HDFS-13616. Batch listing of multiple directories

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

@@ -2207,6 +2207,33 @@ public RemoteIterator<FileStatus> listStatusIterator(final Path p)
     return new DirListingIterator<>(p);
   }
 
+  /**
+   * Batched listing API that returns {@link PartialListing}s for the
+   * passed Paths.
+   *
+   * @param paths List of paths to list.
+   * @return RemoteIterator that returns corresponding PartialListings.
+   * @throws IOException
+   */
+  public RemoteIterator<PartialListing<FileStatus>> batchedListStatusIterator(
+      final List<Path> paths) throws IOException {
+    throw new UnsupportedOperationException("Not implemented");
+  }
+
+  /**
+   * Batched listing API that returns {@link PartialListing}s for the passed
+   * Paths. The PartialListing will contain {@link LocatedFileStatus} entries
+   * with locations.
+   *
+   * @param paths List of paths to list.
+   * @return RemoteIterator that returns corresponding PartialListings.
+   * @throws IOException
+   */
+  public RemoteIterator<PartialListing<LocatedFileStatus>> batchedListLocatedStatusIterator(
+      final List<Path> paths) throws IOException {
+    throw new UnsupportedOperationException("Not implemented");
+  }
+
   /**
    * List the statuses and block locations of the files in the given path.
    * Does not guarantee to return the iterator that traverses statuses

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

@@ -0,0 +1,91 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.fs;
+
+import com.google.common.base.Preconditions;
+import org.apache.commons.lang3.builder.ToStringBuilder;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.ipc.RemoteException;
+
+import java.io.IOException;
+import java.util.List;
+
+/**
+ * A partial listing of the children of a parent directory. Since it is a
+ * partial listing, multiple PartialListing may need to be combined to obtain
+ * the full listing of a parent directory.
+ * <p/>
+ * ListingBatch behaves similar to a Future, in that getting the result via
+ * {@link #get()} will throw an Exception if there was a failure.
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Stable
+public class PartialListing<T extends FileStatus> {
+  private final Path listedPath;
+  private final List<T> partialListing;
+  private final RemoteException exception;
+
+  public PartialListing(Path listedPath, List<T> partialListing) {
+    this(listedPath, partialListing, null);
+  }
+
+  public PartialListing(Path listedPath, RemoteException exception) {
+    this(listedPath, null, exception);
+  }
+
+  private PartialListing(Path listedPath, List<T> partialListing,
+      RemoteException exception) {
+    Preconditions.checkArgument(partialListing == null ^ exception == null);
+    this.partialListing = partialListing;
+    this.listedPath = listedPath;
+    this.exception = exception;
+  }
+
+  /**
+   * Partial listing of the path being listed. In the case where the path is
+   * a file. The list will be a singleton with the file itself.
+   *
+   * @return Partial listing of the path being listed.
+   * @throws IOException if there was an exception getting the listing.
+   */
+  public List<T> get() throws IOException {
+    if (exception != null) {
+      throw exception.unwrapRemoteException();
+    }
+    return partialListing;
+  }
+
+  /**
+   * Path being listed.
+   *
+   * @return the path being listed.
+   */
+  public Path getListedPath() {
+    return listedPath;
+  }
+
+  @Override
+  public String toString() {
+    return new ToStringBuilder(this)
+        .append("listedPath", listedPath)
+        .append("partialListing", partialListing)
+        .append("exception", exception)
+        .toString();
+  }
+}

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

@@ -27,6 +27,7 @@
 import java.net.URI;
 import java.util.EnumSet;
 import java.util.Iterator;
+import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.hadoop.conf.Configuration;
@@ -105,6 +106,10 @@ public FSDataOutputStream create(Path f, FsPermission permission,
     public FileStatus[] listStatusBatch(Path f, byte[] token);
     public FileStatus[] listStatus(Path[] files);
     public FileStatus[] listStatus(Path[] files, PathFilter filter);
+    public RemoteIterator<PartialListing<LocatedFileStatus>> batchedListLocatedStatusIterator(
+        final List<Path> paths) throws IOException;
+    public RemoteIterator<PartialListing<FileStatus>> batchedListStatusIterator(
+        final List<Path> paths) throws IOException;
     public FileStatus[] globStatus(Path pathPattern);
     public FileStatus[] globStatus(Path pathPattern, PathFilter filter);
     public Iterator<LocatedFileStatus> listFiles(Path path,

