1 /*
2  * Copyright 2019 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 class Main {
18   private static final boolean DEBUG = false;
19 
main(String[] args)20   public static void main(String[] args) throws Exception {
21     System.loadLibrary(args[0]);
22     makeVisiblyInitialized();
23     Class<?> testClass = Class.forName("TestClass");  // Request initialized class.
24     boolean is_visibly_initialized = isVisiblyInitialized(testClass);
25     if (DEBUG) {
26       System.out.println((is_visibly_initialized ? "Already" : "Not yet") + " visibly intialized");
27     }
28     if (!is_visibly_initialized) {
29       synchronized(testClass) {
30         Thread t = new Thread() {
31           public void run() {
32             // Regression test: This would have previously deadlocked
33             // trying to lock on testClass. b/138561860
34             makeVisiblyInitialized();
35           }
36         };
37         t.start();
38         t.join();
39       }
40       if (!isVisiblyInitialized(testClass)) {
41         throw new Error("Should be visibly initialized now.");
42       }
43     }
44   }
45 
makeVisiblyInitialized()46   public static native void makeVisiblyInitialized();
isVisiblyInitialized(Class<?> klass)47   public static native boolean isVisiblyInitialized(Class<?> klass);
48 }
49 
50 class TestClass {
51   static {
52     // Add a static constructor that prevents initialization at compile time (app images).
53     Main.isVisiblyInitialized(TestClass.class);  // Native call, discard result.
54   }
55 }
56