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/*
* Copyright (C) 2005 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.common.base;
import com.google.common.base.internal.Finalizer;
import com.google.common.testing.GcFinalization;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Arrays;
import java.util.Collections;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* Unit test for {@link FinalizableReferenceQueue}.
*
* @author Bob Lee
*/
// - depends on details of GC and classloading
// - .class files aren't available
// - possibly no real concept of separate ClassLoaders?
@AndroidIncompatible
public class FinalizableReferenceQueueTest extends TestCase {
private @Nullable FinalizableReferenceQueue frq;
@Override
protected void tearDown() throws Exception {
frq = null;
}
public void testFinalizeReferentCalled() {
final MockReference reference = new MockReference(frq = new FinalizableReferenceQueue());
GcFinalization.awaitDone(
new GcFinalization.FinalizationPredicate() {
@Override
public boolean isDone() {
return reference.finalizeReferentCalled;
}
});
}
static class MockReference extends FinalizableWeakReference<Object> {
volatile boolean finalizeReferentCalled;
MockReference(FinalizableReferenceQueue frq) {
super(new Object(), frq);
}
@Override
public void finalizeReferent() {
finalizeReferentCalled = true;
}
}
/**
* Keeps a weak reference to the underlying reference queue. When this reference is cleared, we
* know that the background thread has stopped and released its strong reference.
*/
private WeakReference<ReferenceQueue<Object>> queueReference;
public void testThatFinalizerStops() {
weaklyReferenceQueue();
GcFinalization.awaitClear(queueReference);
}
/** If we don't keep a strong reference to the reference object, it won't be enqueued. */
@Nullable FinalizableWeakReference<Object> reference;
/** Create the FRQ in a method that goes out of scope so that we're sure it will be reclaimed. */
private void weaklyReferenceQueue() {
frq = new FinalizableReferenceQueue();
queueReference = new WeakReference<>(frq.queue);
/*
* Queue and clear a reference for good measure. We test later on that
* the finalizer thread stopped, but we should test that it actually
* started first.
*/
reference =
new FinalizableWeakReference<Object>(new Object(), frq) {
@Override
public void finalizeReferent() {
reference = null;
frq = null;
}
};
}
public void testDecoupledLoader() {
FinalizableReferenceQueue.DecoupledLoader decoupledLoader =
new FinalizableReferenceQueue.DecoupledLoader() {
@Override
URLClassLoader newLoader(URL base) {
return new DecoupledClassLoader(new URL[] {base});
}
};
Class<?> finalizerCopy = decoupledLoader.loadFinalizer();
assertNotNull(finalizerCopy);
assertNotSame(Finalizer.class, finalizerCopy);
assertNotNull(FinalizableReferenceQueue.getStartFinalizer(finalizerCopy));
}
static class DecoupledClassLoader extends URLClassLoader {
public DecoupledClassLoader(URL[] urls) {
super(urls);
}
@Override
protected synchronized Class<?> loadClass(String name, boolean resolve)
throws ClassNotFoundException {
// Force Finalizer to load from this class loader, not its parent.
if (name.equals(Finalizer.class.getName())) {
Class<?> clazz = findClass(name);
if (resolve) {
resolveClass(clazz);
}
return clazz;
}
return super.loadClass(name, resolve);
}
}
public void testGetFinalizerUrl() {
assertNotNull(getClass().getResource("internal/Finalizer.class"));
}
public void testFinalizeClassHasNoNestedClasses() throws Exception {
// Ensure that the Finalizer class has no nested classes.
// See https://code.google.com/p/guava-libraries/issues/detail?id=1505
assertEquals(Collections.emptyList(), Arrays.asList(Finalizer.class.getDeclaredClasses()));
}
}
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