HDFS-5326. add modifyDirective to cacheAdmin (cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1539839 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -0,0 +1,31 @@
+/**
+ * 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 java.io.IOException;
+
+/**
+ * Exception corresponding to ID not found - EINVAL
+ */
+public class IdNotFoundException extends IOException {
+  static final long serialVersionUID = 0L;
+
+  public IdNotFoundException(String str) {
+    super(str);
+  }
+}

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

@@ -188,6 +188,8 @@ Trunk (Unreleased)
     HDFS-5386. Add feature documentation for datanode caching.
     (Colin Patrick McCabe via cnauroth)
 
+    HDFS-5326. add modifyDirective to cacheAdmin.  (cmccabe)
+
   OPTIMIZATIONS
     HDFS-5349. DNA_CACHE and DNA_UNCACHE should be by blockId only. (cmccabe)
 

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

@@ -117,7 +117,6 @@ import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsBlocksMetadata;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.DatanodeReportType;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants.SafeModeAction;
@@ -2291,7 +2290,7 @@ public class DFSClient implements java.io.Closeable {
     }
   }
 
-  public PathBasedCacheDescriptor addPathBasedCacheDirective(
+  public long addPathBasedCacheDirective(
       PathBasedCacheDirective directive) throws IOException {
     checkOpen();
     try {
@@ -2301,21 +2300,31 @@ public class DFSClient implements java.io.Closeable {
     }
   }
   
-  public void removePathBasedCacheDescriptor(long id)
+  public void modifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive) throws IOException {
+    checkOpen();
+    try {
+      namenode.modifyPathBasedCacheDirective(directive);
+    } catch (RemoteException re) {
+      throw re.unwrapRemoteException();
+    }
+  }
+
+  public void removePathBasedCacheDirective(long id)
       throws IOException {
     checkOpen();
     try {
-      namenode.removePathBasedCacheDescriptor(id);
+      namenode.removePathBasedCacheDirective(id);
     } catch (RemoteException re) {
       throw re.unwrapRemoteException();
     }
   }
   
-  public RemoteIterator<PathBasedCacheDescriptor> listPathBasedCacheDescriptors(
-      String pool, String path) throws IOException {
+  public RemoteIterator<PathBasedCacheDirective> listPathBasedCacheDirectives(
+      PathBasedCacheDirective filter) throws IOException {
     checkOpen();
     try {
-      return namenode.listPathBasedCacheDescriptors(0, pool, path);
+      return namenode.listPathBasedCacheDirectives(0, filter);
     } catch (RemoteException re) {
       throw re.unwrapRemoteException();
     }

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

@@ -211,9 +211,9 @@ public class DFSConfigKeys extends CommonConfigurationKeys {
   public static final String  DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES =
       "dfs.namenode.list.cache.pools.num.responses";
   public static final int     DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES_DEFAULT = 100;
-  public static final String  DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES =
-      "dfs.namenode.list.cache.descriptors.num.responses";
-  public static final int     DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES_DEFAULT = 100;
+  public static final String  DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES =
+      "dfs.namenode.list.cache.directives.num.responses";
+  public static final int     DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES_DEFAULT = 100;
   public static final String  DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS =
       "dfs.namenode.path.based.cache.refresh.interval.ms";
   public static final long    DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS_DEFAULT = 300000L;

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

@@ -68,7 +68,6 @@ import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.HdfsLocatedFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
 import org.apache.hadoop.hdfs.security.token.block.InvalidBlockTokenException;
@@ -82,6 +81,7 @@ import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.util.Progressable;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Preconditions;
 
 
 /****************************************************************
@@ -1586,57 +1586,74 @@ public class DistributedFileSystem extends FileSystem {
   /**
    * Add a new PathBasedCacheDirective.
    * 
-   * @param directive A PathBasedCacheDirectives to add
-   * @return PathBasedCacheDescriptor associated with the added directive
+   * @param directive A directive to add.
+   * @return the ID of the directive that was created.
    * @throws IOException if the directive could not be added
    */
-  public PathBasedCacheDescriptor addPathBasedCacheDirective(
+  public long addPathBasedCacheDirective(
       PathBasedCacheDirective directive) throws IOException {
+    Preconditions.checkNotNull(directive.getPath());
     Path path = new Path(getPathName(fixRelativePart(directive.getPath()))).
         makeQualified(getUri(), getWorkingDirectory());
-    return dfs.addPathBasedCacheDirective(new PathBasedCacheDirective.Builder().
-        setPath(path).
-        setReplication(directive.getReplication()).
-        setPool(directive.getPool()).
-        build());
+    return dfs.addPathBasedCacheDirective(
+        new PathBasedCacheDirective.Builder(directive).
+            setPath(path).
+            build());
   }
   
+  public void modifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive) throws IOException {
+    if (directive.getPath() != null) {
+      directive = new PathBasedCacheDirective.Builder(directive).
+          setPath(new Path(getPathName(fixRelativePart(directive.getPath()))).
+              makeQualified(getUri(), getWorkingDirectory())).build();
+    }
+    dfs.modifyPathBasedCacheDirective(directive);
+  }
+
   /**
-   * Remove a PathBasedCacheDescriptor.
+   * Remove a PathBasedCacheDirective.
    * 
-   * @param descriptor PathBasedCacheDescriptor to remove
-   * @throws IOException if the descriptor could not be removed
+   * @param id identifier of the PathBasedCacheDirective to remove
+   * @throws IOException if the directive could not be removed
    */
-  public void removePathBasedCacheDescriptor(PathBasedCacheDescriptor descriptor)
+  public void removePathBasedCacheDirective(long id)
       throws IOException {
-    dfs.removePathBasedCacheDescriptor(descriptor.getEntryId());
+    dfs.removePathBasedCacheDirective(id);
   }
   
   /**
    * List the set of cached paths of a cache pool. Incrementally fetches results
    * from the server.
    * 
-   * @param pool The cache pool to list, or null to list all pools.
-   * @param path The path name to list, or null to list all paths.
-   * @return A RemoteIterator which returns PathBasedCacheDescriptor objects.
+   * @param filter Filter parameters to use when listing the directives, null to
+   *               list all directives visible to us.
+   * @return A RemoteIterator which returns PathBasedCacheDirective objects.
    */
-  public RemoteIterator<PathBasedCacheDescriptor> listPathBasedCacheDescriptors(
-      String pool, final Path path) throws IOException {
-    String pathName = path != null ? getPathName(fixRelativePart(path)) : null;
-    final RemoteIterator<PathBasedCacheDescriptor> iter =
-        dfs.listPathBasedCacheDescriptors(pool, pathName);
-    return new RemoteIterator<PathBasedCacheDescriptor>() {
+  public RemoteIterator<PathBasedCacheDirective> listPathBasedCacheDirectives(
+      PathBasedCacheDirective filter) throws IOException {
+    if (filter == null) {
+      filter = new PathBasedCacheDirective.Builder().build();
+    }
+    if (filter.getPath() != null) {
+      filter = new PathBasedCacheDirective.Builder(filter).
+          setPath(filter.getPath().
+              makeQualified(getUri(), filter.getPath())).
+                build();
+    }
+    final RemoteIterator<PathBasedCacheDirective> iter =
+        dfs.listPathBasedCacheDirectives(filter);
+    return new RemoteIterator<PathBasedCacheDirective>() {
       @Override
       public boolean hasNext() throws IOException {
         return iter.hasNext();
       }
 
       @Override
-      public PathBasedCacheDescriptor next() throws IOException {
-        PathBasedCacheDescriptor desc = iter.next();
-        Path qualPath = desc.getPath().makeQualified(getUri(), path);
-        return new PathBasedCacheDescriptor(desc.getEntryId(), qualPath,
-            desc.getReplication(), desc.getPool());
+      public PathBasedCacheDirective next() throws IOException {
+        PathBasedCacheDirective desc = iter.next();
+        Path p = desc.getPath().makeQualified(getUri(), desc.getPath());
+        return new PathBasedCacheDirective.Builder(desc).setPath(p).build();
       }
     };
   }

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

@@ -1,108 +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.hdfs.protocol;
-
-import java.io.IOException;
-
-/**
- * An exception which occurred when trying to add a PathBasedCache directive.
- */
-public abstract class AddPathBasedCacheDirectiveException extends IOException {
-  private static final long serialVersionUID = 1L;
-
-  public AddPathBasedCacheDirectiveException(String description) {
-    super(description);
-  }
-
-  public static final class EmptyPathError
-      extends AddPathBasedCacheDirectiveException {
-    private static final long serialVersionUID = 1L;
-
-    public EmptyPathError() {
-      super("empty path in directive");
-    }
-  }
-
-  public static class InvalidPathNameError
-      extends AddPathBasedCacheDirectiveException {
-    private static final long serialVersionUID = 1L;
-
-    public InvalidPathNameError(String msg) {
-      super(msg);
-    }
-
-    public InvalidPathNameError(PathBasedCacheDirective directive) {
-      this("can't handle invalid path name " + directive.getPath());
-    }
-  }
-
-  public static class InvalidPoolNameError
-      extends AddPathBasedCacheDirectiveException {
-    private static final long serialVersionUID = 1L;
-
-    public InvalidPoolNameError(String msg) {
-      super(msg);
-    }
-
-    public InvalidPoolNameError(PathBasedCacheDirective directive) {
-      this("invalid pool name '" + directive.getPool() + "'");
-    }
-  }
-
-  public static class PoolWritePermissionDeniedError
-      extends AddPathBasedCacheDirectiveException {
-    private static final long serialVersionUID = 1L;
-
-    public PoolWritePermissionDeniedError(String msg) {
-      super(msg);
-    }
-
-    public PoolWritePermissionDeniedError(PathBasedCacheDirective directive) {
-      this("write permission denied for pool '" + directive.getPool() + "'");
-    }
-  }
-
-  public static class PathAlreadyExistsInPoolError
-      extends AddPathBasedCacheDirectiveException {
-    private static final long serialVersionUID = 1L;
-
-    public PathAlreadyExistsInPoolError(String msg) {
-      super(msg);
-    }
-
-    public PathAlreadyExistsInPoolError(PathBasedCacheDirective directive) {
-      this("path " + directive.getPath() + " already exists in pool " +
-          directive.getPool());
-    }
-  }
-
-  public static class UnexpectedAddPathBasedCacheDirectiveException
-      extends AddPathBasedCacheDirectiveException {
-    private static final long serialVersionUID = 1L;
-
-    public UnexpectedAddPathBasedCacheDirectiveException(String msg) {
-      super(msg);
-    }
-
-    public UnexpectedAddPathBasedCacheDirectiveException(
-        PathBasedCacheDirective directive) {
-      this("encountered an unexpected error when trying to " +
-          "add PathBasedCache directive " + directive);
-    }
-  }
-}

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

@@ -1099,35 +1099,46 @@ public interface ClientProtocol {
    * Add a PathBasedCache entry to the CacheManager.
    * 
    * @param directive A PathBasedCacheDirective to be added
-   * @return A PathBasedCacheDescriptor associated with the added directive
+   * @return A PathBasedCacheDirective associated with the added directive
    * @throws IOException if the directive could not be added
    */
   @AtMostOnce
-  public PathBasedCacheDescriptor addPathBasedCacheDirective(
+  public long addPathBasedCacheDirective(
       PathBasedCacheDirective directive) throws IOException;
 
   /**
-   * Remove a PathBasedCacheDescriptor from the CacheManager.
+   * Modify a PathBasedCache entry in the CacheManager.
    * 
-   * @param id of a PathBasedCacheDescriptor
-   * @throws IOException if the cache descriptor could not be removed
+   * @return directive The directive to modify.  Must contain 
+   *                   a directive ID.
+   * @throws IOException if the directive could not be modified
    */
   @AtMostOnce
-  public void removePathBasedCacheDescriptor(Long id) throws IOException;
+  public void modifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive) throws IOException;
+
+  /**
+   * Remove a PathBasedCacheDirective from the CacheManager.
+   * 
+   * @param id of a PathBasedCacheDirective
+   * @throws IOException if the cache directive could not be removed
+   */
+  @AtMostOnce
+  public void removePathBasedCacheDirective(long id) throws IOException;
 
   /**
    * List the set of cached paths of a cache pool. Incrementally fetches results
    * from the server.
    * 
    * @param prevId The last listed entry ID, or -1 if this is the first call to
-   *          listPathBasedCacheDescriptors.
-   * @param pool The cache pool to list, or null to list all pools.
-   * @param path The path name to list, or null to list all paths.
-   * @return A RemoteIterator which returns PathBasedCacheDescriptor objects.
+   *               listPathBasedCacheDirectives.
+   * @param filter Parameters to use to filter the list results, 
+   *               or null to display all directives visible to us.
+   * @return A RemoteIterator which returns PathBasedCacheDirective objects.
    */
   @Idempotent
-  public RemoteIterator<PathBasedCacheDescriptor> listPathBasedCacheDescriptors(
-      long prevId, String pool, String path) throws IOException;
+  public RemoteIterator<PathBasedCacheDirective> listPathBasedCacheDirectives(
+      long prevId, PathBasedCacheDirective filter) throws IOException;
 
   /**
    * Add a new cache pool.

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

@@ -1,82 +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.hdfs.protocol;
-
-import org.apache.hadoop.classification.InterfaceAudience;
-import org.apache.hadoop.classification.InterfaceStability;
-import org.apache.hadoop.fs.Path;
-import org.apache.commons.lang.builder.EqualsBuilder;
-import org.apache.commons.lang.builder.HashCodeBuilder;
-
-import com.google.common.base.Preconditions;
-
-/**
- * A directive in a cache pool that includes an identifying ID number.
- */
-@InterfaceStability.Evolving
-@InterfaceAudience.Public
-public final class PathBasedCacheDescriptor extends PathBasedCacheDirective {
-  private final long entryId;
-
-  public PathBasedCacheDescriptor(long entryId, Path path,
-      short replication, String pool) {
-    super(path, replication, pool);
-    Preconditions.checkArgument(entryId > 0);
-    this.entryId = entryId;
-  }
-
-  public long getEntryId() {
-    return entryId;
-  }
-
-  @Override
-  public boolean equals(Object o) {
-    if (o == null) {
-      return false;
-    }
-    if (getClass() != o.getClass()) {
-      return false;
-    }
-    PathBasedCacheDescriptor other = (PathBasedCacheDescriptor)o;
-    return new EqualsBuilder().append(entryId, other.entryId).
-        append(getPath(), other.getPath()).
-        append(getReplication(), other.getReplication()).
-        append(getPool(), other.getPool()).
-        isEquals();
-  }
-
-  @Override
-  public int hashCode() {
-    return new HashCodeBuilder().append(entryId).
-        append(getPath()).
-        append(getReplication()).
-        append(getPool()).
-        hashCode();
-  }
-
-  @Override
-  public String toString() {
-    StringBuilder builder = new StringBuilder();
-    builder.append("{ entryId:").append(entryId).
-      append(", path:").append(getPath()).
-      append(", replication:").append(getReplication()).
-      append(", pool:").append(getPool()).
-      append(" }");
-    return builder.toString();
-  }
-};

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

@@ -17,32 +17,27 @@
  */
 package org.apache.hadoop.hdfs.protocol;
 
-import java.io.IOException;
-
-import com.google.common.base.Preconditions;
+import java.net.URI;
 
 import org.apache.commons.lang.builder.EqualsBuilder;
 import org.apache.commons.lang.builder.HashCodeBuilder;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.Path;
-import org.apache.hadoop.hdfs.DFSUtil;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.InvalidPoolNameError;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.InvalidPathNameError;
 
 /**
- * A directive to add a path to a cache pool.
+ * Describes a path-based cache directive.
  */
 @InterfaceStability.Evolving
 @InterfaceAudience.Public
 public class PathBasedCacheDirective {
-
   /**
    * A builder for creating new PathBasedCacheDirective instances.
    */
   public static class Builder {
+    private Long id;
     private Path path;
-    private short replication = (short)1;
+    private Short replication;
     private String pool;
 
