net.sourceforge.jtds.util
Class TimerThread

java.lang.Object
  java.lang.Thread
      net.sourceforge.jtds.util.TimerThread

All Implemented Interfaces:

java.lang.Runnable

public class TimerThread

extends java.lang.Thread

Simple timer class used to implement login and query timeouts.

This thread runs as a Daemon thread to ensure that the java VM will exit correctly when normal execution is complete.

It provides both a singleton implementation and a default constructor for the case when more than one timer thread is desired.

Version:

$Id: TimerThread.java,v 1.5.2.3 2010-05-17 09:16:06 ickzon Exp $

Author:

Alin Sinpalean, Mike Hutchinson

Nested Class Summary

static interface	TimerThread.TimerListener Interface to be implemented by classes that request timer services.
private static class	TimerThread.TimerRequest Internal class associating a login or query timeout value with a target TimerListener.

Field Summary

private static TimerThread	instance Singleton instance.
private long	nextTimeout Time when the first request time out should occur.
private java.util.LinkedList	timerList List of TimerRequests to execute, ordered by time.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

TimerThread()
Construct a new TimerThread instance.

Method Summary

boolean	cancelTimer(java.lang.Object handle) Remove a redundant timer before it expires.
static TimerThread	getInstance() Singleton getter.
boolean	hasExpired(java.lang.Object handle) Check whether a timer has expired.
void	run() Execute the TimerThread main loop.
java.lang.Object	setTimer(int timeout, TimerThread.TimerListener l) Add a timer request to the queue.
static void	stopTimer() Completely stops the timer and its underlying Java thread, discarding all pending timeouts.
private void	updateNextTimeout() Internal method that updates the value of nextTimeout.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getContextClassLoader, getName, getPriority, getThreadGroup, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setName, setPriority, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

instance

private static TimerThread instance

Singleton instance.

timerList

private final java.util.LinkedList timerList

List of TimerRequests to execute, ordered by time.

nextTimeout

private long nextTimeout

Time when the first request time out should occur.

Constructor Detail

TimerThread

public TimerThread()

Construct a new TimerThread instance.

Method Detail

getInstance

public static TimerThread getInstance()

Singleton getter.

run

public void run()

Execute the TimerThread main loop.

setTimer

public java.lang.Object setTimer(int timeout,
                                 TimerThread.TimerListener l)

Add a timer request to the queue.

The queue is ordered by time so that the head of the list is always the first timer to expire.

Parameters:

timeout - the interval in milliseconds after which the timer will expire

l - TimerListener to be notified on timeout

Returns:

a handle to the timer request, that can later be used with cancelTimer

cancelTimer

public boolean cancelTimer(java.lang.Object handle)

Remove a redundant timer before it expires.

Parameters:

handle - handle to the request to be removed from the queue (a TimerRequest instance)

Returns:

true if timer had not expired

stopTimer

public static void stopTimer()

Completely stops the timer and its underlying Java thread, discarding all pending timeouts. Any subsequent invocation of getInstance() will restart the timer.

hasExpired

public boolean hasExpired(java.lang.Object handle)

Check whether a timer has expired.

Parameters:

handle - handle to the request to be checked for expiry (a TimerRequest instance)

Returns:

true if timer has expired

updateNextTimeout

private void updateNextTimeout()

Internal method that updates the value of nextTimeout.