Prep to remove Semaphore argument to primitiveSignalAtTick (#270)

* Prepare to remove Semaphore argument from primitiveSignalAtTick

The TimingSemaphore is always the same object, so can be stored in the VM
object registry instead of the timing primitive taking it as an argument.
Moving it to the standard VM registry will simplify the timer code.

* Initialize timing semaphore on boot

* Fix lockup on SUnit delay test

Core/Object Arts/Dolphin/Base/BootSessionManager.cls

@@ -23,7 +23,8 @@ initializeSystemPackage
 	We cannot reinitialize all the base system classes after re-load as the class initialize methods are not
 	all safe to re-run. Therefore we must do this selectively."
 
-	STBPrefix initialize!
+	STBPrefix initialize.
+	Delay initializeTimingSemaphore!
 
 keepAlive
 	"We stay alive until explicitly terminated."

Core/Object Arts/Dolphin/Base/Delay.cls

@@ -2,35 +2,36 @@
 
 Object subclass: #Delay
 	instanceVariableNames: 'duration resumptionTime waitSemaphore'
-	classVariableNames: 'AccessProtect Current DefaultResolution HighestResolution ImageClock LowestResolution Pending Resolution TicksPerMillisecond TimingProcess TimingSemaphore'
+	classVariableNames: 'AccessProtect Current DefaultResolution HighestResolution ImageClock LowestResolution Pending Resolution TimingProcess TimingSemaphore'
 	poolDictionaries: ''
 	classInstanceVariableNames: ''!
 Delay guid: (GUID fromString: '{87B4C47B-026E-11D3-9FD7-00A0CC3E4A32}')!
 Delay addClassConstant: 'DefaultResolution' value: 15625!
-Delay comment: '<Delay>s are used to introduce timed pauses in the execution of a <Process>.  Delays can be constructed that specify a duration using the instance creation messages #forMilliseconds: and #forSeconds:, or an absolute time based on the millisecond clock value (#untilMilliseconds:). Once constructed a Delay responds to the #wait message by suspending the active process for the desired duration, or until the desired absolute time is reached. 
+Delay comment: '<Delay>s are used to introduce timed pauses in the execution of a <Process>.  Delays can be constructed that specify a duration using the instance creation messages #forMicroseconds:, #forMilliseconds:, and #forSeconds:, or an absolute time based on the millisecond clock value (#untilMilliseconds:). Once constructed a Delay responds to the #wait message by suspending the active process for the desired duration, or until the desired absolute time is reached. 
 
 Delays are "one-shot" in that once they have expired further attempts to #wait on them will return immediately. This applies even if the Delay was originally constructed to wait for a time interval rather than an absolute time. Therefore if one wishes to delay a process in a loop, new Delay instances should be created as required inside the loop. It is often more convenient to use the ProcessorScheduler>>sleep: message, which wraps up the creation and wait operations inside a convenience message.
 
-Delays are not hard real time, in that the requested delay is the minimum time period that will elapse before the process is restarted. The VM will make a best effort to reschedule the process after the desired delay by using the high-resolution multimedia clock (accurate to 1 millisecond) and high priority threads, but there may still be an arbitrary additional delay before the Process actually restarts depending on the load on the host machine and the relative priority of the Dolphin thread in relation to other OS threads, and the waiting Process in relation to other Processes. There is also some context switching and other processing overhead that will increase the average minimum Delay to a period greater than 1mS, though (depending on machine speed) it should be quite close. 
+Delays are not hard real time, in that the requested delay is the minimum time period that will elapse before the process is restarted. The VM will make a best effort to reschedule the process after the desired delay by using the high-resolution multimedia clock (which is accurate to at best 1 millisecond) and high priority threads, but there may still be an arbitrary additional delay before the Process actually restarts depending on the load on the host machine and the relative priority of the Dolphin thread in relation to other OS threads, and the waiting Process in relation to other Processes. There is also some context switching and other processing overhead that will increase the average minimum Delay to a period greater than 1mS, though (depending on machine speed) it should be quite close. 
 