     /**
@@ -51,7 +46,37 @@ public class PathBasedCacheDirective {
      * @return New PathBasedCacheDirective.
      */
     public PathBasedCacheDirective build() {
-      return new PathBasedCacheDirective(path, replication, pool);
+      return new PathBasedCacheDirective(id, path, replication, pool);
+    }
+
+    /**
+     * Creates an empty builder.
+     */
+    public Builder() {
+    }
+
+    /**
+     * Creates a builder with all elements set to the same values as the
+     * given PathBasedCacheDirective.
+     */
+    public Builder(PathBasedCacheDirective directive) {
+      this.id = directive.getId();
+      // deep-copy URI
+      URI uri = directive.getPath().toUri();
+      this.path = new Path(uri.getScheme(), uri.getAuthority(), uri.getPath());
+      this.replication = directive.getReplication();
+      this.pool = directive.getPool();
+    }
+
+    /**
+     * Sets the id used in this request.
+     * 
+     * @param id The id used in this request.
+     * @return This builder, for call chaining.
+     */
+    public Builder setId(Long id) {
+      this.id = id;
+      return this;
     }
 
     /**
@@ -71,7 +96,7 @@ public class PathBasedCacheDirective {
      * @param replication The replication used in this request.
      * @return This builder, for call chaining.
      */
-    public Builder setReplication(short replication) {
+    public Builder setReplication(Short replication) {
       this.replication = replication;
       return this;
     }
@@ -88,10 +113,25 @@ public class PathBasedCacheDirective {
     }
   }
 
+  private final Long id;
   private final Path path;
-  private final short replication;
+  private final Short replication;
   private final String pool;
 
+  PathBasedCacheDirective(Long id, Path path, Short replication, String pool) {
+    this.id = id;
+    this.path = path;
+    this.replication = replication;
+    this.pool = pool;
+  }
+
+  /**
+   * @return The ID of this directive.
+   */
+  public Long getId() {
+    return id;
+  }
+
   /**
    * @return The path used in this request.
    */
@@ -102,7 +142,7 @@ public class PathBasedCacheDirective {
   /**
    * @return The number of times the block should be cached.
    */
-  public short getReplication() {
+  public Short getReplication() {
     return replication;
   }
 
@@ -113,25 +153,6 @@ public class PathBasedCacheDirective {
     return pool;
   }
 
-  /**
-   * Check if this PathBasedCacheDirective is valid.
-   * 
-   * @throws IOException
-   *     If this PathBasedCacheDirective is not valid.
-   */
-  public void validate() throws IOException {
-    if (!DFSUtil.isValidName(path.toUri().getPath())) {
-      throw new InvalidPathNameError(this);
-    }
-    if (replication <= 0) {
-      throw new IOException("Tried to request a cache replication " +
-          "factor of " + replication + ", but that is less than 1.");
-    }
-    if (pool.isEmpty()) {
-      throw new InvalidPoolNameError(this);
-    }
-  }
-
   @Override
   public boolean equals(Object o) {
     if (o == null) {
@@ -141,7 +162,8 @@ public class PathBasedCacheDirective {
       return false;
     }
     PathBasedCacheDirective other = (PathBasedCacheDirective)o;
-    return new EqualsBuilder().append(getPath(), other.getPath()).
+    return new EqualsBuilder().append(getId(), other.getId()).
+        append(getPath(), other.getPath()).
         append(getReplication(), other.getReplication()).
         append(getPool(), other.getPool()).
         isEquals();
@@ -149,34 +171,35 @@ public class PathBasedCacheDirective {
 
   @Override
   public int hashCode() {
-    return new HashCodeBuilder().append(getPath()).
+    return new HashCodeBuilder().append(id).
+        append(path).
         append(replication).
-        append(getPool()).
+        append(pool).
         hashCode();
   }
 
   @Override
   public String toString() {
     StringBuilder builder = new StringBuilder();
-    builder.append("{ path:").append(path).
-      append(", replication:").append(replication).
-      append(", pool:").append(pool).
-      append(" }");
+    builder.append("{");
+    String prefix = "";
+    if (id != null) {
+      builder.append(prefix).append("id: ").append(id);
+      prefix = ",";
+    }
+    if (path != null) {
+      builder.append(prefix).append("path: ").append(path);
+      prefix = ",";
+    }
+    if (replication != null) {
+      builder.append(prefix).append("replication: ").append(replication);
+      prefix = ",";
+    }
+    if (pool != null) {
+      builder.append(prefix).append("pool: ").append(pool);
+      prefix = ",";
+    }
+    builder.append("}");
     return builder.toString();
   }
-
-  /**
-   * Protected constructor.  Callers use Builder to create new instances.
-   * 
-   * @param path The path used in this request.
-   * @param replication The replication used in this request.
-   * @param pool The pool used in this request.
-   */
-  protected PathBasedCacheDirective(Path path, short replication, String pool) {
-    Preconditions.checkNotNull(path);
-    Preconditions.checkNotNull(pool);
-    this.path = path;
-    this.replication = replication;
-    this.pool = pool;
-  }
 };

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

@@ -64,6 +64,15 @@ public final class PathBasedCacheEntry {
     return replication;
   }
 
+  public PathBasedCacheDirective toDirective() {
+    return new PathBasedCacheDirective.Builder().
+        setId(entryId).
+        setPath(new Path(path)).
+        setReplication(replication).
+        setPool(pool.getPoolName()).
+        build();
+  }
+  
   @Override
   public String toString() {
     StringBuilder builder = new StringBuilder();
@@ -75,11 +84,6 @@ public final class PathBasedCacheEntry {
     return builder.toString();
   }
 
-  public PathBasedCacheDescriptor getDescriptor() {
-    return new PathBasedCacheDescriptor(entryId, new Path(path), replication,
-        pool.getPoolName());
-  }
-  
   @Override
   public boolean equals(Object o) {
     if (o == null) { return false; }

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

@@ -1,85 +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.hdfs.protocol;
-
-import java.io.IOException;
-
-/**
- * An exception which occurred when trying to remove a PathBasedCache entry.
- */
-public abstract class RemovePathBasedCacheDescriptorException extends IOException {
-  private static final long serialVersionUID = 1L;
-
-  public RemovePathBasedCacheDescriptorException(String description) {
-    super(description);
-  }
-
-  public final static class InvalidIdException
-      extends RemovePathBasedCacheDescriptorException {
-    private static final long serialVersionUID = 1L;
-
-    public InvalidIdException(String msg) {
-      super(msg);
-    }
-
-    public InvalidIdException(long entryId) {
-      this("invalid PathBasedCacheDescriptor id " + entryId);
-    }
-  }
-
-  public final static class RemovePermissionDeniedException
-      extends RemovePathBasedCacheDescriptorException {
-    private static final long serialVersionUID = 1L;
-
-    public RemovePermissionDeniedException(String msg) {
-      super(msg);
-    }
-
-    public RemovePermissionDeniedException(long entryId) {
-      this("permission denied when trying to remove " + 
-          "PathBasedCacheDescriptor id " + entryId);
-    }
-  }
-
-  public final static class NoSuchIdException
-      extends RemovePathBasedCacheDescriptorException {
-    private static final long serialVersionUID = 1L;
-
-    public NoSuchIdException(String msg) {
-      super(msg);
-    }
-
-    public NoSuchIdException(long entryId) {
-      this("there is no PathBasedCacheDescriptor with id " + entryId);
-    }
-  }
-
-  public final static class UnexpectedRemovePathBasedCacheDescriptorException
-      extends RemovePathBasedCacheDescriptorException {
-    private static final long serialVersionUID = 1L;
-
-    public UnexpectedRemovePathBasedCacheDescriptorException(String msg) {
-      super(msg);
-    }
-
-    public UnexpectedRemovePathBasedCacheDescriptorException(long id) {
-      this("encountered an unexpected error when trying to " +
-          "remove PathBasedCacheDescriptor with id " + id);
-    }
-  }
-}

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

@@ -1,78 +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.hdfs.protocol;
-
-import java.io.IOException;
-
-import com.google.common.base.Preconditions;
-
-/**
- * An exception which occurred when trying to remove a PathBasedCache entry.
- */
-public abstract class RemovePathBasedCacheEntryException extends IOException {
-  private static final long serialVersionUID = 1L;
-
-  private final long entryId;
-
-  public RemovePathBasedCacheEntryException(String description, long entryId) {
-    super(description);
-    this.entryId = entryId;
-  }
-    
-  public long getEntryId() {
-    return this.entryId;
-  }
-
-  public final static class InvalidIdException
-      extends RemovePathBasedCacheEntryException {
-    private static final long serialVersionUID = 1L;
-
-    public InvalidIdException(long entryId) {
-      super("invalid cache path entry id " + entryId, entryId);
-    }
-  }
-
-  public final static class RemovePermissionDeniedException
-      extends RemovePathBasedCacheEntryException {
-    private static final long serialVersionUID = 1L;
-
-    public RemovePermissionDeniedException(long entryId) {
-      super("permission denied when trying to remove PathBasedCache entry id " +
-        entryId, entryId);
-    }
-  }
-
-  public final static class NoSuchIdException
-      extends RemovePathBasedCacheEntryException {
-    private static final long serialVersionUID = 1L;
-
-    public NoSuchIdException(long entryId) {
-      super("there is no PathBasedCache entry with id " + entryId, entryId);
-    }
-  }
-
-  public final static class UnexpectedRemovePathBasedCacheEntryException
-      extends RemovePathBasedCacheEntryException {
-    private static final long serialVersionUID = 1L;
-
-    public UnexpectedRemovePathBasedCacheEntryException(long id) {
-      super("encountered an unexpected error when trying to " +
-          "remove PathBasedCache entry id " + id, id);
-    }
-  }
-}

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolServerSideTranslatorPB.java

@@ -28,7 +28,6 @@ import org.apache.hadoop.fs.Options.Rename;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.RemoteIterator;
 import org.apache.hadoop.fs.permission.FsPermission;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.EmptyPathError;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
@@ -36,11 +35,7 @@ import org.apache.hadoop.hdfs.protocol.DirectoryListing;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.InvalidIdException;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.NoSuchIdException;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.RemovePermissionDeniedException;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AbandonBlockRequestProto;
@@ -111,24 +106,25 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCa
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCorruptFileBlocksRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCorruptFileBlocksResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDescriptorsElementProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDescriptorsRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDescriptorsResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDirectivesElementProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDirectivesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDirectivesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MetaSaveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MetaSaveResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MkdirsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MkdirsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.PathBasedCacheDirectiveProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyPathBasedCacheDirectiveRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyPathBasedCacheDirectiveResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RecoverLeaseRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RecoverLeaseResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RefreshNodesRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RefreshNodesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolResponseProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemovePathBasedCacheDescriptorRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemovePathBasedCacheDescriptorResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemovePathBasedCacheDirectiveRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemovePathBasedCacheDirectiveResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Rename2RequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Rename2ResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RenameRequestProto;
@@ -177,7 +173,6 @@ import org.apache.hadoop.security.proto.SecurityProtos.GetDelegationTokenRespons
 import org.apache.hadoop.security.proto.SecurityProtos.RenewDelegationTokenRequestProto;
 import org.apache.hadoop.security.proto.SecurityProtos.RenewDelegationTokenResponseProto;
 import org.apache.hadoop.security.token.Token;
-
 import org.apache.commons.lang.StringUtils;
 
 import com.google.common.primitives.Shorts;
@@ -1039,69 +1034,64 @@ public class ClientNamenodeProtocolServerSideTranslatorPB implements
       RpcController controller, AddPathBasedCacheDirectiveRequestProto request)
       throws ServiceException {
     try {
-      PathBasedCacheDirectiveProto proto = request.getDirective();
-      if (StringUtils.isEmpty(proto.getPath())) {
-        throw new EmptyPathError();
-      }
-      PathBasedCacheDirective directive = new PathBasedCacheDirective.Builder().
-          setPath(new Path(proto.getPath())).
-          setReplication(Shorts.checkedCast(proto.getReplication())).
-          setPool(proto.getPool()).
-          build();
-      PathBasedCacheDescriptor descriptor =
-          server.addPathBasedCacheDirective(directive);
-      AddPathBasedCacheDirectiveResponseProto.Builder builder =
-         AddPathBasedCacheDirectiveResponseProto.newBuilder();
-      builder.setDescriptorId(descriptor.getEntryId());
-      return builder.build();
+      return AddPathBasedCacheDirectiveResponseProto.newBuilder().
+              setId(server.addPathBasedCacheDirective(
+                  PBHelper.convert(request.getInfo()))).build();
     } catch (IOException e) {
       throw new ServiceException(e);
     }
   }
 
   @Override
-  public RemovePathBasedCacheDescriptorResponseProto removePathBasedCacheDescriptor(
-      RpcController controller,
-      RemovePathBasedCacheDescriptorRequestProto request)
+  public ModifyPathBasedCacheDirectiveResponseProto modifyPathBasedCacheDirective(
+      RpcController controller, ModifyPathBasedCacheDirectiveRequestProto request)
       throws ServiceException {
     try {
-      server.removePathBasedCacheDescriptor(request.getDescriptorId());
-      RemovePathBasedCacheDescriptorResponseProto.Builder builder =
-         RemovePathBasedCacheDescriptorResponseProto.newBuilder();
-      return builder.build();
+      server.modifyPathBasedCacheDirective(
+          PBHelper.convert(request.getInfo()));
+      return ModifyPathBasedCacheDirectiveResponseProto.newBuilder().build();
+    } catch (IOException e) {
+      throw new ServiceException(e);
+    }
+  }
+
+  @Override
+  public RemovePathBasedCacheDirectiveResponseProto
+      removePathBasedCacheDirective(RpcController controller,
+          RemovePathBasedCacheDirectiveRequestProto request)
+              throws ServiceException {
+    try {
+      server.removePathBasedCacheDirective(request.getId());
+      return RemovePathBasedCacheDirectiveResponseProto.
+          newBuilder().build();
     } catch (IOException e) {
       throw new ServiceException(e);
     }
   }
 
   @Override
-  public ListPathBasedCacheDescriptorsResponseProto listPathBasedCacheDescriptors(
-      RpcController controller, ListPathBasedCacheDescriptorsRequestProto request)
+  public ListPathBasedCacheDirectivesResponseProto listPathBasedCacheDirectives(
+      RpcController controller, ListPathBasedCacheDirectivesRequestProto request)
           throws ServiceException {
     try {
-      RemoteIterator<PathBasedCacheDescriptor> iter =
-         server.listPathBasedCacheDescriptors(request.getPrevId(),
-             request.hasPool() ? request.getPool() : null,
-             request.hasPath() ? request.getPath() : null);
-      ListPathBasedCacheDescriptorsResponseProto.Builder builder =
-          ListPathBasedCacheDescriptorsResponseProto.newBuilder();
+      PathBasedCacheDirective filter =
+          PBHelper.convert(request.getFilter());
+      RemoteIterator<PathBasedCacheDirective> iter =
+         server.listPathBasedCacheDirectives(request.getPrevId(), filter);
+      ListPathBasedCacheDirectivesResponseProto.Builder builder =
+          ListPathBasedCacheDirectivesResponseProto.newBuilder();
       long prevId = 0;
       while (iter.hasNext()) {
-        PathBasedCacheDescriptor directive = iter.next();
+        PathBasedCacheDirective directive = iter.next();
         builder.addElements(
-            ListPathBasedCacheDescriptorsElementProto.newBuilder().
-              setId(directive.getEntryId()).
-              setPath(directive.getPath().toUri().getPath()).
-              setReplication(directive.getReplication()).
-              setPool(directive.getPool()));
-        prevId = directive.getEntryId();
+            ListPathBasedCacheDirectivesElementProto.newBuilder().
+                setInfo(PBHelper.convert(directive)));
+        prevId = directive.getId();
       }
       if (prevId == 0) {
         builder.setHasMore(false);
       } else {
-        iter = server.listPathBasedCacheDescriptors(prevId, 
-            request.hasPool() ? request.getPool() : null,
-            request.hasPath() ? request.getPath() : null);
+        iter = server.listPathBasedCacheDirectives(prevId, filter);
         builder.setHasMore(iter.hasNext());
       }
       return builder.build();

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/ClientNamenodeProtocolTranslatorPB.java

