBufferSize(dfsClient.getConfiguration())));
+            DFSUtilClient.getSmallBufferSize(dfsClient.getConfiguration())));
         blockReplyStream = new DataInputStream(unbufIn);
 
         //
@@ -1738,7 +1782,7 @@ class DataStreamer extends Daemon {
   void queuePacket(DFSPacket packet) {
     synchronized (dataQueue) {
       if (packet == null) return;
-      packet.addTraceParent(Trace.currentSpan());
+      packet.addTraceParent(Tracer.getCurrentSpanId());
       dataQueue.addLast(packet);
       lastQueuedSeqno = packet.getSeqno();
       if (LOG.isDebugEnabled()) {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DistributedFileSystem.java

@@ -62,7 +62,6 @@ import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.fs.permission.FsAction;
 import org.apache.hadoop.fs.StorageType;
-import org.apache.hadoop.hdfs.client.HdfsAdmin;
 import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
 import org.apache.hadoop.hdfs.client.HdfsDataOutputStream;
 import org.apache.hadoop.hdfs.client.impl.CorruptFileBlockIterator;
@@ -110,13 +109,13 @@ public class DistributedFileSystem extends FileSystem {
   private Path workingDir;
   private URI uri;
   private String homeDirPrefix =
-      DFSConfigKeys.DFS_USER_HOME_DIR_PREFIX_DEFAULT;
+      HdfsClientConfigKeys.DFS_USER_HOME_DIR_PREFIX_DEFAULT;
 
   DFSClient dfs;
   private boolean verifyChecksum = true;
   
   static{
-    HdfsConfiguration.init();
+    HdfsConfigurationLoader.init();
   }
 
   public DistributedFileSystem() {
@@ -146,8 +145,8 @@ public class DistributedFileSystem extends FileSystem {
       throw new IOException("Incomplete HDFS URI, no host: "+ uri);
     }
     homeDirPrefix = conf.get(
-        DFSConfigKeys.DFS_USER_HOME_DIR_PREFIX_KEY,
+        HdfsClientConfigKeys.DFS_USER_HOME_DIR_PREFIX_KEY,
-        DFSConfigKeys.DFS_USER_HOME_DIR_PREFIX_DEFAULT);
+        HdfsClientConfigKeys.DFS_USER_HOME_DIR_PREFIX_DEFAULT);
 
     this.dfs = new DFSClient(uri, conf, statistics);
     this.uri = URI.create(uri.getScheme()+"://"+uri.getAuthority());
@@ -172,7 +171,7 @@ public class DistributedFileSystem extends FileSystem {
   @Override
   public void setWorkingDirectory(Path dir) {
     String result = fixRelativePart(dir).toUri().getPath();
-    if (!DFSUtil.isValidName(result)) {
+    if (!DFSUtilClient.isValidName(result)) {
       throw new IllegalArgumentException("Invalid DFS directory name " + 
                                          result);
     }
@@ -196,7 +195,7 @@ public class DistributedFileSystem extends FileSystem {
   private String getPathName(Path file) {
     checkPath(file);
     String result = file.toUri().getPath();
-    if (!DFSUtil.isValidName(result)) {
+    if (!DFSUtilClient.isValidName(result)) {
       throw new IllegalArgumentException("Pathname " + result + " from " +
                                          file+" is not a valid DFS filename.");
     }
@@ -219,8 +218,7 @@ public class DistributedFileSystem extends FileSystem {
     final Path absF = fixRelativePart(p);
     return new FileSystemLinkResolver<BlockLocation[]>() {
       @Override
-      public BlockLocation[] doCall(final Path p)
+      public BlockLocation[] doCall(final Path p) throws IOException {
-          throws IOException, UnresolvedLinkException {
         return dfs.getBlockLocations(getPathName(p), start, len);
       }
       @Override
@@ -449,7 +447,6 @@ public class DistributedFileSystem extends FileSystem {
    * Same as create(), except fails if parent directory doesn't already exist.
    */
   @Override
-  @SuppressWarnings("deprecation")
   public FSDataOutputStream createNonRecursive(final Path f,
       final FsPermission permission, final EnumSet<CreateFlag> flag,
       final int bufferSize, final short replication, final long blockSize,

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/ExternalBlockReader.java

@@ -46,6 +46,9 @@ public final class ExternalBlockReader implements BlockReader {
   @Override
   public int read(byte[] buf, int off, int len) throws IOException {
     int nread = accessor.read(pos, buf, off, len);
+    if (nread < 0) {
+      return nread;
+    }
     pos += nread;
     return nread;
   }
@@ -53,6 +56,9 @@ public final class ExternalBlockReader implements BlockReader {
   @Override
   public int read(ByteBuffer buf) throws IOException {
     int nread = accessor.read(pos, buf);
+    if (nread < 0) {
+      return nread;
+    }
     pos += nread;
     return nread;
   }
@@ -63,7 +69,8 @@ public final class ExternalBlockReader implements BlockReader {
     if (n <= 0) {
       return 0;
     }
-    // You can't skip past the end of the replica.
+    // You can't skip past the last offset that we want to read with this
+    // block reader.
     long oldPos = pos;
     pos += n;
     if (pos > visibleLength) {
@@ -74,12 +81,11 @@ public final class ExternalBlockReader implements BlockReader {
 
