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/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* 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. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire.internal.tcp;
import com.gemstone.gemfire.internal.UniqueIdGenerator;
/** MsgId is used to generate unique ids to attach to messages.
* To get a new id call obtain. When you are done with the id call release.
* Failure to call release will eventually cause obtain to fail with an exception.
* Currently ids are in the range 0..32767 inclusive.
*
* @author Darrel
* @since 5.0.2
*/
public class MsgIdGenerator {
/**
* A value that can be used to indicate that a message does not have an id.
*/
public static final short NO_MSG_ID = -1;
private static final short MAX_ID = 32767;
private static final UniqueIdGenerator uigen = new UniqueIdGenerator(MAX_ID);
private MsgIdGenerator() {
// static only; no constructor
}
/**
* Obtains a message id. Callers of this must call release
* when finished with the id.
* @throws IllegalStateException if all ids have been obtained
*/
public static short obtain() {
return (short)uigen.obtain();
}
public static void release(short id) {
if (id != NO_MSG_ID) {
uigen.release(id);
}
}
}