svn merge -c 1366601 from trunk for HDFS-3667. Add retry support to WebHdfsFileSystem.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1366602 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -191,6 +191,8 @@ Release 2.0.1-alpha - UNRELEASED
 
     HDFS-3697. Enable fadvise readahead by default. (todd)
 
+    HDFS-3667.  Add retry support to WebHdfsFileSystem.  (szetszwo)
+
   BUG FIXES
 
     HDFS-3385. The last block of INodeFileUnderConstruction is not

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/ByteRangeInputStream.java

@@ -57,9 +57,9 @@ public abstract class ByteRangeInputStream extends FSInputStream {
       return url;
     }
 
-    protected abstract HttpURLConnection openConnection() throws IOException;
+    /** Connect to server with a data offset. */
-
+    protected abstract HttpURLConnection connect(final long offset,
-    protected abstract HttpURLConnection openConnection(final long offset) throws IOException;
+        final boolean resolved) throws IOException;
   }
 
   enum StreamStatus {
@@ -85,9 +85,6 @@ public abstract class ByteRangeInputStream extends FSInputStream {
     this.resolvedURL = r;
   }
   
-  protected abstract void checkResponseCode(final HttpURLConnection connection
-      ) throws IOException;
-  
   protected abstract URL getResolvedUrl(final HttpURLConnection connection
       ) throws IOException;
 
@@ -113,13 +110,10 @@ public abstract class ByteRangeInputStream extends FSInputStream {
   protected InputStream openInputStream() throws IOException {
     // Use the original url if no resolved url exists, eg. if
     // it's the first time a request is made.
-    final URLOpener opener =
+    final boolean resolved = resolvedURL.getURL() != null; 
-      (resolvedURL.getURL() == null) ? originalURL : resolvedURL;
+    final URLOpener opener = resolved? resolvedURL: originalURL;
-
-    final HttpURLConnection connection = opener.openConnection(startPos);
-    connection.connect();
-    checkResponseCode(connection);
 
+    final HttpURLConnection connection = opener.connect(startPos, resolved);
     final String cl = connection.getHeaderField(StreamFile.CONTENT_LENGTH);
     if (cl == null) {
       throw new IOException(StreamFile.CONTENT_LENGTH+" header is missing");

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/HftpFileSystem.java

@@ -342,19 +342,28 @@ public class HftpFileSystem extends FileSystem
       super(url);
     }
 
-    @Override
     protected HttpURLConnection openConnection() throws IOException {
       return (HttpURLConnection)URLUtils.openConnection(url);
     }
 
     /** Use HTTP Range header for specifying offset. */
     @Override
-    protected HttpURLConnection openConnection(final long offset) throws IOException {
+    protected HttpURLConnection connect(final long offset,
+        final boolean resolved) throws IOException {
       final HttpURLConnection conn = openConnection();
       conn.setRequestMethod("GET");
       if (offset != 0L) {
         conn.setRequestProperty("Range", "bytes=" + offset + "-");
       }
+      conn.connect();
+
+      //Expects HTTP_OK or HTTP_PARTIAL response codes. 
+      final int code = conn.getResponseCode();
+      if (offset != 0L && code != HttpURLConnection.HTTP_PARTIAL) {
+        throw new IOException("HTTP_PARTIAL expected, received " + code);
+      } else if (offset == 0L && code != HttpURLConnection.HTTP_OK) {
+        throw new IOException("HTTP_OK expected, received " + code);
+      }
       return conn;
     }  
   }
@@ -368,22 +377,6 @@ public class HftpFileSystem extends FileSystem
       this(new RangeHeaderUrlOpener(url), new RangeHeaderUrlOpener(null));
     }
 
-    /** Expects HTTP_OK and HTTP_PARTIAL response codes. */
-    @Override
-    protected void checkResponseCode(final HttpURLConnection connection
-        ) throws IOException {
-      final int code = connection.getResponseCode();
-      if (startPos != 0 && code != HttpURLConnection.HTTP_PARTIAL) {
-        // We asked for a byte range but did not receive a partial content
-        // response...
-        throw new IOException("HTTP_PARTIAL expected, received " + code);
-      } else if (startPos == 0 && code != HttpURLConnection.HTTP_OK) {
-        // We asked for all bytes from the beginning but didn't receive a 200
-        // response (none of the other 2xx codes are valid here)
-        throw new IOException("HTTP_OK expected, received " + code);
-      }
-    }
-
     @Override
     protected URL getResolvedUrl(final HttpURLConnection connection) {
       return connection.getURL();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/NameNodeProxies.java

@@ -259,7 +259,7 @@ public class NameNodeProxies {
    *     
    * Note that dfs.client.retry.max < 0 is not allowed.
    */
-  private static RetryPolicy getDefaultRpcRetryPolicy(Configuration conf) {
+  public static RetryPolicy getDefaultRetryPolicy(Configuration conf) {
     final RetryPolicy multipleLinearRandomRetry = getMultipleLinearRandomRetry(conf);
     if (LOG.isDebugEnabled()) {
       LOG.debug("multipleLinearRandomRetry = " + multipleLinearRandomRetry);
@@ -300,6 +300,13 @@ public class NameNodeProxies {
               + p.getClass().getSimpleName() + ", exception=" + e);
           return p.shouldRetry(e, retries, failovers, isMethodIdempotent);
         }
+
+        @Override
+        public String toString() {
+          return "RetryPolicy[" + multipleLinearRandomRetry + ", "
+              + RetryPolicies.TRY_ONCE_THEN_FAIL.getClass().getSimpleName()
+              + "]";
+        }
       };
     }
   }
@@ -335,7 +342,7 @@ public class NameNodeProxies {
       boolean withRetries) throws IOException {
     RPC.setProtocolEngine(conf, ClientNamenodeProtocolPB.class, ProtobufRpcEngine.class);
 
