javax.realtime
Class Timer

java.lang.Object
  |
  +--javax.realtime.AsyncEvent
        |
        +--javax.realtime.Timer

Direct Known Subclasses:

OneShotTimer, PeriodicTimer

public abstract class Timer

extends AsyncEvent

A Timer is a timed event that measures time relative to a given Clock. This class defines basic functionality available to all timers. Applications will generally use either PeriodicTimer to create an event that is fired repeatedly at regular intervals, of OneShotTimer, which provides the basic facilities of something that ticks along following some time line (real-time, cpu-time, user-time, simulation-time, etc.). All timers are created disabled and do nothing until start() is called.

Field Summary

protected javax.realtime.Clock	defaultClock
protected boolean	enabled
protected javax.realtime.RelativeTime	fireAfter
protected javax.realtime.AsyncEventHandler	handler
protected javax.realtime.AbsoluteTime	lastUpdated
protected boolean	started
protected javax.realtime.RelativeTime	timePassed

Fields inherited from class javax.realtime.AsyncEvent

handlersList

Constructor Summary

protected

Timer(javax.realtime.HighResolutionTime t, javax.realtime.Clock c, javax.realtime.AsyncEventHandler handler) Create a timer that fires at the given time based on the given instance of Clock and is handled by the specified handler.

Method Summary

javax.realtime.ReleaseParameters	createReleaseParameters() Create a ReleaseParameters block appropriate to the timing characteristics of this event.
void	destroy() Destroy the timer and return all possible resources to the system.
void	disable() Disable this timer, preventing it from firing.
void	enable() Re-enable this timer after it has been disabled.
javax.realtime.Clock	getClock() Gets the instance of Clock that this timer is based on.
javax.realtime.AbsoluteTime	getFireTime() Get the time at which this event will fire.
boolean	isRunning() Tests this to determine if this has been started and is in a state (enabled) such that when the given time occurs it will fire the event.
void	reschedule(javax.realtime.HighResolutionTime time) Change the schedule time for this event; can take either absolute or relative times.
void	start() Starts this time.
boolean	stop() Stops a timer that is running and changes its state to not started.

Methods inherited from class javax.realtime.AsyncEvent

addHandler, bindTo, fire, handledBy, removeHandler, setHandler, unbindTo

Methods inherited from class java.lang.Object

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

Field Detail

enabled

protected boolean enabled

started

protected boolean started

defaultClock

protected javax.realtime.Clock defaultClock

fireAfter

protected javax.realtime.RelativeTime fireAfter

handler

protected javax.realtime.AsyncEventHandler handler

timePassed

protected javax.realtime.RelativeTime timePassed

lastUpdated

protected javax.realtime.AbsoluteTime lastUpdated

Constructor Detail

Timer

protected Timer(javax.realtime.HighResolutionTime t,
                javax.realtime.Clock c,
                javax.realtime.AsyncEventHandler handler)

Create a timer that fires at the given time based on the given instance of Clock and is handled by the specified handler.

Parameters:

t - The time to fire the event. Will be converted to absolute time.

handler - The default handler to use for this event. If null, no handler is associated with it and nothing will happen when this event fires until a handler is provided.

Method Detail

createReleaseParameters

public javax.realtime.ReleaseParameters createReleaseParameters()

Create a ReleaseParameters block appropriate to the timing characteristics of this event. The default is the most pessimistic: AperiodicParameters. This is typically called by code that is setting up a handler for this event that will fill in the parts of the release parameters for which it has values, e.g, cost.

Overrides:

createReleaseParameters in class AsyncEvent

Returns:

A new ReleaseParameters object.

destroy

public void destroy()

Destroy the timer and return all possible resources to the system.

disable

public void disable()

Disable this timer, preventing it from firing. It may subsequently be re-enabled. If the timer is disabled when its fire time occurs then it will not fire. However, a disabled timer continues to count while it is disabled and if it is subsequently reabled before its fire time occures and is enabled when its fire time occurs, it will fire.

enable

public void enable()

Re-enable this timer after it has been disabled.

getClock

public javax.realtime.Clock getClock()

Gets the instance of Clock that this timer is based on.

Returns:

The instance of Clock.

getFireTime

public javax.realtime.AbsoluteTime getFireTime()

Get the time at which this event will fire.

Returns:

An instance of AbsoluteTime object representing the absolute time at which this will fire.

isRunning

public boolean isRunning()

Tests this to determine if this has been started and is in a state (enabled) such that when the given time occurs it will fire the event.

Returns:

True if the timer has been started and is in the enabled state. False, if the timer has either not been started, started and is in the disabled state, or started and stopped.

reschedule

public void reschedule(javax.realtime.HighResolutionTime time)

Change the schedule time for this event; can take either absolute or relative times.

Parameters:

time - The time to reschedule for this event firing. If null, the previous fire time is still the time at which this will fire.

start

public void start()

Starts this time. A Timer starts measuring time from when it is started.

stop

public boolean stop()

Stops a timer that is running and changes its state to not started.

Returns:

True, if this was started and enabled and stops this. False, if this was not started or disabled.