/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
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* or http://forgerock.org/license/CDDLv1.0.html.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at legal-notices/CDDLv1_0.txt.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information:
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* Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*
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*
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* Copyright 2010 Sun Microsystems, Inc.
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* Portions copyright 2013-2014 ForgeRock AS.
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*/
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package com.forgerock.opendj.ldap;
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import static com.forgerock.opendj.util.StaticUtils.DEBUG_LOG;
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import static java.util.Collections.newSetFromMap;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.logging.Level;
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import com.forgerock.opendj.util.ReferenceCountedObject;
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/**
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* Checks {@code TimeoutEventListener listeners} for events that have timed out.
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* <p>
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* All listeners registered with the {@code #addListener()} method are called
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* back with {@code TimeoutEventListener#handleTimeout()} to be able to handle
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* the timeout.
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*/
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public final class TimeoutChecker {
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/**
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* Global reference on the timeout checker.
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*/
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public static final ReferenceCountedObject<TimeoutChecker> TIMEOUT_CHECKER =
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new ReferenceCountedObject<TimeoutChecker>() {
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@Override
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protected void destroyInstance(final TimeoutChecker instance) {
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instance.shutdown();
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}
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@Override
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protected TimeoutChecker newInstance() {
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return new TimeoutChecker();
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}
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};
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/**
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* Condition variable used for coordinating the timeout thread.
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*/
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private final Object stateLock = new Object();
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/**
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* The listener set must be safe from CMEs. For example, if the listener is
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* a connection, expiring requests can cause the connection to be closed.
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*/
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private final Set<TimeoutEventListener> listeners =
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newSetFromMap(new ConcurrentHashMap<TimeoutEventListener, Boolean>());
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/**
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* Used to signal thread shutdown.
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*/
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private volatile boolean shutdownRequested = false;
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/**
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* Contains the minimum delay for listeners which were added while the
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* timeout check was not sleeping (i.e. while it was processing listeners).
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*/
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private volatile long pendingListenerMinDelay = Long.MAX_VALUE;
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private TimeoutChecker() {
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final Thread checkerThread = new Thread("OpenDJ LDAP SDK Timeout Checker") {
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@Override
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public void run() {
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DEBUG_LOG.fine("Timeout Checker Starting");
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while (!shutdownRequested) {
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/*
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* New listeners may be added during iteration and may not
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* be included in the computation of the new delay. This
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* could potentially result in the timeout checker waiting
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* longer than it should, or even forever (e.g. if the new
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* listener is the first).
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*/
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final long currentTime = System.currentTimeMillis();
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long delay = Long.MAX_VALUE;
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pendingListenerMinDelay = Long.MAX_VALUE;
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for (final TimeoutEventListener listener : listeners) {
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if (DEBUG_LOG.isLoggable(Level.FINER)) {
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DEBUG_LOG.finer("Checking listener " + listener + " delay = "
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+ delay);
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}
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// May update the connections set.
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final long newDelay = listener.handleTimeout(currentTime);
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if (newDelay > 0) {
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delay = Math.min(newDelay, delay);
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}
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}
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try {
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synchronized (stateLock) {
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// Include any pending listener delays.
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delay = Math.min(pendingListenerMinDelay, delay);
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if (shutdownRequested) {
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// Stop immediately.
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break;
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} else if (delay <= 0) {
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/*
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* If there is at least one connection then the
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* delay should be > 0.
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*/
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stateLock.wait();
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} else {
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stateLock.wait(delay);
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}
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}
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} catch (final InterruptedException e) {
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shutdownRequested = true;
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}
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}
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}
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};
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checkerThread.setDaemon(true);
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checkerThread.start();
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}
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/**
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* Registers a timeout event listener for timeout notification.
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*
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* @param listener
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* The timeout event listener.
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*/
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public void addListener(final TimeoutEventListener listener) {
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/*
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* Only add the listener if it has a non-zero timeout. This assumes that
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* the timeout is fixed.
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*/
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final long timeout = listener.getTimeout();
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if (timeout > 0) {
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listeners.add(listener);
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synchronized (stateLock) {
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pendingListenerMinDelay = Math.min(pendingListenerMinDelay, timeout);
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stateLock.notifyAll();
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}
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}
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}
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/**
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* Deregisters a timeout event listener for timeout notification.
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*
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* @param listener
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* The timeout event listener.
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*/
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public void removeListener(final TimeoutEventListener listener) {
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listeners.remove(listener);
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// No need to signal.
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}
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private void shutdown() {
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synchronized (stateLock) {
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shutdownRequested = true;
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stateLock.notifyAll();
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}
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}
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}
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