-    final RetryPolicy defaultPolicy = getDefaultRpcRetryPolicy(conf);
+    final RetryPolicy defaultPolicy = getDefaultRetryPolicy(conf);
     final long version = RPC.getProtocolVersion(ClientNamenodeProtocolPB.class);
     ClientNamenodeProtocolPB proxy = RPC.getProtocolProxy(
         ClientNamenodeProtocolPB.class, version, address, ugi, conf,

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -55,6 +55,7 @@ import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.ByteRangeInputStream;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.hdfs.NameNodeProxies;
 import org.apache.hadoop.hdfs.protocol.DSQuotaExceededException;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
@@ -88,6 +89,7 @@ import org.apache.hadoop.hdfs.web.resources.ReplicationParam;
 import org.apache.hadoop.hdfs.web.resources.TokenArgumentParam;
 import org.apache.hadoop.hdfs.web.resources.UserParam;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.io.retry.RetryPolicy;
 import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.AccessControlException;
@@ -147,6 +149,7 @@ public class WebHdfsFileSystem extends FileSystem
   private URI uri;
   private Token<?> delegationToken;
   private final AuthenticatedURL.Token authToken = new AuthenticatedURL.Token();
+  private RetryPolicy retryPolicy = null;
   private Path workingDir;
 
   {
@@ -179,6 +182,7 @@ public class WebHdfsFileSystem extends FileSystem
       throw new IllegalArgumentException(e);
     }
     this.nnAddr = NetUtils.createSocketAddr(uri.getAuthority(), getDefaultPort());
+    this.retryPolicy = NameNodeProxies.getDefaultRetryPolicy(conf);
     this.workingDir = getHomeDirectory();
 
     if (UserGroupInformation.isSecurityEnabled()) {
@@ -276,13 +280,13 @@ public class WebHdfsFileSystem extends FileSystem
   }
 
   private static Map<?, ?> validateResponse(final HttpOpParam.Op op,
-      final HttpURLConnection conn) throws IOException {
+      final HttpURLConnection conn, boolean unwrapException) throws IOException {
     final int code = conn.getResponseCode();
     if (code != op.getExpectedHttpResponseCode()) {
       final Map<?, ?> m;
       try {
         m = jsonParse(conn, true);
-      } catch(IOException e) {
+      } catch(Exception e) {
         throw new IOException("Unexpected HTTP response: code=" + code + " != "
             + op.getExpectedHttpResponseCode() + ", " + op.toQueryString()
             + ", message=" + conn.getResponseMessage(), e);
@@ -293,7 +297,30 @@ public class WebHdfsFileSystem extends FileSystem
       }
 
       final RemoteException re = JsonUtil.toRemoteException(m);
-      throw re.unwrapRemoteException(AccessControlException.class,
+      throw unwrapException? toIOException(re): re;
+    }
+    return null;
+  }
+
+  /**
+   * Covert an exception to an IOException.
+   * 
+   * For a non-IOException, wrap it with IOException.
+   * For a RemoteException, unwrap it.
+   * For an IOException which is not a RemoteException, return it. 
+   */
+  private static IOException toIOException(Exception e) {
+    if (!(e instanceof IOException)) {
+      return new IOException(e);
+    }
+
+    final IOException ioe = (IOException)e;
+    if (!(ioe instanceof RemoteException)) {
+      return ioe;
+    }
+
+    final RemoteException re = (RemoteException)ioe;
+    return re.unwrapRemoteException(AccessControlException.class,
         InvalidToken.class,
         AuthenticationException.class,
         AuthorizationException.class,
@@ -305,8 +332,6 @@ public class WebHdfsFileSystem extends FileSystem
         DSQuotaExceededException.class,
         NSQuotaExceededException.class);
   }
-    return null;
-  }
 
   /**
    * Return a URL pointing to given path on the namenode.
@@ -362,68 +387,13 @@ public class WebHdfsFileSystem extends FileSystem
   }
 
