1 /*
2  * Copyright (C) 2018 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 android.testing;
18 
19 import junit.framework.Assert;
20 import java.util.concurrent.Callable;
21 
22 public abstract class PollingCheck {
23     private static final long TIME_SLICE = 50;
24     private long mTimeout = 3000;
25 
26     public static interface PollingCheckCondition {
canProceed()27         boolean canProceed();
28     }
29 
PollingCheck()30     public PollingCheck() {
31     }
32 
PollingCheck(long timeout)33     public PollingCheck(long timeout) {
34         mTimeout = timeout;
35     }
36 
check()37     protected abstract boolean check();
38 
run()39     public void run() {
40         if (check()) {
41             return;
42         }
43 
44         long timeout = mTimeout;
45         while (timeout > 0) {
46             try {
47                 Thread.sleep(TIME_SLICE);
48             } catch (InterruptedException e) {
49                 Assert.fail("unexpected InterruptedException");
50             }
51 
52             if (check()) {
53                 return;
54             }
55 
56             timeout -= TIME_SLICE;
57         }
58 
59         Assert.fail("unexpected timeout");
60     }
61 
check(CharSequence message, long timeout, Callable<Boolean> condition)62     public static void check(CharSequence message, long timeout, Callable<Boolean> condition)
63             throws Exception {
64         while (timeout > 0) {
65             if (condition.call()) {
66                 return;
67             }
68 
69             Thread.sleep(TIME_SLICE);
70             timeout -= TIME_SLICE;
71         }
72 
73         Assert.fail(message.toString());
74     }
75 
waitFor(final PollingCheckCondition condition)76     public static void waitFor(final PollingCheckCondition condition) {
77         new PollingCheck() {
78             @Override
79             protected boolean check() {
80                 return condition.canProceed();
81             }
82         }.run();
83     }
84 
waitFor(long timeout, final PollingCheckCondition condition)85     public static void waitFor(long timeout, final PollingCheckCondition condition) {
86         new PollingCheck(timeout) {
87             @Override
88             protected boolean check() {
89                 return condition.canProceed();
90             }
91         }.run();
92     }
93 }
94 
95