Java tutorial
/************************************************************************************** * Copyright (C) 2008 EsperTech, Inc. All rights reserved. * * http://esper.codehaus.org * * http://www.espertech.com * * ---------------------------------------------------------------------------------- * * The software in this package is published under the terms of the GPL license * * a copy of which has been included with this distribution in the license.txt file. * **************************************************************************************/ package com.espertech.esper.timer; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.util.concurrent.ScheduledFuture; import java.util.concurrent.TimeUnit; /** * Timer task to simply invoke the callback when triggered. */ final class EPLTimerTask implements Runnable { private static final Log log = LogFactory.getLog(EPLTimerTask.class); private final TimerCallback callback; private ScheduledFuture<?> future; private boolean isCancelled; protected boolean _enableStats; protected long _lastDrift; protected long _maxDrift; protected long _totalDrift; protected long _invocationCount; public EPLTimerTask(TimerCallback callback) { this.callback = callback; _enableStats = false; _lastDrift = 0; _maxDrift = 0; _totalDrift = 0; _invocationCount = 0; } public final void run() { if (!isCancelled) { if (_enableStats) { // If we are called early, then delay will be positive. If we are called late, then the delay will be negative. // NOTE: don't allow _enableStats to be set until future has been set if (future != null) { _lastDrift = Math.abs(future.getDelay(TimeUnit.MILLISECONDS)); } _totalDrift += _lastDrift; _invocationCount++; if (_lastDrift > _maxDrift) _maxDrift = _lastDrift; } try { callback.timerCallback(); } catch (Throwable t) { log.error("Timer thread caught unhandled exception: " + t.getMessage(), t); } } } protected void resetStats() { _invocationCount = 0; _lastDrift = 0; _totalDrift = 0; _maxDrift = 0; } public void setCancelled(boolean cancelled) { isCancelled = cancelled; } public void setFuture(ScheduledFuture<?> future) { this.future = future; } }