   private HttpURLConnection getHttpUrlConnection(URL url)
-      throws IOException {
+      throws IOException, AuthenticationException {
     final HttpURLConnection conn;
-    try {
     if (ugi.hasKerberosCredentials()) { 
       conn = new AuthenticatedURL(AUTH).openConnection(url, authToken);
     } else {
       conn = (HttpURLConnection)url.openConnection();
     }
-    } catch (AuthenticationException e) {
-      throw new IOException("Authentication failed, url=" + url, e);
-    }
-    return conn;
-  }
-  
-  private HttpURLConnection httpConnect(final HttpOpParam.Op op, final Path fspath,
-      final Param<?,?>... parameters) throws IOException {
-    final URL url = toUrl(op, fspath, parameters);
-
-    //connect and get response
-    HttpURLConnection conn = getHttpUrlConnection(url);
-    try {
-      conn.setRequestMethod(op.getType().toString());
-      if (op.getDoOutput()) {
-        conn = twoStepWrite(conn, op);
-        conn.setRequestProperty("Content-Type", "application/octet-stream");
-      }
-      conn.setDoOutput(op.getDoOutput());
-      conn.connect();
-      return conn;
-    } catch (IOException e) {
-      conn.disconnect();
-      throw e;
-    }
-  }
-  
-  /**
-   * Two-step Create/Append:
-   * Step 1) Submit a Http request with neither auto-redirect nor data. 
-   * Step 2) Submit another Http request with the URL from the Location header with data.
-   * 
-   * The reason of having two-step create/append is for preventing clients to
-   * send out the data before the redirect. This issue is addressed by the
-   * "Expect: 100-continue" header in HTTP/1.1; see RFC 2616, Section 8.2.3.
-   * Unfortunately, there are software library bugs (e.g. Jetty 6 http server
-   * and Java 6 http client), which do not correctly implement "Expect:
-   * 100-continue". The two-step create/append is a temporary workaround for
-   * the software library bugs.
-   */
-  static HttpURLConnection twoStepWrite(HttpURLConnection conn,
-      final HttpOpParam.Op op) throws IOException {
-    //Step 1) Submit a Http request with neither auto-redirect nor data. 
-    conn.setInstanceFollowRedirects(false);
-    conn.setDoOutput(false);
-    conn.connect();
-    validateResponse(HttpOpParam.TemporaryRedirectOp.valueOf(op), conn);
-    final String redirect = conn.getHeaderField("Location");
-    conn.disconnect();
-
-    //Step 2) Submit another Http request with the URL from the Location header with data.
-    conn = (HttpURLConnection)new URL(redirect).openConnection();
-    conn.setRequestMethod(op.getType().toString());
-    conn.setChunkedStreamingMode(32 << 10); //32kB-chunk
     return conn;
   }
 
@@ -439,12 +409,158 @@ public class WebHdfsFileSystem extends FileSystem
    */
   private Map<?, ?> run(final HttpOpParam.Op op, final Path fspath,
       final Param<?,?>... parameters) throws IOException {
-    final HttpURLConnection conn = httpConnect(op, fspath, parameters);
+    return new Runner(op, fspath, parameters).run().json;
+  }
+
+  /**
+   * This class is for initialing a HTTP connection, connecting to server,
+   * obtaining a response, and also handling retry on failures.
+   */
+  class Runner {
+    private final HttpOpParam.Op op;
+    private final URL url;
+    private final boolean redirected;
+
+    private boolean checkRetry;
+    private HttpURLConnection conn = null;
+    private Map<?, ?> json = null;
+
+    Runner(final HttpOpParam.Op op, final URL url, final boolean redirected) {
+      this.op = op;
+      this.url = url;
+      this.redirected = redirected;
+    }
+
+    Runner(final HttpOpParam.Op op, final Path fspath,
+        final Param<?,?>... parameters) throws IOException {
+      this(op, toUrl(op, fspath, parameters), false);
+    }
+
+    Runner(final HttpOpParam.Op op, final HttpURLConnection conn) {
+      this(op, null, false);
+      this.conn = conn;
+    }
+
+    private void init() throws IOException {
+      checkRetry = !redirected;
       try {
-      final Map<?, ?> m = validateResponse(op, conn);
+        conn = getHttpUrlConnection(url);
-      return m != null? m: jsonParse(conn, false);
+      } catch(AuthenticationException ae) {
-    } finally {
+        checkRetry = false;
+        throw new IOException("Authentication failed, url=" + url, ae);
+      }
+    }
+    
+    private void connect() throws IOException {
+      connect(op.getDoOutput());
+    }
+
+    private void connect(boolean doOutput) throws IOException {
+      conn.setRequestMethod(op.getType().toString());
+      conn.setDoOutput(doOutput);
+      conn.setInstanceFollowRedirects(false);
+      conn.connect();
+    }
+
+    private void disconnect() {
+      if (conn != null) {
         conn.disconnect();
+        conn = null;
+      }
+    }
+
+    Runner run() throws IOException {
+      for(int retry = 0; ; retry++) {
+        try {
+          init();
+          if (op.getDoOutput()) {
+            twoStepWrite();
+          } else {
+            getResponse(op != GetOpParam.Op.OPEN);
+          }
+          return this;
+        } catch(IOException ioe) {
+          shouldRetry(ioe, retry);
+        }
+      }
+    }
+
+    private void shouldRetry(final IOException ioe, final int retry
+        ) throws IOException {
+      if (checkRetry) {
+        try {
+          final RetryPolicy.RetryAction a = retryPolicy.shouldRetry(
+              ioe, retry, 0, true);
+          if (a.action == RetryPolicy.RetryAction.RetryDecision.RETRY) {
+            LOG.info("Retrying connect to namenode: " + nnAddr
+                + ". Already tried " + retry + " time(s); retry policy is "
+                + retryPolicy + ", delay " + a.delayMillis + "ms.");      
+            Thread.sleep(a.delayMillis);
+            return;
+          }
+        } catch(Exception e) {
+          LOG.warn("Original exception is ", ioe);
+          throw toIOException(e);
+        }
+      }
+      throw toIOException(ioe);
+    }
+
+    /**
+     * Two-step Create/Append:
+     * Step 1) Submit a Http request with neither auto-redirect nor data. 
+     * Step 2) Submit another Http request with the URL from the Location header with data.
+     * 
+     * The reason of having two-step create/append is for preventing clients to
+     * send out the data before the redirect. This issue is addressed by the
+     * "Expect: 100-continue" header in HTTP/1.1; see RFC 2616, Section 8.2.3.
+     * Unfortunately, there are software library bugs (e.g. Jetty 6 http server
+     * and Java 6 http client), which do not correctly implement "Expect:
+     * 100-continue". The two-step create/append is a temporary workaround for
+     * the software library bugs.
+     */
+    HttpURLConnection twoStepWrite() throws IOException {
+      //Step 1) Submit a Http request with neither auto-redirect nor data. 
+      connect(false);
+      validateResponse(HttpOpParam.TemporaryRedirectOp.valueOf(op), conn, false);
+      final String redirect = conn.getHeaderField("Location");
+      disconnect();
+      checkRetry = false;
+      
+      //Step 2) Submit another Http request with the URL from the Location header with data.
+      conn = (HttpURLConnection)new URL(redirect).openConnection();
+      conn.setChunkedStreamingMode(32 << 10); //32kB-chunk
+      connect();
+      return conn;
+    }
+
+    FSDataOutputStream write(final int bufferSize) throws IOException {
+      return WebHdfsFileSystem.this.write(op, conn, bufferSize);
+    }
+
+    void getResponse(boolean getJsonAndDisconnect) throws IOException {
+      try {
+        connect();
+        if (!redirected && op.getRedirect()) {
+          final String redirect = conn.getHeaderField("Location");
+          json = validateResponse(HttpOpParam.TemporaryRedirectOp.valueOf(op),
+              conn, false);
+          disconnect();
+  
+          checkRetry = false;
+          conn = (HttpURLConnection)new URL(redirect).openConnection();
+          connect();
+        }
+
+        json = validateResponse(op, conn, false);
+        if (json == null && getJsonAndDisconnect) {
+          json = jsonParse(conn, false);
+        }
+      } finally {
+        if (getJsonAndDisconnect) {
+          disconnect();
+        }
+      }
     }
   }
 
