[squeak-dev] Some gotchas with #terminate and #critical:

Igor Stasenko siguctua at gmail.com
Thu Apr 30 06:40:17 UTC 2009

Currently i replacing all calls which affect the scheduling to
redirecting them to Processor, i.e. instead:
self primitiveDoSomething

Processor doSomethingWith: self.

This is to ensure, that no code, in rest of classes , except
ProcessorScheduler deals with scheduling directly.

If i change the Semaphore>>wait method in that way, then it breaks the
trick which sitting in #terminate method :

"Figure out if we are terminating the process while waiting in
			In this case, pop the suspendedContext so that we leave the ensure:
block inside
			Semaphore>>critical: without signaling the semaphore."
			(inSema == true and:[
				suspendedContext method == (Semaphore compiledMethodAt:
#critical:)]) ifTrue:[
					suspendedContext := suspendedContext home.

What you think is following alternative implementation:

critical: mutuallyExcludedBlock			
	| blockValue caught |
	caught := false.
		caught := true.
		[self wait.] ifCurtailed: [ caught:=false ].
		blockValue := mutuallyExcludedBlock value
	] ensure: [caught ifTrue: [self signal]].

avoids the need in having tricks in #terminate?

Best regards,
Igor Stasenko AKA sig.

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