| /******************************************************************************* |
| * Copyright (c) 2000, 2005 IBM Corporation and others. |
| * 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: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.ui.tests.navigator; |
| |
| import org.eclipse.swt.widgets.Display; |
| |
| /** |
| * Runs the event loop of the given display until {@link #condition()} becomes |
| * <code>true</code> or no events have occurred for the supplied timeout. |
| * Between running the event loop, {@link Display#sleep()} is called. |
| * <p> |
| * There is a caveat: the given timeouts must be long enough that the calling |
| * thread can enter <code>Display.sleep()</code> before the timeout elapses, |
| * otherwise, the waiter may time out before <code>sleep</code> is called and |
| * the sleeping thread may never be waken up. |
| * </p> |
| * |
| * @since 3.1 |
| */ |
| public abstract class DisplayHelper { |
| /** |
| * Creates a new instance. |
| */ |
| protected DisplayHelper() { |
| } |
| |
| /** |
| * Until {@link #condition()} becomes <code>true</code> or the timeout |
| * elapses, call {@link Display#sleep()} and run the event loop. |
| * <p> |
| * If <code>timeout < 0</code>, the event loop is never driven and |
| * only the condition is checked. If <code>timeout == 0</code>, the event |
| * loop is driven at most once, but <code>Display.sleep()</code> is never |
| * invoked. |
| * </p> |
| * |
| * @param display the display to run the event loop of |
| * @param timeout the timeout in milliseconds |
| * @return <code>true</code> if the condition became <code>true</code>, |
| * <code>false</code> if the timeout elapsed |
| */ |
| public final boolean waitForCondition(Display display, long timeout) { |
| // if the condition already holds, succeed |
| if (condition()) |
| return true; |
| |
| if (timeout < 0) |
| return false; |
| |
| // if driving the event loop once makes the condition hold, succeed |
| // without spawning a thread. |
| driveEventQueue(display); |
| if (condition()) |
| return true; |
| |
| // if the timeout is negative or zero, fail |
| if (timeout == 0) |
| return false; |
| |
| // repeatedly sleep until condition becomes true or timeout elapses |
| DisplayWaiter waiter= new DisplayWaiter(display); |
| DisplayWaiter.Timeout timeoutState= waiter.start(timeout); |
| boolean condition; |
| try { |
| do { |
| if (display.sleep()) |
| driveEventQueue(display); |
| condition= condition(); |
| } while (!condition && !timeoutState.hasTimedOut()); |
| } finally { |
| waiter.stop(); |
| } |
| return condition; |
| } |
| |
| /** |
| * Call {@link Display#sleep()} and run the event loop until the given |
| * timeout has elapsed. |
| * <p> |
| * If <code>timeout < 0</code>, nothing happens. If |
| * <code>timeout == 0</code>, the event loop is driven exactly once, but |
| * <code>Display.sleep()</code> is never invoked. |
| * </p> |
| * |
| * @param display the display to run the event loop of |
| * @param millis the timeout in milliseconds |
| */ |
| public static void sleep(Display display, long millis) { |
| new DisplayHelper() { |
| public boolean condition() { |
| return false; |
| } |
| }.waitForCondition(display, millis); |
| } |
| |
| /** |
| * Call {@link Display#sleep()} and run the event loop once if |
| * <code>sleep</code> returns before the timeout elapses. Returns |
| * <code>true</code> if any events were processed, <code>false</code> if |
| * not. |
| * <p> |
| * If <code>timeout < 0</code>, nothing happens and false is returned. |
| * If <code>timeout == 0</code>, the event loop is driven exactly once, |
| * but <code>Display.sleep()</code> is never invoked. |
| * </p> |
| * |
| * @param display the display to run the event loop of |
| * @param timeout the timeout in milliseconds |
| * @return <code>true</code> if any event was taken off the event queue, |
| * <code>false</code> if not |
| */ |
| public static boolean runEventLoop(Display display, long timeout) { |
| if (timeout < 0) |
| return false; |
| |
| if (timeout == 0) |
| return driveEventQueue(display); |
| |
| // repeatedly sleep until condition becomes true or timeout elapses |
| DisplayWaiter waiter= new DisplayWaiter(display); |
| DisplayWaiter.Timeout timeoutState= waiter.start(timeout); |
| boolean events= false; |
| if (display.sleep() && !timeoutState.hasTimedOut()) { |
| driveEventQueue(display); |
| events= true; |
| } |
| waiter.stop(); |
| return events; |
| } |
| |
| /** |
| * The condition which has to be met in order for |
| * {@link #waitForCondition(Display, int)} to return before the timeout |
| * elapses. |
| * |
| * @return <code>true</code> if the condition is met, <code>false</code> |
| * if the event loop should be driven some more |
| */ |
| protected abstract boolean condition(); |
| |
| /** |
| * Runs the event loop on the given display. |
| * |
| * @param display the display |
| * @return if <code>display.readAndDispatch</code> returned |
| * <code>true</code> at least once |
| */ |
| private static boolean driveEventQueue(Display display) { |
| boolean events= false; |
| while (display.readAndDispatch()) { |
| events= true; |
| } |
| return events; |
| } |
| |
| /** |
| * Until {@link #condition()} becomes <code>true</code> or the timeout |
| * elapses, call {@link Display#sleep()} and run the event loop. |
| * <p> |
| * If <code>timeout < 0</code>, the event loop is never driven and |
| * only the condition is checked. If <code>timeout == 0</code>, the event |
| * loop is driven at most once, but <code>Display.sleep()</code> is never |
| * invoked. |
| * </p> |
| * <p> |
| * The condition gets rechecked every <code>interval</code> milliseconds, even |
| * if no events were read from the queue. |
| * </p> |
| * |
| * @param display the display to run the event loop of |
| * @param timeout the timeout in milliseconds |
| * @param interval the interval to re-check the condition in milliseconds |
| * @return <code>true</code> if the condition became <code>true</code>, |
| * <code>false</code> if the timeout elapsed |
| */ |
| public final boolean waitForCondition(Display display, long timeout, long interval) { |
| // if the condition already holds, succeed |
| if (condition()) |
| return true; |
| |
| if (timeout < 0) |
| return false; |
| |
| // if driving the event loop once makes the condition hold, succeed |
| // without spawning a thread. |
| driveEventQueue(display); |
| if (condition()) |
| return true; |
| |
| // if the timeout is negative or zero, fail |
| if (timeout == 0) |
| return false; |
| |
| // repeatedly sleep until condition becomes true or timeout elapses |
| DisplayWaiter waiter= new DisplayWaiter(display, true); |
| long currentTimeMillis= System.currentTimeMillis(); |
| long finalTimeout= timeout + currentTimeMillis; |
| if (finalTimeout < currentTimeMillis) |
| finalTimeout= Long.MAX_VALUE; |
| boolean condition; |
| try { |
| do { |
| waiter.restart(interval); |
| if (display.sleep()) |
| driveEventQueue(display); |
| condition= condition(); |
| } while (!condition && finalTimeout > System.currentTimeMillis()); |
| } finally { |
| waiter.stop(); |
| } |
| return condition; |
| } |
| |
| } |