1 /*
2  * Copyright (C) 2015 The Android Open Source Project
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 import java.io.BufferedReader;
18 import java.io.File;
19 import java.io.FileReader;
20 import java.lang.ref.WeakReference;
21 import java.lang.reflect.Constructor;
22 import java.lang.reflect.Method;
23 
24 public class Main {
25     static final String DEX_FILE = System.getenv("DEX_LOCATION") + "/141-class-unload-ex.jar";
26     static final String LIBRARY_SEARCH_PATH = System.getProperty("java.library.path");
27     static String nativeLibraryName;
28 
main(String[] args)29     public static void main(String[] args) throws Exception {
30         nativeLibraryName = args[0];
31         Class<?> pathClassLoader = Class.forName("dalvik.system.PathClassLoader");
32         if (pathClassLoader == null) {
33             throw new AssertionError("Couldn't find path class loader class");
34         }
35         Constructor<?> constructor =
36             pathClassLoader.getDeclaredConstructor(String.class, String.class, ClassLoader.class);
37         try {
38             testUnloadClass(constructor);
39             testUnloadLoader(constructor);
40             // Test that we don't unload if we have an instance.
41             testNoUnloadInstance(constructor);
42             // Test JNI_OnLoad and JNI_OnUnload.
43             testLoadAndUnloadLibrary(constructor);
44             // Test that stack traces keep the classes live.
45             testStackTrace(constructor);
46             // Stress test to make sure we dont leak memory.
47             stressTest(constructor);
48             // Test that the oat files are unloaded.
49             testOatFilesUnloaded(getPid());
50             // Test that objects keep class loader live for sticky GC.
51             testStickyUnload(constructor);
52         } catch (Exception e) {
53             e.printStackTrace();
54         }
55     }
56 
testOatFilesUnloaded(int pid)57     private static void testOatFilesUnloaded(int pid) throws Exception {
58         System.loadLibrary(nativeLibraryName);
59         // Stop the JIT to ensure its threads and work queue are not keeping classes
60         // artifically alive.
61         stopJit();
62         doUnloading();
63         System.runFinalization();
64         BufferedReader reader = new BufferedReader(new FileReader ("/proc/" + pid + "/maps"));
65         String line;
66         int count = 0;
67         while ((line = reader.readLine()) != null) {
68             if (line.contains("@141-class-unload-ex.jar")) {
69                 System.out.println(line);
70                 ++count;
71             }
72         }
73         System.out.println("Number of loaded unload-ex maps " + count);
74         startJit();
75     }
76 
stressTest(Constructor<?> constructor)77     private static void stressTest(Constructor<?> constructor) throws Exception {
78         for (int i = 0; i <= 100; ++i) {
79             setUpUnloadLoader(constructor, false);
80             if (i % 10 == 0) {
81                 Runtime.getRuntime().gc();
82             }
83         }
84     }
85 
doUnloading()86     private static void doUnloading() {
87       // Do multiple GCs to prevent rare flakiness if some other thread is keeping the
88       // classloader live.
89       for (int i = 0; i < 5; ++i) {
90          Runtime.getRuntime().gc();
91       }
92     }
93 
testUnloadClass(Constructor<?> constructor)94     private static void testUnloadClass(Constructor<?> constructor) throws Exception {
95         WeakReference<Class> klass = setUpUnloadClassWeak(constructor);
96         // No strong references to class loader, should get unloaded.
97         doUnloading();
98         WeakReference<Class> klass2 = setUpUnloadClassWeak(constructor);
99         doUnloading();
100         // If the weak reference is cleared, then it was unloaded.
101         System.out.println(klass.get());
102         System.out.println(klass2.get());
103     }
104 
testUnloadLoader(Constructor<?> constructor)105     private static void testUnloadLoader(Constructor<?> constructor)
106         throws Exception {
107       WeakReference<ClassLoader> loader = setUpUnloadLoader(constructor, true);
108       // No strong references to class loader, should get unloaded.
109       doUnloading();
110       // If the weak reference is cleared, then it was unloaded.
111       System.out.println(loader.get());
112     }
113 
testStackTrace(Constructor<?> constructor)114     private static void testStackTrace(Constructor<?> constructor) throws Exception {
115         Class<?> klass = setUpUnloadClass(constructor);
116         WeakReference<Class> weak_klass = new WeakReference(klass);
117         Method stackTraceMethod = klass.getDeclaredMethod("generateStackTrace");
118         Throwable throwable = (Throwable) stackTraceMethod.invoke(klass);
119         stackTraceMethod = null;
120         klass = null;
121         doUnloading();
122         boolean isNull = weak_klass.get() == null;
123         System.out.println("class null " + isNull + " " + throwable.getMessage());
124     }
125 
testLoadAndUnloadLibrary(Constructor<?> constructor)126     private static void testLoadAndUnloadLibrary(Constructor<?> constructor) throws Exception {
127         WeakReference<ClassLoader> loader = setUpLoadLibrary(constructor);
128         // No strong references to class loader, should get unloaded.
129         doUnloading();
130         // If the weak reference is cleared, then it was unloaded.
