1 /* 2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 19 * CA 95054 USA or visit www.sun.com if you need additional information or 20 * have any questions. 21 */ 22 23 /* 24 * This file is available under and governed by the GNU General Public 25 * License version 2 only, as published by the Free Software Foundation. 26 * However, the following notice accompanied the original version of this 27 * file: 28 * 29 * Written by Doug Lea with assistance from members of JCP JSR-166 30 * Expert Group and released to the public domain, as explained at 31 * http://creativecommons.org/licenses/publicdomain 32 */ 33 34 /* 35 * @test 36 * @bug 4486658 37 * @compile -source 1.5 ExchangeLoops.java 38 * @run main/timeout=720 ExchangeLoops 39 * @summary checks to make sure a pipeline of exchangers passes data. 40 */ 41 42 import java.util.concurrent.*; 43 44 public class ExchangeLoops { 45 static final ExecutorService pool = Executors.newCachedThreadPool(); 46 static boolean print = false; 47 48 static class Int { 49 public int value; 50 Int(int i) { value = i; } 51 } 52 53 54 public static void main(String[] args) throws Exception { 55 int maxStages = 5; 56 int iters = 10000; 57 58 if (args.length > 0) 59 maxStages = Integer.parseInt(args[0]); 60 61 print = false; 62 System.out.println("Warmup..."); 63 oneRun(2, 100000); 64 print = true; 65 66 for (int i = 2; i <= maxStages; i += (i+1) >>> 1) { 67 System.out.print("Threads: " + i + "\t: "); 68 oneRun(i, iters); 69 } 70 pool.shutdown(); 71 if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS)) 72 throw new Error(); 73 } 74 75 static class Stage implements Runnable { 76 final int iters; 77 final Exchanger<Int> left; 78 final Exchanger<Int> right; 79 final CyclicBarrier barrier; 80 volatile int result; 81 Stage (Exchanger<Int> left, 82 Exchanger<Int> right, 83 CyclicBarrier b, int iters) { 84 this.left = left; 85 this.right = right; 86 barrier = b; 87 this.iters = iters; 88 } 89 90 public void run() { 91 try { 92 barrier.await(); 93 Int item = new Int(hashCode()); 94 for (int i = 0; i < iters; ++i) { 95 if (left != null) { 96 item.value = LoopHelpers.compute1(item.value); 97 Int other = left.exchange(item); 98 if (other == item || other == null) 99 throw new Error("Failed Exchange"); 100 item = other; 101 102 } 103 if (right != null) { 104 item.value = LoopHelpers.compute2(item.value); 105 Int other = right.exchange(item); 106 if (other == item || other == null) 107 throw new Error("Failed Exchange"); 108 item = other; 109 } 110 } 111 barrier.await(); 112 113 } 114 catch (Exception ie) { 115 ie.printStackTrace(); 116 return; 117 } 118 } 119 } 120 121 static void oneRun(int nthreads, int iters) throws Exception { 122 LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); 123 CyclicBarrier barrier = new CyclicBarrier(nthreads + 1, timer); 124 Exchanger<Int> l = null; 125 Exchanger<Int> r = new Exchanger<Int>(); 126 for (int i = 0; i < nthreads; ++i) { 127 pool.execute(new Stage(l, r, barrier, iters)); 128 l = r; 129 r = (i+2 < nthreads) ? new Exchanger<Int>() : null; 130 } 131 barrier.await(); 132 barrier.await(); 133 long time = timer.getTime(); 134 if (print) 135 System.out.println(LoopHelpers.rightJustify(time / (iters * nthreads + iters * (nthreads-2))) + " ns per transfer"); 136 } 137 138 }