@@ -51,7 +51,6 @@ import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
 import org.apache.hadoop.hdfs.protocol.NSQuotaExceededException;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
@@ -101,17 +100,16 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCa
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsResponseElementProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCachePoolsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListCorruptFileBlocksRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDescriptorsElementProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDescriptorsRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDescriptorsResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDirectivesRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ListPathBasedCacheDirectivesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MetaSaveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.MkdirsRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyCachePoolRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.PathBasedCacheDirectiveProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.ModifyPathBasedCacheDirectiveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RecoverLeaseRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RefreshNodesRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemoveCachePoolRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemovePathBasedCacheDescriptorRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RemovePathBasedCacheDirectiveRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Rename2RequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RenameRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.RenameSnapshotRequestProto;
@@ -1005,55 +1003,53 @@ public class ClientNamenodeProtocolTranslatorPB implements
   }
 
   @Override
-  public PathBasedCacheDescriptor addPathBasedCacheDirective(
+  public long addPathBasedCacheDirective(
       PathBasedCacheDirective directive) throws IOException {
     try {
-      AddPathBasedCacheDirectiveRequestProto.Builder builder =
-          AddPathBasedCacheDirectiveRequestProto.newBuilder();
-      builder.setDirective(PathBasedCacheDirectiveProto.newBuilder()
-          .setPath(directive.getPath().toUri().getPath())
-          .setReplication(directive.getReplication())
-          .setPool(directive.getPool())
-          .build());
-      AddPathBasedCacheDirectiveResponseProto result = 
-          rpcProxy.addPathBasedCacheDirective(null, builder.build());
-      return new PathBasedCacheDescriptor(result.getDescriptorId(),
-          directive.getPath(), directive.getReplication(),
-          directive.getPool());
+      return rpcProxy.addPathBasedCacheDirective(null, 
+              AddPathBasedCacheDirectiveRequestProto.newBuilder().
+                  setInfo(PBHelper.convert(directive)).build()).getId();
     } catch (ServiceException e) {
       throw ProtobufHelper.getRemoteException(e);
     }
   }
 
   @Override
-  public void removePathBasedCacheDescriptor(Long id)
+  public void modifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive) throws IOException {
+    try {
+      rpcProxy.modifyPathBasedCacheDirective(null,
+          ModifyPathBasedCacheDirectiveRequestProto.newBuilder().
+              setInfo(PBHelper.convert(directive)).build());
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
+  @Override
+  public void removePathBasedCacheDirective(long id)
       throws IOException {
     try {
-      RemovePathBasedCacheDescriptorRequestProto.Builder builder =
-          RemovePathBasedCacheDescriptorRequestProto.newBuilder();
-      builder.setDescriptorId(id);
-      rpcProxy.removePathBasedCacheDescriptor(null, builder.build());
+      rpcProxy.removePathBasedCacheDirective(null,
+          RemovePathBasedCacheDirectiveRequestProto.newBuilder().
+              setId(id).build());
     } catch (ServiceException e) {
       throw ProtobufHelper.getRemoteException(e);
     }
   }
 
   private static class BatchedPathBasedCacheEntries
-      implements BatchedEntries<PathBasedCacheDescriptor> {
-    private ListPathBasedCacheDescriptorsResponseProto response;
+      implements BatchedEntries<PathBasedCacheDirective> {
+    private ListPathBasedCacheDirectivesResponseProto response;
 
-    BatchedPathBasedCacheEntries(ListPathBasedCacheDescriptorsResponseProto response) {
+    BatchedPathBasedCacheEntries(
+        ListPathBasedCacheDirectivesResponseProto response) {
       this.response = response;
     }
 
     @Override
-    public PathBasedCacheDescriptor get(int i) {
-      ListPathBasedCacheDescriptorsElementProto elementProto =
-        response.getElements(i);
-      return new PathBasedCacheDescriptor(elementProto.getId(),
-          new Path(elementProto.getPath()),
-          Shorts.checkedCast(elementProto.getReplication()),
-          elementProto.getPool());
+    public PathBasedCacheDirective get(int i) {
+      return PBHelper.convert(response.getElements(i).getInfo());
     }
 
     @Override
@@ -1068,31 +1064,25 @@ public class ClientNamenodeProtocolTranslatorPB implements
   }
 
   private class PathBasedCacheEntriesIterator
-      extends BatchedRemoteIterator<Long, PathBasedCacheDescriptor> {
-    private final String pool;
-    private final String path;
+      extends BatchedRemoteIterator<Long, PathBasedCacheDirective> {
+    private final PathBasedCacheDirective filter;
 
-    public PathBasedCacheEntriesIterator(long prevKey, String pool, String path) {
+    public PathBasedCacheEntriesIterator(long prevKey,
+        PathBasedCacheDirective filter) {
       super(prevKey);
-      this.pool = pool;
-      this.path = path;
+      this.filter = filter;
     }
 
     @Override
-    public BatchedEntries<PathBasedCacheDescriptor> makeRequest(
+    public BatchedEntries<PathBasedCacheDirective> makeRequest(
         Long nextKey) throws IOException {
-      ListPathBasedCacheDescriptorsResponseProto response;
+      ListPathBasedCacheDirectivesResponseProto response;
       try {
-        ListPathBasedCacheDescriptorsRequestProto.Builder builder =
-            ListPathBasedCacheDescriptorsRequestProto.newBuilder().setPrevId(nextKey);
-        if (pool != null) {
-          builder.setPool(pool);
-        }
-        if (path != null) {
-          builder.setPath(path);
-        }
-        ListPathBasedCacheDescriptorsRequestProto req = builder.build();
-        response = rpcProxy.listPathBasedCacheDescriptors(null, req);
+        response = rpcProxy.listPathBasedCacheDirectives(null,
+            ListPathBasedCacheDirectivesRequestProto.newBuilder().
+                setPrevId(nextKey).
+                setFilter(PBHelper.convert(filter)).
+                build());
       } catch (ServiceException e) {
         throw ProtobufHelper.getRemoteException(e);
       }
@@ -1100,15 +1090,19 @@ public class ClientNamenodeProtocolTranslatorPB implements
     }
 
     @Override
-    public Long elementToPrevKey(PathBasedCacheDescriptor element) {
-      return element.getEntryId();
+    public Long elementToPrevKey(PathBasedCacheDirective element) {
+      return element.getId();
     }
   }
 
   @Override
-  public RemoteIterator<PathBasedCacheDescriptor> listPathBasedCacheDescriptors(long prevId,
-      String pool, String path) throws IOException {
-    return new PathBasedCacheEntriesIterator(prevId, pool, path);
+  public RemoteIterator<PathBasedCacheDirective>
+      listPathBasedCacheDirectives(long prevId,
+          PathBasedCacheDirective filter) throws IOException {
+    if (filter == null) {
+      filter = new PathBasedCacheDirective.Builder().build();
+    }
+    return new PathBasedCacheEntriesIterator(prevId, filter);
   }
 
   @Override

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocolPB/PBHelper.java

@@ -28,6 +28,7 @@ import java.util.List;
 import org.apache.hadoop.fs.ContentSummary;
 import org.apache.hadoop.fs.CreateFlag;
 import org.apache.hadoop.fs.FsServerDefaults;
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.ha.HAServiceProtocol.HAServiceState;
 import org.apache.hadoop.ha.proto.HAServiceProtocolProtos;
@@ -37,6 +38,7 @@ import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
+import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo.AdminStates;
 import org.apache.hadoop.hdfs.protocol.DirectoryListing;
@@ -55,6 +57,7 @@ import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.Create
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.DatanodeReportTypeProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetFsStatsResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.SafeModeActionProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.PathBasedCacheDirectiveInfoProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BalancerBandwidthCommandProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockCommandProto;
 import org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos.BlockIdCommandProto;
@@ -152,6 +155,7 @@ import org.apache.hadoop.util.DataChecksum;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
+import com.google.common.primitives.Shorts;
 import com.google.protobuf.ByteString;
 import com.google.protobuf.CodedInputStream;
 
@@ -1559,6 +1563,45 @@ public class PBHelper {
     return DataChecksum.Type.valueOf(type.getNumber());
   }
 
+  public static PathBasedCacheDirectiveInfoProto convert
+      (PathBasedCacheDirective directive) {
+    PathBasedCacheDirectiveInfoProto.Builder builder = 
+        PathBasedCacheDirectiveInfoProto.newBuilder();
+    if (directive.getId() != null) {
+      builder.setId(directive.getId());
+    }
+    if (directive.getPath() != null) {
+      builder.setPath(directive.getPath().toUri().getPath());
+    }
+    if (directive.getReplication() != null) {
+      builder.setReplication(directive.getReplication());
+    }
+    if (directive.getPool() != null) {
+      builder.setPool(directive.getPool());
+    }
+    return builder.build();
+  }
+
+  public static PathBasedCacheDirective convert
+      (PathBasedCacheDirectiveInfoProto proto) {
+    PathBasedCacheDirective.Builder builder =
+        new PathBasedCacheDirective.Builder();
+    if (proto.hasId()) {
+      builder.setId(proto.getId());
+    }
+    if (proto.hasPath()) {
+      builder.setPath(new Path(proto.getPath()));
+    }
+    if (proto.hasReplication()) {
+      builder.setReplication(Shorts.checkedCast(
+          proto.getReplication()));
+    }
+    if (proto.hasPool()) {
+      builder.setPool(proto.getPool());
+    }
+    return builder.build();
+  }
+  
   public static HdfsProtos.ChecksumTypeProto convert(DataChecksum.Type type) {
     return HdfsProtos.ChecksumTypeProto.valueOf(type.id);
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CacheManager.java

@@ -19,14 +19,13 @@ package org.apache.hadoop.hdfs.server.namenode;
 
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES_DEFAULT;
-import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_CACHING_ENABLED_KEY;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_CACHING_ENABLED_DEFAULT;
-import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES_DEFAULT;
+import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS_DEFAULT;
 
-import java.io.Closeable;
 import java.io.DataInput;
 import java.io.DataOutput;
 import java.io.IOException;
@@ -44,33 +43,22 @@ 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.IdNotFoundException;
 import org.apache.hadoop.fs.BatchedRemoteIterator.BatchedListEntries;
-import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsAction;
 import org.apache.hadoop.hdfs.DFSUtil;
 import org.apache.hadoop.hdfs.protocol.Block;
-import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
-import org.apache.hadoop.hdfs.protocol.BlockListAsLongs.BlockReportIterator;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.InvalidPoolNameError;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.UnexpectedAddPathBasedCacheDirectiveException;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.PoolWritePermissionDeniedError;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheEntry;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.InvalidIdException;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.NoSuchIdException;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.UnexpectedRemovePathBasedCacheDescriptorException;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.RemovePermissionDeniedException;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockManager;
 import org.apache.hadoop.hdfs.server.blockmanagement.CacheReplicationMonitor;
 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList;
 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList.Type;
-import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.ReplicaState;
 import org.apache.hadoop.hdfs.server.namenode.metrics.NameNodeMetrics;
 import org.apache.hadoop.hdfs.server.namenode.startupprogress.Phase;
 import org.apache.hadoop.hdfs.server.namenode.startupprogress.StartupProgress;
@@ -78,6 +66,7 @@ import org.apache.hadoop.hdfs.server.namenode.startupprogress.StartupProgress.Co
 import org.apache.hadoop.hdfs.server.namenode.startupprogress.Step;
 import org.apache.hadoop.hdfs.server.namenode.startupprogress.StepType;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.security.AccessControlException;
 import org.apache.hadoop.util.GSet;
 import org.apache.hadoop.util.LightWeightGSet;
 import org.apache.hadoop.util.Time;
@@ -111,7 +100,7 @@ public final class CacheManager {
   /**
    * Cache entries, sorted by ID.
    *
-   * listPathBasedCacheDescriptors relies on the ordering of elements in this map 
+   * listPathBasedCacheDirectives relies on the ordering of elements in this map
    * to track what has already been listed by the client.
    */
   private final TreeMap<Long, PathBasedCacheEntry> entriesById =
@@ -143,7 +132,7 @@ public final class CacheManager {
   /**
    * Maximum number of cache pool directives to list in one operation.
    */
-  private final int maxListCacheDescriptorsResponses;
+  private final int maxListCacheDirectivesNumResponses;
 
   /**
    * Interval between scans in milliseconds.
@@ -191,9 +180,9 @@ public final class CacheManager {
     this.maxListCachePoolsResponses = conf.getInt(
         DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES,
         DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES_DEFAULT);
-    this.maxListCacheDescriptorsResponses = conf.getInt(
-        DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES,
-        DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES_DEFAULT);
+    this.maxListCacheDirectivesNumResponses = conf.getInt(
+        DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES,
+        DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES_DEFAULT);
     scanIntervalMs = conf.getLong(
         DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS,
         DFS_NAMENODE_PATH_BASED_CACHE_REFRESH_INTERVAL_MS_DEFAULT);
@@ -266,132 +255,239 @@ public final class CacheManager {
     return nextEntryId++;
   }
 
-  public PathBasedCacheDescriptor addDirective(
-      PathBasedCacheDirective directive, FSPermissionChecker pc)
-      throws IOException {
-    assert namesystem.hasWriteLock();
-    CachePool pool = cachePools.get(directive.getPool());
-    if (pool == null) {
-      LOG.info("addDirective " + directive + ": pool not found.");
-      throw new InvalidPoolNameError(directive);
-    }
-    if ((pc != null) && (!pc.checkPermission(pool, FsAction.WRITE))) {
-      LOG.info("addDirective " + directive + ": write permission denied.");
-      throw new PoolWritePermissionDeniedError(directive);
-    }
-    try {
-      directive.validate();
-    } catch (IOException ioe) {
-      LOG.info("addDirective " + directive + ": validation failed: "
-          + ioe.getClass().getName() + ": " + ioe.getMessage());
-      throw ioe;
-    }
-    
-    // Add a new entry with the next available ID.
-    PathBasedCacheEntry entry;
-    try {
-      entry = new PathBasedCacheEntry(getNextEntryId(),
-          directive.getPath().toUri().getPath(),
-          directive.getReplication(), pool);
-    } catch (IOException ioe) {
-      throw new UnexpectedAddPathBasedCacheDirectiveException(directive);
-    }
-    LOG.info("addDirective " + directive + ": added cache directive "
-        + directive);
-
-    // Success!
-    // First, add it to the various maps
+  private void addInternal(PathBasedCacheEntry entry) {
     entriesById.put(entry.getEntryId(), entry);
-    String path = directive.getPath().toUri().getPath();
+    String path = entry.getPath();
     List<PathBasedCacheEntry> entryList = entriesByPath.get(path);
     if (entryList == null) {
       entryList = new ArrayList<PathBasedCacheEntry>(1);
       entriesByPath.put(path, entryList);
     }
     entryList.add(entry);
+  }
+
+  public PathBasedCacheDirective addDirective(
+      PathBasedCacheDirective directive, FSPermissionChecker pc)
+      throws IOException {
+    assert namesystem.hasWriteLock();
+    PathBasedCacheEntry entry;
+    try {
+      if (directive.getPool() == null) {
+        throw new IdNotFoundException("addDirective: no pool was specified.");
+      }
+      if (directive.getPool().isEmpty()) {
+        throw new IdNotFoundException("addDirective: pool name was empty.");
+      }
+      CachePool pool = cachePools.get(directive.getPool());
+      if (pool == null) {
+        throw new IdNotFoundException("addDirective: no such pool as " +
+            directive.getPool());
+      }
+      if ((pc != null) && (!pc.checkPermission(pool, FsAction.WRITE))) {
+        throw new AccessControlException("addDirective: write " +
+            "permission denied for pool " + directive.getPool());
+      }
+      if (directive.getPath() == null) {
+        throw new IOException("addDirective: no path was specified.");
+      }
+      String path = directive.getPath().toUri().getPath();
+      if (!DFSUtil.isValidName(path)) {
+        throw new IOException("addDirective: path '" + path + "' is invalid.");
+      }
+      short replication = directive.getReplication() == null ? 
+          (short)1 : directive.getReplication();
+      if (replication <= 0) {
+        throw new IOException("addDirective: replication " + replication +
+            " is invalid.");
+      }
+      long id;
+      if (directive.getId() != null) {
+        // We are loading an entry from the edit log.
+        // Use the ID from the edit log.
+        id = directive.getId();
+      } else {
+        // Add a new entry with the next available ID.
+        id = getNextEntryId();
+      }
+      entry = new PathBasedCacheEntry(id, path, replication, pool);
+      addInternal(entry);
+    } catch (IOException e) {
+      LOG.warn("addDirective " + directive + ": failed.", e);
+      throw e;
+    }
+    LOG.info("addDirective " + directive + ": succeeded.");
     if (monitor != null) {
       monitor.kick();
     }
-    return entry.getDescriptor();
+    return entry.toDirective();
+  }
+
+  public void modifyDirective(PathBasedCacheDirective directive,
+      FSPermissionChecker pc) throws IOException {
+    assert namesystem.hasWriteLock();
+    String idString =
+        (directive.getId() == null) ?
+            "(null)" : directive.getId().toString();
+    try {
+      // Check for invalid IDs.
+      Long id = directive.getId();
+      if (id == null) {
+        throw new IdNotFoundException("modifyDirective: " +
+            "no ID to modify was supplied.");
+      }
+      if (id <= 0) {
+        throw new IdNotFoundException("modifyDirective " + id +
+            ": invalid non-positive directive ID.");
+      }
+      // Find the entry.
+      PathBasedCacheEntry prevEntry = entriesById.get(id);
+      if (prevEntry == null) {
+        throw new IdNotFoundException("modifyDirective " + id +
+            ": id not found.");
+      }
+      if ((pc != null) &&
+          (!pc.checkPermission(prevEntry.getPool(), FsAction.WRITE))) {
+        throw new AccessControlException("modifyDirective " + id +
+            ": permission denied for initial pool " + prevEntry.getPool());
+      }
+      String path = prevEntry.getPath();
+      if (directive.getPath() != null) {
+        path = directive.getPath().toUri().getPath();
+        if (!DFSUtil.isValidName(path)) {
+          throw new IOException("modifyDirective " + id + ": new path " +
+              path + " is not valid.");
+        }
+      }
+      short replication = (directive.getReplication() != null) ?
+          directive.getReplication() : prevEntry.getReplication();
+      if (replication <= 0) {
+        throw new IOException("modifyDirective: replication " + replication +
+            " is invalid.");
+      }
+      CachePool pool = prevEntry.getPool();
+      if (directive.getPool() != null) {
+        pool = cachePools.get(directive.getPool());
+        if (pool == null) {
+          throw new IdNotFoundException("modifyDirective " + id +
+              ": pool " + directive.getPool() + " not found.");
+        }
+        if (directive.getPool().isEmpty()) {
+          throw new IdNotFoundException("modifyDirective: pool name was " +
+              "empty.");
+        }
+        if ((pc != null) &&
+            (!pc.checkPermission(pool, FsAction.WRITE))) {
+          throw new AccessControlException("modifyDirective " + id +
+              ": permission denied for target pool " + pool);
+        }
+      }
+      removeInternal(prevEntry);
+      PathBasedCacheEntry newEntry =
+          new PathBasedCacheEntry(id, path, replication, pool);
+      addInternal(newEntry);
+    } catch (IOException e) {
+      LOG.warn("modifyDirective " + idString + ": failed.", e);
+      throw e;
+    }
+    LOG.info("modifyDirective " + idString + ": successfully applied " +
+        directive);
   }
 
