001 /**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.hadoop.hdfs.server.protocol;
019
020 /*
021 * A system administrator can tune the balancer bandwidth parameter
022 * (dfs.balance.bandwidthPerSec) dynamically by calling
023 * "dfsadmin -setBalanacerBandwidth newbandwidth".
024 * This class is to define the command which sends the new bandwidth value to
025 * each datanode.
026 */
027
028 import java.io.DataInput;
029 import java.io.DataOutput;
030 import java.io.IOException;
031
032 import org.apache.hadoop.io.Writable;
033 import org.apache.hadoop.io.WritableFactories;
034 import org.apache.hadoop.io.WritableFactory;
035
036 /**
037 * Balancer bandwidth command instructs each datanode to change its value for
038 * the max amount of network bandwidth it may use during the block balancing
039 * operation.
040 *
041 * The Balancer Bandwidth Command contains the new bandwidth value as its
042 * payload. The bandwidth value is in bytes per second.
043 */
044 public class BalancerBandwidthCommand extends DatanodeCommand {
045 private final static long BBC_DEFAULTBANDWIDTH = 0L;
046
047 private long bandwidth;
048
049 /**
050 * Balancer Bandwidth Command constructor. Sets bandwidth to 0.
051 */
052 BalancerBandwidthCommand() {
053 this(BBC_DEFAULTBANDWIDTH);
054 }
055
056 /**
057 * Balancer Bandwidth Command constructor.
058 *
059 * @param bandwidth Blanacer bandwidth in bytes per second.
060 */
061 public BalancerBandwidthCommand(long bandwidth) {
062 super(DatanodeProtocol.DNA_BALANCERBANDWIDTHUPDATE);
063 this.bandwidth = bandwidth;
064 }
065
066 /**
067 * Get current value of the max balancer bandwidth in bytes per second.
068 *
069 * @return bandwidth Blanacer bandwidth in bytes per second for this datanode.
070 */
071 public long getBalancerBandwidthValue() {
072 return this.bandwidth;
073 }
074
075 // ///////////////////////////////////////////////
076 // Writable
077 // ///////////////////////////////////////////////
078 static { // register a ctor
079 WritableFactories.setFactory(BalancerBandwidthCommand.class, new WritableFactory() {
080 public Writable newInstance() {
081 return new BalancerBandwidthCommand();
082 }
083 });
084 }
085
086 /**
087 * Writes the bandwidth payload to the Balancer Bandwidth Command packet.
088 * @param out DataOutput stream used for writing commands to the datanode.
089 * @throws IOException
090 */
091 public void write(DataOutput out) throws IOException {
092 super.write(out);
093 out.writeLong(this.bandwidth);
094 }
095
096 /**
097 * Reads the bandwidth payload from the Balancer Bandwidth Command packet.
098 * @param in DataInput stream used for reading commands to the datanode.
099 * @throws IOException
100 */
101 public void readFields(DataInput in) throws IOException {
102 super.readFields(in);
103 this.bandwidth = in.readLong();
104 }
105 }