HDFS-6863. Archival Storage: Support migration for snapshot paths. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-6584@1619627 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -161,4 +161,7 @@ public static enum DatanodeReportType {
   
   public static final String SEPARATOR_DOT_SNAPSHOT_DIR
       = Path.SEPARATOR + DOT_SNAPSHOT_DIR;
+
+  public static final String SEPARATOR_DOT_SNAPSHOT_DIR_SEPARATOR
+      = Path.SEPARATOR + DOT_SNAPSHOT_DIR + Path.SEPARATOR;
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/mover/Mover.java

@@ -17,46 +17,21 @@
  */
 package org.apache.hadoop.hdfs.server.mover;
 
-import java.io.IOException;
-import java.net.URI;
-import java.text.DateFormat;
-import java.util.Arrays;
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Date;
-import java.util.EnumMap;
-import java.util.Iterator;
-import java.util.LinkedList;
-import java.util.List;
-
 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.conf.Configured;
 import org.apache.hadoop.fs.Path;
-import org.apache.hadoop.hdfs.BlockStoragePolicy;
+import org.apache.hadoop.hdfs.*;
-import org.apache.hadoop.hdfs.DFSClient;
+import org.apache.hadoop.hdfs.protocol.*;
-import org.apache.hadoop.hdfs.DFSConfigKeys;
-import org.apache.hadoop.hdfs.DFSUtil;
-import org.apache.hadoop.hdfs.HdfsConfiguration;
-import org.apache.hadoop.hdfs.StorageType;
-import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
-import org.apache.hadoop.hdfs.protocol.DirectoryListing;
-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.LocatedBlocks;
 import org.apache.hadoop.hdfs.server.balancer.Dispatcher;
-import org.apache.hadoop.hdfs.server.balancer.Dispatcher.DBlock;
+import org.apache.hadoop.hdfs.server.balancer.Dispatcher.*;
-import org.apache.hadoop.hdfs.server.balancer.Dispatcher.DDatanode;
 import org.apache.hadoop.hdfs.server.balancer.Dispatcher.DDatanode.StorageGroup;
-import org.apache.hadoop.hdfs.server.balancer.Dispatcher.PendingMove;
-import org.apache.hadoop.hdfs.server.balancer.Dispatcher.Source;
-import org.apache.hadoop.hdfs.server.balancer.Dispatcher.StorageGroupMap;
 import org.apache.hadoop.hdfs.server.balancer.ExitStatus;
 import org.apache.hadoop.hdfs.server.balancer.Matcher;
 import org.apache.hadoop.hdfs.server.balancer.NameNodeConnector;
+import org.apache.hadoop.hdfs.server.namenode.INode;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeStorageReport;
 import org.apache.hadoop.hdfs.server.protocol.StorageReport;
 import org.apache.hadoop.io.IOUtils;
@@ -66,6 +41,11 @@
 import org.apache.hadoop.util.Tool;
 import org.apache.hadoop.util.ToolRunner;
 
+import java.io.IOException;
+import java.net.URI;
+import java.text.DateFormat;
+import java.util.*;
+
 @InterfaceAudience.Private
 public class Mover {
   static final Log LOG = LogFactory.getLog(Mover.class);
@@ -173,14 +153,67 @@ private static long getMaxRemaining(DatanodeStorageReport report, StorageType t)
     return max;
   }
 
+  /**
+   * convert a snapshot path to non-snapshot path. E.g.,
+   * /foo/.snapshot/snapshot-name/bar --> /foo/bar
+   */
+  private static String convertSnapshotPath(String[] pathComponents) {
+    StringBuilder sb = new StringBuilder(Path.SEPARATOR);
+    for (int i = 0; i < pathComponents.length; i++) {
+      if (pathComponents[i].equals(HdfsConstants.DOT_SNAPSHOT_DIR)) {
+        i++;
+      } else {
+        sb.append(pathComponents[i]);
+      }
+    }
+    return sb.toString();
+  }
+
   private class Processor {
     private final DFSClient dfs;
+    private final List<String> snapshottableDirs = new ArrayList<String>();
 
     private Processor() {
       dfs = dispatcher.getDistributedFileSystem().getClient();
     }
 
