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Diffstat (limited to 'jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/SynchronizedQueue.java')
-rw-r--r-- | jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/SynchronizedQueue.java | 348 |
1 files changed, 0 insertions, 348 deletions
diff --git a/jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/SynchronizedQueue.java b/jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/SynchronizedQueue.java deleted file mode 100644 index c35a4aa133..0000000000 --- a/jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/SynchronizedQueue.java +++ /dev/null @@ -1,348 +0,0 @@ -/******************************************************************************* - * Copyright (c) 2009 Oracle. All rights reserved. - * This program and the accompanying materials are made available under the - * terms of the Eclipse Public License v1.0, which accompanies this distribution - * and is available at http://www.eclipse.org/legal/epl-v10.html. - * - * Contributors: - * Oracle - initial API and implementation - ******************************************************************************/ -package org.eclipse.jpt.utility.internal; - -import java.io.Serializable; -import java.util.NoSuchElementException; - -import org.eclipse.jpt.utility.Command; - -/** - * Thread-safe implementation of the {@link Queue} interface. - * This also provides protocol for suspending a thread until the - * queue is empty or not empty, with optional time-outs. - */ -public class SynchronizedQueue<E> - implements Queue<E>, Serializable -{ - /** Backing queue. */ - private final Queue<E> queue; - - /** Object to synchronize on. */ - private final Object mutex; - - private static final long serialVersionUID = 1L; - - - // ********** constructors ********** - - /** - * Construct a synchronized queue that wraps the - * specified queue and locks on the specified mutex. - */ - public SynchronizedQueue(Queue<E> queue, Object mutex) { - super(); - if (queue == null) { - throw new NullPointerException(); - } - this.queue = queue; - this.mutex = mutex; - } - - /** - * Construct a synchronized queue that wraps the - * specified queue and locks on itself. - */ - public SynchronizedQueue(Queue<E> queue) { - super(); - if (queue == null) { - throw new NullPointerException(); - } - this.queue = queue; - this.mutex = this; - } - - /** - * Construct an empty synchronized queue that locks on the specified mutex. - */ - public SynchronizedQueue(Object mutex) { - this(new SimpleQueue<E>(), mutex); - } - - /** - * Construct an empty synchronized queue that locks on itself. - */ - public SynchronizedQueue() { - this(new SimpleQueue<E>()); - } - - - // ********** Queue implementation ********** - - public void enqueue(E element) { - synchronized (this.mutex) { - this.enqueue_(element); - } - } - - /** - * Pre-condition: synchronized - */ - private void enqueue_(E element) { - this.queue.enqueue(element); - this.mutex.notifyAll(); - } - - public E dequeue() { - synchronized (this.mutex) { - return this.dequeue_(); - } - } - - /** - * Pre-condition: synchronized - */ - private E dequeue_() { - E element = this.queue.dequeue(); - this.mutex.notifyAll(); - return element; - } - - public E peek() { - synchronized (this.mutex) { - return this.queue.peek(); - } - } - - public boolean isEmpty() { - synchronized (this.mutex) { - return this.queue.isEmpty(); - } - } - - - // ********** indefinite waits ********** - - /** - * Suspend the current thread until the queue's empty status changes - * to the specified value. - */ - public void waitUntilEmptyIs(boolean empty) throws InterruptedException { - synchronized (this.mutex) { - this.waitUntilEmptyIs_(empty); - } - } - - /** - * Pre-condition: synchronized - */ - private void waitUntilEmptyIs_(boolean empty) throws InterruptedException { - while (this.queue.isEmpty() != empty) { - this.mutex.wait(); - } - } - - /** - * Suspend the current thread until the queue is empty. - */ - public void waitUntilEmpty() throws InterruptedException { - this.waitUntilEmptyIs(true); - } - - /** - * Suspend the current thread until the queue has something on it. - */ - public void waitUntilNotEmpty() throws InterruptedException { - this.waitUntilEmptyIs(false); - } - - /** - * Suspend the current thread until the queue is empty, - * then "enqueue" the specified item to the tail of the queue - * and continue executing. - */ - public void waitToEnqueue(E element) throws InterruptedException { - synchronized (this.mutex) { - this.waitUntilEmptyIs_(true); - this.enqueue_(element); - } - } - - /** - * Suspend the current thread until the queue has something on it, - * then "dequeue" an item from the head of the queue and return it. - */ - public Object waitToDequeue() throws InterruptedException { - synchronized (this.mutex) { - this.waitUntilEmptyIs_(false); - return this.dequeue_(); - } - } - - - // ********** timed waits ********** - - /** - * Suspend the current thread until the queue's empty status changes - * to the specified value or the specified