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/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Written by Doug Lea with assistance from members of JCP JSR-166
* Expert Group and released to the public domain, as explained at
* http://creativecommons.org/publicdomain/zero/1.0/
*/
/*
* @test
* @bug 4486658
* @summary checks to make sure a pipeline of exchangers passes data.
* @library /lib/testlibrary/
*/
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.Exchanger;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import jdk.testlibrary.Utils;
public class ExchangeLoops {
static final long LONG_DELAY_MS = Utils.adjustTimeout(10_000);
static final ExecutorService pool = Executors.newCachedThreadPool();
static boolean print = false;
static class Int {
public int value;
Int(int i) { value = i; }
}
public static void main(String[] args) throws Exception {
int maxStages = 5;
int iters = 2000;
if (args.length > 0)
maxStages = Integer.parseInt(args[0]);
print = false;
System.out.println("Warmup...");
oneRun(2, iters);
print = true;
for (int i = 2; i <= maxStages; i += (i+1) >>> 1) {
System.out.print("Threads: " + i + "\t: ");
oneRun(i, iters);
}
pool.shutdown();
if (! pool.awaitTermination(LONG_DELAY_MS, MILLISECONDS))
throw new Error();
}
static class Stage implements Runnable {
final int iters;
final Exchanger<Int> left;
final Exchanger<Int> right;
final CyclicBarrier barrier;
volatile int result;
Stage(Exchanger<Int> left,
Exchanger<Int> right,
CyclicBarrier b, int iters) {
this.left = left;
this.right = right;
barrier = b;
this.iters = iters;
}
public void run() {
try {
barrier.await();
Int item = new Int(hashCode());
for (int i = 0; i < iters; ++i) {
if (left != null) {
item.value = LoopHelpers.compute1(item.value);
Int other = left.exchange(item);
if (other == item || other == null)
throw new Error("Failed Exchange");
item = other;
}
if (right != null) {
item.value = LoopHelpers.compute2(item.value);
Int other = right.exchange(item);
if (other == item || other == null)
throw new Error("Failed Exchange");
item = other;
}
}
barrier.await();
}
catch (Exception ex) {
ex.printStackTrace();
return;
}
}
}
static void oneRun(int nthreads, int iters) throws Exception {
LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
CyclicBarrier barrier = new CyclicBarrier(nthreads + 1, timer);
Exchanger<Int> l = null;
Exchanger<Int> r = new Exchanger<>();
for (int i = 0; i < nthreads; ++i) {
pool.execute(new Stage(l, r, barrier, iters));
l = r;
r = (i+2 < nthreads) ? new Exchanger<Int>() : null;
}
barrier.await();
barrier.await();
long time = timer.getTime();
if (print)
System.out.println(LoopHelpers.rightJustify(time / (iters * nthreads + iters * (nthreads-2))) + " ns per transfer");
}
}
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