   @Override
   public int available() throws IOException {
-    // We return the amount of bytes that we haven't read yet from the
+    // We return the amount of bytes between the current offset and the visible
-    // replica, based on our current position.  Some of the other block
+    // length.  Some of the other block readers return a shorter length than
-    // readers return a shorter length than that.  The only advantage to
+    // that.  The only advantage to returning a shorter length is that the
-    // returning a shorter length is that the DFSInputStream will
+    // DFSInputStream will trash your block reader and create a new one if
-    // trash your block reader and create a new one if someone tries to
+    // someone tries to seek() beyond the available() region.
-    // seek() beyond the available() region.
     long diff = visibleLength - pos;
     if (diff > Integer.MAX_VALUE) {
       return Integer.MAX_VALUE;

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/HdfsConfigurationLoader.java

@@ -0,0 +1,44 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.conf.Configuration;
+
+/**
+ * Load default HDFS configuration resources.
+ */
+@InterfaceAudience.Private
+class HdfsConfigurationLoader {
+
+  static {
+    // adds the default resources
+    Configuration.addDefaultResource("hdfs-default.xml");
+    Configuration.addDefaultResource("hdfs-site.xml");
+  }
+
+  /**
+   * This method is here so that when invoked, default resources are added if
+   * they haven't already been previously loaded.  Upon loading this class, the
+   * static initializer block above will be executed to add the default
+   * resources. It is safe for this method to be called multiple times
+   * as the static initializer block will only get invoked once.
+   */
+  public static void init() {
+  }
+}