@@ -578,7 +694,7 @@ public class WebHdfsFileSystem extends FileSystem
           super.close();
         } finally {
           try {
-            validateResponse(op, conn);
+            validateResponse(op, conn, true);
           } finally {
             conn.disconnect();
           }
@@ -594,13 +710,14 @@ public class WebHdfsFileSystem extends FileSystem
     statistics.incrementWriteOps(1);
 
     final HttpOpParam.Op op = PutOpParam.Op.CREATE;
-    final HttpURLConnection conn = httpConnect(op, f, 
+    return new Runner(op, f, 
         new PermissionParam(applyUMask(permission)),
         new OverwriteParam(overwrite),
         new BufferSizeParam(bufferSize),
         new ReplicationParam(replication),
-        new BlockSizeParam(blockSize));
+        new BlockSizeParam(blockSize))
-    return write(op, conn, bufferSize);
+      .run()
+      .write(bufferSize);
   }
 
   @Override
@@ -609,9 +726,9 @@ public class WebHdfsFileSystem extends FileSystem
     statistics.incrementWriteOps(1);
 
     final HttpOpParam.Op op = PostOpParam.Op.APPEND;
-    final HttpURLConnection conn = httpConnect(op, f, 
+    return new Runner(op, f, new BufferSizeParam(bufferSize))
-        new BufferSizeParam(bufferSize));
+      .run()
-    return write(op, conn, bufferSize);
+      .write(bufferSize);
   }
 
   @SuppressWarnings("deprecation")
@@ -638,26 +755,17 @@ public class WebHdfsFileSystem extends FileSystem
   }
 
   class OffsetUrlOpener extends ByteRangeInputStream.URLOpener {
-    /** The url with offset parameter */
-    private URL offsetUrl;
-  
     OffsetUrlOpener(final URL url) {
       super(url);
     }
 
-    /** Open connection with offset url. */
+    /** Setup offset url and connect. */
     @Override
-    protected HttpURLConnection openConnection() throws IOException {
+    protected HttpURLConnection connect(final long offset,
-      return getHttpUrlConnection(offsetUrl);
+        final boolean resolved) throws IOException {
-    }
+      final URL offsetUrl = offset == 0L? url
-
+          : new URL(url + "&" + new OffsetParam(offset));
-    /** Setup offset url before open connection. */
+      return new Runner(GetOpParam.Op.OPEN, offsetUrl, resolved).run().conn;
-    @Override
-    protected HttpURLConnection openConnection(final long offset) throws IOException {
-      offsetUrl = offset == 0L? url: new URL(url + "&" + new OffsetParam(offset));
-      final HttpURLConnection conn = openConnection();
-      conn.setRequestMethod("GET");
-      return conn;
     }  
   }
 
@@ -699,12 +807,6 @@ public class WebHdfsFileSystem extends FileSystem
       super(o, r);
     }
 
