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

/**
 * 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.shell;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.fs.BlockLocation;
import org.apache.hadoop.fs.PathIOException;

/**
 * Modifies the replication factor
 */
@InterfaceAudience.Private
@InterfaceStability.Unstable

class SetReplication extends FsCommand {
  public static void registerCommands(CommandFactory factory) {
    factory.addClass(SetReplication.class, "-setrep");
  }
  
  public static final String NAME = "setrep";
  public static final String USAGE = "[-R] [-w] <rep> <path> ...";
  public static final String DESCRIPTION =
    "Set the replication level of a file. If <path> is a directory " +
    "then the command recursively changes the replication factor of " +
    "all files under the directory tree rooted at <path>.\n" +
    "-w: It requests that the command waits for the replication " +
    "to complete. This can potentially take a very long time.\n" +
    "-R: It is accepted for backwards compatibility. It has no effect.";
  
  protected short newRep = 0;
  protected List<PathData> waitList = new LinkedList<PathData>();
  protected boolean waitOpt = false;
  
  @Override
  protected void processOptions(LinkedList<String> args) throws IOException {
    CommandFormat cf = new CommandFormat(2, Integer.MAX_VALUE, "R", "w");
    cf.parse(args);
    waitOpt = cf.getOpt("w");
    setRecursive(true);
    
    try {
      newRep = Short.parseShort(args.removeFirst());
    } catch (NumberFormatException nfe) {
      displayWarning("Illegal replication, a positive integer expected");
      throw nfe;
    }
    if (newRep < 1) {
      throw new IllegalArgumentException("replication must be >= 1");
    }
  }

  @Override
  protected void processArguments(LinkedList<PathData> args)
  throws IOException {
    super.processArguments(args);
    if (waitOpt) waitForReplication();
  }

  @Override
  protected void processPath(PathData item) throws IOException {
    if (item.stat.isSymlink()) {
      throw new PathIOException(item.toString(), "Symlinks unsupported");
    }
    
    if (item.stat.isFile()) {
      if (!item.fs.setReplication(item.path, newRep)) {
        throw new IOException("Could not set replication for: " + item);
      }
      out.println("Replication " + newRep + " set: " + item);
      if (waitOpt) waitList.add(item);
    } 
  }

  /**
   * Wait for all files in waitList to have replication number equal to rep.
   */
  private void waitForReplication() throws IOException {
    for (PathData item : waitList) {
      out.print("Waiting for " + item + " ...");
      out.flush();

      boolean printedWarning = false;
      boolean done = false;
      while (!done) {
        item.refreshStatus();    
        BlockLocation[] locations =
          item.fs.getFileBlockLocations(item.stat, 0, item.stat.getLen());

        int i = 0;
        for(; i < locations.length; i++) {
          int currentRep = locations[i].getHosts().length;
          if (currentRep != newRep) {
            if (!printedWarning && currentRep > newRep) {
              out.println("\nWARNING: the waiting time may be long for "
                  + "DECREASING the number of replications.");
              printedWarning = true;
            }
            break;
          }
        }
        done = i == locations.length;
        if (done) break;
        
        out.print(".");
        out.flush();
        try {Thread.sleep(10000);} catch (InterruptedException e) {}
      }
      out.println(" done");
    }
  }
}