1 /*
2  * Copyright (C) 2017 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 package art.test;
18 
19 import java.util.concurrent.locks.ReentrantLock;
20 
21 public class TestWatcher {
22   // Lock to synchronize access to the static state of this class.
23   private static final ReentrantLock lock = new ReentrantLock();
24   private static volatile boolean criticalFailure = false;
25   private static boolean reportingEnabled = true;
26   private static boolean doingReport = false;
27 
MonitorEnter()28   private static void MonitorEnter() {
29     lock.lock();
30   }
31 
MonitorExit()32   private static void MonitorExit() {
33     // Need to do this manually since we need to notify critical failure but would deadlock if
34     // waited for the unlock.
35     if (!lock.isHeldByCurrentThread()) {
36       NotifyCriticalFailure();
37       throw new IllegalMonitorStateException("Locking error!");
38     } else {
39       lock.unlock();
40     }
41   }
42 
43   // Stops reporting. Must be paired with an EnableReporting call.
DisableReporting()44   public static void DisableReporting() {
45     MonitorEnter();
46     reportingEnabled = false;
47   }
48 
49   // Stops reporting. Must be paired with a DisableReporting call.
EnableReporting()50   public static void EnableReporting() {
51     reportingEnabled = true;
52     MonitorExit();
53   }
54 
NotifyCriticalFailure()55   public static void NotifyCriticalFailure() {
56     criticalFailure = true;
57   }
58 
NotifyConstructed(Object o)59   public static void NotifyConstructed(Object o) {
60     if (criticalFailure) {
61       // Something went very wrong. We are probably trying to report it so don't get in the way.
62       return;
63     }
64     MonitorEnter();
65     // We could enter an infinite loop if println allocates (which it does) so we disable
66     // reporting while we are doing a report. Since we are synchronized we won't miss any
67     // allocations.
68     if (reportingEnabled && !doingReport) {
69       doingReport = true;
70       System.out.println("Object allocated of type '" + o.getClass().getName() + "'");
71       doingReport = false;
72     }
73     MonitorExit();
74   }
75 }
76