/*
* Copyright (c) 2000, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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 General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
package sun.jvm.hotspot.utilities;
/** The backend for the message queue abstraction. This class is
instantiated first and queried to provide the two "sides" of the
message queue. */
import java.util.LinkedList;
public class MessageQueueBackend {
// The two queues
private MessageQueueImpl leftRightQueue;
private MessageQueueImpl rightLeftQueue;
public MessageQueueBackend() {
LinkedList leftRightPipe = new LinkedList();
LinkedList rightLeftPipe = new LinkedList();
leftRightQueue = new MessageQueueImpl(rightLeftPipe, leftRightPipe);
rightLeftQueue = new MessageQueueImpl(leftRightPipe, rightLeftPipe);
}
/** Get one of the two symmetric sides of this message queue. */
public MessageQueue getFirstQueue() {
return leftRightQueue;
}
/** Get second of the two symmetric sides of this message queue. */
public MessageQueue getSecondQueue() {
return rightLeftQueue;
}
private class MessageQueueImpl implements MessageQueue {
private LinkedList readList;
private LinkedList writeList;
public MessageQueueImpl(LinkedList listToReadFrom, LinkedList listToWriteTo) {
readList = listToReadFrom;
writeList = listToWriteTo;
}
public Object readMessage() {
synchronized(readList) {
while (readList.isEmpty()) {
try {
readList.wait();
}
catch (InterruptedException e) {
}
}
return readList.removeFirst();
}
}
public Object readMessageWithTimeout(long millis) {
synchronized(readList) {
if (readList.isEmpty()) {
if (millis == 0) {
return null;
}
try {
readList.wait(millis);
}
catch (InterruptedException e) {
}
}
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