HDFS-4095. Add some snapshot related metrics. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-2802@1404881 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.HDFS-2802.txt

@@ -42,3 +42,5 @@ Branch-2802 Snapshot (Unreleased)
   (Jing Zhao via suresh)
 
   HDFS-4116. Add auditlog for some snapshot operations. (Jing Zhao via suresh)
+
+  HDFS-4095. Add some snapshot related metrics. (Jing Zhao via suresh)

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

@@ -3579,6 +3579,16 @@ public int getTotalLoad() {
     return datanodeStatistics.getXceiverCount();
   }
   
+  @Metric({ "SnapshottableDirectories", "Number of snapshottable directories" })
+  public long getNumSnapshottableDirs() {
+    return this.snapshotManager.getNumSnapshottableDirs();
+  }
+
+  @Metric({ "Snapshots", "The number of snapshots" })
+  public long getNumSnapshots() {
+    return this.snapshotManager.getNumSnapshots();
+  }
+
   int getNumberOfDatanodes(DatanodeReportType type) {
     readLock();
     try {
@@ -5542,7 +5552,8 @@ public void allowSnapshot(String path) throws SafeModeException, IOException {
   @VisibleForTesting
   public void disallowSnapshot(String snapshotRoot)
       throws SafeModeException, IOException {
-    // TODO: implement
+    // TODO: implement, also need to update metrics in corresponding
+    // SnapshotManager method 
     
     if (auditLog.isInfoEnabled() && isExternalInvocation()) {
       logAuditEvent(UserGroupInformation.getCurrentUser(), getRemoteIp(),

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

@@ -1080,18 +1080,21 @@ public void createSnapshot(String snapshotName, String snapshotRoot)
       throw new IOException("createSnapshot: Pathname too long.  Limit "
           + MAX_PATH_LENGTH + " characters, " + MAX_PATH_DEPTH + " levels.");
     }
+    metrics.incrCreateSnapshotOps();
     namesystem.createSnapshot(snapshotName, snapshotRoot);
   }
 
   @Override
   // Client Protocol
   public void allowSnapshot(String snapshotRoot) throws IOException {
+    metrics.incrAllowSnapshotOps();
     namesystem.allowSnapshot(snapshotRoot);
   }
 
   @Override
   // Client Protocol
   public void disallowSnapshot(String snapshot) throws IOException {
+    metrics.incrDisAllowSnapshotOps();
     namesystem.disallowSnapshot(snapshot);
   }
 }

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

@@ -57,6 +57,12 @@ public class NameNodeMetrics {
   @Metric MutableCounterLong createSymlinkOps;
   @Metric MutableCounterLong getLinkTargetOps;
   @Metric MutableCounterLong filesInGetListingOps;
+  @Metric("Number of allowSnapshot operations")
+  MutableCounterLong allowSnapshotOps;
+  @Metric("Number of disallowSnapshot operations")
+  MutableCounterLong disallowSnapshotOps;
+  @Metric("Number of createSnapshot operations")
+  MutableCounterLong createSnapshotOps;
 
   @Metric("Journal transactions") MutableRate transactions;
   @Metric("Journal syncs") MutableRate syncs;
@@ -159,6 +165,18 @@ public void incrGetLinkTargetOps() {
     getLinkTargetOps.incr();
   }
 
+  public void incrAllowSnapshotOps() {
+    allowSnapshotOps.incr();
+  }
+  
+  public void incrDisAllowSnapshotOps() {
+    disallowSnapshotOps.incr();
+  }
+  
+  public void incrCreateSnapshotOps() {
+    createSnapshotOps.incr();
+  }
+  
   public void addTransaction(long latency) {
     transactions.add(latency);
   }

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

@@ -20,6 +20,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.atomic.AtomicLong;
 
 import org.apache.hadoop.hdfs.server.namenode.FSDirectory;
 import org.apache.hadoop.hdfs.server.namenode.FSNamesystem;
@@ -30,9 +31,11 @@
 import org.apache.hadoop.hdfs.server.namenode.INodeSymlink;
 
 /** Manage snapshottable directories and their snapshots. */
-public class SnapshotManager {
+public class SnapshotManager implements SnapshotStats {
   private final FSNamesystem namesystem;
   private final FSDirectory fsdir;
+  private AtomicLong numSnapshottableDirs = new AtomicLong();
+  private AtomicLong numSnapshots = new AtomicLong();
   
   /** All snapshottable directories in the namesystem. */
   private final List<INodeDirectorySnapshottable> snapshottables
@@ -67,6 +70,7 @@ public void setSnapshottable(final String path, final int snapshotQuota
     } finally {
       namesystem.writeUnlock();
     }
+    numSnapshottableDirs.getAndIncrement();
   }
 
   /**
@@ -78,6 +82,7 @@ public void setSnapshottable(final String path, final int snapshotQuota
   public void createSnapshot(final String snapshotName, final String path
       ) throws IOException {
     new SnapshotCreation(path).run(snapshotName);
+    numSnapshots.getAndIncrement();
   }
   
   /**
@@ -174,4 +179,15 @@ private INodeFileSnapshot processINodeFile(final INodeDirectory parent,
       return snapshot;
     }
   }
+
+  @Override
+  public long getNumSnapshottableDirs() {
+    return numSnapshottableDirs.get();
+  }
+
+  @Override
+  public long getNumSnapshots() {
+    return numSnapshots.get();
+  }
+  
 }

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

@@ -0,0 +1,36 @@
+/**
+ * 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.server.namenode.snapshot;
+
+/**
+ * This is an interface used to retrieve statistic information related to
+ * snapshots
+ */
+public interface SnapshotStats {
+
+  /**
+   * @return The number of snapshottale directories in the system 
+   */
+  public long getNumSnapshottableDirs();
+  
+  /**
+   * @return The number of directories that have been snapshotted
+   */
+  public long getNumSnapshots();
+  
+}