131         System.out.println(loader.get());
132     }
133 
testNoUnloadHelper(ClassLoader loader)134     private static Object testNoUnloadHelper(ClassLoader loader) throws Exception {
135         Class<?> intHolder = loader.loadClass("IntHolder");
136         return intHolder.newInstance();
137     }
138 
139     static class Pair {
Pair(Object o, ClassLoader l)140       public Pair(Object o, ClassLoader l) {
141         object = o;
142         classLoader = new WeakReference<ClassLoader>(l);
143       }
144 
145       public Object object;
146       public WeakReference<ClassLoader> classLoader;
147     }
148 
testNoUnloadInstanceHelper(Constructor<?> constructor)149     private static Pair testNoUnloadInstanceHelper(Constructor<?> constructor) throws Exception {
150         ClassLoader loader = (ClassLoader) constructor.newInstance(
151             DEX_FILE, LIBRARY_SEARCH_PATH, ClassLoader.getSystemClassLoader());
152         Object o = testNoUnloadHelper(loader);
153         return new Pair(o, loader);
154     }
155 
testNoUnloadInstance(Constructor<?> constructor)156     private static void testNoUnloadInstance(Constructor<?> constructor) throws Exception {
157         Pair p = testNoUnloadInstanceHelper(constructor);
158         doUnloading();
159         // If the class loader was unloded too early due to races, just pass the test.
160         boolean isNull = p.classLoader.get() == null;
161         System.out.println("loader null " + isNull);
162     }
163 
setUpUnloadClass(Constructor<?> constructor)164     private static Class<?> setUpUnloadClass(Constructor<?> constructor) throws Exception {
165         ClassLoader loader = (ClassLoader) constructor.newInstance(
166             DEX_FILE, LIBRARY_SEARCH_PATH, ClassLoader.getSystemClassLoader());
167         Class<?> intHolder = loader.loadClass("IntHolder");
168         Method getValue = intHolder.getDeclaredMethod("getValue");
169         Method setValue = intHolder.getDeclaredMethod("setValue", Integer.TYPE);
170         // Make sure we don't accidentally preserve the value in the int holder, the class
171         // initializer should be re-run.
172         System.out.println((int) getValue.invoke(intHolder));
173         setValue.invoke(intHolder, 2);
174         System.out.println((int) getValue.invoke(intHolder));
175         waitForCompilation(intHolder);
176         return intHolder;
177     }
178 
allocObjectInOtherClassLoader(Constructor<?> constructor)179     private static Object allocObjectInOtherClassLoader(Constructor<?> constructor)
180             throws Exception {
181       ClassLoader loader = (ClassLoader) constructor.newInstance(
182               DEX_FILE, LIBRARY_SEARCH_PATH, ClassLoader.getSystemClassLoader());
183       return loader.loadClass("IntHolder").newInstance();
184     }
185 
186     // Regression test for public issue 227182.
testStickyUnload(Constructor<?> constructor)187     private static void testStickyUnload(Constructor<?> constructor) throws Exception {
188         String s = "";
189         for (int i = 0; i < 10; ++i) {
190             s = "";
191             // The object is the only thing preventing the class loader from being unloaded.
192             Object o = allocObjectInOtherClassLoader(constructor);
193             for (int j = 0; j < 1000; ++j) {
194                 s += j + " ";
195             }
196             // Make sure the object still has a valid class (hasn't been incorrectly unloaded).
197             s += o.getClass().getName();
198             o = null;
199         }
200         System.out.println("Too small " + (s.length() < 1000));
201     }
202 
setUpUnloadClassWeak(Constructor<?> constructor)203     private static WeakReference<Class> setUpUnloadClassWeak(Constructor<?> constructor)
204             throws Exception {
205         return new WeakReference<Class>(setUpUnloadClass(constructor));
206     }
207 
setUpUnloadLoader(Constructor<?> constructor, boolean waitForCompilation)208     private static WeakReference<ClassLoader> setUpUnloadLoader(Constructor<?> constructor,
209                                                                 boolean waitForCompilation)
210         throws Exception {
211         ClassLoader loader = (ClassLoader) constructor.newInstance(
212             DEX_FILE, LIBRARY_SEARCH_PATH, ClassLoader.getSystemClassLoader());
213         Class<?> intHolder = loader.loadClass("IntHolder");
214         Method setValue = intHolder.getDeclaredMethod("setValue", Integer.TYPE);
215         setValue.invoke(intHolder, 2);
216         if (waitForCompilation) {
217             waitForCompilation(intHolder);
218         }
219         return new WeakReference(loader);
220     }
221 
waitForCompilation(Class<?> intHolder)222     private static void waitForCompilation(Class<?> intHolder) throws Exception {
223       // Load the native library so that we can call waitForCompilation.
224       Method loadLibrary = intHolder.getDeclaredMethod("loadLibrary", String.class);
225       loadLibrary.invoke(intHolder, nativeLibraryName);
226       // Wait for JIT compilation to finish since the async threads may prevent unloading.
227       Method waitForCompilation = intHolder.getDeclaredMethod("waitForCompilation");
228       waitForCompilation.invoke(intHolder);
229     }
230 
setUpLoadLibrary(Constructor<?> constructor)231     private static WeakReference<ClassLoader> setUpLoadLibrary(Constructor<?> constructor)
232         throws Exception {
233         ClassLoader loader = (ClassLoader) constructor.newInstance(
234             DEX_FILE, LIBRARY_SEARCH_PATH, ClassLoader.getSystemClassLoader());
235         Class<?> intHolder = loader.loadClass("IntHolder");
236         Method loadLibrary = intHolder.getDeclaredMethod("loadLibrary", String.class);
237         loadLibrary.invoke(intHolder, nativeLibraryName);
238         waitForCompilation(intHolder);
239         return new WeakReference(loader);
240     }
241 
getPid()242     private static int getPid() throws Exception {
243       return Integer.parseInt(new File("/proc/self").getCanonicalFile().getName());
244     }
245 
stopJit()246     public static native void stopJit();
startJit()247     public static native void startJit();
248 }
249