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/NameNodeProxiesClient.java

@@ -0,0 +1,366 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.hdfs;
+
+import java.io.IOException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Proxy;
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.client.HdfsClientConfigKeys;
+import org.apache.hadoop.hdfs.client.impl.DfsClientConf;
+import org.apache.hadoop.hdfs.protocol.ClientProtocol;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants;
+import org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolPB;
+import org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB;
+import org.apache.hadoop.hdfs.server.namenode.SafeModeException;
+import org.apache.hadoop.hdfs.server.namenode.ha.AbstractNNFailoverProxyProvider;
+import org.apache.hadoop.hdfs.server.namenode.ha.WrappedFailoverProxyProvider;
+import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.retry.DefaultFailoverProxyProvider;
+import org.apache.hadoop.io.retry.FailoverProxyProvider;
+import org.apache.hadoop.io.retry.LossyRetryInvocationHandler;
+import org.apache.hadoop.io.retry.RetryPolicies;
+import org.apache.hadoop.io.retry.RetryPolicy;
+import org.apache.hadoop.io.retry.RetryProxy;
+import org.apache.hadoop.io.retry.RetryUtils;
+import org.apache.hadoop.ipc.ProtobufRpcEngine;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.net.NetUtils;
+import org.apache.hadoop.security.SecurityUtil;
+import org.apache.hadoop.security.UserGroupInformation;
+
+/**
+ * Create proxy objects with {@link ClientProtocol} to communicate with a remote
+ * NN. Generally use {@link NameNodeProxiesClient#createProxyWithClientProtocol(
+ * Configuration, URI, AtomicBoolean)}, which will create either an HA- or
+ * non-HA-enabled client proxy as appropriate.
+ *
+ * For creating proxy objects with other protocols, please see
+ * {@link NameNodeProxies#createProxy(Configuration, URI, Class)}.
+ */
+@InterfaceAudience.Private
+public class NameNodeProxiesClient {
+
+  private static final Logger LOG = LoggerFactory.getLogger(
+      NameNodeProxiesClient.class);
+
+  /**
+   * Wrapper for a client proxy as well as its associated service ID.
+   * This is simply used as a tuple-like return type for created NN proxy.
+   */
+  public static class ProxyAndInfo<PROXYTYPE> {
+    private final PROXYTYPE proxy;
+    private final Text dtService;
+    private final InetSocketAddress address;
+
+    public ProxyAndInfo(PROXYTYPE proxy, Text dtService,
+                        InetSocketAddress address) {
+      this.proxy = proxy;
+      this.dtService = dtService;
+      this.address = address;
+    }
+
+    public PROXYTYPE getProxy() {
+      return proxy;
+    }
+
+    public Text getDelegationTokenService() {
+      return dtService;
+    }
+
+    public InetSocketAddress getAddress() {
+      return address;
+    }
+  }
+
+  /**
+   * Creates the namenode proxy with the ClientProtocol. This will handle
+   * creation of either HA- or non-HA-enabled proxy objects, depending upon
+   * if the provided URI is a configured logical URI.
+   *
+   * @param conf the configuration containing the required IPC
+   *        properties, client failover configurations, etc.
+   * @param nameNodeUri the URI pointing either to a specific NameNode
+   *        or to a logical nameservice.
+   * @param fallbackToSimpleAuth set to true or false during calls to indicate
+   *        if a secure client falls back to simple auth
+   * @return an object containing both the proxy and the associated
+   *         delegation token service it corresponds to
+   * @throws IOException if there is an error creating the proxy
+   * @see {@link NameNodeProxies#createProxy(Configuration, URI, Class)}.
+   */
+  public static ProxyAndInfo<ClientProtocol> createProxyWithClientProtocol(
+      Configuration conf, URI nameNodeUri, AtomicBoolean fallbackToSimpleAuth)
+      throws IOException {
+    AbstractNNFailoverProxyProvider<ClientProtocol> failoverProxyProvider =
+        createFailoverProxyProvider(conf, nameNodeUri, ClientProtocol.class,
+            true, fallbackToSimpleAuth);
+
+    if (failoverProxyProvider == null) {
+      InetSocketAddress nnAddr = DFSUtilClient.getNNAddress(nameNodeUri);
+      Text dtService = SecurityUtil.buildTokenService(nnAddr);
+      ClientProtocol proxy = createNonHAProxyWithClientProtocol(nnAddr, conf,
+          UserGroupInformation.getCurrentUser(), true, fallbackToSimpleAuth);
+      return new ProxyAndInfo<>(proxy, dtService, nnAddr);
+    } else {
+      return createHAProxy(conf, nameNodeUri, ClientProtocol.class,
+          failoverProxyProvider);
+    }
+  }
+
+  /**
+   * Generate a dummy namenode proxy instance that utilizes our hacked
+   * {@link LossyRetryInvocationHandler}. Proxy instance generated using this
+   * method will proactively drop RPC responses. Currently this method only
+   * support HA setup. null will be returned if the given configuration is not
+   * for HA.
+   *
+   * @param config the configuration containing the required IPC
+   *        properties, client failover configurations, etc.
+   * @param nameNodeUri the URI pointing either to a specific NameNode
+   *        or to a logical nameservice.
+   * @param xface the IPC interface which should be created
+   * @param numResponseToDrop The number of responses to drop for each RPC call
+   * @param fallbackToSimpleAuth set to true or false during calls to indicate
+   *        if a secure client falls back to simple auth
+   * @return an object containing both the proxy and the associated
+   *         delegation token service it corresponds to. Will return null of the
+   *         given configuration does not support HA.
+   * @throws IOException if there is an error creating the proxy
+   */
+  public static <T> ProxyAndInfo<T> createProxyWithLossyRetryHandler(
+      Configuration config, URI nameNodeUri, Class<T> xface,
+      int numResponseToDrop, AtomicBoolean fallbackToSimpleAuth)
+      throws IOException {
+    Preconditions.checkArgument(numResponseToDrop > 0);
+    AbstractNNFailoverProxyProvider<T> failoverProxyProvider =
+        createFailoverProxyProvider(config, nameNodeUri, xface, true,
+            fallbackToSimpleAuth);
+
+    if (failoverProxyProvider != null) { // HA case
+      int delay = config.getInt(
+          HdfsClientConfigKeys.Failover.SLEEPTIME_BASE_KEY,
+          HdfsClientConfigKeys.Failover.SLEEPTIME_BASE_DEFAULT);
+      int maxCap = config.getInt(
+          HdfsClientConfigKeys.Failover.SLEEPTIME_MAX_KEY,
+          HdfsClientConfigKeys.Failover.SLEEPTIME_MAX_DEFAULT);
+      int maxFailoverAttempts = config.getInt(
+          HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_KEY,
+          HdfsClientConfigKeys.Failover.MAX_ATTEMPTS_DEFAULT);
+      int maxRetryAttempts = config.getInt(
+          HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_KEY,
+          HdfsClientConfigKeys.Retry.MAX_ATTEMPTS_DEFAULT);
+      InvocationHandler dummyHandler = new LossyRetryInvocationHandler<>(
+              numResponseToDrop, failoverProxyProvider,
+              RetryPolicies.failoverOnNetworkException(
+                  RetryPolicies.TRY_ONCE_THEN_FAIL, maxFailoverAttempts,
+                  Math.max(numResponseToDrop + 1, maxRetryAttempts), delay,
+                  maxCap));
+
+      @SuppressWarnings("unchecked")
