1adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project/* 229957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 329957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * 429957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * This code is free software; you can redistribute it and/or modify it 529957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * under the terms of the GNU General Public License version 2 only, as 629957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * published by the Free Software Foundation. Oracle designates this 729957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * particular file as subject to the "Classpath" exception as provided 829957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * by Oracle in the LICENSE file that accompanied this code. 929957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * 1029957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * This code is distributed in the hope that it will be useful, but WITHOUT 1129957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1229957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1329957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * version 2 for more details (a copy is included in the LICENSE file that 1429957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * accompanied this code). 1529957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * 1629957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * You should have received a copy of the GNU General Public License version 1729957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * 2 along with this work; if not, write to the Free Software Foundation, 1829957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 1929957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * 2029957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2129957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * or visit www.oracle.com if you need additional information or have any 2229957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * questions. 2329957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer */ 2429957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer 2529957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer/* 2629957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * This file is available under and governed by the GNU General Public 2729957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * License version 2 only, as published by the Free Software Foundation. 2829957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * However, the following notice accompanied the original version of this 2929957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * file: 3029957558cf0db700bfaae360a80c42dc3871d0e5Tobias Thierer * 31adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Written by Doug Lea with assistance from members of JCP JSR-166 32adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Expert Group and released to the public domain, as explained at 33a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * http://creativecommons.org/publicdomain/zero/1.0/ 34adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 35adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 36adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectpackage java.util.concurrent; 37edf43d27e240d82106f39ae91404963c23987234Narayan Kamath 3891770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravleimport java.util.concurrent.locks.Condition; 3991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravleimport java.util.concurrent.locks.ReentrantLock; 40adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 41adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project/** 42adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * A synchronization aid that allows a set of threads to all wait for 43adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * each other to reach a common barrier point. CyclicBarriers are 44adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * useful in programs involving a fixed sized party of threads that 45adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * must occasionally wait for each other. The barrier is called 46adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <em>cyclic</em> because it can be re-used after the waiting threads 47adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * are released. 48adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 4991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * <p>A {@code CyclicBarrier} supports an optional {@link Runnable} command 50adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * that is run once per barrier point, after the last thread in the party 51bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * arrives, but before any threads are released. 52adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * This <em>barrier action</em> is useful 53adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * for updating shared-state before any of the parties continue. 54bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 55b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * <p><b>Sample usage:</b> Here is an example of using a barrier in a 56b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * parallel decomposition design: 57a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * 58b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * <pre> {@code 59adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * class Solver { 60adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * final int N; 61adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * final float[][] data; 62adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * final CyclicBarrier barrier; 63bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 64adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * class Worker implements Runnable { 65adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * int myRow; 66adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Worker(int row) { myRow = row; } 67adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * public void run() { 68adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * while (!done()) { 69adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * processRow(myRow); 70adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 71adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * try { 72bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * barrier.await(); 73bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * } catch (InterruptedException ex) { 74bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * return; 75bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * } catch (BrokenBarrierException ex) { 76bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * return; 77adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * } 78adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * } 79adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * } 80adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * } 81adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 82adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * public Solver(float[][] matrix) { 83adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * data = matrix; 84adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * N = matrix.length; 85b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * Runnable barrierAction = 86b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * new Runnable() { public void run() { mergeRows(...); }}; 87b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * barrier = new CyclicBarrier(N, barrierAction); 88adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 89b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * List<Thread> threads = new ArrayList<>(N); 90b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * for (int i = 0; i < N; i++) { 91b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * Thread thread = new Thread(new Worker(i)); 92b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * threads.add(thread); 93b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * thread.start(); 94b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * } 95b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * 96b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * // wait until done 97b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * for (Thread thread : threads) 98b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * thread.join(); 99adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * } 100a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * }}</pre> 101a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * 102bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Here, each worker thread processes a row of the matrix then waits at the 103adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * barrier until all rows have been processed. When all rows are processed 104bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * the supplied {@link Runnable} barrier action is executed and merges the 105adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * rows. If the merger 10691770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * determines that a solution has been found then {@code done()} will return 10791770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code true} and each worker will terminate. 108adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 109adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the barrier action does not rely on the parties being suspended when 110adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * it is executed, then any of the threads in the party could execute that 111adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * action when it is released. To facilitate this, each invocation of 112adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * {@link #await} returns the arrival index of that thread at the barrier. 113bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * You can then choose which thread should execute the barrier action, for 114adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * example: 115b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * <pre> {@code 116a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * if (barrier.await() == 0) { 117a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * // log the completion of this iteration 118a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson * }}</pre> 119adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 12091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * <p>The {@code CyclicBarrier} uses an all-or-none breakage model 121bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * for failed synchronization attempts: If a thread leaves a barrier 122bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * point prematurely because of interruption, failure, or timeout, all 123bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * other threads waiting at that barrier point will also leave 124bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * abnormally via {@link BrokenBarrierException} (or 125bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * {@link InterruptedException} if they too were interrupted at about 126bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * the same time). 127bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 128bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <p>Memory consistency effects: Actions in a thread prior to calling 129bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * {@code await()} 130bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> 131bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * actions that are part of the barrier action, which in turn 132bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <i>happen-before</i> actions following a successful return from the 133bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * corresponding {@code await()} in other threads. 134adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 135adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @since 1.5 136adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @see CountDownLatch 137adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 138adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @author Doug Lea 139adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 140adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Projectpublic class CyclicBarrier { 141bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson /** 142bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Each use of the barrier is represented as a generation instance. 143bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * The generation changes whenever the barrier is tripped, or 144bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * is reset. There can be many generations associated with threads 145bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * using the barrier - due to the non-deterministic way the lock 146bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * may be allocated to waiting threads - but only one of these 14791770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * can be active at a time (the one to which {@code count} applies) 148bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * and all the rest are either broken or tripped. 149bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * There need not be an active generation if there has been a break 150bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * but no subsequent reset. 151bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson */ 152bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson private static class Generation { 153b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak boolean broken; // initially false 154bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson } 155bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson 156adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** The lock for guarding barrier entry */ 157adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private final ReentrantLock lock = new ReentrantLock(); 158adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** Condition to wait on until tripped */ 159adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private final Condition trip = lock.newCondition(); 160adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** The number of parties */ 161adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private final int parties; 162edf43d27e240d82106f39ae91404963c23987234Narayan Kamath /** The command to run when tripped */ 163adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private final Runnable barrierCommand; 164bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson /** The current generation */ 165bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson private Generation generation = new Generation(); 166adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 167adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 168adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Number of parties still waiting. Counts down from parties to 0 169bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * on each generation. It is reset to parties on each new 170bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * generation or when broken. 171adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 172bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson private int count; 173adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 174adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 175bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Updates state on barrier trip and wakes up everyone. 176bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Called only while holding lock. 177bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson */ 178adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private void nextGeneration() { 179bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson // signal completion of last generation 180adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project trip.signalAll(); 181bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson // set up next generation 182bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson count = parties; 183bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson generation = new Generation(); 184adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 185adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 186adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 187bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Sets current barrier generation as broken and wakes up everyone. 188bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Called only while holding lock. 189adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 190adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project private void breakBarrier() { 191bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson generation.broken = true; 192bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson count = parties; 193adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project trip.signalAll(); 194adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 195adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 196adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 197adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Main barrier code, covering the various policies. 198adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 199bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson private int dowait(boolean timed, long nanos) 200bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson throws InterruptedException, BrokenBarrierException, 201bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson TimeoutException { 202adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project final ReentrantLock lock = this.lock; 203adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.lock(); 204adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project try { 205bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson final Generation g = generation; 206adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 207bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson if (g.broken) 208adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project throw new BrokenBarrierException(); 209adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 210adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project if (Thread.interrupted()) { 211adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project breakBarrier(); 212adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project throw new InterruptedException(); 213adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 214adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 215a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson int index = --count; 216a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson if (index == 0) { // tripped 217a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson boolean ranAction = false; 218a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson try { 219a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson final Runnable command = barrierCommand; 220a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson if (command != null) 221a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson command.run(); 222a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson ranAction = true; 223a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson nextGeneration(); 224a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson return 0; 225a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson } finally { 226a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson if (!ranAction) 227a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson breakBarrier(); 228a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson } 229a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson } 230adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 231bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson // loop until tripped, broken, interrupted, or timed out 232adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project for (;;) { 233adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project try { 234bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson if (!timed) 235adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project trip.await(); 236adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project else if (nanos > 0L) 237adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project nanos = trip.awaitNanos(nanos); 238adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } catch (InterruptedException ie) { 239bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson if (g == generation && ! g.broken) { 240bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson breakBarrier(); 241bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson throw ie; 242bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson } else { 243bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson // We're about to finish waiting even if we had not 244bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson // been interrupted, so this interrupt is deemed to 245bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson // "belong" to subsequent execution. 246bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson Thread.currentThread().interrupt(); 247bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson } 248adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 249bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson 250bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson if (g.broken) 251adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project throw new BrokenBarrierException(); 252adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 253bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson if (g != generation) 254adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project return index; 255adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 256adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project if (timed && nanos <= 0L) { 257adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project breakBarrier(); 258adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project throw new TimeoutException(); 259adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 260adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 261adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } finally { 262adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.unlock(); 263adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 264adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 265adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 266adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 26791770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Creates a new {@code CyclicBarrier} that will trip when the 268adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * given number of parties (threads) are waiting upon it, and which 269adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * will execute the given barrier action when the barrier is tripped, 270adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * performed by the last thread entering the barrier. 271adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 272adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param parties the number of threads that must invoke {@link #await} 273bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * before the barrier is tripped 274adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param barrierAction the command to execute when the barrier is 275bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * tripped, or {@code null} if there is no action 276bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * @throws IllegalArgumentException if {@code parties} is less than 1 277adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 278adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public CyclicBarrier(int parties, Runnable barrierAction) { 279adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project if (parties <= 0) throw new IllegalArgumentException(); 280bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson this.parties = parties; 281adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project this.count = parties; 282adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project this.barrierCommand = barrierAction; 283adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 284adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 285adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 28691770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * Creates a new {@code CyclicBarrier} that will trip when the 287adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * given number of parties (threads) are waiting upon it, and 288bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * does not perform a predefined action when the barrier is tripped. 289adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 290adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param parties the number of threads that must invoke {@link #await} 291bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * before the barrier is tripped 292bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * @throws IllegalArgumentException if {@code parties} is less than 1 293adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 294adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public CyclicBarrier(int parties) { 295adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project this(parties, null); 296adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 297adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 298adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 299adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Returns the number of parties required to trip this barrier. 300bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 301bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * @return the number of parties required to trip this barrier 302bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson */ 303adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public int getParties() { 304adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project return parties; 305adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 306adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 307adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 308bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Waits until all {@linkplain #getParties parties} have invoked 30991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code await} on this barrier. 310adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 311adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the current thread is not the last to arrive then it is 312adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * disabled for thread scheduling purposes and lies dormant until 313bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * one of the following things happens: 314adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <ul> 315adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>The last thread arrives; or 316bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <li>Some other thread {@linkplain Thread#interrupt interrupts} 317bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * the current thread; or 318bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <li>Some other thread {@linkplain Thread#interrupt interrupts} 319bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * one of the other waiting threads; or 320adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>Some other thread times out while waiting for barrier; or 321adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>Some other thread invokes {@link #reset} on this barrier. 322adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * </ul> 323bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 324adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the current thread: 325adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <ul> 326adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>has its interrupted status set on entry to this method; or 327bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <li>is {@linkplain Thread#interrupt interrupted} while waiting 328adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * </ul> 329adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * then {@link InterruptedException} is thrown and the current thread's 330adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * interrupted status is cleared. 331adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 332bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <p>If the barrier is {@link #reset} while any thread is waiting, 333bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * or if the barrier {@linkplain #isBroken is broken} when 33491770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code await} is invoked, or while any thread is waiting, then 335bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * {@link BrokenBarrierException} is thrown. 336adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 337bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <p>If any thread is {@linkplain Thread#interrupt interrupted} while waiting, 338bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * then all other waiting threads will throw 339adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * {@link BrokenBarrierException} and the barrier is placed in the broken 340adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * state. 341adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 342adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the current thread is the last thread to arrive, and a 343adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * non-null barrier action was supplied in the constructor, then the 344bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * current thread runs the action before allowing the other threads to 345adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * continue. 346adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * If an exception occurs during the barrier action then that exception 347adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * will be propagated in the current thread and the barrier is placed in 348adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the broken state. 349adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 350adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @return the arrival index of the current thread, where index 35191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code getParties() - 1} indicates the first 352bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * to arrive and zero indicates the last to arrive 353bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * @throws InterruptedException if the current thread was interrupted 354bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * while waiting 355adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @throws BrokenBarrierException if <em>another</em> thread was 356bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * interrupted or timed out while the current thread was 357bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * waiting, or the barrier was reset, or the barrier was 358bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * broken when {@code await} was called, or the barrier 35991770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * action (if present) failed due to an exception 360adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 361adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public int await() throws InterruptedException, BrokenBarrierException { 362adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project try { 363adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project return dowait(false, 0L); 364adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } catch (TimeoutException toe) { 365a807b4d808d2591894daf13aab179b2e9c46a2f5Jesse Wilson throw new Error(toe); // cannot happen 366adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 367adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 368adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 369adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 370bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * Waits until all {@linkplain #getParties parties} have invoked 37191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code await} on this barrier, or the specified waiting time elapses. 372adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 373adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the current thread is not the last to arrive then it is 374adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * disabled for thread scheduling purposes and lies dormant until 375adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * one of the following things happens: 376adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <ul> 377adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>The last thread arrives; or 378adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>The specified timeout elapses; or 379bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <li>Some other thread {@linkplain Thread#interrupt interrupts} 380bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * the current thread; or 381bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <li>Some other thread {@linkplain Thread#interrupt interrupts} 382bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * one of the other waiting threads; or 383adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>Some other thread times out while waiting for barrier; or 384adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>Some other thread invokes {@link #reset} on this barrier. 385adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * </ul> 386bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 387adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the current thread: 388adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <ul> 389adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <li>has its interrupted status set on entry to this method; or 390bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <li>is {@linkplain Thread#interrupt interrupted} while waiting 391adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * </ul> 392adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * then {@link InterruptedException} is thrown and the current thread's 393adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * interrupted status is cleared. 394adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 395bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <p>If the specified waiting time elapses then {@link TimeoutException} 396bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * is thrown. If the time is less than or equal to zero, the 397bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * method will not wait at all. 398adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 399bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <p>If the barrier is {@link #reset} while any thread is waiting, 400bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * or if the barrier {@linkplain #isBroken is broken} when 40191770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code await} is invoked, or while any thread is waiting, then 402bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * {@link BrokenBarrierException} is thrown. 403bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 404bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * <p>If any thread is {@linkplain Thread#interrupt interrupted} while 405bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * waiting, then all other waiting threads will throw {@link 406bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * BrokenBarrierException} and the barrier is placed in the broken 407adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * state. 408adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 409adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * <p>If the current thread is the last thread to arrive, and a 410adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * non-null barrier action was supplied in the constructor, then the 411bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * current thread runs the action before allowing the other threads to 412adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * continue. 413adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * If an exception occurs during the barrier action then that exception 414adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * will be propagated in the current thread and the barrier is placed in 415adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * the broken state. 416adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 417adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param timeout the time to wait for the barrier 418adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @param unit the time unit of the timeout parameter 419adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @return the arrival index of the current thread, where index 42091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * {@code getParties() - 1} indicates the first 421bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * to arrive and zero indicates the last to arrive 422bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * @throws InterruptedException if the current thread was interrupted 423bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * while waiting 424b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * @throws TimeoutException if the specified timeout elapses. 425b8b75116273ecfdb8ffdd1869b1c0dd04570a95ePrzemyslaw Szczepaniak * In this case the barrier will be broken. 426adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @throws BrokenBarrierException if <em>another</em> thread was 427bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * interrupted or timed out while the current thread was 428bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * waiting, or the barrier was reset, or the barrier was broken 429bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * when {@code await} was called, or the barrier action (if 43091770798d8b9280d48d30df2ed7f63b3ed9b036fCalin Juravle * present) failed due to an exception 431adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 432bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson public int await(long timeout, TimeUnit unit) 433bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson throws InterruptedException, 434bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson BrokenBarrierException, 435bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson TimeoutException { 436adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project return dowait(true, unit.toNanos(timeout)); 437adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 438adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 439adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 440adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Queries if this barrier is in a broken state. 441bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * 442bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * @return {@code true} if one or more parties broke out of this 443bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * barrier due to interruption or timeout since 444bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * construction or the last reset, or a barrier action 445bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson * failed due to an exception; {@code false} otherwise. 446adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 447adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public boolean isBroken() { 448adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project final ReentrantLock lock = this.lock; 449adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.lock(); 450adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project try { 451bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson return generation.broken; 452adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } finally { 453adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.unlock(); 454adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 455adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 456adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 457adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 458adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Resets the barrier to its initial state. If any parties are 459adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * currently waiting at the barrier, they will return with a 460adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * {@link BrokenBarrierException}. Note that resets <em>after</em> 461adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * a breakage has occurred for other reasons can be complicated to 462adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * carry out; threads need to re-synchronize in some other way, 463adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * and choose one to perform the reset. It may be preferable to 464adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * instead create a new barrier for subsequent use. 465adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project */ 466adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public void reset() { 467adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project final ReentrantLock lock = this.lock; 468adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.lock(); 469adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project try { 470bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson breakBarrier(); // break the current generation 471bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson nextGeneration(); // start a new generation 472adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } finally { 473adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.unlock(); 474adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 475adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 476adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project 477adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project /** 478adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * Returns the number of parties currently waiting at the barrier. 479adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * This method is primarily useful for debugging and assertions. 480adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * 481adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project * @return the number of parties currently blocked in {@link #await} 482bba8d1acd6dfff06c94d761c67a30154ca5ca5dfJesse Wilson */ 483adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project public int getNumberWaiting() { 484adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project final ReentrantLock lock = this.lock; 485adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.lock(); 486adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project try { 487adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project return parties - count; 488adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } finally { 489adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project lock.unlock(); 490adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 491adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project } 492adc854b798c1cfe3bfd4c27d68d5cee38ca617daThe Android Open Source Project} 493