/**
* Copyright 2010 The Apache Software Foundation
*
* 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.hbase;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.io.Writable;
/**
* HMsg is used to send messages between master and regionservers. Messages are
* sent as payload on the regionserver-to-master heartbeats. Region assignment
* does not use this mechanism. It goes via zookeeper.
*
* <p>Most of the time the messages are simple but some messages are accompanied
* by the region affected. HMsg may also carry an optional message.
*
* <p>TODO: Clean out all messages that go from master to regionserver; by
* design, these are to go via zk from here on out.
*/
public class HMsg implements Writable {
public static final HMsg [] STOP_REGIONSERVER_ARRAY =
new HMsg [] {new HMsg(Type.STOP_REGIONSERVER)};
public static final HMsg [] EMPTY_HMSG_ARRAY = new HMsg[0];
public static enum Type {
/** Master tells region server to stop.
*/
STOP_REGIONSERVER,
/**
* Region server split the region associated with this message.
*/
REGION_SPLIT,
/**
* When RegionServer receives this message, it goes into a sleep that only
* an exit will cure. This message is sent by unit tests simulating
* pathological states.
*/
TESTING_BLOCK_REGIONSERVER,
}
private Type type = null;
private HRegionInfo info = null;
private byte[] message = null;
private HRegionInfo daughterA = null;
private HRegionInfo daughterB = null;
/** Default constructor. Used during deserialization */
public HMsg() {
this(null);
}
/**
* Construct a message with the specified message and empty HRegionInfo
* @param type Message type
*/
public HMsg(final HMsg.Type type) {
this(type, new HRegionInfo(), null);
}
/**
* Construct a message with the specified message and HRegionInfo
* @param type Message type
* @param hri Region to which message <code>type</code> applies
*/
public HMsg(final HMsg.Type type, final HRegionInfo hri) {
this(type, hri, null);
}
/**
* Construct a message with the specified message and HRegionInfo
*
* @param type Message type
* @param hri Region to which message <code>type</code> applies. Cannot be
* null. If no info associated, used other Constructor.
* @param msg Optional message (Stringified exception, etc.)
*/
public HMsg(final HMsg.Type type, final HRegionInfo hri, final byte[] msg) {
this(type, hri, null, null, msg);
}
/**
* Construct a message with the specified message and HRegionInfo
*
* @param type Message type
* @param hri Region to which message <code>type</code> applies. Cannot be
* null. If no info associated, used other Constructor.
* @param daughterA
* @param daughterB
* @param msg Optional message (Stringified exception, etc.)
*/
public HMsg(final HMsg.Type type, final HRegionInfo hri,
final HRegionInfo daughterA, final HRegionInfo daughterB, final byte[] msg) {
this.type = type;
if (hri == null) {
throw new NullPointerException("Region cannot be null");
}
this.info = hri;
this.message = msg;
this.daughterA = daughterA;
this.daughterB = daughterB;
}
/**
* @return Region info or null if none associated with this message type.
*/
public HRegionInfo getRegionInfo() {
return this.info;
}
/** @return the type of message */
public Type getType() {
return this.type;
}
/**
* @param other Message type to compare to
* @return True if we are of same message type as <code>other</code>
*/
public boolean isType(final HMsg.Type other) {
return this.type.equals(other);
}
/** @return the message type */
public byte[] getMessage() {
return this.message;
}
/**
* @return First daughter if Type is MSG_REPORT_SPLIT_INCLUDES_DAUGHTERS else
* null
*/
public HRegionInfo getDaughterA() {
return this.daughterA;
}
/**
* @return Second daughter if Type is MSG_REPORT_SPLIT_INCLUDES_DAUGHTERS else
* null
*/
public HRegionInfo getDaughterB() {
return this.daughterB;
}
/**
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append(this.type.toString());
// If null or empty region, don't bother printing it out.
if (this.info != null && this.info.getRegionName().length > 0) {
sb.append(": ");
sb.append(this.info.getRegionNameAsString());
}
if (this.message != null && this.message.length > 0) {
sb.append(": " + Bytes.toString(this.message));
}
return sb.toString();
}
/**
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (getClass() != obj.getClass()) {
return false;
}
HMsg that = (HMsg)obj;
return this.type.equals(that.type) &&
(this.info != null)? this.info.equals(that.info):
that.info == null;
}
/**
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
int result = this.type.hashCode();
if (this.info != null) {
result ^= this.info.hashCode();
}
return result;
}
// ////////////////////////////////////////////////////////////////////////////
// Writable
//////////////////////////////////////////////////////////////////////////////
/**
* @see org.apache.hadoop.io.Writable#write(java.io.DataOutput)
*/
public void write(DataOutput out) throws IOException {
out.writeInt(this.type.ordinal());
this.info.write(out);
if (this.message == null || this.message.length == 0) {
out.writeBoolean(false);
} else {
out.writeBoolean(true);
Bytes.writeByteArray(out, this.message);
}
if (this.type.equals(Type.REGION_SPLIT)) {
this.daughterA.write(out);
this.daughterB.write(out);
}
}
/**
* @see org.apache.hadoop.io.Writable#readFields(java.io.DataInput)
*/
public void readFields(DataInput in) throws IOException {
int ordinal = in.readInt();
this.type = HMsg.Type.values()[ordinal];
this.info.readFields(in);
boolean hasMessage = in.readBoolean();
if (hasMessage) {
this.message = Bytes.readByteArray(in);
}
if (this.type.equals(Type.REGION_SPLIT)) {
this.daughterA = new HRegionInfo();
this.daughterB = new HRegionInfo();
this.daughterA.readFields(in);
this.daughterB.readFields(in);
}
}
}