-    @Override
-    protected void checkResponseCode(final HttpURLConnection connection
-        ) throws IOException {
-      validateResponse(GetOpParam.Op.OPEN, connection);
-    }
-
     /** Remove offset parameter before returning the resolved url. */
     @Override
     protected URL getResolvedUrl(final HttpURLConnection connection

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/DeleteOpParam.java

@@ -43,6 +43,11 @@ public class DeleteOpParam extends HttpOpParam<DeleteOpParam.Op> {
       return false;
     }
 
+    @Override
+    public boolean getRedirect() {
+      return false;
+    }
+
     @Override
     public int getExpectedHttpResponseCode() {
       return expectedHttpResponseCode;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/GetOpParam.java

@@ -23,25 +23,27 @@ import java.net.HttpURLConnection;
 public class GetOpParam extends HttpOpParam<GetOpParam.Op> {
   /** Get operations. */
   public static enum Op implements HttpOpParam.Op {
-    OPEN(HttpURLConnection.HTTP_OK),
+    OPEN(true, HttpURLConnection.HTTP_OK),
 
-    GETFILESTATUS(HttpURLConnection.HTTP_OK),
+    GETFILESTATUS(false, HttpURLConnection.HTTP_OK),
-    LISTSTATUS(HttpURLConnection.HTTP_OK),
+    LISTSTATUS(false, HttpURLConnection.HTTP_OK),
-    GETCONTENTSUMMARY(HttpURLConnection.HTTP_OK),
+    GETCONTENTSUMMARY(false, HttpURLConnection.HTTP_OK),
-    GETFILECHECKSUM(HttpURLConnection.HTTP_OK),
+    GETFILECHECKSUM(true, HttpURLConnection.HTTP_OK),
 
-    GETHOMEDIRECTORY(HttpURLConnection.HTTP_OK),
+    GETHOMEDIRECTORY(false, HttpURLConnection.HTTP_OK),
-    GETDELEGATIONTOKEN(HttpURLConnection.HTTP_OK),
+    GETDELEGATIONTOKEN(false, HttpURLConnection.HTTP_OK),
-    GETDELEGATIONTOKENS(HttpURLConnection.HTTP_OK),
+    GETDELEGATIONTOKENS(false, HttpURLConnection.HTTP_OK),
 
     /** GET_BLOCK_LOCATIONS is a private unstable op. */
-    GET_BLOCK_LOCATIONS(HttpURLConnection.HTTP_OK),
+    GET_BLOCK_LOCATIONS(false, HttpURLConnection.HTTP_OK),
 
-    NULL(HttpURLConnection.HTTP_NOT_IMPLEMENTED);
+    NULL(false, HttpURLConnection.HTTP_NOT_IMPLEMENTED);
 
+    final boolean redirect;
     final int expectedHttpResponseCode;
 
-    Op(final int expectedHttpResponseCode) {
+    Op(final boolean redirect, final int expectedHttpResponseCode) {
+      this.redirect = redirect;
       this.expectedHttpResponseCode = expectedHttpResponseCode;
     }
 
@@ -55,6 +57,11 @@ public class GetOpParam extends HttpOpParam<GetOpParam.Op> {
       return false;
     }
 
+    @Override
+    public boolean getRedirect() {
+      return redirect;
+    }
+
     @Override
     public int getExpectedHttpResponseCode() {
       return expectedHttpResponseCode;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/HttpOpParam.java

@@ -17,6 +17,10 @@
  */
 package org.apache.hadoop.hdfs.web.resources;
 
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
 import javax.ws.rs.core.Response;
 
 
@@ -42,6 +46,9 @@ public abstract class HttpOpParam<E extends Enum<E> & HttpOpParam.Op>
     /** @return true if the operation will do output. */
     public boolean getDoOutput();
 
+    /** @return true if the operation will be redirected. */
+    public boolean getRedirect();
+
     /** @return true the expected http response code. */
     public int getExpectedHttpResponseCode();
 
@@ -51,15 +58,25 @@ public abstract class HttpOpParam<E extends Enum<E> & HttpOpParam.Op>
 
   /** Expects HTTP response 307 "Temporary Redirect". */
   public static class TemporaryRedirectOp implements Op {
-    static final TemporaryRedirectOp CREATE = new TemporaryRedirectOp(PutOpParam.Op.CREATE);
+    static final TemporaryRedirectOp CREATE = new TemporaryRedirectOp(
-    static final TemporaryRedirectOp APPEND = new TemporaryRedirectOp(PostOpParam.Op.APPEND);
+        PutOpParam.Op.CREATE);
+    static final TemporaryRedirectOp APPEND = new TemporaryRedirectOp(
+        PostOpParam.Op.APPEND);
+    static final TemporaryRedirectOp OPEN = new TemporaryRedirectOp(
+        GetOpParam.Op.OPEN);
+    static final TemporaryRedirectOp GETFILECHECKSUM = new TemporaryRedirectOp(
+        GetOpParam.Op.GETFILECHECKSUM);
+    
+    static final List<TemporaryRedirectOp> values
+        = Collections.unmodifiableList(Arrays.asList(
+            new TemporaryRedirectOp[]{CREATE, APPEND, OPEN, GETFILECHECKSUM}));
 
