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 43 testFinalizeReferentCalled()44 public void testFinalizeReferentCalled() { 45 final MockReference reference = new MockReference(frq = new FinalizableReferenceQueue()); 46 47 GcFinalization.awaitDone( 48 new GcFinalization.FinalizationPredicate() { 49 @Override 50 public boolean isDone() { 51 return reference.finalizeReferentCalled; 52 } 53 }); 54 } 55 56 static class MockReference extends FinalizableWeakReference<Object> { 57 58 volatile boolean finalizeReferentCalled; 59 MockReference(FinalizableReferenceQueue frq)60 MockReference(FinalizableReferenceQueue frq) { 61 super(new Object(), frq); 62 } 63 64 @Override finalizeReferent()65 public void finalizeReferent() { 66 finalizeReferentCalled = true; 67 } 68 } 69 70 /** 71 * Keeps a weak reference to the underlying reference queue. When this reference is cleared, we 72 * know that the background thread has stopped and released its strong reference. 73 */ 74 private WeakReference<ReferenceQueue<Object>> queueReference; 75 76 testThatFinalizerStops()77 public void testThatFinalizerStops() { 78 weaklyReferenceQueue(); 79 GcFinalization.awaitClear(queueReference); 80 } 81 82 /** If we don't keep a strong reference to the reference object, it won't be enqueued. */ 83 FinalizableWeakReference<Object> reference; 84 85 /** Create the FRQ in a method that goes out of scope so that we're sure it will be reclaimed. */ weaklyReferenceQueue()86 private void weaklyReferenceQueue() { 87 frq = new FinalizableReferenceQueue(); 88 queueReference = new WeakReference<>(frq.queue); 89 90 /* 91 * Queue and clear a reference for good measure. We test later on that 92 * the finalizer thread stopped, but we should test that it actually 93 * started first. 94 */ 95 reference = 96 new FinalizableWeakReference<Object>(new Object(), frq) { 97 @Override 98 public void finalizeReferent() { 99 reference = null; 100 frq = null; 101 } 102 }; 103 } 104 105 @AndroidIncompatible // no concept of separate ClassLoaders testDecoupledLoader()106 public void testDecoupledLoader() { 107 FinalizableReferenceQueue.DecoupledLoader decoupledLoader = 108 new FinalizableReferenceQueue.DecoupledLoader() { 109 @Override 110 URLClassLoader newLoader(URL base) { 111 return new DecoupledClassLoader(new URL[] {base}); 112 } 113 }; 114 115 Class<?> finalizerCopy = decoupledLoader.loadFinalizer(); 116 117 assertNotNull(finalizerCopy); 118 assertNotSame(Finalizer.class, finalizerCopy); 119 120 assertNotNull(FinalizableReferenceQueue.getStartFinalizer(finalizerCopy)); 121 } 122 123 static class DecoupledClassLoader extends URLClassLoader { 124 DecoupledClassLoader(URL[] urls)125 public DecoupledClassLoader(URL[] urls) { 126 super(urls); 127 } 128 129 @Override loadClass(String name, boolean resolve)130 protected synchronized Class<?> loadClass(String name, boolean resolve) 131 throws ClassNotFoundException { 132 // Force Finalizer to load from this class loader, not its parent. 133 if (name.equals(Finalizer.class.getName())) { 134 Class<?> clazz = findClass(name); 135 if (resolve) { 136 resolveClass(clazz); 137 } 138 return clazz; 139 } 140 141 return super.loadClass(name, resolve); 142 } 143 } 144 145 @AndroidIncompatible // TODO(cpovirk): How significant is this failure? testGetFinalizerUrl()146 public void testGetFinalizerUrl() { 147 assertNotNull(getClass().getResource("internal/Finalizer.class")); 148 } 149 testFinalizeClassHasNoNestedClasses()150 public void testFinalizeClassHasNoNestedClasses() throws Exception { 151 // Ensure that the Finalizer class has no nested classes. 152 // See https://code.google.com/p/guava-libraries/issues/detail?id=1505 153 assertEquals(Collections.emptyList(), Arrays.asList(Finalizer.class.getDeclaredClasses())); 154 } 155 } 156