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Apache Geode provides a database-like consistency model, reliable transaction processing and a shared-nothing architecture to maintain very low latency performance with high concurrency processing
/*
* Licensed to the Apache Software Foundation (ASF) under one or more contributor license
* agreements. See the NOTICE file distributed with this work for additional information regarding
* copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the License. You may obtain a
* copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package org.apache.geode.internal;
import java.lang.ref.WeakReference;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Timer;
import java.util.TimerTask;
import org.apache.logging.log4j.Logger;
import org.apache.geode.CancelException;
import org.apache.geode.SystemFailure;
import org.apache.geode.distributed.internal.InternalDistributedSystem;
import org.apache.geode.internal.i18n.LocalizedStrings;
import org.apache.geode.internal.logging.LogService;
import org.apache.geode.internal.logging.log4j.LocalizedMessage;
/**
* Instances of this class are like {@link Timer}, but are associated with a "swarm", which can be
* cancelled as a group with {@link #cancelSwarm(Object)}.
*
* @see Timer
* @see TimerTask
*
* TODO -- with Java 1.5, this will be a template type so that the swarm's class can be
* specified.
*/
public final class SystemTimer {
private static final Logger logger = LogService.getLogger();
final static private boolean isIBM =
"IBM Corporation".equals(System.getProperty("java.vm.vendor"));
/**
* Extra debugging for this class
*/
// private static final boolean DEBUG = true;
static final boolean DEBUG = false;
/**
* the underlying {@link Timer}
*/
final private Timer timer;
/**
* True if this timer has been cancelled
*/
private boolean cancelled = false;
/**
* the swarm to which this timer belongs
*/
final private Object /* T */ swarm;
@Override
public String toString() {
StringBuffer sb = new StringBuffer();
sb.append("SystemTimer[");
sb.append("swarm = " + swarm);
// sb.append("; timer = " + timer);
sb.append("]");
return sb.toString();
}
/**
* List of all of the swarms in the system
*
* @guarded.By self
*/
// >>>
static private final HashMap allSwarms = new HashMap();
/**
* Add the given timer is in the given swarm. Used only by constructors.
*
* @param swarm swarm to add the timer to
* @param t timer to add
*/
static private void addToSwarm(Object /* T */ swarm, SystemTimer t) {
final boolean isDebugEnabled = logger.isTraceEnabled();
// Get or add list of timers for this swarm...
ArrayList /* ArrayList> */ swarmSet;
synchronized (allSwarms) {
swarmSet = (ArrayList) allSwarms.get(swarm);
if (swarmSet == null) {
if (isDebugEnabled) {
logger.trace("SystemTimer#addToSwarm: created swarm {}", swarm);
}
swarmSet = new ArrayList();
allSwarms.put(swarm, swarmSet);
}
} // synchronized
// Add the timer to the swarm's list
if (isDebugEnabled) {
logger.trace("SystemTimer#addToSwarm: adding timer <{}>", t);
}
WeakReference /* WeakReference */ wr = new WeakReference(t);
synchronized (swarmSet) {
swarmSet.add(wr);
} // synchronized
}
/**
* time that the last sweep was done
*
* @see #sweepAllSwarms
*/
private static long lastSweepAllTime = 0;
/**
* Interval, in milliseconds, to sweep all swarms, measured from when the last sweep finished
*
* @see #sweepAllSwarms
*/
private static final long SWEEP_ALL_INTERVAL = 2 * 60 * 1000; // 2 minutes
/**
* Manually garbage collect {@link #allSwarms}, if it hasn't happened in a while.
*
* @see #lastSweepAllTime
*/
static private void sweepAllSwarms() {
if (System.currentTimeMillis() < lastSweepAllTime + SWEEP_ALL_INTERVAL) {
// Too soon.
return;
}
final boolean isDebugEnabled = logger.isTraceEnabled();
synchronized (allSwarms) {
Iterator it = allSwarms.entrySet().iterator();
while (it.hasNext()) { // iterate over allSwarms
Map.Entry entry = (Map.Entry) it.next();
ArrayList swarm = (ArrayList) entry.getValue();
synchronized (swarm) {
Iterator it2 = swarm.iterator();
while (it2.hasNext()) { // iterate over current swarm
WeakReference wr = (WeakReference) it2.next();
SystemTimer st = (SystemTimer) wr.get();
if (st == null) {
// Remove stale reference
it2.remove();
continue;
}
// Get rid of a cancelled timer; it's not interesting.
if (st.cancelled) {
it2.remove();
continue;
}
} // iterate over current swarm
if (swarm.size() == 0) { // Remove unused swarm
it.remove();
if (isDebugEnabled) {
logger.trace("SystemTimer#sweepAllSwarms: removed unused swarm {}", entry.getKey());
}
} // Remove unused swarm
} // synchronized swarm
} // iterate over allSwarms
} // synchronized allSwarms
// Collect time at END of sweep. It means an extra call to the system
// timer, but makes this potentially less active.
lastSweepAllTime = System.currentTimeMillis();
}
/**
* Remove given timer from the swarm.
