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/*
* Filename: ApproximateClock.java
*
* Copyright 2000-2001 by iPlanet/Sun Microsystems, Inc.,
* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
* All rights reserved.
*
* This software is the confidential and proprietary information
* of iPlanet/Sun Microsystems, Inc. ("Confidential Information").
* You shall not disclose such Confidential Information and shall
* use it only in accordance with the terms of the license
* agreement you entered into with iPlanet/Sun Microsystems.
*/
/**
* <BR> <I>$Source: /cvs/glassfish/appserv-commons/src/java/com/sun/enterprise/util/ApproximateClock.java,v $</I>
* @author $Author: tcfujii $
* @version $Revision: 1.4 $ $Date: 2007/05/05 05:32:06 $
*/
package com.sun.enterprise.util;
/**
* ApproximateClock returns the approximate time instead of
* calling (the expensive) System.currentTimeMillis().
* The method getTime() returns the approximate time. The correctness
* of the time depends on the delay that is passed in the constructor.
* A background thread updates the time every 'delay' milliseconds.
* The exact time can still be obtained by using the getActualTime()
* method.
*/
//Bug
import java.util.logging.Logger;
import java.util.logging.Level;
import com.sun.logging.LogDomains;
//Bug
public class ApproximateClock
implements Runnable
{
//Bug
static Logger _logger=LogDomains.getLogger(LogDomains.UTIL_LOGGER);
//Bug
private long sleepTime = 1000;
private long now;
private Thread timerThread;
private long[] time;
private int index = 0;
private int nextIndex;
/**
* Creates an ApproximateClock.
* @param delay The time interval to update time
*/
public ApproximateClock (long delay) {
setDelay(delay);
timerThread = new Thread(this, "ApproximateClock");
timerThread.setDaemon(true);
time = new long[2];
time[0] = System.currentTimeMillis();
timerThread.start();
}
/**
* Returns the actual/correct time. Same as calling System.currentTimeMillis()
* @return The current time (Same as System.currentTimeMillis())
*/
public long getActualTime() {
nextIndex = 1 - index;
time[nextIndex] = System.currentTimeMillis();
index = nextIndex;
return time[index];
}
/**
* Returns the approximate time. Returns the time that was updated
* (utmost) 'delay' milliseconds earlier.
* @return The approximate time
*/
public long getTime() {
return time[index];
}
/**
* Set the delay for updating the time.
* @param The delay (in milliseconds) between updates.
*/
public void setDelay(long delay) {
sleepTime = (delay < 1) ? 1 : delay;
}
/**
* Returns the delay
* @return The delay (in milliseconds) between updates.
*/
public long getDelay() {
return sleepTime;
}
/**
* The thread's run method to update the time periodically
*/
public final void run() {
while (true) {
try {
getActualTime();
Thread.sleep(sleepTime);
} catch (InterruptedException inEx) {
break;
}
}
}
public static void main(String[] args)
throws Exception
{
int count = 100000000;
long time=0, t1=0, t2 = 0;
t1 = System.currentTimeMillis();
for (int i=0; i<count; i++) {
time = System.currentTimeMillis();
}
t2 = System.currentTimeMillis();
//Bug System.out.println("sys.currentTimeMillis() took: " + ((t2 - t1) / 1000.0) + " seconds " + time);
_logger.log(Level.FINE,"sys.currentTimeMillis() took: " + ((t2 - t1) / 1000.0) + " seconds " + time);
t1 = System.currentTimeMillis();
ApproximateClock clock = new ApproximateClock(3000);
for (int i=0; i<count; i++) {
time = clock.getTime();
}
t2 = System.currentTimeMillis();
//Bug System.out.println("clcok.getTime() took: " + ((t2 - t1) / 1000.0) + " seconds " + time);
_logger.log(Level.FINE,"clock.getTime() took: " + ((t2 - t1) / 1000.0) + " seconds " + time);
}
}
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