HDFS-15488. Add a command to list all snapshots for a snaphottable root with snapshot Ids. (#2166)

Author: bshashikant

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

@@ -22,6 +22,7 @@
       <Class name="org.apache.hadoop.hdfs.util.StripedBlockUtil$ChunkByteArray"/>
       <Class name="org.apache.hadoop.hdfs.protocol.SnapshotDiffReportListing$DiffReportListingEntry"/>
       <Class name="org.apache.hadoop.hdfs.protocol.SnapshotDiffReportListing"/>
+      <Class name="org.apache.hadoop.hdfs.protocol.SnapshotStatus"/>
     </Or>
     <Bug pattern="EI_EXPOSE_REP,EI_EXPOSE_REP2" />
   </Match>

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

@@ -150,6 +150,7 @@
 import org.apache.hadoop.hdfs.protocol.ZoneReencryptionStatus;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReportListing;
+import org.apache.hadoop.hdfs.protocol.SnapshotStatus;
 import org.apache.hadoop.hdfs.protocol.datatransfer.DataTransferProtoUtil;
 import org.apache.hadoop.hdfs.protocol.datatransfer.IOStreamPair;
 import org.apache.hadoop.hdfs.protocol.datatransfer.ReplaceDatanodeOnFailure;
@@ -2190,6 +2191,24 @@ public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
     }
   }
 
+  /**
+   * Get listing of all the snapshots for a snapshottable directory.
+   *
+   * @return Information about all the snapshots for a snapshottable directory
+   * @throws IOException If an I/O error occurred
+   * @see ClientProtocol#getSnapshotListing(String)
+   */
+  public SnapshotStatus[] getSnapshotListing(String snapshotRoot)
+      throws IOException {
+    checkOpen();
+    try (TraceScope ignored = tracer.newScope("getSnapshotListing")) {
+      return namenode.getSnapshotListing(snapshotRoot);
+    } catch (RemoteException re) {
+      throw re.unwrapRemoteException();
+    }
+  }
+
+
   /**
    * Allow snapshot on a directory.
    *

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

@@ -111,6 +111,7 @@ public enum OpType {
     SET_XATTR("op_set_xattr"),
     GET_SNAPSHOT_DIFF("op_get_snapshot_diff"),
     GET_SNAPSHOTTABLE_DIRECTORY_LIST("op_get_snapshottable_directory_list"),
+    GET_SNAPSHOT_LIST("op_get_snapshot_list"),
     TRUNCATE(CommonStatisticNames.OP_TRUNCATE),
     UNSET_EC_POLICY("op_unset_ec_policy"),
     UNSET_STORAGE_POLICY("op_unset_storage_policy");

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

@@ -109,6 +109,7 @@
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReportListing.DiffReportListingEntry;
 import org.apache.hadoop.hdfs.client.impl.SnapshotDiffReportGenerator;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
+import org.apache.hadoop.hdfs.protocol.SnapshotStatus;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.net.NetUtils;
@@ -2148,6 +2149,19 @@ public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
     return dfs.getSnapshottableDirListing();
   }
 
+  /**
+   * @return all the snapshots for a snapshottable directory
+   * @throws IOException
+   */
+  public SnapshotStatus[] getSnapshotListing(Path snapshotRoot)
+      throws IOException {
+    Path absF = fixRelativePart(snapshotRoot);
+    statistics.incrementReadOps(1);
+    storageStatistics
+        .incrementOpCounter(OpType.GET_SNAPSHOT_LIST);
+    return dfs.getSnapshotListing(getPathName(absF));
+  }
+
   @Override
   public void deleteSnapshot(final Path snapshotDir, final String snapshotName)
       throws IOException {

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

@@ -727,6 +727,18 @@ BatchedDirectoryListing getBatchedListing(
   SnapshottableDirectoryStatus[] getSnapshottableDirListing()
       throws IOException;
 