+      T proxy = (T) Proxy.newProxyInstance(
+          failoverProxyProvider.getInterface().getClassLoader(),
+          new Class[]{xface}, dummyHandler);
+      Text dtService;
+      if (failoverProxyProvider.useLogicalURI()) {
+        dtService = HAUtilClient.buildTokenServiceForLogicalUri(nameNodeUri,
+            HdfsConstants.HDFS_URI_SCHEME);
+      } else {
+        dtService = SecurityUtil.buildTokenService(
+            DFSUtilClient.getNNAddress(nameNodeUri));
+      }
+      return new ProxyAndInfo<>(proxy, dtService,
+          DFSUtilClient.getNNAddress(nameNodeUri));
+    } else {
+      LOG.warn("Currently creating proxy using " +
+          "LossyRetryInvocationHandler requires NN HA setup");
+      return null;
+    }
+  }
+
+  /** Creates the Failover proxy provider instance*/
+  @VisibleForTesting
+  public static <T> AbstractNNFailoverProxyProvider<T> createFailoverProxyProvider(
+      Configuration conf, URI nameNodeUri, Class<T> xface, boolean checkPort,
+      AtomicBoolean fallbackToSimpleAuth) throws IOException {
+    Class<FailoverProxyProvider<T>> failoverProxyProviderClass = null;
+    AbstractNNFailoverProxyProvider<T> providerNN;
+    try {
+      // Obtain the class of the proxy provider
+      failoverProxyProviderClass = getFailoverProxyProviderClass(conf,
+          nameNodeUri);
+      if (failoverProxyProviderClass == null) {
+        return null;
+      }
+      // Create a proxy provider instance.
+      Constructor<FailoverProxyProvider<T>> ctor = failoverProxyProviderClass
+          .getConstructor(Configuration.class, URI.class, Class.class);
+      FailoverProxyProvider<T> provider = ctor.newInstance(conf, nameNodeUri,
+          xface);
+
+      // If the proxy provider is of an old implementation, wrap it.
+      if (!(provider instanceof AbstractNNFailoverProxyProvider)) {
+        providerNN = new WrappedFailoverProxyProvider<>(provider);
+      } else {
+        providerNN = (AbstractNNFailoverProxyProvider<T>)provider;
+      }
+    } catch (Exception e) {
+      final String message = "Couldn't create proxy provider " +
+          failoverProxyProviderClass;
+      LOG.debug(message, e);
+      if (e.getCause() instanceof IOException) {
+        throw (IOException) e.getCause();
+      } else {
+        throw new IOException(message, e);
+      }
+    }
+
+    // Check the port in the URI, if it is logical.
+    if (checkPort && providerNN.useLogicalURI()) {
+      int port = nameNodeUri.getPort();
+      if (port > 0 &&
+          port != HdfsClientConfigKeys.DFS_NAMENODE_RPC_PORT_DEFAULT) {
+        // Throwing here without any cleanup is fine since we have not
+        // actually created the underlying proxies yet.
+        throw new IOException("Port " + port + " specified in URI "
+            + nameNodeUri + " but host '" + nameNodeUri.getHost()
+            + "' is a logical (HA) namenode"
+            + " and does not use port information.");
+      }
+    }
+    providerNN.setFallbackToSimpleAuth(fallbackToSimpleAuth);
+    return providerNN;
+  }
+
+  /** Gets the configured Failover proxy provider's class */
+  @VisibleForTesting
+  public static <T> Class<FailoverProxyProvider<T>> getFailoverProxyProviderClass(
+      Configuration conf, URI nameNodeUri) throws IOException {
+    if (nameNodeUri == null) {
+      return null;
+    }
+    String host = nameNodeUri.getHost();
+    String configKey = HdfsClientConfigKeys.Failover.PROXY_PROVIDER_KEY_PREFIX
+        + "." + host;
+    try {
+      @SuppressWarnings("unchecked")
+      Class<FailoverProxyProvider<T>> ret = (Class<FailoverProxyProvider<T>>)
+          conf.getClass(configKey, null, FailoverProxyProvider.class);
+      return ret;
+    } catch (RuntimeException e) {
+      if (e.getCause() instanceof ClassNotFoundException) {
+        throw new IOException("Could not load failover proxy provider class "
+            + conf.get(configKey) + " which is configured for authority "
+            + nameNodeUri, e);
+      } else {
+        throw e;
+      }
+    }
+  }
+
+  /**
+   * Creates an explicitly HA-enabled proxy object.
+   *
+   * @param conf the configuration object
+   * @param nameNodeUri the URI pointing either to a specific NameNode or to a
+   *        logical nameservice.
+   * @param xface the IPC interface which should be created
+   * @param failoverProxyProvider Failover proxy provider
+   * @return an object containing both the proxy and the associated
+   *         delegation token service it corresponds to
+   * @throws IOException
+   */
+  @SuppressWarnings("unchecked")
+  public static <T> ProxyAndInfo<T> createHAProxy(
+      Configuration conf, URI nameNodeUri, Class<T> xface,
+      AbstractNNFailoverProxyProvider<T> failoverProxyProvider)
+      throws IOException {
+    Preconditions.checkNotNull(failoverProxyProvider);
+    // HA case
+    DfsClientConf config = new DfsClientConf(conf);
+    T proxy = (T) RetryProxy.create(xface, failoverProxyProvider,
+        RetryPolicies.failoverOnNetworkException(
+            RetryPolicies.TRY_ONCE_THEN_FAIL, config.getMaxFailoverAttempts(),
+            config.getMaxRetryAttempts(), config.getFailoverSleepBaseMillis(),
+            config.getFailoverSleepMaxMillis()));
+
+    Text dtService;
+    if (failoverProxyProvider.useLogicalURI()) {
+      dtService = HAUtilClient.buildTokenServiceForLogicalUri(nameNodeUri,
+          HdfsConstants.HDFS_URI_SCHEME);
+    } else {
+      dtService = SecurityUtil.buildTokenService(
+          DFSUtilClient.getNNAddress(nameNodeUri));
+    }
+    return new ProxyAndInfo<>(proxy, dtService,
+        DFSUtilClient.getNNAddress(nameNodeUri));
+  }
+
+  public static ClientProtocol createNonHAProxyWithClientProtocol(
+      InetSocketAddress address, Configuration conf, UserGroupInformation ugi,
+      boolean withRetries, AtomicBoolean fallbackToSimpleAuth)
+      throws IOException {
+    RPC.setProtocolEngine(conf, ClientNamenodeProtocolPB.class,
+        ProtobufRpcEngine.class);
+
+    final RetryPolicy defaultPolicy =
+        RetryUtils.getDefaultRetryPolicy(
+            conf,
+            HdfsClientConfigKeys.Retry.POLICY_ENABLED_KEY,
+            HdfsClientConfigKeys.Retry.POLICY_ENABLED_DEFAULT,
+            HdfsClientConfigKeys.Retry.POLICY_SPEC_KEY,
+            HdfsClientConfigKeys.Retry.POLICY_SPEC_DEFAULT,
+            SafeModeException.class.getName());
+
+    final long version = RPC.getProtocolVersion(ClientNamenodeProtocolPB.class);
+    ClientNamenodeProtocolPB proxy = RPC.getProtocolProxy(
+        ClientNamenodeProtocolPB.class, version, address, ugi, conf,
+        NetUtils.getDefaultSocketFactory(conf),
+        org.apache.hadoop.ipc.Client.getTimeout(conf), defaultPolicy,
+        fallbackToSimpleAuth).getProxy();
+
+    if (withRetries) { // create the proxy with retries
+      Map<String, RetryPolicy> methodNameToPolicyMap = new HashMap<>();
+      ClientProtocol translatorProxy =
+          new ClientNamenodeProtocolTranslatorPB(proxy);
+      return (ClientProtocol) RetryProxy.create(
+          ClientProtocol.class,
+          new DefaultFailoverProxyProvider<>(ClientProtocol.class,
+              translatorProxy),
+          methodNameToPolicyMap,
+          defaultPolicy);
+    } else {
+      return new ClientNamenodeProtocolTranslatorPB(proxy);
+    }
+  }
+
+}