*
* @param t timer to remove
*
* @see #cancel()
*/
static private void removeFromSwarm(SystemTimer t) {
final boolean isDebugEnabled = logger.isTraceEnabled();
synchronized (allSwarms) {
// Get timer's swarm
ArrayList swarmSet = (ArrayList) allSwarms.get(t.swarm);
if (swarmSet == null) {
if (isDebugEnabled) {
logger.trace("SystemTimer#removeFromSwarm: timer already removed: {}", t);
}
return; // already gone
}
// Remove timer from swarm
if (isDebugEnabled) {
logger.trace("SystemTimer#removeFromSwarm: removing timer <{}>", t);
}
synchronized (swarmSet) {
Iterator it = swarmSet.iterator();
while (it.hasNext()) {
WeakReference ref = (WeakReference) it.next();
SystemTimer t2 = (SystemTimer) ref.get();
if (t2 == null) {
// Since we've discovered an empty reference, we should remove it.
it.remove();
continue;
}
if (t2 == t) {
it.remove();
// Don't keep sweeping once we've found it; just quit.
break;
}
if (t2.cancelled) {
// But if we happen to run across a cancelled timer,
// remove it.
it.remove();
continue;
}
} // while
// While we're here, if the swarm has gone to zero size,
// we should remove it.
if (swarmSet.size() == 0) {
allSwarms.remove(t.swarm); // last reference
if (isDebugEnabled) {
logger.trace("SystemTimer#removeFromSwarm: removed last reference to {}", t.swarm);
}
}
} // synchronized swarmSet
} // synchronized allSwarms
sweepAllSwarms(); // Occasionally check global list, use any available logger :-)
}
/**
* Cancel all outstanding timers
*
* @param swarm the swarm to cancel
*/
public static void cancelSwarm(Object /* T */ swarm) {
Assert.assertTrue(swarm instanceof InternalDistributedSystem); // TODO
// Find the swarmSet and remove it
ArrayList swarmSet;
synchronized (allSwarms) {
swarmSet = (ArrayList) allSwarms.get(swarm);
if (swarmSet == null) {
return; // already cancelled
}
// Remove before releasing synchronization, so any fresh timer ends up
// in a new set with same key
allSwarms.remove(swarmSet);
} // synchronized
// Empty the swarmSet
synchronized (swarmSet) {
Iterator it = swarmSet.iterator();
while (it.hasNext()) {
WeakReference wr = (WeakReference) it.next();
SystemTimer st = (SystemTimer) wr.get();
// it.remove(); Not necessary, we're emptying the list...
if (st != null) {
st.cancelled = true; // for safety :-)
st.timer.cancel(); // st.cancel() would just search for it again
}
} // while
} // synchronized
}
public int timerPurge() {
if (logger.isTraceEnabled()) {
logger.trace("SystemTimer#timerPurge of {}", this);
}
// Fix 39585, IBM's java.util.timer's purge() has stack overflow issue
if (isIBM) {
return 0;
}
return this.timer.purge();
}
// This creates a non-daemon timer thread. We don't EVER do this...
// /**
// * @see Timer#Timer()
// *
// * @param swarm the swarm this timer belongs to
// */
// public SystemTimer(DistributedSystem swarm) {
// this.timer = new Timer();
// this.swarm = swarm;
// addToSwarm(swarm, this);
// }
/**
* @see Timer#Timer(boolean)
* @param swarm the swarm this timer belongs to, currently must be a DistributedSystem
* @param isDaemon whether the timer is a daemon. Must be true for GemFire use.
