From c8ba7039b7973edb133e0eb89856f40fad1085d6 Mon Sep 17 00:00:00 2001
From: Andrew Wang <wang@apache.org>
Date: Fri, 16 May 2014 01:19:17 +0000
Subject: [PATCH] HDFS-6345. DFS.listCacheDirectives() should allow filtering
 based on cache directive ID. (wang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1595087 13f79535-47bb-0310-9956-ffa450edef68
---
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt   |  3 +
 .../hdfs/protocol/CacheDirectiveIterator.java | 70 ++++++++++++++++++-
 .../hdfs/server/namenode/CacheManager.java    | 26 +++++--
 .../apache/hadoop/hdfs/tools/CacheAdmin.java  | 10 ++-
 .../server/namenode/TestCacheDirectives.java  |  6 ++
 .../src/test/resources/testCacheAdminConf.xml | 24 +++++++
 6 files changed, 131 insertions(+), 8 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index c5be00f8400..c9a3a31c189 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -112,6 +112,9 @@ Release 2.5.0 - UNRELEASED
     HDFS-5683. Better audit log messages for caching operations.
     (Abhiraj Butala via wang)
 
+    HDFS-6345. DFS.listCacheDirectives() should allow filtering based on
+    cache directive ID. (wang)
+
   OPTIMIZATIONS
 
     HDFS-6214. Webhdfs has poor throughput for files >2GB (daryn)
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
index 1ef5c538e45..676106de10f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/CacheDirectiveIterator.java
@@ -23,6 +23,10 @@ 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.hadoop.fs.InvalidRequestException;
+import org.apache.hadoop.ipc.RemoteException;
+
+import com.google.common.base.Preconditions;
 
 /**
  * CacheDirectiveIterator is a remote iterator that iterates cache directives.
@@ -33,7 +37,7 @@ import org.apache.hadoop.fs.BatchedRemoteIterator;
 public class CacheDirectiveIterator
     extends BatchedRemoteIterator<Long, CacheDirectiveEntry> {
 
-  private final CacheDirectiveInfo filter;
+  private CacheDirectiveInfo filter;
   private final ClientProtocol namenode;
 
   public CacheDirectiveIterator(ClientProtocol namenode,
@@ -43,10 +47,72 @@ public class CacheDirectiveIterator
     this.filter = filter;
   }
 
+  private static CacheDirectiveInfo removeIdFromFilter(CacheDirectiveInfo filter) {
+    CacheDirectiveInfo.Builder builder = new CacheDirectiveInfo.Builder(filter);
+    builder.setId(null);
+    return builder.build();
+  }
+
+  /**
+   * Used for compatibility when communicating with a server version that
+   * does not support filtering directives by ID.
+   */
+  private static class SingleEntry implements
+      BatchedEntries<CacheDirectiveEntry> {
+
+    private final CacheDirectiveEntry entry;
+
+    public SingleEntry(final CacheDirectiveEntry entry) {
+      this.entry = entry;
+    }
+
+    @Override
+    public CacheDirectiveEntry get(int i) {
+      if (i > 0) {
+        return null;
+      }
+      return entry;
+    }
+
+    @Override
+    public int size() {
+      return 1;
+    }
+
+    @Override
+    public boolean hasMore() {
+      return false;
+    }
+  }
+
   @Override
   public BatchedEntries<CacheDirectiveEntry> makeRequest(Long prevKey)
       throws IOException {
-    return namenode.listCacheDirectives(prevKey, filter);
+    BatchedEntries<CacheDirectiveEntry> entries = null;
+    try {
+      entries = namenode.listCacheDirectives(prevKey, filter);
+    } catch (IOException e) {
+      if (e.getMessage().contains("Filtering by ID is unsupported")) {
+        // Retry case for old servers, do the filtering client-side
+        long id = filter.getId();
+        filter = removeIdFromFilter(filter);
+        // Using id - 1 as prevId should get us a window containing the id
+        // This is somewhat brittle, since it depends on directives being
+        // returned in order of ascending ID.
+        entries = namenode.listCacheDirectives(id - 1, filter);
+        for (int i=0; i<entries.size(); i++) {
+          CacheDirectiveEntry entry = entries.get(i);
+          if (entry.getInfo().getId().equals((Long)id)) {
+            return new SingleEntry(entry);
+          }
+        }
+        throw new RemoteException(InvalidRequestException.class.getName(),
+            "Did not find requested id " + id);
+      }
+      throw e;
+    }
+    Preconditions.checkNotNull(entries);
+    return entries;
   }
 