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader.java

@@ -47,9 +47,8 @@ import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -107,6 +106,8 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
   
   private final PeerCache peerCache;
 
+  private final Tracer tracer;
+  
   /* FSInputChecker interface */
   
   /* same interface as inputStream java.io.InputStream#read()
@@ -210,9 +211,8 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
   protected synchronized int readChunk(long pos, byte[] buf, int offset, 
                                        int len, byte[] checksumBuf) 
                                        throws IOException {
-    TraceScope scope =
+    TraceScope scope = tracer.
-        Trace.startSpan("RemoteBlockReader#readChunk(" + blockId + ")",
+        newScope("RemoteBlockReader#readChunk(" + blockId + ")");
-            Sampler.NEVER);
     try {
       return readChunkImpl(pos, buf, offset, len, checksumBuf);
     } finally {
@@ -346,7 +346,7 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
   private RemoteBlockReader(String file, String bpid, long blockId,
       DataInputStream in, DataChecksum checksum, boolean verifyChecksum,
       long startOffset, long firstChunkOffset, long bytesToRead, Peer peer,
-      DatanodeID datanodeID, PeerCache peerCache) {
+      DatanodeID datanodeID, PeerCache peerCache, Tracer tracer) {
     // Path is used only for printing block and file information in debug
     super(new Path("/" + Block.BLOCK_FILE_PREFIX + blockId +
                     ":" + bpid + ":of:"+ file)/*too non path-like?*/,
@@ -378,6 +378,7 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
     bytesPerChecksum = this.checksum.getBytesPerChecksum();
     checksumSize = this.checksum.getChecksumSize();
     this.peerCache = peerCache;
+    this.tracer = tracer;
   }
 
   /**
@@ -402,7 +403,8 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
                                      String clientName, Peer peer,
                                      DatanodeID datanodeID,
                                      PeerCache peerCache,
-                                     CachingStrategy cachingStrategy)
+                                     CachingStrategy cachingStrategy,
+                                     Tracer tracer)
                                        throws IOException {
     // in and out will be closed when sock is closed (by the caller)
     final DataOutputStream out =
@@ -438,7 +440,7 @@ public class RemoteBlockReader extends FSInputChecker implements BlockReader {
 
     return new RemoteBlockReader(file, block.getBlockPoolId(), block.getBlockId(),
         in, checksum, verifyChecksum, startOffset, firstChunkOffset, len,
-        peer, datanodeID, peerCache);
+        peer, datanodeID, peerCache, tracer);
   }
 
   @Override

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/RemoteBlockReader2.java

@@ -48,12 +48,11 @@ import org.apache.hadoop.hdfs.shortcircuit.ClientMmap;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.annotations.VisibleForTesting;
 
+import org.apache.htrace.core.Tracer;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -126,6 +125,8 @@ public class RemoteBlockReader2  implements BlockReader {
 
   private boolean sentStatusCode = false;
 
+  private final Tracer tracer;
+
   @VisibleForTesting
   public Peer getPeer() {
     return peer;
@@ -144,8 +145,8 @@ public class RemoteBlockReader2  implements BlockReader {
     }
 
     if (curDataSlice == null || curDataSlice.remaining() == 0 && bytesNeededToFinish > 0) {
-      TraceScope scope = Trace.startSpan(
+      TraceScope scope = tracer.newScope(
-          "RemoteBlockReader2#readNextPacket(" + blockId + ")", Sampler.NEVER);
+          "RemoteBlockReader2#readNextPacket(" + blockId + ")");
       try {
         readNextPacket();
       } finally {
@@ -172,8 +173,8 @@ public class RemoteBlockReader2  implements BlockReader {
   @Override
   public synchronized int read(ByteBuffer buf) throws IOException {
     if (curDataSlice == null || curDataSlice.remaining() == 0 && bytesNeededToFinish > 0) {
-      TraceScope scope = Trace.startSpan(
+      TraceScope scope = tracer.newScope(
-          "RemoteBlockReader2#readNextPacket(" + blockId + ")", Sampler.NEVER);
+          "RemoteBlockReader2#readNextPacket(" + blockId + ")");
       try {
         readNextPacket();
       } finally {
@@ -292,7 +293,7 @@ public class RemoteBlockReader2  implements BlockReader {
   protected RemoteBlockReader2(String file, String bpid, long blockId,
       DataChecksum checksum, boolean verifyChecksum,
       long startOffset, long firstChunkOffset, long bytesToRead, Peer peer,
-      DatanodeID datanodeID, PeerCache peerCache) {
+      DatanodeID datanodeID, PeerCache peerCache, Tracer tracer) {
     this.isLocal = DFSUtilClient.isLocalAddress(NetUtils.
         createSocketAddr(datanodeID.getXferAddr()));
     // Path is used only for printing block and file information in debug
@@ -313,6 +314,7 @@ public class RemoteBlockReader2  implements BlockReader {
     this.bytesNeededToFinish = bytesToRead + (startOffset - firstChunkOffset);
     bytesPerChecksum = this.checksum.getBytesPerChecksum();
     checksumSize = this.checksum.getChecksumSize();
+    this.tracer = tracer;
   }
 
