389 lines
12 KiB
Java
389 lines
12 KiB
Java
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/*
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* JBoss, Home of Professional Open Source
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*
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* Copyright 2009, Red Hat Middleware LLC, and individual contributors
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* by the @author tags. See the COPYRIGHT.txt in the distribution for a
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* full listing of individual contributors.
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*
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* This is free software; you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this software; if not, write to the Free
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* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
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* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
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*/
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package org.jboss.netty.util;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.Executor;
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import java.util.concurrent.Executors;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.locks.ReadWriteLock;
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import java.util.concurrent.locks.ReentrantReadWriteLock;
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/**
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* @author The Netty Project (netty-dev@lists.jboss.org)
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* @author Trustin Lee (tlee@redhat.com)
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* @version $Rev$, $Date$
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*/
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public class HashedWheelTimer implements Timer {
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private final Executor executor;
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private final Worker worker = new Worker();
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final long tickDuration;
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final long wheelDuration;
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final Set<HashedWheelTimeout>[] wheel;
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final int mask;
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final ReadWriteLock lock = new ReentrantReadWriteLock();
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volatile int wheelCursor;
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public HashedWheelTimer(Executor executor) {
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this(executor, 1, TimeUnit.SECONDS, 64);
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}
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public HashedWheelTimer(
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Executor executor,
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long tickDuration, TimeUnit unit, int ticksPerWheel) {
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if (executor == null) {
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throw new NullPointerException("executor");
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}
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if (unit == null) {
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throw new NullPointerException("unit");
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}
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if (tickDuration <= 0) {
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throw new IllegalArgumentException(
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"tickDuration must be greater than 0: " + tickDuration);
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}
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this.executor = executor;
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// Normalize ticksPerWheel to power of two and initialize the wheel.
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wheel = createWheel(ticksPerWheel);
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mask = wheel.length - 1;
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// Convert checkInterval to nanoseconds.
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this.tickDuration = tickDuration = unit.toNanos(tickDuration);
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// Prevent overflow.
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if (tickDuration == Long.MAX_VALUE ||
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tickDuration >= Long.MAX_VALUE / wheel.length) {
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throw new IllegalArgumentException(
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"tickDuration is too long: " +
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tickDuration + ' ' + unit);
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}
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wheelDuration = tickDuration * wheel.length;
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executor.execute(worker);
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}
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@SuppressWarnings("unchecked")
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private static Set<HashedWheelTimeout>[] createWheel(int ticksPerWheel) {
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if (ticksPerWheel <= 0) {
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throw new IllegalArgumentException(
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"ticksPerWheel must be greater than 0: " + ticksPerWheel);
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}
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if (ticksPerWheel > 1073741824) {
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throw new IllegalArgumentException(
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"ticksPerWheel may not be greater than 2^30: " + ticksPerWheel);
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}
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ticksPerWheel = normalizeTicksPerWheel(ticksPerWheel);
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Set<HashedWheelTimeout>[] buckets = new Set[ticksPerWheel];
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for (int i = 0; i < buckets.length; i ++) {
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buckets[i] = new MapBackedSet<HashedWheelTimeout>(new ConcurrentHashMap<HashedWheelTimeout, Boolean>());
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}
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return buckets;
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}
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private static int normalizeTicksPerWheel(int ticksPerWheel) {
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int normalizedTicksPerWheel = 1;
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while (normalizedTicksPerWheel < ticksPerWheel) {
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normalizedTicksPerWheel <<= 1;
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}
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return normalizedTicksPerWheel;
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}
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public void releaseExternalResources() {
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ExecutorUtil.terminate(executor);
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}
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public Timeout newTimeout(long initialDelay, TimeUnit unit) {
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initialDelay = unit.toNanos(initialDelay);
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checkDelay(initialDelay);
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HashedWheelTimeout timeout;
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lock.readLock().lock();
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try {
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timeout = new HashedWheelTimeout(
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wheelCursor, System.nanoTime(), initialDelay);
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wheel[schedule(timeout)].add(timeout);
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} finally {
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lock.readLock().unlock();
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}
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return timeout;
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}
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private int schedule(HashedWheelTimeout timeout) {
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return schedule(timeout, timeout.initialDelay);
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}
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int schedule(HashedWheelTimeout timeout, final long additionalDelay) {
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synchronized (timeout) {
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final long oldCumulativeDelay = timeout.cumulativeDelay;
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final long newCumulativeDelay = oldCumulativeDelay + additionalDelay;
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final long lastWheelDelay = newCumulativeDelay % wheelDuration;
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final long lastTickDelay = newCumulativeDelay % tickDuration;
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final int relativeIndex =
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(int) (lastWheelDelay / tickDuration) + (lastTickDelay != 0? 1 : 0);
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timeout.deadline = timeout.startTime + newCumulativeDelay;
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timeout.cumulativeDelay = newCumulativeDelay;
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timeout.remainingRounds =
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additionalDelay / wheelDuration -
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(additionalDelay % wheelDuration == 0? 1:0) - timeout.slippedRounds;
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timeout.slippedRounds = 0;
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return timeout.stopIndex = timeout.startIndex + relativeIndex & mask;
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}
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}
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void checkDelay(long delay) {
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if (delay < tickDuration) {
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throw new IllegalArgumentException(
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"delay must be greated than " +
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tickDuration + " nanoseconds");
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}
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}
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private final class Worker implements Runnable {
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private long startTime;
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private long tick;
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Worker() {
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super();
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}
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public void run() {
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List<HashedWheelTimeout> expiredTimeouts =
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new ArrayList<HashedWheelTimeout>();
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startTime = System.nanoTime();
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tick = 1;
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for (;;) {
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waitForNextTick();
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fetchExpiredTimeouts(expiredTimeouts);
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notifyExpiredTimeouts(expiredTimeouts);
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}
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}
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private void fetchExpiredTimeouts(
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List<HashedWheelTimeout> expiredTimeouts) {
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// Find the expired timeouts and decrease the round counter
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// if necessary. Note that we don't send the notification
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// immediately to make sure the listeners are called without
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// an exclusive lock.
