com.cedarsoft.test.utils.MemoryLeakVerifier Maven / Gradle / Ivy
/**
* Copyright (C) cedarsoft GmbH.
*
* Licensed under the GNU General Public License version 3 (the "License")
* with Classpath Exception; you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.cedarsoft.org/gpl3ce
* (GPL 3 with Classpath Exception)
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3 only, as
* published by the Free Software Foundation. cedarsoft GmbH designates this
* particular file as subject to the "Classpath" exception as provided
* by cedarsoft GmbH in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 3 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 3 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
* or visit www.cedarsoft.com if you need additional information or
* have any questions.
*/
package com.cedarsoft.test.utils;
/**
* @author Johannes Schneider ([email protected])
*/
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.awt.EventQueue;
import java.lang.ref.WeakReference;
import java.lang.reflect.InvocationTargetException;
import static org.assertj.core.api.Assertions.assertThat;
/**
* A simple utility class that can verify that an object has been successfully garbage collected.
*/
public class MemoryLeakVerifier {
private static final int MAX_GC_ITERATIONS = 50;
private static final int GC_SLEEP_TIME = 100;
@Nonnull
private final WeakReference reference;
public MemoryLeakVerifier( @Nonnull T object ) {
this.reference = new WeakReference( object );
}
@Nonnull
public WeakReference getReference() {
return reference;
}
@Nullable
public Object getObject() {
return reference.get();
}
/**
* Attempts to perform a full garbage collection so that all weak references will be removed. Usually only
* a single GC is required, but there have been situations where some unused memory is not cleared up on the
* first pass. This method performs a full garbage collection and then validates that the weak reference
* now has been cleared. If it hasn't then the thread will sleep for 50 milliseconds and then retry up to
* 10 more times. If after this the object still has not been collected then the assertion will fail.
*
* Based upon the method described in: http://www.javaworld.com/javaworld/javatips/jw-javatip130.html
*/
public void assertGarbageCollected() {
Runtime runtime = Runtime.getRuntime();
for ( int i = 0; i < MAX_GC_ITERATIONS; i++ ) {
runtime.runFinalization();
//noinspection CallToSystemGC
runtime.gc();
if ( getObject() == null ) {
break;
}
// Pause for a while and then go back around the loop to try again...
try {
EventQueue.invokeAndWait( new NoOp() ); // Wait for the AWT event queue to have completed processing
//noinspection BusyWait
Thread.sleep( GC_SLEEP_TIME );
} catch ( InterruptedException ignore ) {
// Ignore any interrupts and just try again...
} catch ( InvocationTargetException ignore ) {
// Ignore any interrupts and just try again...
}
}
assertThat( getObject() ).describedAs( "object should not exist after " + MAX_GC_ITERATIONS + " collections" ).isNull();
}
private static class NoOp implements Runnable {
@Override
public void run() {
}
}
}