 
@@ -407,7 +409,8 @@ public class RemoteBlockReader2  implements BlockReader {
                                      String clientName,
                                      Peer peer, DatanodeID datanodeID,
                                      PeerCache peerCache,
-                                     CachingStrategy cachingStrategy) throws IOException {
+                                     CachingStrategy cachingStrategy,
+                                     Tracer tracer) throws IOException {
     // in and out will be closed when sock is closed (by the caller)
     final DataOutputStream out = new DataOutputStream(new BufferedOutputStream(
           peer.getOutputStream()));
@@ -440,7 +443,7 @@ public class RemoteBlockReader2  implements BlockReader {
 
     return new RemoteBlockReader2(file, block.getBlockPoolId(), block.getBlockId(),
         checksum, verifyChecksum, startOffset, firstChunkOffset, len, peer,
-        datanodeID, peerCache);
+        datanodeID, peerCache, tracer);
   }
 
   static void checkSuccess(

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/ReplicaAccessor.java

@@ -40,8 +40,9 @@ public abstract class ReplicaAccessor {
    *
    * @return       The number of bytes read.  If the read extends past the end
    *                  of the replica, a short read count will be returned.  We
-   *                  will never return a negative number.  We will never
+   *                  will should return -1 if EOF is reached and no bytes
-   *                  return a short read count unless EOF is reached.
+   *                  can be returned.  We will never return a short read
+   *                  count unless EOF is reached.
    */
   public abstract int read(long pos, byte[] buf, int off, int len)
       throws IOException;
@@ -58,8 +59,9 @@ public abstract class ReplicaAccessor {
    *
    * @return       The number of bytes read.  If the read extends past the end
    *                 of the replica, a short read count will be returned.  We
-   *                 will never return a negative number.  We will never return
+   *                 should return -1 if EOF is reached and no bytes can be
-   *                 a short read count unless EOF is reached.
+   *                 returned.  We will never return a short read count unless
+   *                 EOF is reached.
    */
   public abstract int read(long pos, ByteBuffer buf) throws IOException;
 

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/ReplicaAccessorBuilder.java

@@ -36,6 +36,9 @@ public abstract class ReplicaAccessorBuilder {
   public abstract ReplicaAccessorBuilder
       setBlock(long blockId, String blockPoolId);
 
+  /** Set the genstamp of the block which is being opened. */
+  public abstract ReplicaAccessorBuilder setGenerationStamp(long genstamp);
+
   /**
    * Set whether checksums must be verified.  Checksums should be skipped if
    * the user has disabled checksum verification in the configuration.  Users

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/HdfsClientConfigKeys.java

@@ -143,6 +143,17 @@ public interface HdfsClientConfigKeys {
   String REPLICA_ACCESSOR_BUILDER_CLASSES_KEY =
       PREFIX + "replica.accessor.builder.classes";
 
+  // The number of NN response dropped by client proactively in each RPC call.
+  // For testing NN retry cache, we can set this property with positive value.
+  String  DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_KEY =
+      "dfs.client.test.drop.namenode.response.number";
+  int     DFS_CLIENT_TEST_DROP_NAMENODE_RESPONSE_NUM_DEFAULT = 0;
+  String  DFS_CLIENT_LOCAL_INTERFACES = "dfs.client.local.interfaces";
+  // HDFS client HTrace configuration.
+  String  DFS_CLIENT_HTRACE_PREFIX = "dfs.client.htrace.";
+  String  DFS_USER_HOME_DIR_PREFIX_KEY = "dfs.user.home.dir.prefix";
+  String  DFS_USER_HOME_DIR_PREFIX_DEFAULT = "/user";
+
   /** dfs.client.retry configuration properties */
   interface Retry {
     String PREFIX = HdfsClientConfigKeys.PREFIX + "retry.";

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/impl/LeaseRenewer.java

@@ -27,18 +27,18 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hdfs.DFSClient;
 import org.apache.hadoop.hdfs.DFSOutputStream;
-import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
+import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.util.Daemon;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Time;
 import com.google.common.annotations.VisibleForTesting;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * <p>
@@ -73,7 +73,7 @@ import com.google.common.annotations.VisibleForTesting;
  */
 @InterfaceAudience.Private
 public class LeaseRenewer {
-  static final Log LOG = LogFactory.getLog(LeaseRenewer.class);
+  static final Logger LOG = LoggerFactory.getLogger(LeaseRenewer.class);
 
   static final long LEASE_RENEWER_GRACE_DEFAULT = 60*1000L;
   static final long LEASE_RENEWER_SLEEP_DEFAULT = 1000L;
@@ -165,7 +165,7 @@ public class LeaseRenewer {
   /** The time in milliseconds that the map became empty. */
   private long emptyTime = Long.MAX_VALUE;
   /** A fixed lease renewal time period in milliseconds */
-  private long renewal = HdfsServerConstants.LEASE_SOFTLIMIT_PERIOD/2;
+  private long renewal = HdfsConstants.LEASE_SOFTLIMIT_PERIOD / 2;
 
   /** A daemon for renewing lease */
   private Daemon daemon = null;
@@ -378,7 +378,7 @@ public class LeaseRenewer {
 
     //update renewal time
     if (renewal == dfsc.getConf().getHdfsTimeout()/2) {
-      long min = HdfsServerConstants.LEASE_SOFTLIMIT_PERIOD;
+      long min = HdfsConstants.LEASE_SOFTLIMIT_PERIOD;
       for(DFSClient c : dfsclients) {
         final int timeout = c.getConf().getHdfsTimeout();
         if (timeout > 0 && timeout < min) {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java

@@ -25,11 +25,10 @@ import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.BatchedRemoteIterator;
 import org.apache.hadoop.fs.InvalidRequestException;
 import org.apache.hadoop.ipc.RemoteException;
-import org.apache.htrace.Sampler;
-import org.apache.htrace.Trace;
-import org.apache.htrace.TraceScope;
 
 import com.google.common.base.Preconditions;
+import org.apache.htrace.core.TraceScope;
+import org.apache.htrace.core.Tracer;
 