-  public void removeDescriptor(long id, FSPermissionChecker pc)
+  public void removeInternal(PathBasedCacheEntry existing)
       throws IOException {
     assert namesystem.hasWriteLock();
-    // Check for invalid IDs.
-    if (id <= 0) {
-      LOG.info("removeDescriptor " + id + ": invalid non-positive " +
-          "descriptor ID.");
-      throw new InvalidIdException(id);
-    }
-    // Find the entry.
-    PathBasedCacheEntry existing = entriesById.get(id);
-    if (existing == null) {
-      LOG.info("removeDescriptor " + id + ": entry not found.");
-      throw new NoSuchIdException(id);
-    }
-    CachePool pool = cachePools.get(existing.getDescriptor().getPool());
-    if (pool == null) {
-      LOG.info("removeDescriptor " + id + ": pool not found for directive " +
-        existing.getDescriptor());
-      throw new UnexpectedRemovePathBasedCacheDescriptorException(id);
-    }
-    if ((pc != null) && (!pc.checkPermission(pool, FsAction.WRITE))) {
-      LOG.info("removeDescriptor " + id + ": write permission denied to " +
-          "pool " + pool + " for entry " + existing);
-      throw new RemovePermissionDeniedException(id);
-    }
-    
     // Remove the corresponding entry in entriesByPath.
-    String path = existing.getDescriptor().getPath().toUri().getPath();
+    String path = existing.getPath();
     List<PathBasedCacheEntry> entries = entriesByPath.get(path);
     if (entries == null || !entries.remove(existing)) {
-      throw new UnexpectedRemovePathBasedCacheDescriptorException(id);
+      throw new IdNotFoundException("removeInternal: failed to locate entry " +
+          existing.getEntryId() + " by path " + existing.getPath());
     }
     if (entries.size() == 0) {
       entriesByPath.remove(path);
     }
-    entriesById.remove(id);
+    entriesById.remove(existing.getEntryId());
+  }
+
+  public void removeDirective(long id, FSPermissionChecker pc)
+      throws IOException {
+    assert namesystem.hasWriteLock();
+    try {
+      // Check for invalid IDs.
+      if (id <= 0) {
+        throw new IdNotFoundException("removeDirective " + id + ": invalid " +
+            "non-positive directive ID.");
+      }
+      // Find the entry.
+      PathBasedCacheEntry existing = entriesById.get(id);
+      if (existing == null) {
+        throw new IdNotFoundException("removeDirective " + id +
+            ": id not found.");
+      }
+      if ((pc != null) &&
+          (!pc.checkPermission(existing.getPool(), FsAction.WRITE))) {
+        throw new AccessControlException("removeDirective " + id +
+            ": write permission denied on pool " +
+            existing.getPool().getPoolName());
+      }
+      removeInternal(existing);
+    } catch (IOException e) {
+      LOG.warn("removeDirective " + id + " failed.", e);
+      throw e;
+    }
     if (monitor != null) {
       monitor.kick();
     }
-    LOG.info("removeDescriptor successful for PathCacheEntry id " + id);
+    LOG.info("removeDirective " + id + ": succeeded.");
   }
 
-  public BatchedListEntries<PathBasedCacheDescriptor> 
-        listPathBasedCacheDescriptors(long prevId, String filterPool,
-            String filterPath, FSPermissionChecker pc) throws IOException {
+  public BatchedListEntries<PathBasedCacheDirective> 
+        listPathBasedCacheDirectives(long prevId,
+            PathBasedCacheDirective filter,
+            FSPermissionChecker pc) throws IOException {
     assert namesystem.hasReadOrWriteLock();
     final int NUM_PRE_ALLOCATED_ENTRIES = 16;
-    if (filterPath != null) {
+    String filterPath = null;
+    if (filter.getId() != null) {
+      throw new IOException("we currently don't support filtering by ID");
+    }
+    if (filter.getPath() != null) {
+      filterPath = filter.getPath().toUri().getPath();
       if (!DFSUtil.isValidName(filterPath)) {
-        throw new IOException("invalid path name '" + filterPath + "'");
+        throw new IOException("listPathBasedCacheDirectives: invalid " +
+            "path name '" + filterPath + "'");
       }
     }
-    ArrayList<PathBasedCacheDescriptor> replies =
-        new ArrayList<PathBasedCacheDescriptor>(NUM_PRE_ALLOCATED_ENTRIES);
+    if (filter.getReplication() != null) {
+      throw new IOException("we currently don't support filtering " +
+          "by replication");
+    }
+    ArrayList<PathBasedCacheDirective> replies =
+        new ArrayList<PathBasedCacheDirective>(NUM_PRE_ALLOCATED_ENTRIES);
     int numReplies = 0;
-    SortedMap<Long, PathBasedCacheEntry> tailMap = entriesById.tailMap(prevId + 1);
+    SortedMap<Long, PathBasedCacheEntry> tailMap =
+      entriesById.tailMap(prevId + 1);
     for (Entry<Long, PathBasedCacheEntry> cur : tailMap.entrySet()) {
-      if (numReplies >= maxListCacheDescriptorsResponses) {
-        return new BatchedListEntries<PathBasedCacheDescriptor>(replies, true);
+      if (numReplies >= maxListCacheDirectivesNumResponses) {
+        return new BatchedListEntries<PathBasedCacheDirective>(replies, true);
       }
       PathBasedCacheEntry curEntry = cur.getValue();
-      PathBasedCacheDirective directive = cur.getValue().getDescriptor();
-      if (filterPool != null && 
-          !directive.getPool().equals(filterPool)) {
+      PathBasedCacheDirective directive = cur.getValue().toDirective();
+      if (filter.getPool() != null && 
+          !directive.getPool().equals(filter.getPool())) {
         continue;
       }
       if (filterPath != null &&
           !directive.getPath().toUri().getPath().equals(filterPath)) {
         continue;
       }
-      if (pc.checkPermission(curEntry.getPool(), FsAction.READ)) {
-        replies.add(cur.getValue().getDescriptor());
+      if ((pc == null) ||
+          (pc.checkPermission(curEntry.getPool(), FsAction.READ))) {
+        replies.add(cur.getValue().toDirective());
         numReplies++;
       }
     }
-    return new BatchedListEntries<PathBasedCacheDescriptor>(replies, false);
+    return new BatchedListEntries<PathBasedCacheDirective>(replies, false);
   }
 
   /**
@@ -553,7 +649,8 @@ public final class CacheManager {
           blockManager.getDatanodeManager().getDatanode(datanodeID);
       if (datanode == null || !datanode.isAlive) {
         throw new IOException(
-            "processCacheReport from dead or unregistered datanode: " + datanode);
+            "processCacheReport from dead or unregistered datanode: " +
+            datanode);
       }
       processCacheReportImpl(datanode, blockIds);
     } finally {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java

@@ -39,7 +39,6 @@ import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheEntry;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.server.common.HdfsServerConstants.NamenodeRole;
 import org.apache.hadoop.hdfs.server.common.Storage.FormatConfirmable;
@@ -47,6 +46,7 @@ import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AddCachePoolOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AddOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AddPathBasedCacheDirectiveOp;
+import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.ModifyPathBasedCacheDirectiveOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AllocateBlockIdOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.AllowSnapshotOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.CancelDelegationTokenOp;
@@ -63,7 +63,7 @@ import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.ModifyCachePoolOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.OpInstanceCache;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.ReassignLeaseOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RemoveCachePoolOp;
-import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RemovePathBasedCacheDescriptorOp;
+import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RemovePathBasedCacheDirectiveOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameOldOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameSnapshotOp;
@@ -956,18 +956,25 @@ public class FSEditLog implements LogsPurgeable {
   
   void logAddPathBasedCacheDirective(PathBasedCacheDirective directive,
       boolean toLogRpcIds) {
-    AddPathBasedCacheDirectiveOp op = AddPathBasedCacheDirectiveOp.getInstance(
-        cache.get())
-        .setPath(directive.getPath().toUri().getPath())
-        .setReplication(directive.getReplication())
-        .setPool(directive.getPool());
+    AddPathBasedCacheDirectiveOp op =
+        AddPathBasedCacheDirectiveOp.getInstance(cache.get())
+            .setDirective(directive);
     logRpcIds(op, toLogRpcIds);
     logEdit(op);
   }
 
-  void logRemovePathBasedCacheDescriptor(Long id, boolean toLogRpcIds) {
-    RemovePathBasedCacheDescriptorOp op =
-        RemovePathBasedCacheDescriptorOp.getInstance(cache.get()).setId(id);
+  void logModifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive, boolean toLogRpcIds) {
+    ModifyPathBasedCacheDirectiveOp op =
+        ModifyPathBasedCacheDirectiveOp.getInstance(
+            cache.get()).setDirective(directive);
+    logRpcIds(op, toLogRpcIds);
+    logEdit(op);
+  }
+
+  void logRemovePathBasedCacheDirective(Long id, boolean toLogRpcIds) {
+    RemovePathBasedCacheDirectiveOp op =
+        RemovePathBasedCacheDirectiveOp.getInstance(cache.get()).setId(id);
     logRpcIds(op, toLogRpcIds);
     logEdit(op);
   }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java

@@ -37,7 +37,6 @@ import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfoUnderConstruction;
@@ -58,9 +57,10 @@ import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.DisallowSnapshotOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.GetDelegationTokenOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.MkdirOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.ModifyCachePoolOp;
+import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.ModifyPathBasedCacheDirectiveOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.ReassignLeaseOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RemoveCachePoolOp;
-import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RemovePathBasedCacheDescriptorOp;
+import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RemovePathBasedCacheDirectiveOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameOldOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameOp;
 import org.apache.hadoop.hdfs.server.namenode.FSEditLogOp.RenameSnapshotOp;
@@ -642,23 +642,28 @@ public class FSEditLogLoader {
     }
     case OP_ADD_PATH_BASED_CACHE_DIRECTIVE: {
       AddPathBasedCacheDirectiveOp addOp = (AddPathBasedCacheDirectiveOp) op;
-      PathBasedCacheDirective d = new PathBasedCacheDirective.Builder().
-          setPath(new Path(addOp.path)).
-          setReplication(addOp.replication).
-          setPool(addOp.pool).
-          build();
-      PathBasedCacheDescriptor descriptor =
-          fsNamesys.getCacheManager().addDirective(d, null);
+      PathBasedCacheDirective result = fsNamesys.
+          getCacheManager().addDirective(addOp.directive, null);
       if (toAddRetryCache) {
-        fsNamesys.addCacheEntryWithPayload(op.rpcClientId, op.rpcCallId,
-            descriptor);
+        Long id = result.getId();
+        fsNamesys.addCacheEntryWithPayload(op.rpcClientId, op.rpcCallId, id);
       }
       break;
     }
-    case OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR: {
-      RemovePathBasedCacheDescriptorOp removeOp =
-          (RemovePathBasedCacheDescriptorOp) op;
-      fsNamesys.getCacheManager().removeDescriptor(removeOp.id, null);
+    case OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE: {
+      ModifyPathBasedCacheDirectiveOp modifyOp =
+          (ModifyPathBasedCacheDirectiveOp) op;
+      fsNamesys.getCacheManager().modifyDirective(
+          modifyOp.directive, null);
+      if (toAddRetryCache) {
+        fsNamesys.addCacheEntry(op.rpcClientId, op.rpcCallId);
+      }
+      break;
+    }
+    case OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE: {
+      RemovePathBasedCacheDirectiveOp removeOp =
+          (RemovePathBasedCacheDirectiveOp) op;
+      fsNamesys.getCacheManager().removeDirective(removeOp.id, null);
       if (toAddRetryCache) {
         fsNamesys.addCacheEntry(op.rpcClientId, op.rpcCallId);
       }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOp.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.hdfs.server.namenode;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ADD;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ADD_CACHE_POOL;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ADD_PATH_BASED_CACHE_DIRECTIVE;
+import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ALLOCATE_BLOCK_ID;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_ALLOW_SNAPSHOT;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_CANCEL_DELEGATION_TOKEN;
@@ -37,7 +38,7 @@ import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_MKDIR;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_MODIFY_CACHE_POOL;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_REASSIGN_LEASE;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_REMOVE_CACHE_POOL;
-import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR;
+import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENAME;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENAME_OLD;
 import static org.apache.hadoop.hdfs.server.namenode.FSEditLogOpCodes.OP_RENAME_SNAPSHOT;
@@ -74,6 +75,7 @@ import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.ChecksumException;
 import org.apache.hadoop.fs.Options.Rename;
+import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.fs.permission.PermissionStatus;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
@@ -84,6 +86,7 @@ import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion;
 import org.apache.hadoop.hdfs.protocol.LayoutVersion.Feature;
+import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.hdfs.util.XMLUtils;
 import org.apache.hadoop.hdfs.util.XMLUtils.InvalidXmlException;
@@ -164,8 +167,10 @@ public abstract class FSEditLogOp {
       inst.put(OP_ALLOCATE_BLOCK_ID, new AllocateBlockIdOp());
       inst.put(OP_ADD_PATH_BASED_CACHE_DIRECTIVE,
           new AddPathBasedCacheDirectiveOp());
-      inst.put(OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR,
-          new RemovePathBasedCacheDescriptorOp());
+      inst.put(OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE,
+          new ModifyPathBasedCacheDirectiveOp());
+      inst.put(OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE,
+          new RemovePathBasedCacheDirectiveOp());
       inst.put(OP_ADD_CACHE_POOL, new AddCachePoolOp());
       inst.put(OP_MODIFY_CACHE_POOL, new ModifyCachePoolOp());
       inst.put(OP_REMOVE_CACHE_POOL, new RemoveCachePoolOp());
@@ -2866,9 +2871,7 @@ public abstract class FSEditLogOp {
    * {@link ClientProtocol#addPathBasedCacheDirective}
    */
   static class AddPathBasedCacheDirectiveOp extends FSEditLogOp {
-    String path;
-    short replication;
-    String pool;
+    PathBasedCacheDirective directive;
 
     public AddPathBasedCacheDirectiveOp() {
       super(OP_ADD_PATH_BASED_CACHE_DIRECTIVE);
@@ -2879,61 +2882,199 @@ public abstract class FSEditLogOp {
           .get(OP_ADD_PATH_BASED_CACHE_DIRECTIVE);
     }
 
