org.erights.e.extern.timer
Class Timer

java.lang.Object
  |
  +--org.erights.e.extern.timer.Timer

public class Timer

extends Object

Untamed: The master control object for timers and clocks.

Conceptually, there's one ephemeral (non-persistent) Timer per vat, but actually there's just one per JVM, where each delayed event remembers which vat it came from, and, when its time comes due, queues that event on that vat. Conceptually, when a vat is shut down, its per-vat-Timer is destroyed with it, freeing all its delayed events. Actually, nothing in the per-jvm-Timer is effected by a vat shutdown, but when these events come due, the attempt to queue them on their originating (and now, shut down) vat will silently fail.

If you build a virtual persistent Timer on top of the ephemeral Timer + org.erights.e.extern.persist.SturdyRefMaker#onRevival, be sure to cancel the onRevival when the timer event is received, not when it is sent. If you cancel the onRevival when the timer event is sent, and if your vat checkpoints after it is sent and before its received, and if your vat then revives from that checkpoint, then your event will be undelivered and lost. To do the cancellation on reception, your virtualization should wrap the real event with a persistent cancelling event.

Author:

Chip Morningstar, Mark S. Miller

Field Summary

private TimerThread	myThread Our timer thread
private static Timer	TheTimer The single permitted instance of this class

Constructor Summary

private

Timer() Private constructor.

Method Summary

void	__printOn(TextWriter out) Enabled:
Clock	every(long resolution, TickReactor target) Enabled: Creates a new clock.
long	now() Enabled: The current time in absolute millis
static Timer	theTimer() Enabled: XXX Return the single permitted Timer object.
Timeout	whenAlarm(long absMillis, Runnable target) Enabled: Sets an alarm to occur after the specified time, unless cancelled.
Ref	whenPast(long absMillis, Object target, String verb, Object[] args) Enabled: When the current time is >= absMillis, evaluate target <- verb(args...).
Ref	whenPast(long absMillis, Thunk target) Enabled: Sets a timeout to occur after the specified time.

Methods inherited from class java.lang.Object

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

Field Detail

TheTimer

private static final Timer TheTimer

The single permitted instance of this class

myThread

private TimerThread myThread

Our timer thread

Constructor Detail

Timer

private Timer()

Private constructor. Just start the timer thread.

Method Detail

now

public long now()

Enabled: The current time in absolute millis

whenAlarm

public Timeout whenAlarm(long absMillis,
                         Runnable target)

Enabled: Sets an alarm to occur after the specified time, unless cancelled.

After the alarm expires, target is eventually sent the run() message.

Parameters:

absMillis - When should the alarm go off?

target - Object to be informed when the time comes

Returns:

A Timeout object that can be used to cancel or identify the timeout.

whenPast

public Ref whenPast(long absMillis,
                    Object target,
                    String verb,
                    Object[] args)

Enabled: When the current time is >= absMillis, evaluate
target <- verb(args...).

Remembers the SendingContext info.

Returns:

a promise for the result of the send.

whenPast

public Ref whenPast(long absMillis,
                    Thunk target)

Enabled: Sets a timeout to occur after the specified time.

After the timer expires, target is eventually sent the run() message.

Parameters:

absMillis - When to time out

target - A thunk to be informed when the time comes

Returns:

A promise for the result of evaluating the thunk.

every

public Clock every(long resolution,
                   TickReactor target)

Enabled: Creates a new clock. The new clock begins life stopped with its tick count at zero.

Parameters:

resolution - The clock tick interval

target - Object to be sent tick notifications

Returns:

A new Clock object according to the given parameters

See Also:

org.erights.e.extern.timer.TickReactor

__printOn

public void __printOn(TextWriter out)
               throws IOException

Enabled:

IOException

theTimer

public static Timer theTimer()

Enabled: XXX Return the single permitted Timer object.

There shouldn't be a single one.