| /******************************************************************************* |
| * Copyright (c) 2007, 2010 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 org.eclipse.jpt.utility.Command; |
| |
| /** |
| * This class provides synchronized access to a <code>boolean</code> value. |
| * It also provides protocol for suspending a thread until the |
| * <code>boolean</code> value is set to <code>true</code> or <code>false</code>, |
| * with optional time-outs. |
| * |
| * @see SimpleBooleanReference |
| */ |
| public class SynchronizedBoolean |
| implements BooleanReference, Cloneable, Serializable |
| { |
| /** Backing <code>boolean</code>. */ |
| private boolean value; |
| |
| /** Object to synchronize on. */ |
| private final Object mutex; |
| |
| private static final long serialVersionUID = 1L; |
| |
| |
| // ********** constructors ********** |
| |
| /** |
| * Create a synchronized <code>boolean</code> with the specified |
| * initial value and mutex. |
| */ |
| public SynchronizedBoolean(boolean value, Object mutex) { |
| super(); |
| this.value = value; |
| this.mutex = mutex; |
| } |
| |
| /** |
| * Create a synchronized <code>boolean</code> with the |
| * specified initial value. |
| * The synchronized <code>boolean</code> itself will be the mutex. |
| */ |
| public SynchronizedBoolean(boolean value) { |
| super(); |
| this.value = value; |
| this.mutex = this; |
| } |
| |
| /** |
| * Create a synchronized <code>boolean</code> |
| * with an initial value of <code>false</code> |
| * and specified mutex. |
| */ |
| public SynchronizedBoolean(Object mutex) { |
| this(false, mutex); |
| } |
| |
| /** |
| * Create a synchronized <code>boolean</code> |
| * with an initial value of <code>false</code>. |
| * The synchronized <code>boolean</code> itself will be the mutex. |
| */ |
| public SynchronizedBoolean() { |
| this(false); |
| } |
| |
| |
| // ********** accessors ********** |
| |
| public boolean getValue() { |
| synchronized (this.mutex) { |
| return this.value; |
| } |
| } |
| |
| public boolean is(boolean v) { |
| synchronized (this.mutex) { |
| return this.value == v; |
| } |
| } |
| |
| public boolean isNot(boolean v) { |
| synchronized (this.mutex) { |
| return this.value != v; |
| } |
| } |
| |
| public boolean isTrue() { |
| synchronized (this.mutex) { |
| return this.value; |
| } |
| } |
| |
| public boolean isFalse() { |
| synchronized (this.mutex) { |
| return ! this.value; |
| } |
| } |
| |
| /** |
| * If the value changes, all waiting threads are notified. |
| */ |
| public boolean setValue(boolean value) { |
| synchronized (this.mutex) { |
| return this.setValue_(value); |
| } |
| } |
| |
| /** |
| * Pre-condition: synchronized |
| */ |
| private boolean setValue_(boolean v) { |
| return (v == this.value) ? v : this.setChangedValue_(v); |
| } |
| |
| /** |
| * Pre-condition: synchronized and new value is different |
| */ |
| private boolean setChangedValue_(boolean v) { |
| this.value = v; |
| this.mutex.notifyAll(); |
| return ! v; |
| } |
| |
| /** |
| * If the value changes, all waiting threads are notified. |
| */ |
| public boolean flip() { |
| synchronized (this.mutex) { |
| return ! this.setChangedValue_( ! this.value); |
| } |
| } |
| |
| /** |
| * If the value changes, all waiting threads are notified. |
| */ |
| public boolean setNot(boolean v) { |
| return this.setValue( ! v); |
| } |
| |
| /** |
| * If the value changes, all waiting threads are notified. |
| */ |
| public boolean setTrue() { |
| return this.setValue(true); |
| } |
| |
| /** |
| * If the value changes, all waiting threads are notified. |
| */ |
| public boolean setFalse() { |
| return this.setValue(false); |
| } |
| |
| /** |
| * Return the object this object locks on while performing |
| * its operations. |
| */ |
| public Object getMutex() { |
| return this.mutex; |
| } |
| |
| |
| // ********** indefinite waits ********** |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes |
| * to the specified value. If the <code>boolean</code> value is already the |
| * specified value, return immediately. |
| */ |
| public void waitUntilValueIs(boolean v) throws InterruptedException { |
| synchronized (this.mutex) { |
| this.waitUntilValueIs_(v); |
| } |
| } |
| |
| /** |
| * Pre-condition: synchronized |
| */ |
| private void waitUntilValueIs_(boolean v) throws InterruptedException { |
