1 /* 2 * Copyright (C) 2005 The Guava Authors 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.common.base; 18 19 import com.google.common.base.internal.Finalizer; 20 import com.google.common.testing.GcFinalization; 21 import java.lang.ref.ReferenceQueue; 22 import java.lang.ref.WeakReference; 23 import java.net.URL; 24 import java.net.URLClassLoader; 25 import java.util.Arrays; 26 import java.util.Collections; 27 import junit.framework.TestCase; 28 29 /** 30 * Unit test for {@link FinalizableReferenceQueue}. 31 * 32 * @author Bob Lee 33 */ 34 public class FinalizableReferenceQueueTest extends TestCase { 35 36 private FinalizableReferenceQueue frq; 37 38 @Override tearDown()39 protected void tearDown() throws Exception { 40 frq = null; 41 } 42 testFinalizeReferentCalled()43 public void testFinalizeReferentCalled() { 44 final MockReference reference = new MockReference(frq = new FinalizableReferenceQueue()); 45 46 GcFinalization.awaitDone( 47 new GcFinalization.FinalizationPredicate() { 48 public boolean isDone() { 49 return reference.finalizeReferentCalled; 50 } 51 }); 52 } 53 54 static class MockReference extends FinalizableWeakReference<Object> { 55 56 volatile boolean finalizeReferentCalled; 57 MockReference(FinalizableReferenceQueue frq)58 MockReference(FinalizableReferenceQueue frq) { 59 super(new Object(), frq); 60 } 61 62 @Override finalizeReferent()63 public void finalizeReferent() { 64 finalizeReferentCalled = true; 65 } 66 } 67 68 /** 69 * Keeps a weak reference to the underlying reference queue. When this reference is cleared, we 70 * know that the background thread has stopped and released its strong reference. 71 */ 72 private WeakReference<ReferenceQueue<Object>> queueReference; 73 testThatFinalizerStops()74 public void testThatFinalizerStops() { 75 weaklyReferenceQueue(); 76 GcFinalization.awaitClear(queueReference); 77 } 78 79 /** If we don't keep a strong reference to the reference object, it won't be enqueued. */ 80 FinalizableWeakReference<Object> reference; 81 82 /** Create the FRQ in a method that goes out of scope so that we're sure it will be reclaimed. */ weaklyReferenceQueue()83 private void weaklyReferenceQueue() { 84 frq = new FinalizableReferenceQueue(); 85 queueReference = new WeakReference<>(frq.queue); 86 87 /* 88 * Queue and clear a reference for good measure. We test later on that 89 * the finalizer thread stopped, but we should test that it actually 90 * started first. 91 */ 92 reference = 93 new FinalizableWeakReference<Object>(new Object(), frq) { 94 @Override 95 public void finalizeReferent() { 96 reference = null; 97 frq = null; 98 } 99 }; 100 } 101 102 @AndroidIncompatible // no concept of separate ClassLoaders testDecoupledLoader()103 public void testDecoupledLoader() { 104 FinalizableReferenceQueue.DecoupledLoader decoupledLoader = 105 new FinalizableReferenceQueue.DecoupledLoader() { 106 @Override 107 URLClassLoader newLoader(URL base) { 108 return new DecoupledClassLoader(new URL[] {base}); 109 } 110 }; 111 112 Class<?> finalizerCopy = decoupledLoader.loadFinalizer(); 113 114 assertNotNull(finalizerCopy); 115 assertNotSame(Finalizer.class, finalizerCopy); 116 117 assertNotNull(FinalizableReferenceQueue.getStartFinalizer(finalizerCopy)); 118 } 119 120 static class DecoupledClassLoader extends URLClassLoader { 121 DecoupledClassLoader(URL[] urls)122 public DecoupledClassLoader(URL[] urls) { 123 super(urls); 124 } 125 126 @Override loadClass(String name, boolean resolve)127 protected synchronized Class<?> loadClass(String name, boolean resolve) 128 throws ClassNotFoundException { 129 // Force Finalizer to load from this class loader, not its parent. 130 if (name.equals(Finalizer.class.getName())) { 131 Class<?> clazz = findClass(name); 132 if (resolve) { 133 resolveClass(clazz); 134 } 135 return clazz; 136 } 137 138 return super.loadClass(name, resolve); 139 } 140 } 141 142 @AndroidIncompatible // TODO(cpovirk): How significant is this failure? testGetFinalizerUrl()143 public void testGetFinalizerUrl() { 144 assertNotNull(getClass().getResource("internal/Finalizer.class")); 145 } 146 testFinalizeClassHasNoNestedClasses()147 public void testFinalizeClassHasNoNestedClasses() throws Exception { 148 // Ensure that the Finalizer class has no nested classes. 149 // See https://code.google.com/p/guava-libraries/issues/detail?id=1505 150 assertEquals(Collections.emptyList(), Arrays.asList(Finalizer.class.getDeclaredClasses())); 151 } 152 } 153