-    public AddPathBasedCacheDirectiveOp setPath(String path) {
-      this.path = path;
+    public AddPathBasedCacheDirectiveOp setDirective(
+        PathBasedCacheDirective directive) {
+      this.directive = directive;
+      assert(directive.getId() != null);
+      assert(directive.getPath() != null);
+      assert(directive.getReplication() != null);
+      assert(directive.getPool() != null);
       return this;
     }
 
-    public AddPathBasedCacheDirectiveOp setReplication(short replication) {
-      this.replication = replication;
-      return this;
+    @Override
+    void readFields(DataInputStream in, int logVersion) throws IOException {
+      long id = FSImageSerialization.readLong(in);
+      String path = FSImageSerialization.readString(in);
+      short replication = FSImageSerialization.readShort(in);
+      String pool = FSImageSerialization.readString(in);
+      directive = new PathBasedCacheDirective.Builder().
+          setId(id).
+          setPath(new Path(path)).
+          setReplication(replication).
+          setPool(pool).
+          build();
+      readRpcIds(in, logVersion);
+    }
+
+    @Override
+    public void writeFields(DataOutputStream out) throws IOException {
+      FSImageSerialization.writeLong(directive.getId(), out);
+      FSImageSerialization.writeString(directive.getPath().toUri().getPath(), out);
+      FSImageSerialization.writeShort(directive.getReplication(), out);
+      FSImageSerialization.writeString(directive.getPool(), out);
+      writeRpcIds(rpcClientId, rpcCallId, out);
+    }
+
+    @Override
+    protected void toXml(ContentHandler contentHandler) throws SAXException {
+      XMLUtils.addSaxString(contentHandler, "ID",
+          directive.getId().toString());
+      XMLUtils.addSaxString(contentHandler, "PATH",
+          directive.getPath().toUri().getPath());
+      XMLUtils.addSaxString(contentHandler, "REPLICATION",
+          Short.toString(directive.getReplication()));
+      XMLUtils.addSaxString(contentHandler, "POOL", directive.getPool());
+      appendRpcIdsToXml(contentHandler, rpcClientId, rpcCallId);
     }
 
-    public AddPathBasedCacheDirectiveOp setPool(String pool) {
-      this.pool = pool;
+    @Override
+    void fromXml(Stanza st) throws InvalidXmlException {
+      directive = new PathBasedCacheDirective.Builder().
+          setId(Long.parseLong(st.getValue("ID"))).
+          setPath(new Path(st.getValue("PATH"))).
+          setReplication(Short.parseShort(st.getValue("REPLICATION"))).
+          setPool(st.getValue("POOL")).
+          build();
+      readRpcIdsFromXml(st);
+    }
+
+    @Override
+    public String toString() {
+      StringBuilder builder = new StringBuilder();
+      builder.append("AddPathBasedCacheDirective [");
+      builder.append("id=" + directive.getId() + ",");
+      builder.append("path=" + directive.getPath().toUri().getPath() + ",");
+      builder.append("replication=" + directive.getReplication() + ",");
+      builder.append("pool=" + directive.getPool());
+      appendRpcIdsToString(builder, rpcClientId, rpcCallId);
+      builder.append("]");
+      return builder.toString();
+    }
+  }
+
+  /**
+   * {@literal @AtMostOnce} for
+   * {@link ClientProtocol#modifyPathBasedCacheDirective}
+   */
+  static class ModifyPathBasedCacheDirectiveOp extends FSEditLogOp {
+    PathBasedCacheDirective directive;
+
+    public ModifyPathBasedCacheDirectiveOp() {
+      super(OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE);
+    }
+
+    static ModifyPathBasedCacheDirectiveOp getInstance(OpInstanceCache cache) {
+      return (ModifyPathBasedCacheDirectiveOp) cache
+          .get(OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE);
+    }
+
+    public ModifyPathBasedCacheDirectiveOp setDirective(
+        PathBasedCacheDirective directive) {
+      this.directive = directive;
+      assert(directive.getId() != null);
       return this;
     }
 
     @Override
     void readFields(DataInputStream in, int logVersion) throws IOException {
-      this.path = FSImageSerialization.readString(in);
-      this.replication = FSImageSerialization.readShort(in);
-      this.pool = FSImageSerialization.readString(in);
+      PathBasedCacheDirective.Builder builder =
+          new PathBasedCacheDirective.Builder();
+      builder.setId(FSImageSerialization.readLong(in));
+      byte flags = in.readByte();
+      if ((flags & 0x1) != 0) {
+        builder.setPath(new Path(FSImageSerialization.readString(in)));
+      }
+      if ((flags & 0x2) != 0) {
+        builder.setReplication(FSImageSerialization.readShort(in));
+      }
+      if ((flags & 0x4) != 0) {
+        builder.setPool(FSImageSerialization.readString(in));
+      }
+      if ((flags & ~0x7) != 0) {
+        throw new IOException("unknown flags set in " +
+            "ModifyPathBasedCacheDirectiveOp: " + flags);
+      }
+      this.directive = builder.build();
       readRpcIds(in, logVersion);
     }
 
     @Override
     public void writeFields(DataOutputStream out) throws IOException {
-      FSImageSerialization.writeString(path, out);
-      FSImageSerialization.writeShort(replication, out);
-      FSImageSerialization.writeString(pool, out);
+      FSImageSerialization.writeLong(directive.getId(), out);
+      byte flags = (byte)(
+          ((directive.getPath() != null) ? 0x1 : 0) |
+          ((directive.getReplication() != null) ? 0x2 : 0) |
+          ((directive.getPool() != null) ? 0x4 : 0)
+        );
+      out.writeByte(flags);
+      if (directive.getPath() != null) {
+        FSImageSerialization.writeString(
+            directive.getPath().toUri().getPath(), out);
+      }
+      if (directive.getReplication() != null) {
+        FSImageSerialization.writeShort(directive.getReplication(), out);
+      }
+      if (directive.getPool() != null) {
+        FSImageSerialization.writeString(directive.getPool(), out);
+      }
       writeRpcIds(rpcClientId, rpcCallId, out);
     }
 
     @Override
     protected void toXml(ContentHandler contentHandler) throws SAXException {
-      XMLUtils.addSaxString(contentHandler, "PATH", path);
-      XMLUtils.addSaxString(contentHandler, "REPLICATION",
-          Short.toString(replication));
-      XMLUtils.addSaxString(contentHandler, "POOL", pool);
+      XMLUtils.addSaxString(contentHandler, "ID",
+          Long.toString(directive.getId()));
+      if (directive.getPath() != null) {
+        XMLUtils.addSaxString(contentHandler, "PATH",
+            directive.getPath().toUri().getPath());
+      }
+      if (directive.getReplication() != null) {
+        XMLUtils.addSaxString(contentHandler, "REPLICATION",
+            Short.toString(directive.getReplication()));
+      }
+      if (directive.getPool() != null) {
+        XMLUtils.addSaxString(contentHandler, "POOL", directive.getPool());
+      }
       appendRpcIdsToXml(contentHandler, rpcClientId, rpcCallId);
     }
 
     @Override
     void fromXml(Stanza st) throws InvalidXmlException {
-      path = st.getValue("PATH");
-      replication = Short.parseShort(st.getValue("REPLICATION"));
-      pool = st.getValue("POOL");
+      PathBasedCacheDirective.Builder builder =
+          new PathBasedCacheDirective.Builder();
+      builder.setId(Long.parseLong(st.getValue("ID")));
+      String path = st.getValueOrNull("PATH");
+      if (path != null) {
+        builder.setPath(new Path(path));
+      }
+      String replicationString = st.getValueOrNull("REPLICATION");
+      if (replicationString != null) {
+        builder.setReplication(Short.parseShort(replicationString));
+      }
+      String pool = st.getValueOrNull("POOL");
+      if (pool != null) {
+        builder.setPool(pool);
+      }
+      this.directive = builder.build();
       readRpcIdsFromXml(st);
     }
 
     @Override
     public String toString() {
       StringBuilder builder = new StringBuilder();
-      builder.append("AddPathBasedCacheDirective [");
-      builder.append("path=" + path + ",");
-      builder.append("replication=" + replication + ",");
-      builder.append("pool=" + pool);
+      builder.append("ModifyPathBasedCacheDirectiveOp[");
+      builder.append("id=").append(directive.getId());
+      if (directive.getPath() != null) {
+        builder.append(",").append("path=").append(directive.getPath());
+      }
+      if (directive.getReplication() != null) {
+        builder.append(",").append("replication=").
+            append(directive.getReplication());
+      }
+      if (directive.getPool() != null) {
+        builder.append(",").append("pool=").append(directive.getPool());
+      }
       appendRpcIdsToString(builder, rpcClientId, rpcCallId);
       builder.append("]");
       return builder.toString();
@@ -2942,21 +3083,21 @@ public abstract class FSEditLogOp {
 
   /**
    * {@literal @AtMostOnce} for
-   * {@link ClientProtocol#removePathBasedCacheDescriptor}
+   * {@link ClientProtocol#removePathBasedCacheDirective}
    */
-  static class RemovePathBasedCacheDescriptorOp extends FSEditLogOp {
+  static class RemovePathBasedCacheDirectiveOp extends FSEditLogOp {
     long id;
 
-    public RemovePathBasedCacheDescriptorOp() {
-      super(OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR);
+    public RemovePathBasedCacheDirectiveOp() {
+      super(OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE);
     }
 
-    static RemovePathBasedCacheDescriptorOp getInstance(OpInstanceCache cache) {
-      return (RemovePathBasedCacheDescriptorOp) cache
-          .get(OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR);
+    static RemovePathBasedCacheDirectiveOp getInstance(OpInstanceCache cache) {
+      return (RemovePathBasedCacheDirectiveOp) cache
+          .get(OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE);
     }
 
-    public RemovePathBasedCacheDescriptorOp setId(long id) {
+    public RemovePathBasedCacheDirectiveOp setId(long id) {
       this.id = id;
       return this;
     }
@@ -2988,7 +3129,7 @@ public abstract class FSEditLogOp {
     @Override
     public String toString() {
       StringBuilder builder = new StringBuilder();
-      builder.append("RemovePathBasedCacheDescriptor [");
+      builder.append("RemovePathBasedCacheDirective [");
       builder.append("id=" + Long.toString(id));
       appendRpcIdsToString(builder, rpcClientId, rpcCallId);
       builder.append("]");

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogOpCodes.java

@@ -64,11 +64,12 @@ public enum FSEditLogOpCodes {
   OP_DISALLOW_SNAPSHOT          ((byte) 30),
   OP_SET_GENSTAMP_V2            ((byte) 31),
   OP_ALLOCATE_BLOCK_ID          ((byte) 32),
-  OP_ADD_PATH_BASED_CACHE_DIRECTIVE        ((byte) 33),
-  OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR    ((byte) 34),
-  OP_ADD_CACHE_POOL             ((byte) 35),
-  OP_MODIFY_CACHE_POOL          ((byte) 36),
-  OP_REMOVE_CACHE_POOL          ((byte) 37);
+  OP_ADD_PATH_BASED_CACHE_DIRECTIVE       ((byte) 33),
+  OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE    ((byte) 34),
+  OP_ADD_CACHE_POOL                       ((byte) 35),
+  OP_MODIFY_CACHE_POOL                    ((byte) 36),
+  OP_REMOVE_CACHE_POOL                    ((byte) 37),
+  OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE    ((byte) 38);
 
   private byte opCode;
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -152,7 +152,6 @@ import org.apache.hadoop.hdfs.HdfsConfiguration;
 import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
 import org.apache.hadoop.hdfs.protocol.Block;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
@@ -7008,7 +7007,7 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     }
   }
 
-  PathBasedCacheDescriptor addPathBasedCacheDirective(
+  long addPathBasedCacheDirective(
       PathBasedCacheDirective directive) throws IOException {
     checkOperation(OperationCategory.WRITE);
     final FSPermissionChecker pc = isPermissionEnabled ?
@@ -7016,20 +7015,26 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     CacheEntryWithPayload cacheEntry =
         RetryCache.waitForCompletion(retryCache, null);
     if (cacheEntry != null && cacheEntry.isSuccess()) {
-      return (PathBasedCacheDescriptor) cacheEntry.getPayload();
+      return (Long) cacheEntry.getPayload();
     }
     boolean success = false;
-    PathBasedCacheDescriptor result = null;
     writeLock();
+    Long result = null;
     try {
       checkOperation(OperationCategory.WRITE);
       if (isInSafeMode()) {
         throw new SafeModeException(
             "Cannot add PathBasedCache directive", safeMode);
       }
-      result = cacheManager.addDirective(directive, pc);
-      getEditLog().logAddPathBasedCacheDirective(directive,
+      if (directive.getId() != null) {
+        throw new IOException("addDirective: you cannot specify an ID " +
+            "for this operation.");
+      }
+      PathBasedCacheDirective effectiveDirective = 
+          cacheManager.addDirective(directive, pc);
+      getEditLog().logAddPathBasedCacheDirective(effectiveDirective,
           cacheEntry != null);
+      result = effectiveDirective.getId();
       success = true;
     } finally {
       writeUnlock();
@@ -7044,7 +7049,40 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     return result;
   }
 
-  void removePathBasedCacheDescriptor(Long id) throws IOException {
+  void modifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive) throws IOException {
+    checkOperation(OperationCategory.WRITE);
+    final FSPermissionChecker pc = isPermissionEnabled ?
+        getPermissionChecker() : null;
+    boolean success = false;
+    CacheEntry cacheEntry = RetryCache.waitForCompletion(retryCache);
+    if (cacheEntry != null && cacheEntry.isSuccess()) {
+      return;
+    }
+    writeLock();
+    try {
+      checkOperation(OperationCategory.WRITE);
+      if (isInSafeMode()) {
+        throw new SafeModeException(
+            "Cannot add PathBasedCache directive", safeMode);
+      }
+      cacheManager.modifyDirective(directive, pc);
+      getEditLog().logModifyPathBasedCacheDirective(directive,
+          cacheEntry != null);
+      success = true;
+    } finally {
+      writeUnlock();
+      if (success) {
+        getEditLog().logSync();
+      }
+      if (isAuditEnabled() && isExternalInvocation()) {
+        logAuditEvent(success, "addPathBasedCacheDirective", null, null, null);
+      }
+      RetryCache.setState(cacheEntry, success);
+    }
+  }
+
+  void removePathBasedCacheDirective(Long id) throws IOException {
     checkOperation(OperationCategory.WRITE);
     final FSPermissionChecker pc = isPermissionEnabled ?
         getPermissionChecker() : null;
@@ -7060,13 +7098,13 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
         throw new SafeModeException(
             "Cannot remove PathBasedCache directives", safeMode);
       }
-      cacheManager.removeDescriptor(id, pc);
-      getEditLog().logRemovePathBasedCacheDescriptor(id, cacheEntry != null);
+      cacheManager.removeDirective(id, pc);
+      getEditLog().logRemovePathBasedCacheDirective(id, cacheEntry != null);
       success = true;
     } finally {
       writeUnlock();
       if (isAuditEnabled() && isExternalInvocation()) {
-        logAuditEvent(success, "removePathBasedCacheDescriptor", null, null,
+        logAuditEvent(success, "removePathBasedCacheDirective", null, null,
             null);
       }
       RetryCache.setState(cacheEntry, success);
@@ -7074,23 +7112,23 @@ public class FSNamesystem implements Namesystem, FSClusterStats,
     getEditLog().logSync();
   }
 