 Example usage:
 	5 timesRepeat: [(Delay forMilliseconds: 500) wait. Sound bell]
 
 Instance Variables:
-	duration		<integer> number of milliseconds to delay Process
-	resumptionTime	<integer> value of millisecond clock at which to resume
-	waitSemaphore	<Semaphore> on which to delay Process
+	duration			<integer> number of microseconds to delay when #wait is sent
+	resumptionTime	<integer> value of VM microsecond clock at which to resume
+	waitSemaphore		<Semaphore> on which to wait
 
 Class Variables:
-	AccessProtect	<Semaphore> protects the class variables in critical regions
-	Current		<Delay> the next scheduled Delay (or nil if none)
-	ImageClock	<integer> millisecond clock value on last image save - used to reschedule delays on image restart
-	Pending		<SortedCollection> of waiting <Delay>s in ascending order of resumptionTime.
-	Resolution	<integer> resolution of millisecond clock, minimum 1
-	TimerMax		<integer> maximum delay recordable with the timing device.  Longer delays are achieved by repeatedly rescheduling until the desired period has elapsed.
-	TimingProcess	<Process> responsible for waking up delayed processes on expiry of Delay
-	TimingSemaphore	<Semaphore> Signalled by the VM at requested times, governing the operation of the TimingProcess.
-'!
+	AccessProtect		<Semaphore>; protects the class variables in critical regions.
+	Current			<Delay>; the next scheduled Delay (or nil if none).
+	DefaultResolution	The default resolution of Delays; <integer> number of microseconds.
+	HighestResolution	The highest requestable resolution for Delays; <integer> number of microseconds.
+	ImageClock		The <integer> microsecond clock value on last image save - used to rebase pending Delays on image restart.
+	LowestResolution	The lowest requestable resolution for Delays; <integer> number of microseconds.
+	Pending			<SortedCollection> of waiting <Delay>s in ascending order of resumptionTime.
+	Resolution			The current <integer> resolution of Delays specified in microseconds.
+	TimingProcess		<Process> responsible for waking up delayed processes on expiry of Delays.
+	TimingSemaphore	<Semaphore> signalled by the VM at requested times, governing the operation of the TimingProcess.'!
 !Delay categoriesForClass!Kernel-Processes! !
 !Delay methodsFor!
 
@@ -146,7 +147,7 @@ schedule
 	we own) to be signalled, which will mean that the assignment to Current
 	must happen before the timing process accesses it. The timing Process
 	will not restart until we exit our critical section."
-	Processor signal: TimingSemaphore afterMilliseconds: self getDuration // 1000.
+	self class signal: TimingSemaphore afterMilliseconds: self getDuration // 1000.
 
 	Current := self!
 
@@ -234,13 +235,13 @@ aboutToIdle
 cancelTimer
 	"Private - Cancel any previously registered timer."
 
-	Processor signal: nil afterMilliseconds: 0.
+	self signal: nil afterMilliseconds: 0.
 !
 
 clampResolution: anInteger
 	"Private - As we are using multimedia timers at present, the shortest delay we
 	can request is 1mS, so we clamp the requested resolution to 1000 as there is no point
-	setting a resolution higher than we can use."
+	setting a resolution higher than we can achieve."
 
 	^anInteger max: 1000!
 
@@ -253,7 +254,7 @@ forkTimingProcess
 
 	AccessProtect critical: [	
 		self cancelTimer.
-		TimingSemaphore isNil ifTrue: [self initializeTimingSemaphore].
+		self initializeTimingSemaphore.
 		TimingProcess isNil ifFalse: [TimingProcess terminate].
 		Current isNil ifFalse: [Current snooze].		"put current back into Pending"
 		self scheduleNext.
@@ -272,6 +273,10 @@ forMicroseconds: anInteger
 	message #wait. The actual delay achieved will depend on the current resolution of the OS
 	timer, which has a maximum resolution on current Windows systems of at best 500uS."
 
+	"Implementation Note: The Dolphin VM's timer is implemented on top of Windows multimedia
+	timers, and these have a maximum resolution of 1mS. Any delay requested shorter than 1mS
+	will result in a wait of at least 1mS."
+
 	^self new duration: anInteger!
 
 forMilliseconds: anInteger
@@ -323,13 +328,13 @@ initialize
 			[Pending := SortedCollection
 						sortBlock: [:delay1 :delay2 | delay1 resumptionTime <= delay2 resumptionTime].
 			Current := nil].
-	TimingSemaphore isNil ifTrue: [self initializeTimingSemaphore]!
+	self initializeTimingSemaphore!
 
 initializeTimingSemaphore
-	"Private - Create the timing semaphore used for communication with the VM's
-	timer services."
+	"Private - Create the timing semaphore used for communication with the VM's timer services."
 