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lock.writeLock().lock();
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try {
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long currentTime = System.nanoTime();
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int newBucketHead = wheelCursor + 1 & mask;
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Set<HashedWheelTimeout> bucket = wheel[wheelCursor];
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wheelCursor = newBucketHead;
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for (Iterator<HashedWheelTimeout> i = bucket.iterator(); i.hasNext();) {
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HashedWheelTimeout timeout = i.next();
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synchronized (timeout) {
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if (timeout.remainingRounds <= 0) {
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if (timeout.deadline <= currentTime) {
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i.remove();
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expiredTimeouts.add(timeout);
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} else {
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// A rare case where a timeout is put for the next
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// round: just wait for the next round.
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timeout.slippedRounds ++;
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}
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} else {
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timeout.remainingRounds --;
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}
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}
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}
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} finally {
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lock.writeLock().unlock();
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}
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}
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private void notifyExpiredTimeouts(
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List<HashedWheelTimeout> expiredTimeouts) {
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// Notify the expired timeouts.
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for (int i = expiredTimeouts.size() - 1; i >= 0; i --) {
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expiredTimeouts.get(i).expire();
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}
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// Clean up the temporary list.
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expiredTimeouts.clear();
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}
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private void waitForNextTick() {
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for (;;) {
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final long currentTime = System.nanoTime();
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final long sleepTime = tickDuration * tick - (currentTime - startTime);
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if (sleepTime <= 0) {
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break;
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}
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try {
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Thread.sleep(sleepTime / 1000000, (int) (sleepTime % 1000000));
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} catch (InterruptedException e) {
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// FIXME: must exit the loop if necessary
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}
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}
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// Reset the tick if overflow is expected.
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if (tickDuration * tick > Long.MAX_VALUE - tickDuration) {
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startTime = System.nanoTime();
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tick = 1;
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} else {
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// Increase the tick if overflow is not likely to happen.
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tick ++;
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}
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}
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}
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private final class HashedWheelTimeout implements Timeout {
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final int startIndex;
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int stopIndex;
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final long startTime;
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long deadline;
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final long initialDelay;
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long cumulativeDelay;
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long remainingRounds;
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long slippedRounds;
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private volatile int extensionCount;
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HashedWheelTimeout(int startIndex, long startTime, long initialDelay) {
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this.startIndex = startIndex;
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this.startTime = startTime;
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this.initialDelay = initialDelay;
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}
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public synchronized void cancel() {
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if (!wheel[stopIndex].remove(this)) {
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return;
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}
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// TODO Notify handlers
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}
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public void extend() {
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extend(initialDelay);
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}
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public void extend(long additionalDelay, TimeUnit unit) {
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extend(unit.toNanos(additionalDelay));
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}
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private void extend(long additionalDelay) {
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checkDelay(additionalDelay);
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lock.readLock().lock();
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try {
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int newStopIndex;
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synchronized (this) {
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newStopIndex = stopIndex = schedule(this, additionalDelay);
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extensionCount ++;
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}
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wheel[newStopIndex].add(this);
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} finally {
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lock.readLock().unlock();
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}
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}
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public synchronized int getExtensionCount() {
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return extensionCount;
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}
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public boolean isCancelled() {
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return false;
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}
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public boolean isExpired() {
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return false;
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}
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public boolean isExtended() {
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return false;
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}
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public void expire() {
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System.out.println("BOOM: " + (System.nanoTime() - startTime) / 1000000);
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extend();
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}
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public void addListener(TimeoutListener listener) {
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}
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public void removeListener(TimeoutListener listener) {
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}
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@Override
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public String toString() {
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long remaining;
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synchronized (this) {
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remaining = deadline - System.nanoTime();
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}
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StringBuilder buf = new StringBuilder();
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buf.append("TimingWheelTimeout(");
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buf.append("timeout: ");
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buf.append(initialDelay);
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buf.append("ns, ");
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buf.append("deadline: ");
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if (remaining > 0) {
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buf.append(remaining);
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buf.append("ns later");
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} else if (remaining < 0) {
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buf.append(-remaining);
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buf.append("ns ago");
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} else {
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buf.append("now");
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}
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return buf.append(')').toString();
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}
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}
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public static void main(String[] args) throws Exception {
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Timer timer = new HashedWheelTimer(
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Executors.newCachedThreadPool(),
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1, TimeUnit.SECONDS, 4);
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//Timeout timeout = timer.newTimeout(1200, TimeUnit.MILLISECONDS);
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timer.newTimeout(1200, TimeUnit.MILLISECONDS);
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}
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}
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