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Diffstat (limited to 'awt/org/apache/harmony/awt/wtk/Synchronizer.java')
| -rw-r--r-- | awt/org/apache/harmony/awt/wtk/Synchronizer.java | 200 |
1 files changed, 0 insertions, 200 deletions
diff --git a/awt/org/apache/harmony/awt/wtk/Synchronizer.java b/awt/org/apache/harmony/awt/wtk/Synchronizer.java deleted file mode 100644 index 3eeaa0b..0000000 --- a/awt/org/apache/harmony/awt/wtk/Synchronizer.java +++ /dev/null @@ -1,200 +0,0 @@ -/* - * 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. - */ -/** - * @author Mikhail Danilov - * @version $Revision$ - */ -package org.apache.harmony.awt.wtk; - -import java.util.Hashtable; -import java.util.LinkedList; - -import org.apache.harmony.awt.internal.nls.Messages; - -/** - * Class synchronizer is to protect AWT state integrity in multithreading environment. - * It is supposed to have a child class per native platform. - * The only instance is created on the first use of one of the core AWT classes. - * Registers WTK on the dispatch thread startup. - * It is just a special kind of mutex. - * - */ - -public class Synchronizer { - //TODO: think about java.util.concurrent use for faster blocking/awaking operations - //TODO: think about all synchronized methods. Is there need to synchronize everything? - - /** - * This field holds the counter of lock operation. - * To free synchronizer unlock method must be called $acquestCounter times. - * Equals to 0 when synchronizer is free. - */ - protected int acquestCounter; - - /** - * This field holds the owner of synchronizer. - * Owner of synchronizer is a last thread that successfully locked synchronizer and - * still havn't freed it. Equals to null when synchronizer is free. - */ - protected Thread owner; - - /** - * This field holds the wait queue. - * Wait queue is a queue where thread wait for synchronizer access. - * Empty when synchronizer is free. - */ - protected final LinkedList<Thread> waitQueue = new LinkedList<Thread>(); - - /** - * The event dispatch thread - */ - protected Thread dispatchThread; - - private final Hashtable<Thread, Integer> storedStates = new Hashtable<Thread, Integer>(); - - /** - * Acquire the lock for this synchronizer. Nested lock is supported. - * If the mutex is already locked by another thread, the current thread will be put - * into wait queue until the lock becomes available. - * All user threads are served in FIFO order. Dispatch thread has higher priority. - * Supposed to be used in Toolkit.lockAWT() only. - */ - public void lock() { - synchronized (this) { - Thread curThread = Thread.currentThread(); - - if (acquestCounter == 0) { - acquestCounter = 1; - owner = curThread; - } else { - if (owner == curThread) { - acquestCounter++; - } else { - if (curThread == dispatchThread) { - waitQueue.addFirst(curThread); - } else { - waitQueue.addLast(curThread); - } - try { - wait(); - } catch (InterruptedException e) { - if (owner != curThread) { - waitQueue.remove(curThread); - // awt.1F=Waiting for resource access thread interrupted not from unlock method. - throw new RuntimeException(Messages - .getString("awt.1F")); //$NON-NLS-1$ - } - } - } - } - } - } - - /** - * Release the lock for this synchronizer. - * If wait queue is not empty the first waiting thread acquires the lock. - * Supposed to be used in Toolkit.unlockAWT() only. - */ - public void unlock() { - synchronized (this) { - if (acquestCounter == 0) { - // awt.20=Can't unlock not locked resource. - throw new RuntimeException(Messages.getString("awt.20")); //$NON-NLS-1$ - } - if (owner != Thread.currentThread()) { - // awt.21=Not owner can't unlock resource. - throw new RuntimeException(Messages.getString("awt.21")); //$NON-NLS-1$ - } - - acquestCounter--; - if (acquestCounter == 0) { - if (waitQueue.size() > 0) { - acquestCounter = 1; - owner = waitQueue.removeFirst(); - owner.interrupt(); - } else { - owner = null; - } - } - } - } - - /** - * Stores state of this synchronizer and frees it. - * Supposed to be used in Toolkit.unsafeInvokeAndWaitUnderAWTLock() only in pair with - * lockAndRestoreState(). - * Do not call it directly. - */ - public void storeStateAndFree() { - synchronized (this) { - Thread curThread = Thread.currentThread(); - - if (owner != curThread) { - // awt.22=Not owner can't free resource. - throw new RuntimeException(Messages.getString("awt.22")); //$NON-NLS-1$ - } - if (storedStates.containsKey(curThread)) { - // awt.23=One thread can't store state several times in a row. - throw new RuntimeException(Messages.getString("awt.23")); //$NON-NLS-1$ - } - - storedStates.put(curThread, new Integer(acquestCounter)); - acquestCounter = 1; - unlock(); - } - } - - /** - * Locks this synchronizer and restores it's state. - * Supposed to be used in Toolkit.unsafeInvokeAndWaitUnderAWTLock() only in pair with - * storeStateAndFree(). - * Do not call it directly. - */ - public void lockAndRestoreState() { - synchronized (this) { - Thread curThread = Thread.currentThread(); - - if (owner == curThread) { - // awt.24=Owner can't overwrite resource state. Lock operations may be lost. - throw new RuntimeException( - Messages.getString("awt.24")); //$NON-NLS-1$ - } - if (!storedStates.containsKey(curThread)) { - // awt.25=No state stored for current thread. - throw new RuntimeException(Messages.getString("awt.25")); //$NON-NLS-1$ - } - - lock(); - acquestCounter = storedStates.get(curThread).intValue(); - storedStates.remove(curThread); - } - } - - /** - * Sets references to WTK and event dispatch thread. - * Called on toolkit startup. - * - * @param wtk - reference to WTK instance - * @param dispatchThread - reference to event dispatch thread - */ - public void setEnvironment(WTK wtk, Thread dispatchThread) { - synchronized (this) { - this.dispatchThread = dispatchThread; - } - } - -} |