-	TimingSemaphore := Semaphore new!
+	TimingSemaphore isNil ifTrue: [TimingSemaphore := Semaphore new].
+	VMLibrary default registryAt: #TimingSemaphore put: TimingSemaphore!
 
 keepAlive
 	"Private - Ensure that there is a timing process, and that it is in a runnable state."
@@ -447,6 +452,20 @@ scheduleNext
 		ifTrue: [Current := nil]
 		ifFalse: [Pending removeFirst schedule]!
 
+signal: aSemaphore afterMilliseconds: anInteger 
+	"Private - Request that the VM signal aSemaphore as soon as possible after the
+	the specified millisecond delay. Cancel any existing request if aSemaphore is 
+	not actuall a Semaphore (typically nil). If anInteger <= 0, then the Semaphore
+	is signalled immediately.
+
+	Primitive failure results:
+		0 - anInteger is not a SmallInteger
+		2 - anInteger was greater than the maximum Delay which can be requested.
+		3 - OS refused to set timer (try KernelLibrary>>getLastError)"
+
+	<primitive: 100>
+	^self primitiveFailed!
+
 timingProcess
 	"Private - Answer the <Process> which is used to manage the list of pending Delays."
 
@@ -482,6 +501,7 @@ untilMilliseconds: millisecondTime
 !Delay class categoriesFor: #resolution:do:!operations!public! !
 !Delay class categoriesFor: #resolution:set:!helpers!public! !
 !Delay class categoriesFor: #scheduleNext!initializing!private! !
+!Delay class categoriesFor: #signal:afterMilliseconds:!private!processes-synchronising! !
 !Delay class categoriesFor: #timingProcess!initializing!private! !
 !Delay class categoriesFor: #untilMilliseconds:!instance creation!public! !
 

Core/Object Arts/Dolphin/Base/DolphinClasses.st

@@ -102,7 +102,7 @@ Object subclass: #DeferredValue
 	classInstanceVariableNames: ''!
 Object subclass: #Delay
 	instanceVariableNames: 'duration resumptionTime waitSemaphore'
-	classVariableNames: 'AccessProtect Current DefaultResolution HighestResolution ImageClock LowestResolution Pending Resolution TicksPerMillisecond TimingProcess TimingSemaphore'
+	classVariableNames: 'AccessProtect Current DefaultResolution HighestResolution ImageClock LowestResolution Pending Resolution TimingProcess TimingSemaphore'
 	poolDictionaries: ''
 	classInstanceVariableNames: ''!
 Object subclass: #DiskVolumeInformation

Core/Object Arts/Dolphin/Base/ProcessorScheduler.cls

@@ -462,20 +462,6 @@ setHighestPriority: priority activeProcess: aProcess
 	activeProcess := aProcess.
 	pendingReturns := Semaphore new!
 
-signal: aSemaphore afterMilliseconds: anInteger 
-	"Private - Request that the VM signal aSemaphore as soon as possible after the
-	the specified millisecond delay. Cancel any existing request if aSemaphore is 
-	not actuall a Semaphore (typically nil). If anInteger <= 0, then the Semaphore
-	is signalled immediately.
-
-	Primitive failure results:
-		0 -	anInteger is not a SmallInteger
-		2 -  anInteger was greater than the maximum Delay which can be requested.
-		3 -	OS refused to set timer (try KernelLibrary>>getLastError)"
-
-	<primitive: 100>
-	^self primitiveFailed!
-
 sleep: anInteger 
 	"Delay the current active process for at least anInteger milliseconds."
 
@@ -693,7 +679,6 @@ zeroDivide: interruptArg
 !ProcessorScheduler categoriesFor: #processesAt:!processes-accessing!public! !
 !ProcessorScheduler categoriesFor: #returnValue:toFrame:!callbacks!must not strip!private! !
 !ProcessorScheduler categoriesFor: #setHighestPriority:activeProcess:!development!initializing!private! !
-!ProcessorScheduler categoriesFor: #signal:afterMilliseconds:!private!processes-synchronising! !
 !ProcessorScheduler categoriesFor: #sleep:!processes-synchronising!public! !
 !ProcessorScheduler categoriesFor: #stackOverflow:!interrupts-handling!private! !
 !ProcessorScheduler categoriesFor: #suspendActive!processes-changing state!public! !

Core/Object Arts/Dolphin/Base/VMLibrary.cls

@@ -682,6 +682,7 @@ initialize
 				at: #LARGE_INTEGER put: 147;
 				at: #UINT_PTR put: 148;
 				at: #INT_PTR put: 149;
+				at: #TimingSemaphore put: 150;
 				isImmutable: true;
 				shrink;
 				yourself)!