*/
public SystemTimer(Object /* T */ swarm, boolean isDaemon) {
Assert.assertTrue(isDaemon); // we don't currently allow non-daemon timers
Assert.assertTrue(swarm instanceof InternalDistributedSystem,
"Attempt to create swarm on " + swarm); // TODO allow template class?
this.timer = new Timer(isDaemon);
this.swarm = swarm;
addToSwarm(swarm, this);
}
/**
* @param name the name to give the timer thread
* @param swarm the swarm this timer belongs to, currently must be a DistributedMember
* @param isDaemon whether the timer is a daemon. Must be true for GemFire use.
*/
public SystemTimer(String name, Object /* T */ swarm, boolean isDaemon) {
Assert.assertTrue(isDaemon); // we don't currently allow non-daemon timers
Assert.assertTrue(swarm instanceof InternalDistributedSystem,
"Attempt to create swarm on " + swarm); // TODO allow template class?
this.timer = new Timer(name, isDaemon);
this.swarm = swarm;
addToSwarm(swarm, this);
}
private void checkCancelled() throws IllegalStateException {
if (this.cancelled) {
throw new IllegalStateException("This timer has been cancelled.");
}
}
/**
* @see Timer#schedule(TimerTask, long)
*/
public void schedule(SystemTimerTask task, long delay) {
checkCancelled();
if (logger.isTraceEnabled()) {
Date tilt = new Date(System.currentTimeMillis() + delay);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
logger.trace("SystemTimer#schedule (long): {}: expect task {} to fire around {}", this, task,
sdf.format(tilt));
}
timer.schedule(task, delay);
}
/**
* @see Timer#schedule(TimerTask, Date)
*/
public void schedule(SystemTimerTask task, Date time) {
checkCancelled();
if (logger.isTraceEnabled()) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
logger.trace("SystemTimer#schedule (Date): {}: expect task {} to fire around {}", this, task,
sdf.format(time));
}
timer.schedule(task, time);
}
// Not currently used, so don't complicate things
// /**
// * @see Timer#schedule(TimerTask, long, long)
// */
// public void schedule(SystemTimerTask task, long delay, long period) {
// // TODO add debug statement
// checkCancelled();
// timer.schedule(task, delay, period);
// }
// Not currently used, so don't complicate things
// /**
// * @see Timer#schedule(TimerTask, Date, long)
// */
// public void schedule(SystemTimerTask task, Date firstTime, long period) {
// // TODO add debug statement
// checkCancelled();
// timer.schedule(task, firstTime, period);
// }
/**
* @see Timer#scheduleAtFixedRate(TimerTask, long, long)
*/
public void scheduleAtFixedRate(SystemTimerTask task, long delay, long period) {
// TODO add debug statement
checkCancelled();
timer.scheduleAtFixedRate(task, delay, period);
}
/**
* @see Timer#schedule(TimerTask, long, long)
*/
public void schedule(SystemTimerTask task, long delay, long period) {
// TODO add debug statement
checkCancelled();
timer.schedule(task, delay, period);
}
// Not currently used, so don't complicate things
// /**
// * @see Timer#scheduleAtFixedRate(TimerTask, Date, long)
// */
// public void scheduleAtFixedRate(SystemTimerTask task, Date firstTime,
// long period) {
// // TODO add debug statement
// checkCancelled();
// timer.scheduleAtFixedRate(task, firstTime, period);
// }
/**
* @see Timer#cancel()
*/
public void cancel() {
this.cancelled = true;
timer.cancel();
removeFromSwarm(this);
}
/**
* Cover class to track behavior of scheduled tasks
*
* @see TimerTask
*/
public abstract static class SystemTimerTask extends TimerTask {
protected static final Logger logger = LogService.getLogger();
/**
* This is your executed action
*/
public abstract void run2();
/**
* Does debug logging, catches critical errors, then delegates to {@link #run2()}
*/
@Override
final public void run() {
final boolean isDebugEnabled = logger.isTraceEnabled();
if (isDebugEnabled) {
logger.trace("SystemTimer.MyTask: starting {}", this);
}
try {
this.run2();
} catch (CancelException ignore) {
// ignore: TimerThreads can fire during or near cache closure
} catch (VirtualMachineError e) {
SystemFailure.initiateFailure(e);
throw e;
} catch (Throwable t) {
SystemFailure.checkFailure();
logger.warn(LocalizedMessage
.create(LocalizedStrings.SystemTimer_TIMER_TASK_0_ENCOUNTERED_EXCEPTION, this), t);
// Don't rethrow, it will just get eaten and kill the timer
}
if (isDebugEnabled) {
logger.trace("SystemTimer.MyTask: finished {}", this);
}
}
}
}