/*******************************************************************************
* Copyright (c) 2005, 2008 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.internal.ide.application;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.core.runtime.jobs.Job;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.application.IWorkbenchConfigurer;
import org.eclipse.ui.internal.ide.IDEWorkbenchMessages;
import org.eclipse.ui.internal.ide.Policy;
/**
* The idle helper detects when the system is idle in order to perform garbage
* collection in a way that minimizes impact on responsiveness of the UI.
* The algorithm for determining when to perform a garbage collection
* is as follows:
*
* - Never gc if there is a test harness present
* - Don't gc if background jobs are running
* - Don't gc if the keyboard or mouse have been active within IDLE_INTERVAL
* - Don't gc if there has been a GC within the minimum gc interval (system property PROP_GC_INTERVAL)
* - After a gc, don't gc again until (duration * GC_DELAY_MULTIPLIER) has elapsed.
* For example, if a GC takes 100ms and the multiplier is 60, don't gc for at least five seconds
* - Never gc again if any single gc takes longer than system property PROP_GC_MAX
*/
class IDEIdleHelper {
/**
* The default minimum time between garbage collections.
*/
private static final int DEFAULT_GC_INTERVAL = 60000;
/**
* The default maximum duration for a garbage collection, beyond which
* the explicit gc mechanism is automatically disabled.
*/
private static final int DEFAULT_GC_MAX = 8000;
/**
* The multiple of the last gc duration before we will consider doing
* another one.
*/
private static final int GC_DELAY_MULTIPLIER = 60;
/**
* The time interval of no keyboard or mouse events after which the system
* is considered idle.
*/
private static final int IDLE_INTERVAL = 5000;
/**
* The name of the boolean system property that specifies whether explicit
* garbage collection is enabled.
*/
private static final String PROP_GC = "ide.gc"; //$NON-NLS-1$
/**
* The name of the integer system property that specifies the minimum time
* interval in milliseconds between garbage collections.
*/
private static final String PROP_GC_INTERVAL = "ide.gc.interval"; //$NON-NLS-1$
/**
* The name of the integer system property that specifies the maximum
* duration for a garbage collection. If this duration is ever exceeded, the
* explicit gc mechanism is disabled for the remainder of the session.
*/
private static final String PROP_GC_MAX = "ide.gc.max"; //$NON-NLS-1$
protected IWorkbenchConfigurer configurer;
private Listener idleListener;
/**
* The last time we garbage collected.
*/
private long lastGC = System.currentTimeMillis();
/**
* The maximum gc duration. If this value is exceeded, the
* entire explicit gc mechanism is disabled.
*/
private int maxGC = DEFAULT_GC_MAX;
/**
* The minimum time interval until the next garbage collection
*/
private int minGCInterval = DEFAULT_GC_INTERVAL;
/**
* The time interval until the next garbage collection
*/
private int nextGCInterval = DEFAULT_GC_INTERVAL;
private Job gcJob;
private Runnable handler;
/**
* Creates and initializes the idle handler
* @param aConfigurer The workbench configurer.
*/
IDEIdleHelper(IWorkbenchConfigurer aConfigurer) {
this.configurer = aConfigurer;
//don't gc while running tests because performance tests are sensitive to timing (see bug 121562)
if (PlatformUI.getTestableObject().getTestHarness() != null) {
return;
}
String enabled = System.getProperty(PROP_GC);
//gc is turned on by default if property is missing
if (enabled != null && enabled.equalsIgnoreCase(Boolean.FALSE.toString())) {
return;
}
//init gc interval
Integer prop = Integer.getInteger(PROP_GC_INTERVAL);
if (prop != null && prop.intValue() >= 0) {
minGCInterval = nextGCInterval = prop.intValue();
}
//init max gc interval
prop = Integer.getInteger(PROP_GC_MAX);
if (prop != null) {
maxGC = prop.intValue();
}
createGarbageCollectionJob();
//hook idle handler
final Display display = configurer.getWorkbench().getDisplay();
handler = new Runnable() {
public void run() {
if (!display.isDisposed() && !configurer.getWorkbench().isClosing()) {
int nextInterval;
final long start = System.currentTimeMillis();
//don't garbage collect if background jobs are running
if (!Job.getJobManager().isIdle()) {
nextInterval = IDLE_INTERVAL;
} else if ((start - lastGC) < nextGCInterval) {
//don't garbage collect if we have collected within the specific interval
nextInterval = nextGCInterval - (int) (start - lastGC);
} else {
gcJob.schedule();
nextInterval = minGCInterval;
}
display.timerExec(nextInterval, this);
}
}
};
idleListener = new Listener() {
public void handleEvent(Event event) {
display.timerExec(IDLE_INTERVAL, handler);
}
};
display.addFilter(SWT.KeyUp, idleListener);
display.addFilter(SWT.MouseUp, idleListener);
}
/**
* Creates the job that performs garbage collection
*/
private void createGarbageCollectionJob() {
gcJob = new Job(IDEWorkbenchMessages.IDEIdleHelper_backgroundGC) {
protected IStatus run(IProgressMonitor monitor) {
final Display display = configurer.getWorkbench().getDisplay();
if (display != null && !display.isDisposed()) {
final long start = System.currentTimeMillis();
System.gc();
System.runFinalization();
lastGC = start;
final int duration = (int) (System.currentTimeMillis() - start);
if (Policy.DEBUG_GC) {
System.out.println("Explicit GC took: " + duration); //$NON-NLS-1$
}
if (duration > maxGC) {
if (Policy.DEBUG_GC) {
System.out.println("Further explicit GCs disabled due to long GC"); //$NON-NLS-1$
}
shutdown();
} else {
//if the gc took a long time, ensure the next gc doesn't happen for awhile
nextGCInterval = Math.max(minGCInterval, GC_DELAY_MULTIPLIER * duration);
if (Policy.DEBUG_GC) {
System.out.println("Next GC to run in: " + nextGCInterval); //$NON-NLS-1$
}
}
}
return Status.OK_STATUS;
}
};
gcJob.setSystem(true);
}
/**
* Shuts down the idle helper, removing any installed listeners, etc.
*/
void shutdown() {
if (idleListener == null) {
return;
}
final Display display = configurer.getWorkbench().getDisplay();
if (display != null && !display.isDisposed()) {
try {
display.asyncExec(new Runnable() {
public void run() {
display.timerExec(-1, handler);
display.removeFilter(SWT.KeyUp, idleListener);
display.removeFilter(SWT.MouseUp, idleListener);
}
});
} catch (SWTException ex) {
// ignore (display might be disposed)
}
}
}
}