| while (this.value != v) { |
| this.mutex.wait(); |
| } |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value |
| * changes to the NOT of the specified value. |
| * If the <code>boolean</code> value is already the NOT of the specified |
| * value, return immediately. |
| */ |
| public void waitUntilValueIsNot(boolean v) throws InterruptedException { |
| this.waitUntilValueIs( ! v); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value |
| * changes to <code>true</code>. |
| * If the <code>boolean</code> value is already <code>true</code>, |
| * return immediately. |
| */ |
| public void waitUntilTrue() throws InterruptedException { |
| this.waitUntilValueIs(true); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value |
| * changes to <code>false</code>. |
| * If the <code>boolean</code> value is already <code>false</code>, |
| * return immediately. |
| */ |
| public void waitUntilFalse() throws InterruptedException { |
| this.waitUntilValueIs(false); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes to |
| * <em>not</em> the specified value, then change it back to the specified |
| * value and continue executing. If the <code>boolean</code> value is already |
| * <em>not</em> the specified value, set the value to the specified value |
| * immediately. |
| */ |
| public void waitToSetValue(boolean v) throws InterruptedException { |
| synchronized (this.mutex) { |
| this.waitUntilValueIs_( ! v); |
| this.setChangedValue_(v); |
| } |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value |
| * changes to <code>false</code>, |
| * then change it back to <code>true</code> and continue executing. |
| * If the <code>boolean</code> value is already <code>false</code>, |
| * set the value to <code>true</code> immediately. |
| */ |
| public void waitToSetTrue() throws InterruptedException { |
| this.waitToSetValue(true); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value |
| * changes to <code>true</code>, |
| * then change it back to <code>false</code> and continue executing. |
| * If the <code>boolean</code> value is already <code>true</code>, |
| * set the value to <code>false</code> immediately. |
| */ |
| public void waitToSetFalse() throws InterruptedException { |
| this.waitToSetValue(false); |
| } |
| |
| |
| // ********** timed waits ********** |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value 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 value was achieved; |
| * return <code>false</code> if a time-out occurred. |
| * If the <code>boolean</code> value is already the specified value, |
| * return <code>true</code> immediately. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public boolean waitUntilValueIs(boolean v, long timeout) throws InterruptedException { |
| synchronized (this.mutex) { |
| return this.waitUntilValueIs_(v, timeout); |
| } |
| } |
| |
| /** |
| * Pre-condition: synchronized |
| */ |
| private boolean waitUntilValueIs_(boolean v, long timeout) throws InterruptedException { |
| if (timeout == 0L) { |
| this.waitUntilValueIs_(v); // 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.value != v) && (remaining > 0L)) { |
| this.mutex.wait(remaining); |
| remaining = stop - System.currentTimeMillis(); |
| } |
| return (this.value == v); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value |
| * changes to the NOT of the specified value or the specified time-out occurs. |
| * The time-out is specified in milliseconds. Return <code>true</code> if |
| * the NOT of the specified value was achieved; |
| * return <code>false</code> if a time-out occurred. |
| * If the <code>boolean</code> value is already the NOT of the specified |
| * value, return immediately. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public void waitUntilValueIsNot(boolean v, long timeout) throws InterruptedException { |
| this.waitUntilValueIs( ! v, timeout); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes |
| * to <code>true</code> or the specified time-out occurs. |
| * The time-out is specified in milliseconds. Return <code>true</code> if |
| * <code>true</code> was achieved; |
| * return <code>false</code> if a time-out occurred. |
| * If the <code>boolean</code> value is already <code>true</code>, |
| * return <code>true</code> immediately. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public boolean waitUntilTrue(long timeout) throws InterruptedException { |
