1 |
/* |
2 |
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
* Expert Group and released to the public domain, as explained at |
4 |
* http://creativecommons.org/publicdomain/zero/1.0/ |
5 |
*/ |
6 |
|
7 |
import java.util.concurrent.*; |
8 |
import java.util.concurrent.atomic.*; |
9 |
import java.util.concurrent.locks.*; |
10 |
|
11 |
class Mutex100M { |
12 |
public static void main(String[] args) throws Exception { |
13 |
int x = loop((int) System.nanoTime(), 100000); |
14 |
x = loop(x, 100000); |
15 |
x = loop(x, 100000); |
16 |
long start = System.nanoTime(); |
17 |
x = loop(x, 100000000); |
18 |
if (x == 0) System.out.print(" "); |
19 |
long time = System.nanoTime() - start; |
20 |
double secs = (double) time / 1000000000.0; |
21 |
System.out.println("time: " + secs); |
22 |
start = System.nanoTime(); |
23 |
x = loop(x, 100000000); |
24 |
if (x == 0) System.out.print(" "); |
25 |
time = System.nanoTime() - start; |
26 |
secs = (double) time / 1000000000.0; |
27 |
System.out.println("time: " + secs); |
28 |
|
29 |
} |
30 |
|
31 |
static final Mutex100M.Mutex lock = new Mutex100M.Mutex(); |
32 |
|
33 |
static int loop(int x, int iters) { |
34 |
final Mutex100M.Mutex l = lock; |
35 |
for (int i = iters; i > 0; --i) { |
36 |
l.lock(); |
37 |
x = x * 134775813 + 1; |
38 |
l.unlock(); |
39 |
} |
40 |
return x; |
41 |
} |
42 |
|
43 |
static final class Mutex extends AbstractQueuedSynchronizer { |
44 |
public boolean isHeldExclusively() { return getState() == 1; } |
45 |
|
46 |
public boolean tryAcquire(int acquires) { |
47 |
return getState() == 0 && compareAndSetState(0, 1); |
48 |
} |
49 |
|
50 |
public boolean tryRelease(int releases) { |
51 |
setState(0); |
52 |
return true; |
53 |
} |
54 |
public Condition newCondition() { return new ConditionObject(); } |
55 |
|
56 |
public void lock() { |
57 |
if (!compareAndSetState(0, 1)) |
58 |
acquire(1); |
59 |
} |
60 |
public boolean tryLock() { |
61 |
return tryAcquire(1); |
62 |
} |
63 |
public void lockInterruptibly() throws InterruptedException { |
64 |
acquireInterruptibly(1); |
65 |
} |
66 |
public boolean tryLock(long timeout, TimeUnit unit) throws InterruptedException { |
67 |
return tryAcquireNanos(1, unit.toNanos(timeout)); |
68 |
} |
69 |
public void unlock() { release(1); } |
70 |
} |
71 |
|
72 |
} |