blockcommand.java

hadoop:Nutch集群平台

/**
 * Copyright 2005 The Apache Software Foundation
 *
 * Licensed 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.dfs;

import org.apache.hadoop.io.*;

import java.io.*;

/****************************************************
 * A BlockCommand is an instruction to a datanode 
 * regarding some blocks under its control.  It tells
 * the DataNode to either invalidate a set of indicated
 * blocks, or to copy a set of indicated blocks to 
 * another DataNode.
 * 
 * @author Mike Cafarella
 ****************************************************/
class BlockCommand implements Writable {

    static {                                      // register a ctor
      WritableFactories.setFactory
        (BlockCommand.class,
         new WritableFactory() {
           public Writable newInstance() { return new BlockCommand(); }
         });
    }
  
    boolean transferBlocks = false;
    boolean invalidateBlocks = false;
    boolean shutdown = false;
    Block blocks[];
    DatanodeInfo targets[][];

    public BlockCommand() {
        this.transferBlocks = false;
        this.invalidateBlocks = false;
        this.shutdown = false;
        this.blocks = new Block[0];
        this.targets = new DatanodeInfo[0][];
    }

    public BlockCommand(Block blocks[], DatanodeInfo targets[][]) {
        this.transferBlocks = true;
        this.invalidateBlocks = false;
        this.shutdown = false;
        this.blocks = blocks;
        this.targets = targets;
    }

    public BlockCommand(Block blocks[]) {
        this.transferBlocks = false;
        this.invalidateBlocks = true;
        this.shutdown = false;
        this.blocks = blocks;
        this.targets = new DatanodeInfo[0][];
    }

    public BlockCommand( boolean doShutdown ) {
      this();
      this.shutdown = doShutdown;
    }

    public boolean transferBlocks() {
        return transferBlocks;
    }

    public boolean invalidateBlocks() {
        return invalidateBlocks;
    }
    
    public boolean shutdownNode() {
      return shutdown;
  }
  
    public Block[] getBlocks() {
        return blocks;
    }

    public DatanodeInfo[][] getTargets() {
        return targets;
    }

    ///////////////////////////////////////////
    // Writable
    ///////////////////////////////////////////
    public void write(DataOutput out) throws IOException {
        out.writeBoolean(transferBlocks);
        out.writeBoolean(invalidateBlocks);        
        out.writeInt(blocks.length);
        for (int i = 0; i < blocks.length; i++) {
            blocks[i].write(out);
        }
        out.writeInt(targets.length);
        for (int i = 0; i < targets.length; i++) {
            out.writeInt(targets[i].length);
            for (int j = 0; j < targets[i].length; j++) {
                targets[i][j].write(out);
            }
        }
    }

    public void readFields(DataInput in) throws IOException {
        this.transferBlocks = in.readBoolean();
        this.invalidateBlocks = in.readBoolean();
        this.blocks = new Block[in.readInt()];
        for (int i = 0; i < blocks.length; i++) {
            blocks[i] = new Block();
            blocks[i].readFields(in);
        }

        this.targets = new DatanodeInfo[in.readInt()][];
        for (int i = 0; i < targets.length; i++) {
            this.targets[i] = new DatanodeInfo[in.readInt()];
            for (int j = 0; j < targets[i].length; j++) {
                targets[i][j] = new DatanodeInfo();
                targets[i][j].readFields(in);
            }
        }
    }
}