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

@@ -124,6 +124,10 @@ public FSDataOutputStream create(Path f, FsPermission permission,
     public FileStatus[] listStatusBatch(Path f, byte[] token);
     public FileStatus[] listStatus(Path[] files);
     public FileStatus[] listStatus(Path[] files, PathFilter filter);
+    public RemoteIterator<PartialListing<LocatedFileStatus>> batchedListLocatedStatusIterator(
+        final List<Path> paths) throws IOException;
+    public RemoteIterator<PartialListing<FileStatus>> batchedListStatusIterator(
+        final List<Path> paths) throws IOException;
     public FileStatus[] globStatus(Path pathPattern);
     public FileStatus[] globStatus(Path pathPattern, PathFilter filter);
 

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

@@ -6,6 +6,7 @@
       <Class name="org.apache.hadoop.hdfs.inotify.EventBatch"/>
       <Class name="org.apache.hadoop.hdfs.protocol.HdfsFileStatus"/>
       <Class name="org.apache.hadoop.hdfs.protocol.LocatedBlock"/>
+      <Class name="org.apache.hadoop.hdfs.protocol.BatchedDirectoryListing" />
       <Class name="org.apache.hadoop.hdfs.protocol.BlockStoragePolicy"/>
       <Class name="org.apache.hadoop.hdfs.protocol.CorruptFileBlocks"/>
       <Class name="org.apache.hadoop.hdfs.protocol.StripedBlockInfo"/>

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

@@ -105,6 +105,7 @@
 import org.apache.hadoop.hdfs.net.Peer;
 import org.apache.hadoop.hdfs.protocol.AclException;
 import org.apache.hadoop.hdfs.protocol.AddErasureCodingPolicyResponse;
+import org.apache.hadoop.hdfs.protocol.BatchedDirectoryListing;
 import org.apache.hadoop.hdfs.protocol.BlockStoragePolicy;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
@@ -1674,6 +1675,24 @@ public DirectoryListing listPaths(String src,  byte[] startAfter,
     }
   }
 
+  /**
+   * Get a batched listing for the indicated directories
+   *
+   * @see ClientProtocol#getBatchedListing(String[], byte[], boolean)
+   */
+  public BatchedDirectoryListing batchedListPaths(
+      String[] srcs, byte[] startAfter, boolean needLocation)
+      throws IOException {
+    checkOpen();
+    try {
+      return namenode.getBatchedListing(srcs, startAfter, needLocation);
+    } catch(RemoteException re) {
+      throw re.unwrapRemoteException(AccessControlException.class,
+          FileNotFoundException.class,
+          UnresolvedPathException.class);
+    }
+  }
+
   /**
    * Get the file info for a specific file or directory.
    * @param src The string representation of the path to the file
@@ -1693,7 +1712,7 @@ public HdfsFileStatus getFileInfo(String src) throws IOException {
     }
   }
 
-  /**
+ /**
    * Get the file info for a specific file or directory.
    * @param src The string representation of the path to the file
    * @param needBlockToken Include block tokens in {@link LocatedBlocks}.

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

@@ -21,6 +21,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Preconditions;
+import com.google.common.collect.Lists;
 import org.apache.commons.collections.list.TreeList;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -49,6 +50,7 @@
 import org.apache.hadoop.fs.GlobalStorageStatistics;
 import org.apache.hadoop.fs.GlobalStorageStatistics.StorageStatisticsProvider;
 import org.apache.hadoop.fs.InvalidPathHandleException;
+import org.apache.hadoop.fs.PartialListing;
 import org.apache.hadoop.fs.PathHandle;
 import org.apache.hadoop.fs.LocatedFileStatus;
 import org.apache.hadoop.fs.Options;
@@ -73,6 +75,7 @@
 import org.apache.hadoop.hdfs.client.HdfsDataOutputStream;
 import org.apache.hadoop.hdfs.client.impl.CorruptFileBlockIterator;
 import org.apache.hadoop.hdfs.protocol.AddErasureCodingPolicyResponse;
+import org.apache.hadoop.hdfs.protocol.BatchedDirectoryListing;
 import org.apache.hadoop.hdfs.protocol.BlockStoragePolicy;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveEntry;
 import org.apache.hadoop.hdfs.protocol.CacheDirectiveInfo;
@@ -81,6 +84,7 @@
 import org.apache.hadoop.hdfs.protocol.ClientProtocol;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
 import org.apache.hadoop.hdfs.protocol.DirectoryListing;
+import org.apache.hadoop.hdfs.protocol.HdfsPartialListing;
 import org.apache.hadoop.hdfs.protocol.EncryptionZone;
 import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicy;
 import org.apache.hadoop.hdfs.protocol.ErasureCodingPolicyInfo;
@@ -108,6 +112,8 @@
 import org.apache.hadoop.security.token.DelegationTokenIssuer;
 import org.apache.hadoop.util.ChunkedArrayList;
 import org.apache.hadoop.util.Progressable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nonnull;
 import java.io.FileNotFoundException;
@@ -120,6 +126,7 @@
 import java.util.EnumSet;
 import java.util.List;
 import java.util.Map;
+import java.util.NoSuchElementException;
 import java.util.Optional;
 
 import static org.apache.hadoop.fs.impl.PathCapabilitiesSupport.validatePathCapabilityArgs;
@@ -1292,6 +1299,110 @@ public T next() throws IOException {
     }
   }
 