+  /**
+   * Get listing of all the snapshots for a snapshottable directory.
+   *
+   * @return Information about all the snapshots for a snapshottable directory
+   * @throws IOException If an I/O error occurred
+   */
+  @Idempotent
+  @ReadOnly(isCoordinated = true)
+  SnapshotStatus[] getSnapshotListing(String snapshotRoot)
+      throws IOException;
+
+
   ///////////////////////////////////////
   // System issues and management
   ///////////////////////////////////////

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

@@ -0,0 +1,226 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.PrintStream;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.EnumSet;
+
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.permission.FsPermission;
+import org.apache.hadoop.hdfs.DFSUtilClient;
+
+/**
+ * Metadata about a snapshottable directory.
+ */
+public class SnapshotStatus {
+  /**
+   * Basic information of the snapshot directory.
+   */
+  private final HdfsFileStatus dirStatus;
+
+  /**
+   * Snapshot ID for the snapshot.
+   */
+  private final int snapshotID;
+
+  /**
+   * Full path of the parent.
+   */
+  private byte[] parentFullPath;
+
+  public SnapshotStatus(long modificationTime, long accessTime,
+                        FsPermission permission,
+                        EnumSet<HdfsFileStatus.Flags> flags,
+                        String owner, String group, byte[] localName,
+                        long inodeId, int childrenNum, int snapshotID,
+                        byte[] parentFullPath) {
+    this.dirStatus = new HdfsFileStatus.Builder()
+        .isdir(true)
+        .mtime(modificationTime)
+        .atime(accessTime)
+        .perm(permission)
+        .flags(flags)
+        .owner(owner)
+        .group(group)
+        .path(localName)
+        .fileId(inodeId)
+        .children(childrenNum)
+        .build();
+    this.snapshotID = snapshotID;
+    this.parentFullPath = parentFullPath;
+  }
+
+  public SnapshotStatus(HdfsFileStatus dirStatus,
+                        int snapshotNumber, byte[] parentFullPath) {
+    this.dirStatus = dirStatus;
+    this.snapshotID = snapshotNumber;
+    this.parentFullPath = parentFullPath;
+  }
+
+  /**
+   * sets the prent path name.
+   * @param path parent path
+   */
+  public void setParentFullPath(byte[] path) {
+    parentFullPath = path;
+  }
+
+  /**
+   * @return snapshot id for the snapshot
+   */
+  public int getSnapshotID() {
+    return snapshotID;
+  }
+
+  /**
+   * @return The basic information of the directory
+   */
+  public HdfsFileStatus getDirStatus() {
+    return dirStatus;
+  }
+
+  /**
+   * @return Full path of the file
+   */
+  public byte[] getParentFullPath() {
+    return parentFullPath;
+  }
+
+  /**
+   * @return Full path of the snapshot
+   */
+  public Path getFullPath() {
+    String parentFullPathStr =
+        (parentFullPath == null || parentFullPath.length == 0) ?
+            "/" : DFSUtilClient.bytes2String(parentFullPath);
+    return new Path(getSnapshotPath(parentFullPathStr,
+        dirStatus.getLocalName()));
+  }
+
+  /**
+   * Print a list of {@link SnapshotStatus} out to a given stream.
+   *
+   * @param stats The list of {@link SnapshotStatus}
+   * @param out   The given stream for printing.
+   */
+  public static void print(SnapshotStatus[] stats,
+                           PrintStream out) {
+    if (stats == null || stats.length == 0) {
+      out.println();
+      return;
+    }
+    int maxRepl = 0, maxLen = 0, maxOwner = 0, maxGroup = 0;
+    int maxSnapshotID = 0;
+    for (SnapshotStatus status : stats) {
+      maxRepl = maxLength(maxRepl, status.dirStatus.getReplication());
+      maxLen = maxLength(maxLen, status.dirStatus.getLen());
+      maxOwner = maxLength(maxOwner, status.dirStatus.getOwner());
+      maxGroup = maxLength(maxGroup, status.dirStatus.getGroup());
+      maxSnapshotID = maxLength(maxSnapshotID, status.snapshotID);
+    }
+
+    String lineFormat = "%s%s " // permission string
+        + "%" + maxRepl + "s "
+        + (maxOwner > 0 ? "%-" + maxOwner + "s " : "%s")
+        + (maxGroup > 0 ? "%-" + maxGroup + "s " : "%s")
+        + "%" + maxLen + "s "
+        + "%s " // mod time
+        + "%" + maxSnapshotID + "s "
+        + "%s"; // path
+    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm");
+
+    for (SnapshotStatus status : stats) {
+      String line = String.format(lineFormat, "d",
+          status.dirStatus.getPermission(),
+          status.dirStatus.getReplication(),
+          status.dirStatus.getOwner(),
+          status.dirStatus.getGroup(),
+          String.valueOf(status.dirStatus.getLen()),
+          dateFormat.format(new Date(status.dirStatus.getModificationTime())),
+          status.snapshotID,
+          getSnapshotPath(DFSUtilClient.bytes2String(status.parentFullPath),
+              status.dirStatus.getLocalName())
+      );
+      out.println(line);
+    }
+  }
+
+  private static int maxLength(int n, Object value) {
+    return Math.max(n, String.valueOf(value).length());
+  }
+
+  public static class Bean {
+    private final String path;
+    private final int snapshotID;
+    private final long modificationTime;
+    private final short permission;
+    private final String owner;
+    private final String group;
+
+    public Bean(String path, int snapshotID, long
+        modificationTime, short permission, String owner, String group) {
+      this.path = path;
+      this.snapshotID = snapshotID;
+      this.modificationTime = modificationTime;
+      this.permission = permission;
+      this.owner = owner;
+      this.group = group;
+    }
+
+    public String getPath() {
+      return path;
+    }
+
+    public int getSnapshotID() {
+      return snapshotID;
+    }
+
+    public long getModificationTime() {
+      return modificationTime;
+    }
+
+    public short getPermission() {
+      return permission;
+    }
+
+    public String getOwner() {
+      return owner;
+    }
+
+    public String getGroup() {
+      return group;
+    }
+  }
+
+  static String getSnapshotPath(String snapshottableDir,
+                                String snapshotRelativePath) {
+    String parentFullPathStr =
+        snapshottableDir == null || snapshottableDir.isEmpty() ?
+            "/" : snapshottableDir;
+    final StringBuilder b = new StringBuilder(parentFullPathStr);
+    if (b.charAt(b.length() - 1) != Path.SEPARATOR_CHAR) {
+      b.append(Path.SEPARATOR);
+    }
+    return b.append(HdfsConstants.DOT_SNAPSHOT_DIR)
+        .append(Path.SEPARATOR)
+        .append(snapshotRelativePath)
+        .toString();
+  }
+}