   @Override
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CacheManager.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CacheManager.java
index bd549b152d6..1d74cf3af4b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CacheManager.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CacheManager.java
@@ -691,15 +691,25 @@ public final class CacheManager {
     assert namesystem.hasReadLock();
     final int NUM_PRE_ALLOCATED_ENTRIES = 16;
     String filterPath = null;
-    if (filter.getId() != null) {
-      throw new IOException("Filtering by ID is unsupported.");
-    }
     if (filter.getPath() != null) {
       filterPath = validatePath(filter);
     }
     if (filter.getReplication() != null) {
-      throw new IOException("Filtering by replication is unsupported.");
+      throw new InvalidRequestException(
+          "Filtering by replication is unsupported.");
     }
+
+    // Querying for a single ID
+    final Long id = filter.getId();
+    if (id != null) {
+      if (!directivesById.containsKey(id)) {
+        throw new InvalidRequestException("Did not find requested id " + id);
+      }
+      // Since we use a tailMap on directivesById, setting prev to id-1 gets
+      // us the directive with the id (if present)
+      prevId = id - 1;
+    }
+
     ArrayList<CacheDirectiveEntry> replies =
         new ArrayList<CacheDirectiveEntry>(NUM_PRE_ALLOCATED_ENTRIES);
     int numReplies = 0;
@@ -711,6 +721,14 @@ public final class CacheManager {
       }
       CacheDirective curDirective = cur.getValue();
       CacheDirectiveInfo info = cur.getValue().toInfo();
+
+      // If the requested ID is present, it should be the first item.
+      // Hitting this case means the ID is not present, or we're on the second
+      // item and should break out.
+      if (id != null &&
+          !(info.getId().equals(id))) {
+        break;
+      }
       if (filter.getPool() != null && 
           !info.getPool().equals(filter.getPool())) {
         continue;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/CacheAdmin.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/CacheAdmin.java
index b7ac968dede..3325570c7d0 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/CacheAdmin.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/CacheAdmin.java
@@ -503,19 +503,21 @@ public class CacheAdmin extends Configured implements Tool {
 
     @Override
     public String getShortUsage() {
-      return "[" + getName() + " [-stats] [-path <path>] [-pool <pool>]]\n";
+      return "[" + getName()
+          + " [-stats] [-path <path>] [-pool <pool>] [-id <id>]\n";
     }
 
     @Override
     public String getLongUsage() {
       TableListing listing = getOptionDescriptionListing();
+      listing.addRow("-stats", "List path-based cache directive statistics.");
       listing.addRow("<path>", "List only " +
           "cache directives with this path. " +
           "Note that if there is a cache directive for <path> " +
           "in a cache pool that we don't have read access for, it " + 
           "will not be listed.");
       listing.addRow("<pool>", "List only path cache directives in that pool.");
-      listing.addRow("-stats", "List path-based cache directive statistics.");
+      listing.addRow("<id>", "List the cache directive with this id.");
       return getShortUsage() + "\n" +
         "List cache directives.\n\n" +
         listing.toString();
@@ -534,6 +536,10 @@ public class CacheAdmin extends Configured implements Tool {
         builder.setPool(poolFilter);
       }
       boolean printStats = StringUtils.popOption("-stats", args);
+      String idFilter = StringUtils.popOptionWithArgument("-id", args);
+      if (idFilter != null) {
+        builder.setId(Long.parseLong(idFilter));
+      }
       if (!args.isEmpty()) {
         System.err.println("Can't understand argument: " + args.get(0));
         return 1;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java
index ecc738aadcd..ed124603f3d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestCacheDirectives.java
@@ -477,6 +477,12 @@ public class TestCacheDirectives {
     iter = dfs.listCacheDirectives(
         new CacheDirectiveInfo.Builder().setPool("pool2").build());
     validateListAll(iter, betaId);
+    iter = dfs.listCacheDirectives(
+        new CacheDirectiveInfo.Builder().setId(alphaId2).build());
+    validateListAll(iter, alphaId2);
+    iter = dfs.listCacheDirectives(
+        new CacheDirectiveInfo.Builder().setId(relativeId).build());
+    validateListAll(iter, relativeId);
 
     dfs.removeCacheDirective(betaId);
     iter = dfs.listCacheDirectives(
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/resources/testCacheAdminConf.xml b/hadoop-hdfs-project/hadoop-hdfs/src/test/resources/testCacheAdminConf.xml
index 13f1b9ae14d..058eec59aa5 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/resources/testCacheAdminConf.xml
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/resources/testCacheAdminConf.xml
@@ -519,5 +519,29 @@
         </comparator>
       </comparators>
     </test>
+
+    <test> <!--Tested -->
+      <description>Testing listing a single cache directive</description>
+      <test-commands>
+        <cache-admin-command>-addPool pool1</cache-admin-command>
+        <cache-admin-command>-addDirective -path /foo -pool pool1 -ttl 2d</cache-admin-command>
+        <cache-admin-command>-addDirective -path /bar -pool pool1 -ttl 24h</cache-admin-command>
+        <cache-admin-command>-addDirective -path /baz -replication 2 -pool pool1 -ttl 60m</cache-admin-command>
+        <cache-admin-command>-listDirectives -stats -id 30</cache-admin-command>
+      </test-commands>
+      <cleanup-commands>
+        <cache-admin-command>-removePool pool1</cache-admin-command>
+      </cleanup-commands>
+      <comparators>
+        <comparator>
+          <type>SubstringComparator</type>
+          <expected-output>Found 1 entry</expected-output>
+        </comparator>
+        <comparator>
+          <type>SubstringComparator</type>
+          <expected-output>30 pool1      1</expected-output>
+        </comparator>
+      </comparators>
+    </test>
   </tests>
 </configuration>