| 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 |
|
| 10 |
/** |
| 11 |
* A simple test for evaluating different implementations of |
| 12 |
* CopyOnWriteArrayList.addIfAbsent. |
| 13 |
* |
| 14 |
* This benchmark differs from COWALAddIfAbsentLoops mainly by having |
| 15 |
* a more expensive element equals method. |
| 16 |
*/ |
| 17 |
public class COWALAddIfAbsentStringLoops { |
| 18 |
|
| 19 |
static final int SIZE = Integer.getInteger("size", 25000); |
| 20 |
|
| 21 |
/** |
| 22 |
* Set to 1 for 0% cache hit ratio (every addIfAbsent a cache miss). |
| 23 |
* Set to 2 for 50% cache hit ratio. |
| 24 |
*/ |
| 25 |
static final int CACHE_HIT_FACTOR = Integer.getInteger("cache.hit.factor", 1); |
| 26 |
|
| 27 |
static final int MAX_STRIPES = Integer.getInteger("max.stripes", 4); |
| 28 |
|
| 29 |
static final int REPS = Integer.getInteger("reps", 3); |
| 30 |
|
| 31 |
public static void main(String[] args) throws Exception { |
| 32 |
for (int reps = 0; reps < REPS; ++reps) { |
| 33 |
for (int i = 1; i <= MAX_STRIPES; ++i) |
| 34 |
test(i); |
| 35 |
} |
| 36 |
} |
| 37 |
|
| 38 |
static final AtomicInteger result = new AtomicInteger(); |
| 39 |
|
| 40 |
public static void test(int n) throws Exception { |
| 41 |
result.set(0); |
| 42 |
Thread[] ts = new Thread[CACHE_HIT_FACTOR*n]; |
| 43 |
Phaser started = new Phaser(ts.length + 1); |
| 44 |
CopyOnWriteArrayList<String> list = |
| 45 |
new CopyOnWriteArrayList<String>(); |
| 46 |
for (int i = 0; i < ts.length; ++i) |
| 47 |
(ts[i] = new Thread(new Task(i%n, n, list, started))).start(); |
| 48 |
long p = started.arriveAndAwaitAdvance(); |
| 49 |
long st = System.nanoTime(); |
| 50 |
for (Thread thread : ts) |
| 51 |
thread.join(); |
| 52 |
double secs = ((double)System.nanoTime() - st) / (1000L * 1000 * 1000); |
| 53 |
System.out.println("Threads: " + n + " Time: " + secs); |
| 54 |
if (result.get() != SIZE) |
| 55 |
throw new Error(); |
| 56 |
} |
| 57 |
|
| 58 |
static final class Task implements Runnable { |
| 59 |
final int id, stride; |
| 60 |
final CopyOnWriteArrayList<String> list; |
| 61 |
final Phaser started; |
| 62 |
Task(int id, int stride, |
| 63 |
CopyOnWriteArrayList<String> list, Phaser started) { |
| 64 |
this.id = id; |
| 65 |
this.stride = stride; |
| 66 |
this.list = list; |
| 67 |
this.started = started; |
| 68 |
} |
| 69 |
public void run() { |
| 70 |
final CopyOnWriteArrayList<String> list = this.list; |
| 71 |
int origin = id, inc = stride, adds = 0; |
| 72 |
started.arriveAndAwaitAdvance(); |
| 73 |
for (int i = origin; i < SIZE; i += inc) { |
| 74 |
if (list.addIfAbsent("asjdklfjsdfjsdjf" + i)) |
| 75 |
++adds; |
| 76 |
} |
| 77 |
result.getAndAdd(adds); |
| 78 |
} |
| 79 |
} |
| 80 |
} |