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

@@ -89,6 +89,7 @@
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReportListing;
 import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
+import org.apache.hadoop.hdfs.protocol.SnapshotStatus;
 import org.apache.hadoop.hdfs.protocol.proto.AclProtos.GetAclStatusRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.AclProtos.GetAclStatusResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.AclProtos.ModifyAclEntriesRequestProto;
@@ -150,6 +151,8 @@
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshotDiffReportListingResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshottableDirListingRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshottableDirListingResponseProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshotListingRequestProto;
+import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetSnapshotListingResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetStoragePoliciesRequestProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetStoragePoliciesResponseProto;
 import org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos.GetStoragePolicyRequestProto;
@@ -1299,6 +1302,25 @@ public SnapshottableDirectoryStatus[] getSnapshottableDirListing()
     }
   }
 
+  @Override
+  public SnapshotStatus[] getSnapshotListing(String path)
+      throws IOException {
+    GetSnapshotListingRequestProto req =
+        GetSnapshotListingRequestProto.newBuilder()
+            .setSnapshotRoot(path).build();
+    try {
+      GetSnapshotListingResponseProto result = rpcProxy
+          .getSnapshotListing(null, req);
+
+      if (result.hasSnapshotList()) {
+        return PBHelperClient.convert(result.getSnapshotList());
+      }
+      return null;
+    } catch (ServiceException e) {
+      throw ProtobufHelper.getRemoteException(e);
+    }
+  }
+
   @Override
   public SnapshotDiffReport getSnapshotDiffReport(String snapshotRoot,
       String fromSnapshot, String toSnapshot) throws IOException {