-  BatchedListEntries<PathBasedCacheDescriptor> listPathBasedCacheDescriptors(
-      long startId, String pool, String path) throws IOException {
+  BatchedListEntries<PathBasedCacheDirective> listPathBasedCacheDirectives(
+      long startId, PathBasedCacheDirective filter) throws IOException {
     checkOperation(OperationCategory.READ);
     final FSPermissionChecker pc = isPermissionEnabled ?
         getPermissionChecker() : null;
-    BatchedListEntries<PathBasedCacheDescriptor> results;
+    BatchedListEntries<PathBasedCacheDirective> results;
     readLock();
     boolean success = false;
     try {
       checkOperation(OperationCategory.READ);
       results =
-          cacheManager.listPathBasedCacheDescriptors(startId, pool, path, pc);
+          cacheManager.listPathBasedCacheDirectives(startId, filter, pc);
       success = true;
     } finally {
       readUnlock();
       if (isAuditEnabled() && isExternalInvocation()) {
-        logAuditEvent(success, "listPathBasedCacheDescriptors", null, null,
+        logAuditEvent(success, "listPathBasedCacheDirectives", null, null,
             null);
       }
     }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/NameNodeRpcServer.java

@@ -62,7 +62,6 @@ import org.apache.hadoop.hdfs.HDFSPolicyProvider;
 import org.apache.hadoop.hdfs.protocol.AlreadyBeingCreatedException;
 import org.apache.hadoop.hdfs.protocol.BlockListAsLongs;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.CorruptFileBlocks;
 import org.apache.hadoop.hdfs.protocol.DatanodeID;
@@ -1234,46 +1233,52 @@ class NameNodeRpcServer implements NamenodeProtocols {
   }
 
   @Override
-  public PathBasedCacheDescriptor addPathBasedCacheDirective(
+  public long addPathBasedCacheDirective(
       PathBasedCacheDirective path) throws IOException {
     return namesystem.addPathBasedCacheDirective(path);
   }
 
   @Override
-  public void removePathBasedCacheDescriptor(Long id) throws IOException {
-    namesystem.removePathBasedCacheDescriptor(id);
+  public void modifyPathBasedCacheDirective(
+      PathBasedCacheDirective directive) throws IOException {
+    namesystem.modifyPathBasedCacheDirective(directive);
   }
 
-  private class ServerSidePathBasedCacheEntriesIterator
-      extends BatchedRemoteIterator<Long, PathBasedCacheDescriptor> {
-
-    private final String pool;
+  @Override
+  public void removePathBasedCacheDirective(long id) throws IOException {
+    namesystem.removePathBasedCacheDirective(id);
+  }
 
-    private final String path;
+  private class ServerSidePathBasedCacheEntriesIterator
+      extends BatchedRemoteIterator<Long, PathBasedCacheDirective> {
 
-    public ServerSidePathBasedCacheEntriesIterator(Long firstKey, String pool,
-        String path) {
+    private final PathBasedCacheDirective filter;
+    
+    public ServerSidePathBasedCacheEntriesIterator(Long firstKey, 
+        PathBasedCacheDirective filter) {
       super(firstKey);
-      this.pool = pool;
-      this.path = path;
+      this.filter = filter;
     }
 
     @Override
-    public BatchedEntries<PathBasedCacheDescriptor> makeRequest(
+    public BatchedEntries<PathBasedCacheDirective> makeRequest(
         Long nextKey) throws IOException {
-      return namesystem.listPathBasedCacheDescriptors(nextKey, pool, path);
+      return namesystem.listPathBasedCacheDirectives(nextKey, filter);
     }
 
     @Override
-    public Long elementToPrevKey(PathBasedCacheDescriptor entry) {
-      return entry.getEntryId();
+    public Long elementToPrevKey(PathBasedCacheDirective entry) {
+      return entry.getId();
     }
   }
   
   @Override
-  public RemoteIterator<PathBasedCacheDescriptor> listPathBasedCacheDescriptors(long prevId,
-      String pool, String path) throws IOException {
-    return new ServerSidePathBasedCacheEntriesIterator(prevId, pool, path);
+  public RemoteIterator<PathBasedCacheDirective> listPathBasedCacheDirectives(long prevId,
+      PathBasedCacheDirective filter) throws IOException {
+    if (filter == null) {
+      filter = new PathBasedCacheDirective.Builder().build();
+    }
+    return new ServerSidePathBasedCacheEntriesIterator(prevId, filter);
   }
 
   @Override

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/CacheAdmin.java

@@ -30,11 +30,8 @@ import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.RemoteIterator;
 import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException;
 import org.apache.hadoop.hdfs.server.namenode.CachePool;
 import org.apache.hadoop.hdfs.tools.TableListing.Justification;
 import org.apache.hadoop.ipc.RemoteException;
@@ -180,11 +177,9 @@ public class CacheAdmin extends Configured implements Tool {
           setPool(poolName).
           build();
       try {
-        PathBasedCacheDescriptor descriptor =
-            dfs.addPathBasedCacheDirective(directive);
-        System.out.println("Added PathBasedCache entry "
-            + descriptor.getEntryId());
-      } catch (AddPathBasedCacheDirectiveException e) {
+        long id = dfs.addPathBasedCacheDirective(directive);
+        System.out.println("Added PathBasedCache entry " + id);
+      } catch (IOException e) {
         System.err.println(prettifyException(e));
         return 2;
       }
@@ -243,9 +238,9 @@ public class CacheAdmin extends Configured implements Tool {
       }
       DistributedFileSystem dfs = getDFS(conf);
       try {
-        dfs.getClient().removePathBasedCacheDescriptor(id);
+        dfs.getClient().removePathBasedCacheDirective(id);
         System.out.println("Removed PathBasedCache directive " + id);
-      } catch (RemovePathBasedCacheDescriptorException e) {
+      } catch (IOException e) {
         System.err.println(prettifyException(e));
         return 2;
       }
@@ -289,16 +284,18 @@ public class CacheAdmin extends Configured implements Tool {
         return 1;
       }
       DistributedFileSystem dfs = getDFS(conf);
-      RemoteIterator<PathBasedCacheDescriptor> iter =
-          dfs.listPathBasedCacheDescriptors(null, new Path(path));
+      RemoteIterator<PathBasedCacheDirective> iter =
+          dfs.listPathBasedCacheDirectives(
+              new PathBasedCacheDirective.Builder().
+                  setPath(new Path(path)).build());
       int exitCode = 0;
       while (iter.hasNext()) {
-        PathBasedCacheDescriptor entry = iter.next();
+        PathBasedCacheDirective directive = iter.next();
         try {
-          dfs.removePathBasedCacheDescriptor(entry);
+          dfs.removePathBasedCacheDirective(directive.getId());
           System.out.println("Removed PathBasedCache directive " +
-              entry.getEntryId());
-        } catch (RemovePathBasedCacheDescriptorException e) {
+              directive.getId());
+        } catch (IOException e) {
           System.err.println(prettifyException(e));
           exitCode = 2;
         }
@@ -338,8 +335,16 @@ public class CacheAdmin extends Configured implements Tool {
 
     @Override
     public int run(Configuration conf, List<String> args) throws IOException {
+      PathBasedCacheDirective.Builder builder =
+          new PathBasedCacheDirective.Builder();
       String pathFilter = StringUtils.popOptionWithArgument("-path", args);
+      if (pathFilter != null) {
+        builder.setPath(new Path(pathFilter));
+      }
       String poolFilter = StringUtils.popOptionWithArgument("-pool", args);
+      if (poolFilter != null) {
+        builder.setPool(poolFilter);
+      }
       if (!args.isEmpty()) {
         System.err.println("Can't understand argument: " + args.get(0));
         return 1;
@@ -350,15 +355,14 @@ public class CacheAdmin extends Configured implements Tool {
           addField("PATH", Justification.LEFT).
           build();
       DistributedFileSystem dfs = getDFS(conf);
-      RemoteIterator<PathBasedCacheDescriptor> iter =
-          dfs.listPathBasedCacheDescriptors(poolFilter, pathFilter != null ?
-              new Path(pathFilter) : null);
+      RemoteIterator<PathBasedCacheDirective> iter =
+          dfs.listPathBasedCacheDirectives(builder.build());
       int numEntries = 0;
       while (iter.hasNext()) {
-        PathBasedCacheDescriptor entry = iter.next();
+        PathBasedCacheDirective directive = iter.next();
         String row[] = new String[] {
-            "" + entry.getEntryId(), entry.getPool(),
-            entry.getPath().toUri().getPath(),
+            "" + directive.getId(), directive.getPool(),
+            directive.getPath().toUri().getPath(),
         };
         tableListing.addRow(row);
         numEntries++;

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/util/XMLUtils.java

@@ -252,9 +252,24 @@ public class XMLUtils {
      * @return            the entry
      */
     public String getValue(String name) throws InvalidXmlException {
-      if (!subtrees.containsKey(name)) {
+      String ret = getValueOrNull(name);
+      if (ret == null) {
         throw new InvalidXmlException("no entry found for " + name);
       }
+      return ret;
+    }
+
+    /** 
+     * Pull a string entry from a stanza, or null.
+     *
+     * @param name        entry to look for
+     * 
+     * @return            the entry, or null if it was not found.
+     */
+    public String getValueOrNull(String name) throws InvalidXmlException {
+      if (!subtrees.containsKey(name)) {
+        return null;
+      }
       LinkedList <Stanza> l = subtrees.get(name);
       if (l.size() != 1) {
         throw new InvalidXmlException("More than one value found for " + name);

hadoop-hdfs-project/hadoop-hdfs/src/main/proto/ClientNamenodeProtocol.proto

@@ -363,42 +363,46 @@ message IsFileClosedResponseProto {
   required bool result = 1;
 }
 
-message PathBasedCacheDirectiveProto {
-  required string path = 1;
-  required uint32 replication = 2;
-  required string pool = 3;
+message PathBasedCacheDirectiveInfoProto {
+  optional int64 id = 1;
+  optional string path = 2;
+  optional uint32 replication = 3;
+  optional string pool = 4;
 }
 
 message AddPathBasedCacheDirectiveRequestProto {
-  required PathBasedCacheDirectiveProto directive = 1;
+  required PathBasedCacheDirectiveInfoProto info = 1;
 }
 
 message AddPathBasedCacheDirectiveResponseProto {
-  required int64 descriptorId = 1;
+  required int64 id = 1;
+}
+
+message ModifyPathBasedCacheDirectiveRequestProto {
+  required PathBasedCacheDirectiveInfoProto info = 1;
 }
 
-message RemovePathBasedCacheDescriptorRequestProto {
-  required int64 descriptorId = 1;
+message ModifyPathBasedCacheDirectiveResponseProto {
 }
 
-message RemovePathBasedCacheDescriptorResponseProto {
+message RemovePathBasedCacheDirectiveRequestProto {
+  required int64 id = 1;
+}
+
+message RemovePathBasedCacheDirectiveResponseProto {
 }
 
-message ListPathBasedCacheDescriptorsRequestProto {
+message ListPathBasedCacheDirectivesRequestProto {
   required int64 prevId = 1;
-  optional string pool = 2;
-  optional string path = 3;
+  required PathBasedCacheDirectiveInfoProto filter = 2;
 }
 
-message ListPathBasedCacheDescriptorsElementProto {
-  required int64 id = 1;
-  required string pool = 2;
-  required uint32 replication = 3;
-  required string path = 4;
+message ListPathBasedCacheDirectivesElementProto {
+  required PathBasedCacheDirectiveInfoProto info = 1;
 }
 
-message ListPathBasedCacheDescriptorsResponseProto {
-  repeated ListPathBasedCacheDescriptorsElementProto elements = 1;
+message ListPathBasedCacheDirectivesResponseProto {
+  repeated ListPathBasedCacheDirectivesElementProto elements = 1;
   required bool hasMore = 2;
 }
 
@@ -631,10 +635,12 @@ service ClientNamenodeProtocol {
   rpc getFileInfo(GetFileInfoRequestProto) returns(GetFileInfoResponseProto);
   rpc addPathBasedCacheDirective(AddPathBasedCacheDirectiveRequestProto)
       returns (AddPathBasedCacheDirectiveResponseProto);
-  rpc removePathBasedCacheDescriptor(RemovePathBasedCacheDescriptorRequestProto)
-      returns (RemovePathBasedCacheDescriptorResponseProto);
-  rpc listPathBasedCacheDescriptors(ListPathBasedCacheDescriptorsRequestProto)
-      returns (ListPathBasedCacheDescriptorsResponseProto);
+  rpc modifyPathBasedCacheDirective(ModifyPathBasedCacheDirectiveRequestProto)
+      returns (ModifyPathBasedCacheDirectiveResponseProto);
+  rpc removePathBasedCacheDirective(RemovePathBasedCacheDirectiveRequestProto)
+      returns (RemovePathBasedCacheDirectiveResponseProto);
+  rpc listPathBasedCacheDirectives(ListPathBasedCacheDirectivesRequestProto)
+      returns (ListPathBasedCacheDirectivesResponseProto);
   rpc addCachePool(AddCachePoolRequestProto)
       returns(AddCachePoolResponseProto);
   rpc modifyCachePool(ModifyCachePoolRequestProto)

hadoop-hdfs-project/hadoop-hdfs/src/main/resources/hdfs-default.xml

@@ -1487,10 +1487,10 @@
 </property>
 
 <property>
-  <name>dfs.namenode.list.cache.descriptors.num.responses</name>
+  <name>dfs.namenode.list.cache.directives.num.responses</name>
   <value>100</value>
   <description>
-    This value controls the number of cache descriptors that the NameNode will
+    This value controls the number of cache directives that the NameNode will
     send over the wire in response to a listDirectives RPC.
   </description>
 </property>

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

@@ -993,19 +993,26 @@ public class DFSTestUtil {
       locatedBlocks = DFSClientAdapter.callGetBlockLocations(
           cluster.getNameNodeRpc(nnIndex), filePath, 0L, bytes.length);
     } while (locatedBlocks.isUnderConstruction());
-    // OP_ADD_CACHE_POOL 35
+    // OP_ADD_CACHE_POOL
     filesystem.addCachePool(new CachePoolInfo("pool1"));
-    // OP_MODIFY_CACHE_POOL 36
+    // OP_MODIFY_CACHE_POOL
     filesystem.modifyCachePool(new CachePoolInfo("pool1").setWeight(99));
-    // OP_ADD_PATH_BASED_CACHE_DIRECTIVE 33
-    PathBasedCacheDescriptor pbcd = filesystem.addPathBasedCacheDirective(
+    // OP_ADD_PATH_BASED_CACHE_DIRECTIVE
+    long id = filesystem.addPathBasedCacheDirective(
         new PathBasedCacheDirective.Builder().
             setPath(new Path("/path")).
+            setReplication((short)1).
             setPool("pool1").
             build());
-    // OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR 34
-    filesystem.removePathBasedCacheDescriptor(pbcd);
-    // OP_REMOVE_CACHE_POOL 37
+    // OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE
+    filesystem.modifyPathBasedCacheDirective(
+        new PathBasedCacheDirective.Builder().
+            setId(id).
+            setReplication((short)2).
+            build());
+    // OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE
+    filesystem.removePathBasedCacheDirective(id);
+    // OP_REMOVE_CACHE_POOL
     filesystem.removeCachePool("pool1");
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/protocolPB/TestClientNamenodeProtocolServerSideTranslatorPB.java