+  @Override
+  public RemoteIterator<PartialListing<FileStatus>> batchedListStatusIterator(
+      final List<Path> paths) throws IOException {
+    List<Path> absPaths = Lists.newArrayListWithCapacity(paths.size());
+    for (Path p : paths) {
+      absPaths.add(fixRelativePart(p));
+    }
+    return new PartialListingIterator<>(absPaths, false);
+  }
+
+  @Override
+  public RemoteIterator<PartialListing<LocatedFileStatus>> batchedListLocatedStatusIterator(
+      final List<Path> paths) throws IOException {
+    List<Path> absPaths = Lists.newArrayListWithCapacity(paths.size());
+    for (Path p : paths) {
+      absPaths.add(fixRelativePart(p));
+    }
+    return new PartialListingIterator<>(absPaths, true);
+  }
+
+  private static final Logger LBI_LOG =
+      LoggerFactory.getLogger(PartialListingIterator.class);
+
+  private class PartialListingIterator<T extends FileStatus>
+      implements RemoteIterator<PartialListing<T>> {
+
+    private List<Path> paths;
+    private String[] srcs;
+    private boolean needLocation;
+    private BatchedDirectoryListing batchedListing;
+    private int listingIdx = 0;
+
+    PartialListingIterator(List<Path> paths, boolean needLocation)
+        throws IOException {
+      this.paths = paths;
+      this.srcs = new String[paths.size()];
+      for (int i = 0; i < paths.size(); i++) {
+        this.srcs[i] = getPathName(paths.get(i));
+      }
+      this.needLocation = needLocation;
+
+      // Do the first listing
+      statistics.incrementReadOps(1);
+      storageStatistics.incrementOpCounter(OpType.LIST_LOCATED_STATUS);
+      batchedListing = dfs.batchedListPaths(
+          srcs, HdfsFileStatus.EMPTY_NAME, needLocation);
+      LBI_LOG.trace("Got batchedListing: {}", batchedListing);
+      if (batchedListing == null) { // the directory does not exist
+        throw new FileNotFoundException("One or more paths do not exist.");
+      }
+    }
+
+    @Override
+    public boolean hasNext() throws IOException {
+      if (batchedListing == null) {
+        return false;
+      }
+      // If we're done with the current batch, try to get the next batch
+      if (listingIdx >= batchedListing.getListings().length) {
+        if (!batchedListing.hasMore()) {
+          LBI_LOG.trace("No more elements");
+          return false;
+        }
+        batchedListing = dfs.batchedListPaths(
+            srcs, batchedListing.getStartAfter(), needLocation);
+        LBI_LOG.trace("Got batchedListing: {}", batchedListing);
+        listingIdx = 0;
+      }
+      return listingIdx < batchedListing.getListings().length;
+    }
+
+    @Override
+    @SuppressWarnings("unchecked")
+    public PartialListing<T> next() throws IOException {
+      if (!hasNext()) {
+        throw new NoSuchElementException("No more entries");
+      }
+      HdfsPartialListing listing = batchedListing.getListings()[listingIdx];
+      listingIdx++;
+
+      Path parent = paths.get(listing.getParentIdx());
+
+      if (listing.getException() != null) {
+        return new PartialListing<>(parent, listing.getException());
+      }
+
+      // Qualify paths for the client.
+      List<HdfsFileStatus> statuses = listing.getPartialListing();
+      List<T> qualifiedStatuses =
+          Lists.newArrayListWithCapacity(statuses.size());
+
+      for (HdfsFileStatus status : statuses) {
+        if (needLocation) {
+          qualifiedStatuses.add((T)((HdfsLocatedFileStatus) status)
+              .makeQualifiedLocated(getUri(), parent));
+        } else {
+          qualifiedStatuses.add((T)status.makeQualified(getUri(), parent));
+        }
+      }
+
+      return new PartialListing<>(parent, qualifiedStatuses);
+    }
+  }
+
   /**
    * Create a directory, only when the parent directories exist.
    *