     /** Get an object for the given op. */
     public static TemporaryRedirectOp valueOf(final Op op) {
-      if (op == CREATE.op) {
+      for(TemporaryRedirectOp t : values) {
-        return CREATE;
+        if (op == t.op) {
-      } else if (op == APPEND.op) {
+          return t;
-        return APPEND;
+        }
       }
       throw new IllegalArgumentException(op + " not found.");
     }
@@ -80,6 +97,11 @@ public abstract class HttpOpParam<E extends Enum<E> & HttpOpParam.Op>
       return op.getDoOutput();
     }
 
+    @Override
+    public boolean getRedirect() {
+      return false;
+    }
+
     /** Override the original expected response with "Temporary Redirect". */
     @Override
     public int getExpectedHttpResponseCode() {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/PostOpParam.java

@@ -43,6 +43,11 @@ public class PostOpParam extends HttpOpParam<PostOpParam.Op> {
       return true;
     }
 
+    @Override
+    public boolean getRedirect() {
+      return true;
+    }
+
     @Override
     public int getExpectedHttpResponseCode() {
       return expectedHttpResponseCode;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/PutOpParam.java

@@ -39,11 +39,11 @@ public class PutOpParam extends HttpOpParam<PutOpParam.Op> {
     
     NULL(false, HttpURLConnection.HTTP_NOT_IMPLEMENTED);
 
-    final boolean doOutput;
+    final boolean doOutputAndRedirect;
     final int expectedHttpResponseCode;
 
-    Op(final boolean doOutput, final int expectedHttpResponseCode) {
+    Op(final boolean doOutputAndRedirect, final int expectedHttpResponseCode) {
-      this.doOutput = doOutput;
+      this.doOutputAndRedirect = doOutputAndRedirect;
       this.expectedHttpResponseCode = expectedHttpResponseCode;
     }
 
@@ -54,7 +54,12 @@ public class PutOpParam extends HttpOpParam<PutOpParam.Op> {
 
     @Override
     public boolean getDoOutput() {
-      return doOutput;
+      return doOutputAndRedirect;
+    }
+
+    @Override
+    public boolean getRedirect() {
+      return doOutputAndRedirect;
     }
 
     @Override

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientRetries.java

@@ -47,6 +47,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.commons.logging.impl.Log4JLogger;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.fs.FSDataInputStream;
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileChecksum;
 import org.apache.hadoop.fs.FileStatus;
@@ -66,6 +67,7 @@ import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.NotReplicatedYetException;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
+import org.apache.hadoop.hdfs.web.WebHdfsTestUtil;
 import org.apache.hadoop.io.IOUtils;
 import org.apache.hadoop.io.LongWritable;
 import org.apache.hadoop.io.Writable;
@@ -74,6 +76,7 @@ import org.apache.hadoop.ipc.RPC;
 import org.apache.hadoop.ipc.RemoteException;
 import org.apache.hadoop.ipc.Server;
 import org.apache.hadoop.net.NetUtils;
+import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.hadoop.util.Time;
 import org.apache.log4j.Level;
@@ -772,13 +775,17 @@ public class TestDFSClientRetries {
   /** Test client retry with namenode restarting. */
   @Test
   public void testNamenodeRestart() throws Exception {
+    namenodeRestartTest(new Configuration(), false);
+  }
+
+  public static void namenodeRestartTest(final Configuration conf,
+      final boolean isWebHDFS) throws Exception {
     ((Log4JLogger)DFSClient.LOG).getLogger().setLevel(Level.ALL);
 
     final List<Exception> exceptions = new ArrayList<Exception>();
 
     final Path dir = new Path("/testNamenodeRestart");
 
-    final Configuration conf = new Configuration();
     conf.setBoolean(DFSConfigKeys.DFS_CLIENT_RETRY_POLICY_ENABLED_KEY, true);
 
     final short numDatanodes = 3;
@@ -788,16 +795,18 @@ public class TestDFSClientRetries {
     try {
       cluster.waitActive();
       final DistributedFileSystem dfs = cluster.getFileSystem();
+      final FileSystem fs = isWebHDFS?
+          WebHdfsTestUtil.getWebHdfsFileSystem(conf): dfs;
       final URI uri = dfs.getUri();
       assertTrue(HdfsUtils.isHealthy(uri));
 
       //create a file
       final long length = 1L << 20;
       final Path file1 = new Path(dir, "foo"); 
-      DFSTestUtil.createFile(dfs, file1, length, numDatanodes, 20120406L);
+      DFSTestUtil.createFile(fs, file1, length, numDatanodes, 20120406L);
 
       //get file status
-      final FileStatus s1 = dfs.getFileStatus(file1);
+      final FileStatus s1 = fs.getFileStatus(file1);
       assertEquals(length, s1.getLen());
 
       //shutdown namenode
@@ -805,6 +814,25 @@ public class TestDFSClientRetries {
       cluster.shutdownNameNode(0);
       assertFalse(HdfsUtils.isHealthy(uri));
 
