Your own timer : StopWatch « Development Class « Java
Your own timer
/*
* Copyright (c) 1998-2002 Carnegie Mellon University. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
* ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY
* NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
import java.util.Vector;
public class Timer {
int interval;
boolean periodic;
boolean isExpired = false;
static TimerManager manager = new TimerManager ();
long deadline;
Timer next, prev;
public Timer () {
}
public void set (int msecDelay, boolean periodic) {
interval = msecDelay;
this.periodic = periodic;
isExpired = false;
if (!manager.isAlive ()) {
System.err.println ("TimerManager: restarting");
manager = new TimerManager ();
}
manager.register (this, System.currentTimeMillis () + msecDelay);
}
public int getInterval () {
return interval;
}
public boolean getPeriodic () {
return periodic;
}
public void cancel () {
manager.delete (this);
}
protected void alarm () {
}
public boolean expired () {
return isExpired;
}
/*
public static void main (String[] args) {
for (int i=0; i<args.length; ++i) {
boolean periodic = (args[i].charAt (0) == 'p');
if (periodic) args[i] = args[i].substring (1);
new TestTimer (args[i], Integer.parseInt (args[i]), periodic);
}
while (true) Thread.yield ();
}
*/
}
class TimerManager extends Thread {
Timer first, last;
/*
static ThreadGroup rootThreadGroup;
static {
rootThreadGroup = Thread.currentThread().getThreadGroup();
while (rootThreadGroup.getParent() != null)
rootThreadGroup = rootThreadGroup.getParent();
}
*/
public TimerManager () {
super (/* rootThreadGroup, */ "Timer Manager");
setDaemon (true);
start ();
}
public synchronized void register (Timer t, long deadline) {
t.deadline = deadline;
delete (t); // just in case it's already registered
//System.err.println ("TimerManager: set " + t + " to go off at " + deadline);
insertion:
{
for (Timer u = first; u != null; u = u.next) {
if (t.deadline < u.deadline) {
if (u.prev != null)
u.prev.next = t;
else
first = t;
t.prev = u.prev;
t.next = u;
u.prev = t;
break insertion;
}
}
if (last != null) {
last.next = t;
t.prev = last;
t.next = null;
last = t;
} else {
first = last = t;
}
}
//System.err.println ("TimerManager: waking up background thread");
notifyAll ();
}
public synchronized void delete (Timer t) {
if (t.next != null)
t.next.prev = t.prev;
if (t.prev != null)
t.prev.next = t.next;
if (t == last)
last = t.prev;
if (t == first)
first = t.next;
t.next = null;
t.prev = null;
}
static final int FOREVER = 60000; // wake up at least every 60 seconds
public synchronized void run () {
while (true) {
try {
//System.err.println ("TimerManager: awake");
if (first == null) {
//System.err.println ("TimerManager: waiting forever");
wait (FOREVER);
//System.err.println ("TimerManager: woke up");
}
else {
Timer t = first;
long now = System.currentTimeMillis ();
if (t.deadline <= now) {
// System.err.println ("TimerManager: timer " + t + " just went off at " + now);
try {
t.isExpired = true;
t.alarm ();
} catch (Throwable e) {
if (e instanceof ThreadDeath)
throw (ThreadDeath)e;
else
e.printStackTrace ();
}
if (t.periodic) {
register (t, now + t.interval);
}
else {
delete (t);
}
}
else {
//System.err.println ("TimerManager: waiting for " + (t.deadline - now) + " msec");
wait (t.deadline - now);
//System.err.println ("TimerManager: woke up");
}
}
} catch (InterruptedException e) {}
}
}
}
/*
class TestTimer extends Timer {
String message;
public TestTimer (String message, int millisec, boolean periodic) {
this.message = message;
set (millisec, periodic);
}
public void alarm () {
System.out.println (message);
}
}
*/
