1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
|
/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.util.Arrays;
import java.util.concurrent.CountDownLatch;
public class Main {
public static void main(String[] args) throws Exception {
System.loadLibrary(args[1]);
doTest();
doTestOtherThreadWait();
doTestOtherThreadBusyLoop();
}
public static void doTest() throws Exception {
System.out.println("###################");
System.out.println("### Same thread ###");
System.out.println("###################");
System.out.println("From top");
Recurse.foo(4, 0, 25, null);
Recurse.foo(4, 1, 25, null);
Recurse.foo(4, 0, 5, null);
Recurse.foo(4, 2, 5, null);
System.out.println("From bottom");
Recurse.foo(4, -1, 25, null);
Recurse.foo(4, -5, 5, null);
Recurse.foo(4, -7, 5, null);
}
public static void doTestOtherThreadWait() throws Exception {
System.out.println();
System.out.println("################################");
System.out.println("### Other thread (suspended) ###");
System.out.println("################################");
final ControlData data = new ControlData();
data.waitFor = new Object();
Thread t = new Thread() {
public void run() {
Recurse.foo(4, 0, 0, data);
}
};
t.start();
data.reached.await();
Thread.yield();
Thread.sleep(500); // A little bit of time...
System.out.println("From top");
print(t, 0, 25);
print(t, 1, 25);
print(t, 0, 5);
print(t, 2, 5);
System.out.println("From bottom");
print(t, -1, 25);
print(t, -5, 5);
print(t, -7, 5);
// Let the thread make progress and die.
synchronized(data.waitFor) {
data.waitFor.notifyAll();
}
t.join();
}
public static void doTestOtherThreadBusyLoop() throws Exception {
System.out.println();
System.out.println("###########################");
System.out.println("### Other thread (live) ###");
System.out.println("###########################");
final ControlData data = new ControlData();
Thread t = new Thread() {
public void run() {
Recurse.foo(4, 0, 0, data);
}
};
t.start();
data.reached.await();
Thread.yield();
Thread.sleep(500); // A little bit of time...
System.out.println("From top");
print(t, 0, 25);
print(t, 1, 25);
print(t, 0, 5);
print(t, 2, 5);
System.out.println("From bottom");
print(t, -1, 25);
print(t, -5, 5);
print(t, -7, 5);
// Let the thread stop looping and die.
data.stop = true;
t.join();
}
public static void print(String[][] stack) {
System.out.println("---------");
for (String[] stackElement : stack) {
for (String part : stackElement) {
System.out.print(' ');
System.out.print(part);
}
System.out.println();
}
}
public static void print(Thread t, int start, int max) {
print(getStackTrace(t, start, max));
}
// Wrap generated stack traces into a class to separate them nicely.
public static class Recurse {
public static int foo(int x, int start, int max, ControlData data) {
bar(x, start, max, data);
return 0;
}
private static long bar(int x, int start, int max, ControlData data) {
baz(x, start, max, data);
return 0;
}
private static Object baz(int x, int start, int max, ControlData data) {
if (x == 0) {
printOrWait(start, max, data);
} else {
foo(x - 1, start, max, data);
}
return null;
}
private static void printOrWait(int start, int max, ControlData data) {
if (data == null) {
print(Thread.currentThread(), start, max);
} else {
if (data.waitFor != null) {
synchronized (data.waitFor) {
data.reached.countDown();
try {
data.waitFor.wait(); // Use wait() as it doesn't have a "hidden" Java call-graph.
} catch (Throwable t) {
throw new RuntimeException(t);
}
}
} else {
data.reached.countDown();
while (!data.stop) {
// Busy-loop.
}
}
}
}
}
public static class ControlData {
CountDownLatch reached = new CountDownLatch(1);
Object waitFor = null;
volatile boolean stop = false;
}
public static native String[][] getStackTrace(Thread thread, int start, int max);
}
|