 /**
  * CacheDirectiveIterator is a remote iterator that iterates cache directives.
@@ -42,14 +41,14 @@ public class CacheDirectiveIterator
 
   private CacheDirectiveInfo filter;
   private final ClientProtocol namenode;
-  private final Sampler<?> traceSampler;
+  private final Tracer tracer;
 
   public CacheDirectiveIterator(ClientProtocol namenode,
-      CacheDirectiveInfo filter, Sampler<?> traceSampler) {
+      CacheDirectiveInfo filter, Tracer tracer) {
     super(0L);
     this.namenode = namenode;
     this.filter = filter;
-    this.traceSampler = traceSampler;
+    this.tracer = tracer;
   }
 
   private static CacheDirectiveInfo removeIdFromFilter(CacheDirectiveInfo filter) {
@@ -94,7 +93,7 @@ public class CacheDirectiveIterator
   public BatchedEntries<CacheDirectiveEntry> makeRequest(Long prevKey)
       throws IOException {
     BatchedEntries<CacheDirectiveEntry> entries = null;
-    TraceScope scope = Trace.startSpan("listCacheDirectives", traceSampler);
+    TraceScope scope = tracer.newScope("listCacheDirectives");
     try {
       entries = namenode.listCacheDirectives(prevKey, filter);
     } catch (IOException e) {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/CachePoolIterator.java

@@ -23,9 +23,8 @@ import java.io.IOException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.BatchedRemoteIterator;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 
 /**
  * CachePoolIterator is a remote iterator that iterates cache pools.
@@ -37,18 +36,18 @@ public class CachePoolIterator
     extends BatchedRemoteIterator<String, CachePoolEntry> {
 
   private final ClientProtocol namenode;
-  private final Sampler traceSampler;
+  private final Tracer tracer;
 
-  public CachePoolIterator(ClientProtocol namenode, Sampler traceSampler) {
+  public CachePoolIterator(ClientProtocol namenode, Tracer tracer) {
     super("");
     this.namenode = namenode;
-    this.traceSampler = traceSampler;
+    this.tracer = tracer;
   }
 
   @Override
   public BatchedEntries<CachePoolEntry> makeRequest(String prevKey)
       throws IOException {
-    TraceScope scope = Trace.startSpan("listCachePools", traceSampler);
+    TraceScope scope = tracer.newScope("listCachePools");
     try {
       return namenode.listCachePools(prevKey);
     } finally {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/EncryptionZoneIterator.java

@@ -23,9 +23,8 @@ import java.io.IOException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.BatchedRemoteIterator;
-import org.apache.htrace.Sampler;
+import org.apache.htrace.core.TraceScope;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceScope;
 
 /**
  * EncryptionZoneIterator is a remote iterator that iterates over encryption
@@ -37,19 +36,18 @@ public class EncryptionZoneIterator
     extends BatchedRemoteIterator<Long, EncryptionZone> {
 
   private final ClientProtocol namenode;
-  private final Sampler<?> traceSampler;
+  private final Tracer tracer;
 
-  public EncryptionZoneIterator(ClientProtocol namenode,
+  public EncryptionZoneIterator(ClientProtocol namenode, Tracer tracer) {
-                                Sampler<?> traceSampler) {
     super(Long.valueOf(0));
     this.namenode = namenode;
-    this.traceSampler = traceSampler;
+    this.tracer = tracer;
   }
 
   @Override
   public BatchedEntries<EncryptionZone> makeRequest(Long prevId)
       throws IOException {
-    TraceScope scope = Trace.startSpan("listEncryptionZones", traceSampler);
+    TraceScope scope = tracer.newScope("listEncryptionZones");
     try {
       return namenode.listEncryptionZones(prevId);
     } finally {

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsConstants.java

@@ -93,6 +93,29 @@ public final class HdfsConstants {
   //for write pipeline
   public static final int WRITE_TIMEOUT_EXTENSION = 5 * 1000;
 
+  /**
+   * For a HDFS client to write to a file, a lease is granted; During the lease
+   * period, no other client can write to the file. The writing client can
+   * periodically renew the lease. When the file is closed, the lease is
+   * revoked. The lease duration is bound by this soft limit and a
+   * {@link HdfsConstants#LEASE_HARDLIMIT_PERIOD hard limit}. Until the
+   * soft limit expires, the writer has sole write access to the file. If the
+   * soft limit expires and the client fails to close the file or renew the
+   * lease, another client can preempt the lease.
+   */
+  public static final long LEASE_SOFTLIMIT_PERIOD = 60 * 1000;
+  /**
+   * For a HDFS client to write to a file, a lease is granted; During the lease
+   * period, no other client can write to the file. The writing client can
+   * periodically renew the lease. When the file is closed, the lease is
+   * revoked. The lease duration is bound by a
+   * {@link HdfsConstants#LEASE_SOFTLIMIT_PERIOD soft limit} and this hard
+   * limit. If after the hard limit expires and the client has failed to renew
+   * the lease, HDFS assumes that the client has quit and will automatically
+   * close the file on behalf of the writer, and recover the lease.
+   */
+  public static final long LEASE_HARDLIMIT_PERIOD = 60 * LEASE_SOFTLIMIT_PERIOD;
+
   // SafeMode actions
   public enum SafeModeAction {
     SAFEMODE_LEAVE, SAFEMODE_ENTER, SAFEMODE_GET

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/DataTransferProtoUtil.java

@@ -35,10 +35,8 @@ import org.apache.hadoop.hdfs.security.token.block.BlockTokenIdentifier;
 import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.SpanId;
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.Tracer;
-import org.apache.htrace.TraceInfo;
-import org.apache.htrace.TraceScope;
 
