
DIRECTORY
Rope
;

CommTimer: CEDAR DEFINITIONS ~ {

Timer: TYPE ~ REF TimerObject;
TimerObject: TYPE;

Event: TYPE ~ RECORD [
ref: REF EventObject,
gen: CARD		-- generation number, guarantees uniqueness
];
nullEvent: Event ~ [NIL, 0];
IsNullEvent: PROC [e: Event] RETURNS [BOOL] ~ INLINE { RETURN[e.ref = NIL] };
EventObject: TYPE;
CreateTimer: PROC [grainSizeMsec: INT, expectedWaitMsec: INT] RETURNS [t: Timer];

DestroyTimer: PROC [t: Timer, doEvents: BOOL ¬ FALSE];

GrainSizeMsec: PROC [t: Timer] RETURNS [grainSizeMsec: INT];

MsecSinceCreated: PROC [t: Timer] RETURNS [msecSinceCreated: INT];
EventProc: TYPE ~ PROC [clientData: REF];

ScheduleEvent: PROC [t: Timer, waitMsec: INT, proc: EventProc, clientData: REF ¬ NIL]
RETURNS [e: Event];

CancelEvent: PROC [t: Timer, e: Event];

MsecUntilOccurs: PROC [t: Timer, e: Event] RETURNS [msecUntilOccurs: INT];
Error: ERROR[codes: LIST OF ATOM, msg: Rope.ROPE];
}.
   F  
CommTimer.mesa
Copyright Ó 1988, 1991 by Xerox Corporation.  All rights reserved.
Demers, October 9, 1990 5:04 pm PDT
Timers and Events
Timer Manipulation
Create a timer with the given granularity, optimized for event waits of no more than the expected interval.
Destroy a timer.  It is expensive to drop one on the floor.
If doEvents is TRUE, each pending event goes off as the timer is destroyed.
Event Manipulation
Proc to be called (at high priority) when an event occurs.  It is the client's responsibility to ensure that this returns quickly, by doing a FORK and SetPriority if necessary.
Arrange for proc[clientData] to be called at high priority after waitMsec has passed.
Cancel a scheduled event.  If the event has already occurred this is a no-op.
Approximate.
Errors
Failures:
$badGrainSize
$staleEvent
$staleTimer
...
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