| return this.waitUntilValueIs(true, timeout); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes |
| * to <code>false</code> or the specified time-out occurs. |
| * The time-out is specified in milliseconds. Return <code>true</code> if |
| * <code>false</code> was achieved; |
| * return <code>false</code> if a time-out occurred. |
| * If the <code>boolean</code> value is already <code>true</code>, |
| * return <code>true</code> immediately. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public boolean waitUntilFalse(long timeout) throws InterruptedException { |
| return this.waitUntilValueIs(false, timeout); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes |
| * to <em>not</em> the specified value, then change it back to the specified |
| * value and continue executing. If the <code>boolean</code> value does not |
| * change to <code>false</code> before the time-out, simply continue |
| * executing without changing the value. |
| * The time-out is specified in milliseconds. Return <code>true</code> |
| * if the value was set to the specified value; return <code>false</code> |
| * if a time-out occurred. If the <code>boolean</code> value is already |
| * <em>not</em> the specified value, set the value to the specified value |
| * immediately and return <code>true</code>. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public boolean waitToSetValue(boolean v, long timeout) throws InterruptedException { |
| synchronized (this.mutex) { |
| boolean success = this.waitUntilValueIs_( ! v, timeout); |
| if (success) { |
| this.setChangedValue_(v); |
| } |
| return success; |
| } |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes |
| * to <code>false</code>, then change it back to <code>true</code> and |
| * continue executing. If the <code>boolean</code> value does not change to |
| * <code>false</code> before the time-out, simply continue executing without |
| * changing the value. The time-out is specified in milliseconds. Return |
| * <code>true</code> if the value was set to <code>true</code>; |
| * return <code>false</code> if a time-out occurred. If the |
| * <code>boolean</code> value is already <code>false</code>, set the |
| * value to <code>true</code> immediately and return <code>true</code>. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public boolean waitToSetTrue(long timeout) throws InterruptedException { |
| return this.waitToSetValue(true, timeout); |
| } |
| |
| /** |
| * Suspend the current thread until the <code>boolean</code> value changes |
| * to <code>true</code>, then change it back to <code>false</code> and |
| * continue executing. If the <code>boolean</code> value does not change to |
| * <code>true</code> before the time-out, simply continue executing without |
| * changing the value. The time-out is specified in milliseconds. Return |
| * <code>true</code> if the value was set to <code>false</code>; |
| * return <code>false</code> if a time-out occurred. If the |
| * <code>boolean</code> value is already <code>true</code>, set the |
| * value to <code>false</code> immediately and return <code>true</code>. |
| * If the time-out is zero, wait indefinitely. |
| */ |
| public boolean waitToSetFalse(long timeout) throws InterruptedException { |
| return this.waitToSetValue(false, timeout); |
| } |
| |
| |
| // ********** synchronized behavior ********** |
| |
| /** |
| * If the current thread is not interrupted, execute the specified command |
| * with the mutex locked. This is useful for initializing the value from another |
| * thread. |
| */ |
| public void execute(Command command) throws InterruptedException { |
| if (Thread.interrupted()) { |
| throw new InterruptedException(); |
| } |
| synchronized (this.mutex) { |
| command.execute(); |
| } |
| } |
| |
| |
| // ********** standard methods ********** |
| |
| @Override |
| public SynchronizedBoolean clone() { |
| try { |
| synchronized (this.mutex) { |
| return (SynchronizedBoolean) super.clone(); |
| } |
| } catch (CloneNotSupportedException ex) { |
| throw new InternalError(); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return '[' + String.valueOf(this.getValue()) + ']'; |
| } |
| |
| private void writeObject(java.io.ObjectOutputStream s) throws java.io.IOException { |
| synchronized (this.mutex) { |
| s.defaultWriteObject(); |
| } |
| } |
| |
| } |