 /**
  * Static utilities for dealing with the protocol buffers used by the
@@ -89,39 +87,21 @@ public abstract class DataTransferProtoUtil {
     BaseHeaderProto.Builder builder =  BaseHeaderProto.newBuilder()
       .setBlock(PBHelperClient.convert(blk))
       .setToken(PBHelperClient.convert(blockToken));
-    if (Trace.isTracing()) {
+    SpanId spanId = Tracer.getCurrentSpanId();
-      Span s = Trace.currentSpan();
+    if (spanId.isValid()) {
       builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder()
-          .setTraceId(s.getTraceId())
+          .setTraceId(spanId.getHigh())
-          .setParentId(s.getSpanId()));
+          .setParentId(spanId.getLow()));
     }
     return builder.build();
   }
 
-  public static TraceInfo fromProto(DataTransferTraceInfoProto proto) {
+  public static SpanId fromProto(DataTransferTraceInfoProto proto) {
-    if (proto == null) return null;
+    if ((proto != null) && proto.hasTraceId() &&
-    if (!proto.hasTraceId()) return null;
+          proto.hasParentId()) {
-    return new TraceInfo(proto.getTraceId(), proto.getParentId());
+      return new SpanId(proto.getTraceId(), proto.getParentId());
     }
-
+    return null;
-  public static TraceScope continueTraceSpan(ClientOperationHeaderProto header,
-      String description) {
-    return continueTraceSpan(header.getBaseHeader(), description);
-  }
-
-  public static TraceScope continueTraceSpan(BaseHeaderProto header,
-      String description) {
-    return continueTraceSpan(header.getTraceInfo(), description);
-  }
-
-  public static TraceScope continueTraceSpan(DataTransferTraceInfoProto proto,
-      String description) {
-    TraceScope scope = null;
-    TraceInfo info = fromProto(proto);
-    if (info != null) {
-      scope = Trace.startSpan(description, info);
-    }
-    return scope;
   }
 
   public static void checkBlockOpStatus(
@@ -137,6 +117,7 @@ public abstract class DataTransferProtoUtil {
       } else {
         throw new IOException(
           "Got error"
+          + ", status=" + response.getStatus().name()
           + ", status message " + response.getMessage()
           + ", " + logInfo
         );

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/protocol/datatransfer/Sender.java

@@ -48,8 +48,8 @@ import org.apache.hadoop.hdfs.shortcircuit.ShortCircuitShm.SlotId;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.DataChecksum;
 
-import org.apache.htrace.Trace;
+import org.apache.htrace.core.SpanId;
-import org.apache.htrace.Span;
+import org.apache.htrace.core.Tracer;
 
 import com.google.protobuf.Message;
 
@@ -200,10 +200,11 @@ public class Sender implements DataTransferProtocol {
     ReleaseShortCircuitAccessRequestProto.Builder builder =
         ReleaseShortCircuitAccessRequestProto.newBuilder().
         setSlotId(PBHelperClient.convert(slotId));
-    if (Trace.isTracing()) {
+    SpanId spanId = Tracer.getCurrentSpanId();
-      Span s = Trace.currentSpan();
+    if (spanId.isValid()) {
-      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder()
+      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder().
-          .setTraceId(s.getTraceId()).setParentId(s.getSpanId()));
+          setTraceId(spanId.getHigh()).
+          setParentId(spanId.getLow()));
     }
     ReleaseShortCircuitAccessRequestProto proto = builder.build();
     send(out, Op.RELEASE_SHORT_CIRCUIT_FDS, proto);
@@ -214,10 +215,11 @@ public class Sender implements DataTransferProtocol {
     ShortCircuitShmRequestProto.Builder builder =
         ShortCircuitShmRequestProto.newBuilder().
         setClientName(clientName);
-    if (Trace.isTracing()) {
+    SpanId spanId = Tracer.getCurrentSpanId();
-      Span s = Trace.currentSpan();
+    if (spanId.isValid()) {
-      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder()
+      builder.setTraceInfo(DataTransferTraceInfoProto.newBuilder().
-          .setTraceId(s.getTraceId()).setParentId(s.getSpanId()));
+          setTraceId(spanId.getHigh()).
+          setParentId(spanId.getLow()));
     }
     ShortCircuitShmRequestProto proto = builder.build();
     send(out, Op.REQUEST_SHORT_CIRCUIT_SHM, proto);

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/AbstractNNFailoverProxyProvider.java

@@ -26,7 +26,7 @@ import org.apache.hadoop.io.retry.FailoverProxyProvider;
 public abstract class AbstractNNFailoverProxyProvider<T> implements
    FailoverProxyProvider <T> {
 
-  protected AtomicBoolean fallbackToSimpleAuth;
+  private AtomicBoolean fallbackToSimpleAuth;
 
   /**
    * Inquire whether logical HA URI is used for the implementation. If it is
@@ -48,4 +48,8 @@ public abstract class AbstractNNFailoverProxyProvider<T> implements
       AtomicBoolean fallbackToSimpleAuth) {
     this.fallbackToSimpleAuth = fallbackToSimpleAuth;
   }
+
+  public synchronized AtomicBoolean getFallbackToSimpleAuth() {
+    return fallbackToSimpleAuth;
+  }
 }

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/WrappedFailoverProxyProvider.java

@@ -17,18 +17,9 @@
  */
 package org.apache.hadoop.hdfs.server.namenode.ha;
 
-import java.io.Closeable;
 import java.io.IOException;
-import java.net.InetSocketAddress;
-import java.net.URI;
 
-import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
 import org.apache.hadoop.io.retry.FailoverProxyProvider;
-import org.apache.hadoop.ipc.RPC;
-import org.apache.hadoop.security.UserGroupInformation;
-
-import com.google.common.base.Preconditions;
 
 /**
  * A NNFailoverProxyProvider implementation which wrapps old implementations