+      //namenode is down, read the file in a thread
+      final Thread reader = new Thread(new Runnable() {
+        @Override
+        public void run() {
+          try {
+            //it should retry till namenode is up.
+            final FileSystem fs = createFsWithDifferentUsername(conf, isWebHDFS);
+            final FSDataInputStream in = fs.open(file1);
+            int count = 0;
+            for(; in.read() != -1; count++);
+            in.close();
+            assertEquals(s1.getLen(), count);
+          } catch (Exception e) {
+            exceptions.add(e);
+          }
+        }
+      });
+      reader.start();
+
       //namenode is down, create another file in a thread
       final Path file3 = new Path(dir, "file"); 
       final Thread thread = new Thread(new Runnable() {
@@ -812,7 +840,7 @@ public class TestDFSClientRetries {
         public void run() {
           try {
             //it should retry till namenode is up.
-            final FileSystem fs = AppendTestUtil.createHdfsWithDifferentUsername(conf);
+            final FileSystem fs = createFsWithDifferentUsername(conf, isWebHDFS);
             DFSTestUtil.createFile(fs, file3, length, numDatanodes, 20120406L);
           } catch (Exception e) {
             exceptions.add(e);
@@ -839,12 +867,15 @@ public class TestDFSClientRetries {
       }).start();
 
       //namenode is down, it should retry until namenode is up again. 
-      final FileStatus s2 = dfs.getFileStatus(file1);
+      final FileStatus s2 = fs.getFileStatus(file1);
       assertEquals(s1, s2);
 
       //check file1 and file3
       thread.join();
-      assertEquals(dfs.getFileChecksum(file1), dfs.getFileChecksum(file3));
+      assertEquals(s1.getLen(), fs.getFileStatus(file3).getLen());
+      assertEquals(fs.getFileChecksum(file1), fs.getFileChecksum(file3));
+
+      reader.join();
 
       //enter safe mode
       assertTrue(HdfsUtils.isHealthy(uri));
@@ -869,8 +900,8 @@ public class TestDFSClientRetries {
 
       //namenode is in safe mode, create should retry until it leaves safe mode.
       final Path file2 = new Path(dir, "bar");
-      DFSTestUtil.createFile(dfs, file2, length, numDatanodes, 20120406L);
+      DFSTestUtil.createFile(fs, file2, length, numDatanodes, 20120406L);
-      assertEquals(dfs.getFileChecksum(file1), dfs.getFileChecksum(file2));
+      assertEquals(fs.getFileChecksum(file1), fs.getFileChecksum(file2));
       
       assertTrue(HdfsUtils.isHealthy(uri));
 
@@ -878,7 +909,7 @@ public class TestDFSClientRetries {
       final Path nonExisting = new Path(dir, "nonExisting");
       LOG.info("setPermission: " + nonExisting);
       try {
-        dfs.setPermission(nonExisting, new FsPermission((short)0));
+        fs.setPermission(nonExisting, new FsPermission((short)0));
         fail();
       } catch(FileNotFoundException fnfe) {
         LOG.info("GOOD!", fnfe);
@@ -896,6 +927,17 @@ public class TestDFSClientRetries {
     }
   }
 
+  public static FileSystem createFsWithDifferentUsername(
+      final Configuration conf, final boolean isWebHDFS
+      ) throws IOException, InterruptedException {
+    String username = UserGroupInformation.getCurrentUser().getShortUserName()+"_XXX";
+    UserGroupInformation ugi = 
+      UserGroupInformation.createUserForTesting(username, new String[]{"supergroup"});
+    
+    return isWebHDFS? WebHdfsTestUtil.getWebHdfsFileSystemAs(ugi, conf)
+        : DFSTestUtil.getFileSystemAs(ugi, conf);
+  }
+
   @Test
   public void testMultipleLinearRandomRetry() {
     parseMultipleLinearRandomRetry(null, "");

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/TestDelegationTokenForProxyUser.java

@@ -44,7 +44,6 @@ import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
-import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
@@ -140,9 +139,7 @@ public class TestDelegationTokenForProxyUser {
           .doAs(new PrivilegedExceptionAction<Token<DelegationTokenIdentifier>>() {
             @Override
             public Token<DelegationTokenIdentifier> run() throws IOException {
-              DistributedFileSystem dfs = (DistributedFileSystem) cluster
+              return cluster.getFileSystem().getDelegationToken("RenewerUser");
-                  .getFileSystem();
-              return dfs.getDelegationToken("RenewerUser");
             }
           });
       DelegationTokenIdentifier identifier = new DelegationTokenIdentifier();
@@ -206,7 +203,7 @@ public class TestDelegationTokenForProxyUser {
       final PutOpParam.Op op = PutOpParam.Op.CREATE;
       final URL url = WebHdfsTestUtil.toUrl(webhdfs, op,  f, new DoAsParam(PROXY_USER));
       HttpURLConnection conn = (HttpURLConnection) url.openConnection();
-      conn = WebHdfsTestUtil.twoStepWrite(conn, op);
+      conn = WebHdfsTestUtil.twoStepWrite(webhdfs, op, conn);
       final FSDataOutputStream out = WebHdfsTestUtil.write(webhdfs, op, conn, 4096);
       out.write("Hello, webhdfs user!".getBytes());
       out.close();
@@ -221,7 +218,7 @@ public class TestDelegationTokenForProxyUser {
       final PostOpParam.Op op = PostOpParam.Op.APPEND;
       final URL url = WebHdfsTestUtil.toUrl(webhdfs, op,  f, new DoAsParam(PROXY_USER));
       HttpURLConnection conn = (HttpURLConnection) url.openConnection();
-      conn = WebHdfsTestUtil.twoStepWrite(conn, op);
+      conn = WebHdfsTestUtil.twoStepWrite(webhdfs, op, conn);
       final FSDataOutputStream out = WebHdfsTestUtil.write(webhdfs, op, conn, 4096);
       out.write("\nHello again!".getBytes());
       out.close();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestOffsetUrlInputStream.java

