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Message.java
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Message.java
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/*
* Copyright (c) 2002-2015 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.cluster.com.message;
import java.io.Serializable;
import java.net.URI;
import java.util.HashMap;
import java.util.Map;
/**
* Message for state machines which can be sent out to instances in the cluster as well.
* <p>
* These are typically produced and consumed by a {@link org.neo4j.cluster.statemachine.StateMachine}.
*/
public class Message<MESSAGETYPE extends MessageType>
implements Serializable
{
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> to( MESSAGETYPE messageType, URI to )
{
return to( messageType, to, null );
}
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> to( MESSAGETYPE messageType, URI to,
Object payload )
{
return new Message<MESSAGETYPE>( messageType, payload ).setHeader( TO, to.toString() );
}
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> respond( MESSAGETYPE messageType,
Message<?> message, Object payload )
{
return message.hasHeader( Message.FROM ) ?
new Message<MESSAGETYPE>( messageType, payload ).setHeader( TO, message.getHeader( Message.FROM ) ) :
internal( messageType, payload );
}
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> internal( MESSAGETYPE message )
{
return internal( message, null );
}
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> internal( MESSAGETYPE message, Object payload )
{
return new Message<MESSAGETYPE>( message, payload );
}
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> timeout( MESSAGETYPE message,
Message<?> causedBy )
{
return timeout( message, causedBy, null );
}
public static <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> timeout( MESSAGETYPE message,
Message<?> causedBy, Object payload )
{
Message<MESSAGETYPE> timeout = causedBy.copyHeadersTo( new Message<>( message, payload ),
Message.CONVERSATION_ID, Message.CREATED_BY );
int timeoutCount = 0;
if ( causedBy.hasHeader( TIMEOUT_COUNT ) )
{
timeoutCount = Integer.parseInt( causedBy.getHeader( TIMEOUT_COUNT ) ) + 1;
}
timeout.setHeader( TIMEOUT_COUNT, "" + timeoutCount );
return timeout;
}
// Standard headers
public static final String CONVERSATION_ID = "conversation-id";
public static final String CREATED_BY = "created-by";
public static final String TIMEOUT_COUNT = "timeout-count";
public static final String FROM = "from";
public static final String TO = "to";
public static final String INSTANCE_ID = "instance-id";
final private MESSAGETYPE messageType;
final private Object payload;
final private Map<String, String> headers = new HashMap<String, String>();
protected Message( MESSAGETYPE messageType, Object payload )
{
this.messageType = messageType;
this.payload = payload;
}
public MESSAGETYPE getMessageType()
{
return messageType;
}
public <T> T getPayload()
{
return (T) payload;
}
public Message<MESSAGETYPE> setHeader( String name, String value )
{
if ( value == null )
{
throw new IllegalArgumentException( String.format( "Header %s may not be set to null", name ) );
}
headers.put( name, value );
return this;
}
public boolean hasHeader( String name )
{
return headers.containsKey( name );
}
public boolean isInternal()
{
return !headers.containsKey( Message.TO );
}
public String getHeader( String name )
throws IllegalArgumentException
{
String value = headers.get( name );
if ( value == null )
{
throw new IllegalArgumentException( "No such header:" + name );
}
return value;
}
public <MESSAGETYPE extends MessageType> Message<MESSAGETYPE> copyHeadersTo( Message<MESSAGETYPE> message,
String... names )
{
if ( names.length == 0 )
{
for ( Map.Entry<String, String> header : headers.entrySet() )
{
if ( !message.hasHeader( header.getKey() ) )
{
message.setHeader( header.getKey(), header.getValue() );
}
}
}
else
{
for ( String name : names )
{
String value = headers.get( name );
if ( value != null && !message.hasHeader( name ) )
{
message.setHeader( name, value );
}
}
}
return message;
}
@Override
public boolean equals( Object o )
{
if ( this == o )
{
return true;
}
if ( o == null || getClass() != o.getClass() )
{
return false;
}
Message message = (Message) o;
if ( headers != null ? !headers.equals( message.headers ) : message.headers != null )
{
return false;
}
if ( messageType != null ? !messageType.equals( message.messageType ) : message.messageType != null )
{
return false;
}
if ( payload != null ? !payload.equals( message.payload ) : message.payload != null )
{
return false;
}
return true;
}
@Override
public int hashCode()
{
int result = messageType != null ? messageType.hashCode() : 0;
result = 31 * result + (payload != null ? payload.hashCode() : 0);
result = 31 * result + (headers != null ? headers.hashCode() : 0);
return result;
}
@Override
public String toString()
{
return messageType.name() + headers + (payload != null && payload instanceof String ? ": " + payload : "");
}
}