@@ -1,57 +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.hdfs.protocolPB;
-
-import static org.junit.Assert.*;
-import static org.mockito.Mockito.*;
-
-import org.junit.Test;
-
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.EmptyPathError;
-import org.apache.hadoop.hdfs.protocol.ClientProtocol;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.AddPathBasedCacheDirectiveRequestProto;
-import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.PathBasedCacheDirectiveProto;
-
-import com.google.protobuf.RpcController;
-import com.google.protobuf.ServiceException;
-
-public class TestClientNamenodeProtocolServerSideTranslatorPB {
-
-  @Test
-  public void testAddPathBasedCacheDirectiveEmptyPathError() throws Exception {
-    ClientProtocol server = mock(ClientProtocol.class);
-    RpcController controller = mock(RpcController.class);
-    AddPathBasedCacheDirectiveRequestProto request = 
-        AddPathBasedCacheDirectiveRequestProto.newBuilder().
-            setDirective(PathBasedCacheDirectiveProto.newBuilder().
-                setPath("").
-                setPool("pool").
-                setReplication(1).
-                build()).
-            build();
-    ClientNamenodeProtocolServerSideTranslatorPB translator =
-        new ClientNamenodeProtocolServerSideTranslatorPB(server);
-    try {
-      translator.addPathBasedCacheDirective(controller, request);
-      fail("Expected ServiceException");
-    } catch (ServiceException e) {
-      assertNotNull(e.getCause());
-      assertTrue(e.getCause() instanceof EmptyPathError);
-    }
-  }
-}

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/OfflineEditsViewerHelper.java

@@ -42,7 +42,6 @@ import org.apache.hadoop.hdfs.MiniDFSCluster;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
 import org.apache.hadoop.hdfs.server.common.Util;
@@ -242,14 +241,20 @@ public class OfflineEditsViewerHelper {
         .setMode(new FsPermission((short)0700))
         .setWeight(1989));
     // OP_ADD_PATH_BASED_CACHE_DIRECTIVE 33
-    PathBasedCacheDescriptor descriptor =
-        dfs.addPathBasedCacheDirective(new PathBasedCacheDirective.Builder().
+    long id = dfs.addPathBasedCacheDirective(
+        new PathBasedCacheDirective.Builder().
             setPath(new Path("/bar")).
             setReplication((short)1).
             setPool(pool).
             build());
-    // OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR 34
-    dfs.removePathBasedCacheDescriptor(descriptor);
+    // OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE 38
+    dfs.modifyPathBasedCacheDirective(
+        new PathBasedCacheDirective.Builder().
+            setId(id).
+            setPath(new Path("/bar2")).
+            build());
+    // OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE 34
+    dfs.removePathBasedCacheDirective(id);
     // OP_REMOVE_CACHE_POOL 37
     dfs.removeCachePool(pool);
     // sync to disk, otherwise we parse partial edits

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestNamenodeRetryCache.java

@@ -413,7 +413,7 @@ public class TestNamenodeRetryCache {
     
     LightWeightCache<CacheEntry, CacheEntry> cacheSet = 
         (LightWeightCache<CacheEntry, CacheEntry>) namesystem.getRetryCache().getCacheSet();
-    assertEquals(19, cacheSet.size());
+    assertEquals(20, cacheSet.size());
     
     Map<CacheEntry, CacheEntry> oldEntries = 
         new HashMap<CacheEntry, CacheEntry>();
@@ -432,7 +432,7 @@ public class TestNamenodeRetryCache {
     assertTrue(namesystem.hasRetryCache());
     cacheSet = (LightWeightCache<CacheEntry, CacheEntry>) namesystem
         .getRetryCache().getCacheSet();
-    assertEquals(19, cacheSet.size());
+    assertEquals(20, cacheSet.size());
     iter = cacheSet.iterator();
     while (iter.hasNext()) {
       CacheEntry entry = iter.next();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestPathBasedCacheRequests.java

@@ -42,6 +42,7 @@ import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.FileSystemTestHelper;
+import org.apache.hadoop.fs.IdNotFoundException;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.RemoteIterator;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -49,17 +50,12 @@ 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.protocol.AddPathBasedCacheDirectiveException.InvalidPathNameError;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.InvalidPoolNameError;
-import org.apache.hadoop.hdfs.protocol.AddPathBasedCacheDirectiveException.PoolWritePermissionDeniedError;
 import org.apache.hadoop.hdfs.protocol.CachePoolInfo;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.InvalidIdException;
-import org.apache.hadoop.hdfs.protocol.RemovePathBasedCacheDescriptorException.NoSuchIdException;
 import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList.Type;
 import org.apache.hadoop.hdfs.server.protocol.NamenodeProtocols;
 import org.apache.hadoop.io.nativeio.NativeIO;
+import org.apache.hadoop.security.AccessControlException;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.hadoop.util.GSet;
@@ -86,7 +82,7 @@ public class TestPathBasedCacheRequests {
     conf = new HdfsConfiguration();
     // set low limits here for testing purposes
     conf.setInt(DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_POOLS_NUM_RESPONSES, 2);
-    conf.setInt(DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_DESCRIPTORS_NUM_RESPONSES, 2);
+    conf.setInt(DFSConfigKeys.DFS_NAMENODE_LIST_CACHE_DIRECTIVES_NUM_RESPONSES, 2);
     cluster = new MiniDFSCluster.Builder(conf).numDataNodes(1).build();
     cluster.waitActive();
     dfs = cluster.getFileSystem();
@@ -296,21 +292,21 @@ public class TestPathBasedCacheRequests {
   }
 
   private static void validateListAll(
-      RemoteIterator<PathBasedCacheDescriptor> iter,
-      PathBasedCacheDescriptor... descriptors) throws Exception {
-    for (PathBasedCacheDescriptor descriptor: descriptors) {
+      RemoteIterator<PathBasedCacheDirective> iter,
+      Long... ids) throws Exception {
+    for (Long id: ids) {
       assertTrue("Unexpectedly few elements", iter.hasNext());
-      assertEquals("Unexpected descriptor", descriptor, iter.next());
+      assertEquals("Unexpected directive ID", id, iter.next().getId());
     }
     assertFalse("Unexpectedly many list elements", iter.hasNext());
   }
 
-  private static PathBasedCacheDescriptor addAsUnprivileged(
+  private static long addAsUnprivileged(
       final PathBasedCacheDirective directive) throws Exception {
     return unprivilegedUser
-        .doAs(new PrivilegedExceptionAction<PathBasedCacheDescriptor>() {
+        .doAs(new PrivilegedExceptionAction<Long>() {
           @Override
-          public PathBasedCacheDescriptor run() throws IOException {
+          public Long run() throws IOException {
             DistributedFileSystem myDfs =
                 (DistributedFileSystem) FileSystem.get(conf);
             return myDfs.addPathBasedCacheDirective(directive);
@@ -342,12 +338,12 @@ public class TestPathBasedCacheRequests {
         setPool("pool1").
         build();
 
-    PathBasedCacheDescriptor alphaD = addAsUnprivileged(alpha);
-    PathBasedCacheDescriptor alphaD2 = addAsUnprivileged(alpha);
-    assertFalse("Expected to get unique descriptors when re-adding an "
+    long alphaId = addAsUnprivileged(alpha);
+    long alphaId2 = addAsUnprivileged(alpha);
+    assertFalse("Expected to get unique directives when re-adding an "
         + "existing PathBasedCacheDirective",
-        alphaD.getEntryId() == alphaD2.getEntryId());
-    PathBasedCacheDescriptor betaD = addAsUnprivileged(beta);
+        alphaId == alphaId2);
+    long betaId = addAsUnprivileged(beta);
 
     try {
       addAsUnprivileged(new PathBasedCacheDirective.Builder().
@@ -355,8 +351,8 @@ public class TestPathBasedCacheRequests {
           setPool("no_such_pool").
           build());
       fail("expected an error when adding to a non-existent pool.");
-    } catch (IOException ioe) {
-      assertTrue(ioe instanceof InvalidPoolNameError);
+    } catch (IdNotFoundException ioe) {
+      GenericTestUtils.assertExceptionContains("no such pool as", ioe);
     }
 
     try {
@@ -366,8 +362,9 @@ public class TestPathBasedCacheRequests {
           build());
       fail("expected an error when adding to a pool with " +
           "mode 0 (no permissions for anyone).");
-    } catch (IOException ioe) {
-      assertTrue(ioe instanceof PoolWritePermissionDeniedError);
+    } catch (AccessControlException e) {
+      GenericTestUtils.
+          assertExceptionContains("permission denied for pool", e);
     }
 
     try {
@@ -378,7 +375,7 @@ public class TestPathBasedCacheRequests {
       fail("expected an error when adding a malformed path " +
           "to the cache directives.");
     } catch (IllegalArgumentException e) {
-      // expected
+      GenericTestUtils.assertExceptionContains("is not a valid DFS filename", e);
     }
 
     try {
@@ -389,59 +386,74 @@ public class TestPathBasedCacheRequests {
           build());
       Assert.fail("expected an error when adding a PathBasedCache " +
           "directive with an empty pool name.");
-    } catch (IOException ioe) {
-      Assert.assertTrue(ioe instanceof InvalidPoolNameError);
+    } catch (IdNotFoundException e) {
+      GenericTestUtils.assertExceptionContains("pool name was empty", e);
     }
 
-    PathBasedCacheDescriptor deltaD = addAsUnprivileged(delta);
+    long deltaId = addAsUnprivileged(delta);
 
     // We expect the following to succeed, because DistributedFileSystem
     // qualifies the path.
-    PathBasedCacheDescriptor relativeD = addAsUnprivileged(
+    long relativeId = addAsUnprivileged(
         new PathBasedCacheDirective.Builder().
             setPath(new Path("relative")).
             setPool("pool1").
             build());
 
-    RemoteIterator<PathBasedCacheDescriptor> iter;
-    iter = dfs.listPathBasedCacheDescriptors(null, null);
-    validateListAll(iter, alphaD, alphaD2, betaD, deltaD, relativeD);
-    iter = dfs.listPathBasedCacheDescriptors("pool3", null);
+    RemoteIterator<PathBasedCacheDirective> iter;
+    iter = dfs.listPathBasedCacheDirectives(null);
+    validateListAll(iter, alphaId, alphaId2, betaId, deltaId, relativeId );
+    iter = dfs.listPathBasedCacheDirectives(
+        new PathBasedCacheDirective.Builder().setPool("pool3").build());
     Assert.assertFalse(iter.hasNext());
-    iter = dfs.listPathBasedCacheDescriptors("pool1", null);
-    validateListAll(iter, alphaD, alphaD2, deltaD, relativeD);
-    iter = dfs.listPathBasedCacheDescriptors("pool2", null);
-    validateListAll(iter, betaD);
-
-    dfs.removePathBasedCacheDescriptor(betaD);
-    iter = dfs.listPathBasedCacheDescriptors("pool2", null);
+    iter = dfs.listPathBasedCacheDirectives(
+        new PathBasedCacheDirective.Builder().setPool("pool1").build());
+    validateListAll(iter, alphaId, alphaId2, deltaId, relativeId );
+    iter = dfs.listPathBasedCacheDirectives(
+        new PathBasedCacheDirective.Builder().setPool("pool2").build());
+    validateListAll(iter, betaId);
+
+    dfs.removePathBasedCacheDirective(betaId);
+    iter = dfs.listPathBasedCacheDirectives(
+        new PathBasedCacheDirective.Builder().setPool("pool2").build());
     Assert.assertFalse(iter.hasNext());
 
     try {
-      dfs.removePathBasedCacheDescriptor(betaD);
+      dfs.removePathBasedCacheDirective(betaId);
       Assert.fail("expected an error when removing a non-existent ID");
-    } catch (IOException ioe) {
-      Assert.assertTrue(ioe instanceof NoSuchIdException);
+    } catch (IdNotFoundException e) {
+      GenericTestUtils.assertExceptionContains("id not found", e);
     }
 
     try {
-      proto.removePathBasedCacheDescriptor(-42l);
+      proto.removePathBasedCacheDirective(-42l);
       Assert.fail("expected an error when removing a negative ID");
-    } catch (IOException ioe) {
-      Assert.assertTrue(ioe instanceof InvalidIdException);
+    } catch (IdNotFoundException e) {
+      GenericTestUtils.assertExceptionContains(
+          "invalid non-positive directive ID", e);
     }
     try {
-      proto.removePathBasedCacheDescriptor(43l);
+      proto.removePathBasedCacheDirective(43l);
       Assert.fail("expected an error when removing a non-existent ID");
-    } catch (IOException ioe) {
-      Assert.assertTrue(ioe instanceof NoSuchIdException);
-    }
-
-    dfs.removePathBasedCacheDescriptor(alphaD);
-    dfs.removePathBasedCacheDescriptor(alphaD2);
-    dfs.removePathBasedCacheDescriptor(deltaD);
-    dfs.removePathBasedCacheDescriptor(relativeD);
-    iter = dfs.listPathBasedCacheDescriptors(null, null);
+    } catch (IdNotFoundException e) {
+      GenericTestUtils.assertExceptionContains("id not found", e);
+    }
+
+    dfs.removePathBasedCacheDirective(alphaId);
+    dfs.removePathBasedCacheDirective(alphaId2);
+    dfs.removePathBasedCacheDirective(deltaId);
+
+    dfs.modifyPathBasedCacheDirective(new PathBasedCacheDirective.Builder().
+        setId(relativeId).
+        setReplication((short)555).
+        build());
+    iter = dfs.listPathBasedCacheDirectives(null);
+    assertTrue(iter.hasNext());
+    PathBasedCacheDirective modified = iter.next();
+    assertEquals(relativeId, modified.getId().longValue());
+    assertEquals((short)555, modified.getReplication().shortValue());
+    dfs.removePathBasedCacheDirective(relativeId);
+    iter = dfs.listPathBasedCacheDirectives(null);
     assertFalse(iter.hasNext());
   }
 
@@ -481,16 +493,16 @@ public class TestPathBasedCacheRequests {
           new PathBasedCacheDirective.Builder().
             setPath(new Path(entryPrefix + i)).setPool(pool).build());
     }
-    RemoteIterator<PathBasedCacheDescriptor> dit
-        = dfs.listPathBasedCacheDescriptors(null, null);
+    RemoteIterator<PathBasedCacheDirective> dit
+        = dfs.listPathBasedCacheDirectives(null);
     for (int i=0; i<numEntries; i++) {
       assertTrue("Unexpected # of cache entries: " + i, dit.hasNext());
-      PathBasedCacheDescriptor cd = dit.next();
-      assertEquals(i+1, cd.getEntryId());
+      PathBasedCacheDirective cd = dit.next();
+      assertEquals(i+1, cd.getId().longValue());
       assertEquals(entryPrefix + i, cd.getPath().toUri().getPath());
       assertEquals(pool, cd.getPool());
     }
-    assertFalse("Unexpected # of cache descriptors found", dit.hasNext());
+    assertFalse("Unexpected # of cache directives found", dit.hasNext());
   
     // Restart namenode
     cluster.restartNameNode();
@@ -506,15 +518,15 @@ public class TestPathBasedCacheRequests {
     assertEquals(weight, (int)info.getWeight());
     assertFalse("Unexpected # of cache pools found", pit.hasNext());
   