+    private void getSnapshottableDirs() {
+      SnapshottableDirectoryStatus[] dirs = null;
+      try {
+        dirs = dfs.getSnapshottableDirListing();
+      } catch (IOException e) {
+        LOG.warn("Failed to get snapshottable directories."
+            + " Ignore and continue.", e);
+      }
+      if (dirs != null) {
+        for (SnapshottableDirectoryStatus dir : dirs) {
+          snapshottableDirs.add(dir.getFullPath().toString());
+        }
+      }
+    }
+
+    /**
+     * @return true if the given path is a snapshot path and the corresponding
+     * INode is still in the current fsdirectory.
+     */
+    private boolean isSnapshotPathInCurrent(String path) throws IOException {
+      // if the parent path contains "/.snapshot/", this is a snapshot path
+      if (path.contains(HdfsConstants.SEPARATOR_DOT_SNAPSHOT_DIR_SEPARATOR)) {
+        String[] pathComponents = INode.getPathNames(path);
+        if (HdfsConstants.DOT_SNAPSHOT_DIR
+            .equals(pathComponents[pathComponents.length - 2])) {
+          // this is a path for a specific snapshot (e.g., /foo/.snapshot/s1)
+          return false;
+        }
+        String nonSnapshotPath = convertSnapshotPath(pathComponents);
+        return dfs.getFileInfo(nonSnapshotPath) != null;
+      } else {
+        return false;
+      }
+    }
+
     private void processNamespace() {
+      getSnapshottableDirs();
       try {
         processDirRecursively("", dfs.getFileInfo("/"));
       } catch (IOException e) {
@@ -188,21 +221,13 @@ private void processNamespace() {
       }
     }
 
-    private void processDirRecursively(String parent, HdfsFileStatus status) {
+    private void processChildrenList(String fullPath) {
-      if (status.isSymlink()) {
-        return; //ignore symlinks
-      } else if (status.isDir()) {
-        String dir = status.getFullName(parent);
-        if (!dir.endsWith(Path.SEPARATOR)) {
-          dir = dir + Path.SEPARATOR; 
-        }
-
       for (byte[] lastReturnedName = HdfsFileStatus.EMPTY_NAME;;) {
         final DirectoryListing children;
         try {
-            children = dfs.listPaths(dir, lastReturnedName, true);
+          children = dfs.listPaths(fullPath, lastReturnedName, true);
         } catch(IOException e) {
-            LOG.warn("Failed to list directory " + dir
+          LOG.warn("Failed to list directory " + fullPath
               + ". Ignore the directory and continue.", e);
           return;
         }
@@ -210,7 +235,7 @@ private void processDirRecursively(String parent, HdfsFileStatus status) {
           return;
         }
         for (HdfsFileStatus child : children.getPartialListing()) {
-            processDirRecursively(dir, child);
+          processDirRecursively(fullPath, child);
         }
         if (!children.hasMore()) {
           lastReturnedName = children.getLastName();
@@ -218,7 +243,35 @@ private void processDirRecursively(String parent, HdfsFileStatus status) {
           return;
         }
       }
+    }
+
+    private void processDirRecursively(String parent, HdfsFileStatus status) {
+      String fullPath = status.getFullName(parent);
+      if (status.isSymlink()) {
+        return; //ignore symlinks
+      } else if (status.isDir()) {
+        if (!fullPath.endsWith(Path.SEPARATOR)) {
+          fullPath = fullPath + Path.SEPARATOR; 
+        }
+
+        processChildrenList(fullPath);
+        // process snapshots if this is a snapshottable directory
+        if (snapshottableDirs.contains(fullPath)) {
+          final String dirSnapshot = fullPath + HdfsConstants.DOT_SNAPSHOT_DIR;
+          processChildrenList(dirSnapshot);
+        }
       } else { // file
+        try {
+          if (isSnapshotPathInCurrent(fullPath)) {
+            // the full path is a snapshot path but it is also included in the
+            // current directory tree, thus ignore it.
+            return;
+          }
+        } catch (IOException e) {
+          LOG.warn("Failed to check the status of " + parent
+              + ". Ignore it and continue.", e);
+          return;
+        }
         processFile(parent, (HdfsLocatedFileStatus)status);
       }
     }

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

@@ -719,7 +719,7 @@ static byte[][] getPathComponents(String[] strings) {
    * @throws AssertionError if the given path is invalid.
    * @return array of path components.
    */
-  static String[] getPathNames(String path) {
+  public static String[] getPathNames(String path) {
     if (path == null || !path.startsWith(Path.SEPARATOR)) {
       throw new AssertionError("Absolute path required");
     }