@@ -18,22 +18,10 @@
 package org.apache.hadoop.hdfs.web;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.fail;
-import static org.mockito.Mockito.doReturn;
-import static org.mockito.Mockito.spy;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
 
 import java.io.IOException;
-import java.net.URI;
 import java.net.URL;
 
-import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.fs.FileSystem;
-import org.apache.hadoop.hdfs.TestByteRangeInputStream.MockHttpURLConnection;
-import org.apache.hadoop.hdfs.web.WebHdfsFileSystem.OffsetUrlInputStream;
-import org.apache.hadoop.hdfs.web.WebHdfsFileSystem.OffsetUrlOpener;
 import org.junit.Test;
 
 public class TestOffsetUrlInputStream {
@@ -73,65 +61,4 @@ public class TestOffsetUrlInputStream {
           WebHdfsFileSystem.removeOffsetParam(new URL(s)).toString());
     }
   }
-  
-  @Test
-  public void testByteRange() throws Exception {
-    final Configuration conf = new Configuration(); 
-    final String uri = WebHdfsFileSystem.SCHEME  + "://localhost:50070/";
-    final WebHdfsFileSystem webhdfs = (WebHdfsFileSystem)FileSystem.get(new URI(uri), conf);
-
-    OffsetUrlOpener ospy = spy(webhdfs.new OffsetUrlOpener(new URL("http://test/")));
-    doReturn(new MockHttpURLConnection(ospy.getURL())).when(ospy)
-        .openConnection();
-    OffsetUrlOpener rspy = spy(webhdfs.new OffsetUrlOpener((URL) null));
-    doReturn(new MockHttpURLConnection(rspy.getURL())).when(rspy)
-        .openConnection();
-    final OffsetUrlInputStream is = new OffsetUrlInputStream(ospy, rspy);
-
-    assertEquals("getPos wrong", 0, is.getPos());
-
-    is.read();
-
-    assertNull("Initial call made incorrectly (Range Check)", ospy
-        .openConnection().getRequestProperty("Range"));
-
-    assertEquals("getPos should be 1 after reading one byte", 1, is.getPos());
-
-    is.read();
-
-    assertEquals("getPos should be 2 after reading two bytes", 2, is.getPos());
-
-    // No additional connections should have been made (no seek)
-
-    rspy.setURL(new URL("http://resolvedurl/"));
-
-    is.seek(100);
-    is.read();
-
-    assertEquals("getPos should be 101 after reading one byte", 101,
-        is.getPos());
-
-    verify(rspy, times(1)).openConnection();
-
-    is.seek(101);
-    is.read();
-
-    verify(rspy, times(1)).openConnection();
-
-    // Seek to 101 should not result in another request"
-
-    is.seek(2500);
-    is.read();
-
-    ((MockHttpURLConnection) rspy.openConnection()).setResponseCode(206);
-    is.seek(0);
-
-    try {
-      is.read();
-      fail("Exception should be thrown when 206 response is given "
-           + "but 200 is expected");
-    } catch (IOException e) {
-      WebHdfsFileSystem.LOG.info(e.toString());
-    }
-  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsRetries.java

@@ -0,0 +1,37 @@
+/**
+ * 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.web;
+
+import org.apache.commons.logging.impl.Log4JLogger;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hdfs.TestDFSClientRetries;
+import org.apache.hadoop.hdfs.server.namenode.web.resources.NamenodeWebHdfsMethods;
+import org.apache.log4j.Level;
+import org.junit.Test;
+
+/** Test WebHdfsFileSystem retry on failures. */
+public class TestWebHdfsRetries {
+  /** Test client retry with namenode restarting. */
+  @Test
+  public void testNamenodeRestart() throws Exception {
+    ((Log4JLogger)NamenodeWebHdfsMethods.LOG).getLogger().setLevel(Level.ALL);
+    final Configuration conf = WebHdfsTestUtil.createConf();
+    TestDFSClientRetries.namenodeRestartTest(conf, true);
+  }
+}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/WebHdfsTestUtil.java

@@ -79,13 +79,9 @@ public class WebHdfsTestUtil {
     return WebHdfsFileSystem.jsonParse(conn, false);
   }
   
-  public static HttpURLConnection twoStepWrite(HttpURLConnection conn,
+  public static HttpURLConnection twoStepWrite(final WebHdfsFileSystem webhdfs,
-      final HttpOpParam.Op op) throws IOException {
+      final HttpOpParam.Op op, HttpURLConnection conn) throws IOException {
-    conn.setRequestMethod(op.getType().toString());
+    return webhdfs.new Runner(op, conn).twoStepWrite();
-    conn = WebHdfsFileSystem.twoStepWrite(conn, op);
-    conn.setDoOutput(true);
-    conn.connect();
-    return conn;
   }
 
   public static FSDataOutputStream write(final WebHdfsFileSystem webhdfs,