time-out occurs. - * The time-out is specified in milliseconds. Return <code>true</code> if the specified - * empty status was achieved; return <code>false</code> if a time-out occurred. - * If the queue's empty status is already the specified value, - * return <code>true</code> immediately. - * If the time-out is zero, wait indefinitely. - */ - public boolean waitUntilEmptyIs(boolean empty, long timeout) throws InterruptedException { - synchronized (this.mutex) { - return this.waitUntilEmptyIs_(empty, timeout); - } - } - - /** - * Pre-condition: synchronized - */ - private boolean waitUntilEmptyIs_(boolean empty, long timeout) throws InterruptedException { - if (timeout == 0L) { - this.waitUntilEmptyIs_(empty); // wait indefinitely until notified - return true; // if it ever comes back, the condition was met - } - - long stop = System.currentTimeMillis() + timeout; - long remaining = timeout; - while ((this.queue.isEmpty() != empty) && (remaining > 0L)) { - this.mutex.wait(remaining); - remaining = stop - System.currentTimeMillis(); - } - return (this.queue.isEmpty() == empty); - } - - /** - * Suspend the current thread until the queue is empty - * or the specified time-out occurs. - * The time-out is specified in milliseconds. Return <code>true</code> if - * the queue is empty; return <code>false</code> if a time-out occurred. - * If the queue is already empty, return <code>true</code> immediately. - * If the time-out is zero, wait indefinitely. - */ - public boolean waitUntilEmpty(long timeout) throws InterruptedException { - return this.waitUntilEmptyIs(true, timeout); - } - - /** - * Suspend the current thread until the queue has something on it. - * or the specified time-out occurs. - * The time-out is specified in milliseconds. Return <code>true</code> if - * the queue is not empty; return <code>false</code> if a time-out occurred. - * If the queue already has something on it, return <code>true</code> immediately. - * If the time-out is zero, wait indefinitely. - */ - public boolean waitUntilNotEmpty(long timeout) throws InterruptedException { - return this.waitUntilEmptyIs(false, timeout); - } - - /** - * Suspend the current thread until the queue is empty, - * then "enqueue" the specified item to the tail of the queue - * and continue executing. If the queue is not emptied out - * before the time-out, simply continue executing without - * "enqueueing" the item. - * The time-out is specified in milliseconds. Return <code>true</code> if the - * item was enqueued; return <code>false</code> if a time-out occurred. - * If the queue is already empty, "enqueue" the specified item and - * return <code>true</code> immediately. - * If the time-out is zero, wait indefinitely. - */ - public boolean waitToEnqueue(E element, long timeout) throws InterruptedException { - synchronized (this.mutex) { - boolean success = this.waitUntilEmptyIs_(true, timeout); - if (success) { - this.enqueue_(element); - } - return success; - } - } - - /** - * Suspend the current thread until the queue has something on it, - * then "dequeue" an item from the head of the queue and return it. - * If the queue is empty and nothing is "enqueued" on to it before the - * time-out, throw a no such element exception. - * The time-out is specified in milliseconds. - * If the queue is not empty, "dequeue" an item and - * return it immediately. - * If the time-out is zero, wait indefinitely. - */ - public Object waitToDequeue(long timeout) throws InterruptedException { - synchronized (this.mutex) { - boolean success = this.waitUntilEmptyIs_(false, timeout); - if (success) { - return this.dequeue_(); - } - throw new NoSuchElementException(); - } - } - - - // ********** synchronized behavior ********** - - /** - * If the current thread is not interrupted, execute the specified command - * with the mutex locked. This is useful for initializing the queue in another - * thread. - */ - public void execute(Command command) throws InterruptedException { - if (Thread.interrupted()) { - throw new InterruptedException(); - } - synchronized (this.mutex) { - command.execute(); - } - } - - - // ********** additional public protocol ********** - - /** - * "Drain" all the current items from the queue into specified queue. - */ - public void drainTo(Queue<E> q) { - synchronized (this.mutex) { - this.drainTo_(q); - } - } - - /** - * Pre-condition: synchronized - */ - private void drainTo_(Queue<E> q) { - boolean changed = false; - while ( ! this.queue.isEmpty()) { - q.enqueue(this.queue.dequeue()); - changed = true; - } - if (changed) { - this.mutex.notifyAll(); - } - } - - /** - * Return the object the queue locks on while performing - * its operations. - */ - public Object getMutex() { - return this.mutex; - } - - - // ********** standard methods ********** - - @Override - public String toString() { - synchronized (this.mutex) { - return '[' + this.queue.toString() + ']'; - } - } - - private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { - synchronized (this.mutex) { - s.defaultWriteObject(); - } - } - -} |