-    dit = dfs.listPathBasedCacheDescriptors(null, null);
+    dit = dfs.listPathBasedCacheDirectives(null);
     for (int i=0; i<numEntries; i++) {
       assertTrue("Unexpected # of cache entries: " + i, dit.hasNext());
-      PathBasedCacheDescriptor cd = dit.next();
-      assertEquals(i+1, cd.getEntryId());
+      PathBasedCacheDirective cd = dit.next();
+      assertEquals(i+1, cd.getId().longValue());
       assertEquals(entryPrefix + i, cd.getPath().toUri().getPath());
       assertEquals(pool, cd.getPool());
     }
-    assertFalse("Unexpected # of cache descriptors found", dit.hasNext());
+    assertFalse("Unexpected # of cache directives found", dit.hasNext());
   }
 
   private static void waitForCachedBlocks(NameNode nn,
@@ -625,21 +637,16 @@ public class TestPathBasedCacheRequests {
               setPath(new Path(paths.get(i))).
               setPool(pool).
               build();
-        PathBasedCacheDescriptor descriptor =
-            nnRpc.addPathBasedCacheDirective(directive);
-        assertEquals("Descriptor does not match requested path",
-            new Path(paths.get(i)), descriptor.getPath());
-        assertEquals("Descriptor does not match requested pool", pool,
-            descriptor.getPool());
+        nnRpc.addPathBasedCacheDirective(directive);
         expected += numBlocksPerFile;
         waitForCachedBlocks(namenode, expected, expected);
       }
       // Uncache and check each path in sequence
-      RemoteIterator<PathBasedCacheDescriptor> entries =
-          nnRpc.listPathBasedCacheDescriptors(0, null, null);
+      RemoteIterator<PathBasedCacheDirective> entries =
+          nnRpc.listPathBasedCacheDirectives(0, null);
       for (int i=0; i<numFiles; i++) {
-        PathBasedCacheDescriptor descriptor = entries.next();
-        nnRpc.removePathBasedCacheDescriptor(descriptor.getEntryId());
+        PathBasedCacheDirective directive = entries.next();
+        nnRpc.removePathBasedCacheDirective(directive.getId());
         expected -= numBlocksPerFile;
         waitForCachedBlocks(namenode, expected, expected);
       }
@@ -723,17 +730,15 @@ public class TestPathBasedCacheRequests {
       }
       waitForCachedBlocks(namenode, 0, 0);
       // cache entire directory
-      PathBasedCacheDescriptor descriptor = dfs.addPathBasedCacheDirective(
+      long id = dfs.addPathBasedCacheDirective(
             new PathBasedCacheDirective.Builder().
               setPath(new Path("/foo")).
               setReplication((short)2).
               setPool(pool).
               build());
-      assertEquals("Descriptor does not match requested pool", pool,
-          descriptor.getPool());
       waitForCachedBlocks(namenode, 4, 8);
       // remove and watch numCached go to 0
-      dfs.removePathBasedCacheDescriptor(descriptor);
+      dfs.removePathBasedCacheDirective(id);
       waitForCachedBlocks(namenode, 0, 0);
     } finally {
       cluster.shutdown();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestRetryCacheWithHA.java

@@ -61,7 +61,6 @@ import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
 import org.apache.hadoop.hdfs.protocol.HdfsFileStatus;
 import org.apache.hadoop.hdfs.protocol.LocatedBlock;
 import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
-import org.apache.hadoop.hdfs.protocol.PathBasedCacheDescriptor;
 import org.apache.hadoop.hdfs.protocol.PathBasedCacheDirective;
 import org.apache.hadoop.hdfs.server.blockmanagement.BlockInfoUnderConstruction;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
@@ -151,7 +150,7 @@ public class TestRetryCacheWithHA {
     FSNamesystem fsn0 = cluster.getNamesystem(0);
     LightWeightCache<CacheEntry, CacheEntry> cacheSet = 
         (LightWeightCache<CacheEntry, CacheEntry>) fsn0.getRetryCache().getCacheSet();
-    assertEquals(19, cacheSet.size());
+    assertEquals(20, cacheSet.size());
     
     Map<CacheEntry, CacheEntry> oldEntries = 
         new HashMap<CacheEntry, CacheEntry>();
@@ -172,7 +171,7 @@ public class TestRetryCacheWithHA {
     FSNamesystem fsn1 = cluster.getNamesystem(1);
     cacheSet = (LightWeightCache<CacheEntry, CacheEntry>) fsn1
         .getRetryCache().getCacheSet();
-    assertEquals(19, cacheSet.size());
+    assertEquals(20, cacheSet.size());
     iter = cacheSet.iterator();
     while (iter.hasNext()) {
       CacheEntry entry = iter.next();
@@ -739,35 +738,34 @@ public class TestRetryCacheWithHA {
   
   /** addPathBasedCacheDirective */
   class AddPathBasedCacheDirectiveOp extends AtMostOnceOp {
-    private String pool;
-    private String path;
-    private PathBasedCacheDescriptor descriptor;
+    private PathBasedCacheDirective directive;
+    private Long result;
 
-    AddPathBasedCacheDirectiveOp(DFSClient client, String pool, String path) {
+    AddPathBasedCacheDirectiveOp(DFSClient client,
+        PathBasedCacheDirective directive) {
       super("addPathBasedCacheDirective", client);
-      this.pool = pool;
-      this.path = path;
+      this.directive = directive;
     }
 
     @Override
     void prepare() throws Exception {
-      dfs.addCachePool(new CachePoolInfo(pool));
+      dfs.addCachePool(new CachePoolInfo(directive.getPool()));
     }
 
     @Override
     void invoke() throws Exception {
-      descriptor = client.addPathBasedCacheDirective(
-          new PathBasedCacheDirective.Builder().
-              setPath(new Path(path)).
-              setPool(pool).
-              build());
+      result = client.addPathBasedCacheDirective(directive);
     }
 
     @Override
     boolean checkNamenodeBeforeReturn() throws Exception {
       for (int i = 0; i < CHECKTIMES; i++) {
-        RemoteIterator<PathBasedCacheDescriptor> iter =
-            dfs.listPathBasedCacheDescriptors(pool, new Path(path));
+        RemoteIterator<PathBasedCacheDirective> iter =
+            dfs.listPathBasedCacheDirectives(
+                new PathBasedCacheDirective.Builder().
+                    setPool(directive.getPool()).
+                    setPath(directive.getPath()).
+                    build());
         if (iter.hasNext()) {
           return true;
         }
@@ -778,43 +776,99 @@ public class TestRetryCacheWithHA {
 
     @Override
     Object getResult() {
-      return descriptor;
+      return result;
     }
   }
 
-  /** removePathBasedCacheDescriptor */
-  class RemovePathBasedCacheDescriptorOp extends AtMostOnceOp {
-    private String pool;
-    private String path;
-    private PathBasedCacheDescriptor descriptor;
+  /** modifyPathBasedCacheDirective */
+  class ModifyPathBasedCacheDirectiveOp extends AtMostOnceOp {
+    private final PathBasedCacheDirective directive;
+    private final short newReplication;
+    private long id;
 
-    RemovePathBasedCacheDescriptorOp(DFSClient client, String pool,
-        String path) {
-      super("removePathBasedCacheDescriptor", client);
-      this.pool = pool;
-      this.path = path;
+    ModifyPathBasedCacheDirectiveOp(DFSClient client,
+        PathBasedCacheDirective directive, short newReplication) {
+      super("modifyPathBasedCacheDirective", client);
+      this.directive = directive;
+      this.newReplication = newReplication;
     }
 
     @Override
     void prepare() throws Exception {
-      dfs.addCachePool(new CachePoolInfo(pool));
-      descriptor = dfs.addPathBasedCacheDirective(
+      dfs.addCachePool(new CachePoolInfo(directive.getPool()));
+      id = client.addPathBasedCacheDirective(directive);
+    }
+
+    @Override
+    void invoke() throws Exception {
+      client.modifyPathBasedCacheDirective(
           new PathBasedCacheDirective.Builder().
-              setPath(new Path(path)).
-              setPool(pool).
+              setId(id).
+              setReplication(newReplication).
               build());
     }
 
+    @Override
+    boolean checkNamenodeBeforeReturn() throws Exception {
+      for (int i = 0; i < CHECKTIMES; i++) {
+        RemoteIterator<PathBasedCacheDirective> iter =
+            dfs.listPathBasedCacheDirectives(
+                new PathBasedCacheDirective.Builder().
+                    setPool(directive.getPool()).
+                    setPath(directive.getPath()).
+                    build());
+        while (iter.hasNext()) {
+          PathBasedCacheDirective result = iter.next();
+          if ((result.getId() == id) &&
+              (result.getReplication().shortValue() == newReplication)) {
+            return true;
+          }
+        }
+        Thread.sleep(1000);
+      }
+      return false;
+    }
+
+    @Override
+    Object getResult() {
+      return null;
+    }
+  }
+
+  /** removePathBasedCacheDirective */
+  class RemovePathBasedCacheDirectiveOp extends AtMostOnceOp {
+    private PathBasedCacheDirective directive;
+    private long id;
+
+    RemovePathBasedCacheDirectiveOp(DFSClient client, String pool,
+        String path) {
+      super("removePathBasedCacheDirective", client);
+      this.directive = new PathBasedCacheDirective.Builder().
+          setPool(pool).
+          setPath(new Path(path)).
+          build();
+    }
+
+    @Override
+    void prepare() throws Exception {
+      dfs.addCachePool(new CachePoolInfo(directive.getPool()));
+      id = dfs.addPathBasedCacheDirective(directive);
+    }
+
     @Override
     void invoke() throws Exception {
-      client.removePathBasedCacheDescriptor(descriptor.getEntryId());
+      client.removePathBasedCacheDirective(id);
     }
 
     @Override
     boolean checkNamenodeBeforeReturn() throws Exception {
       for (int i = 0; i < CHECKTIMES; i++) {
-        RemoteIterator<PathBasedCacheDescriptor> iter =
-            dfs.listPathBasedCacheDescriptors(pool, new Path(path));
+        RemoteIterator<PathBasedCacheDirective> iter =
+            dfs.listPathBasedCacheDirectives(
+                new PathBasedCacheDirective.Builder().
+                  setPool(directive.getPool()).
+                  setPath(directive.getPath()).
+                  build());
         if (!iter.hasNext()) {
           return true;
         }
@@ -1019,14 +1073,30 @@ public class TestRetryCacheWithHA {
   @Test (timeout=60000)
   public void testAddPathBasedCacheDirective() throws Exception {
     DFSClient client = genClientWithDummyHandler();
-    AtMostOnceOp op = new AddPathBasedCacheDirectiveOp(client, "pool", "/path");
+    AtMostOnceOp op = new AddPathBasedCacheDirectiveOp(client, 
+        new PathBasedCacheDirective.Builder().
+            setPool("pool").
+            setPath(new Path("/path")).
+            build());
+    testClientRetryWithFailover(op);
+  }
+
+  @Test (timeout=60000)
+  public void testModifyPathBasedCacheDirective() throws Exception {
+    DFSClient client = genClientWithDummyHandler();
+    AtMostOnceOp op = new ModifyPathBasedCacheDirectiveOp(client, 
+        new PathBasedCacheDirective.Builder().
+            setPool("pool").
+            setPath(new Path("/path")).
+            setReplication((short)1).build(),
+        (short)555);
     testClientRetryWithFailover(op);
   }
 
   @Test (timeout=60000)
   public void testRemovePathBasedCacheDescriptor() throws Exception {
     DFSClient client = genClientWithDummyHandler();
-    AtMostOnceOp op = new RemovePathBasedCacheDescriptorOp(client, "pool",
+    AtMostOnceOp op = new RemovePathBasedCacheDirectiveOp(client, "pool",
         "/path");
     testClientRetryWithFailover(op);
   }

hadoop-hdfs-project/hadoop-hdfs/src/test/resources/editsStored.xml

@@ -843,6 +843,7 @@
     <OPCODE>OP_ADD_PATH_BASED_CACHE_DIRECTIVE</OPCODE>
     <DATA>
       <TXID>63</TXID>
+      <ID>1</ID>
       <PATH>/bar</PATH>
       <REPLICATION>1</REPLICATION>
       <POOL>poolparty</POOL>
@@ -851,10 +852,20 @@
     </DATA>
   </RECORD>
   <RECORD>
-    <OPCODE>OP_REMOVE_PATH_BASED_CACHE_DESCRIPTOR</OPCODE>
+    <OPCODE>OP_MODIFY_PATH_BASED_CACHE_DIRECTIVE</OPCODE>
     <DATA>
       <TXID>64</TXID>
       <ID>1</ID>
+      <REPLICATION>2</REPLICATION>
+      <RPC_CLIENTID></RPC_CLIENTID>
+      <RPC_CALLID>-2</RPC_CALLID>
+    </DATA>
+  </RECORD>
+  <RECORD>
+    <OPCODE>OP_REMOVE_PATH_BASED_CACHE_DIRECTIVE</OPCODE>
+    <DATA>
+      <TXID>65</TXID>
+      <ID>1</ID>
       <RPC_CLIENTID>27ac79f0-d378-4933-824b-c2a188968d97</RPC_CLIENTID>
       <RPC_CALLID>78</RPC_CALLID>
     </DATA>
@@ -862,7 +873,7 @@
   <RECORD>
     <OPCODE>OP_REMOVE_CACHE_POOL</OPCODE>
     <DATA>
-      <TXID>65</TXID>
+      <TXID>66</TXID>
       <POOLNAME>poolparty</POOLNAME>
       <RPC_CLIENTID>27ac79f0-d378-4933-824b-c2a188968d97</RPC_CLIENTID>
       <RPC_CALLID>79</RPC_CALLID>
@@ -871,7 +882,7 @@
   <RECORD>
     <OPCODE>OP_ADD</OPCODE>
     <DATA>
-      <TXID>66</TXID>
+      <TXID>67</TXID>
       <LENGTH>0</LENGTH>
       <INODEID>16393</INODEID>
       <PATH>/hard-lease-recovery-test</PATH>
@@ -893,21 +904,21 @@
   <RECORD>
     <OPCODE>OP_ALLOCATE_BLOCK_ID</OPCODE>
     <DATA>
-      <TXID>67</TXID>
+      <TXID>68</TXID>
       <BLOCK_ID>1073741834</BLOCK_ID>
     </DATA>
   </RECORD>
   <RECORD>
     <OPCODE>OP_SET_GENSTAMP_V2</OPCODE>
     <DATA>
-      <TXID>68</TXID>
+      <TXID>69</TXID>
       <GENSTAMPV2>1010</GENSTAMPV2>
     </DATA>
   </RECORD>
   <RECORD>
     <OPCODE>OP_UPDATE_BLOCKS</OPCODE>
     <DATA>
-      <TXID>69</TXID>
+      <TXID>70</TXID>
       <PATH>/hard-lease-recovery-test</PATH>
       <BLOCK>
         <BLOCK_ID>1073741834</BLOCK_ID>
@@ -921,7 +932,7 @@
   <RECORD>
     <OPCODE>OP_UPDATE_BLOCKS</OPCODE>
     <DATA>
-      <TXID>70</TXID>
+      <TXID>71</TXID>
       <PATH>/hard-lease-recovery-test</PATH>
       <BLOCK>
         <BLOCK_ID>1073741834</BLOCK_ID>
@@ -935,14 +946,14 @@
   <RECORD>
     <OPCODE>OP_SET_GENSTAMP_V2</OPCODE>
     <DATA>
-      <TXID>71</TXID>
+      <TXID>72</TXID>
       <GENSTAMPV2>1011</GENSTAMPV2>
     </DATA>
   </RECORD>
   <RECORD>
     <OPCODE>OP_REASSIGN_LEASE</OPCODE>
     <DATA>
-      <TXID>72</TXID>
+      <TXID>73</TXID>
       <LEASEHOLDER>DFSClient_NONMAPREDUCE_-134124999_1</LEASEHOLDER>
       <PATH>/hard-lease-recovery-test</PATH>
       <NEWHOLDER>HDFS_NameNode</NEWHOLDER>
@@ -951,14 +962,14 @@
   <RECORD>
     <OPCODE>OP_SET_GENSTAMP_V2</OPCODE>
     <DATA>
-      <TXID>73</TXID>
+      <TXID>74</TXID>
       <GENSTAMPV2>1012</GENSTAMPV2>
     </DATA>
   </RECORD>
   <RECORD>
     <OPCODE>OP_REASSIGN_LEASE</OPCODE>
     <DATA>
-      <TXID>74</TXID>
+      <TXID>75</TXID>
       <LEASEHOLDER>HDFS_NameNode</LEASEHOLDER>
       <PATH>/hard-lease-recovery-test</PATH>
       <NEWHOLDER>HDFS_NameNode</NEWHOLDER>
@@ -967,7 +978,7 @@
   <RECORD>
     <OPCODE>OP_CLOSE</OPCODE>
     <DATA>
-      <TXID>75</TXID>
+      <TXID>76</TXID>
       <LENGTH>0</LENGTH>
       <INODEID>0</INODEID>
       <PATH>/hard-lease-recovery-test</PATH>
@@ -992,7 +1003,7 @@
   <RECORD>
     <OPCODE>OP_END_LOG_SEGMENT</OPCODE>
     <DATA>
-      <TXID>76</TXID>
+      <TXID>77</TXID>
     </DATA>
   </RECORD>
 </EDITS>