On Tue, 19 Jan 1999 19:11:40 -0500 (EST) "Lex Spoon" <lex at cc.gatech.edu> wrote: 
>
>However, I never figured out how to preempt a process in Squeak....  If someone *does* figure it out, it would make Scamper a whole lot nicer to use.
>

Lex,

The approach I've experimented with in the past was to create a higher-priority process to do the interrupting. Below is an alternative to #fork or #forkAt: which allows more than one priority level to be chosen for a process. The priority will be adjusted according to the given time slices, effectively giving the process greater or lesser access to cpu cycles and greater or lesser interruptibility. I haven't fooled with this in some time, so I can't make any guarantees, but I seem to remember it working fairly well - the process being debugged was one of the main problems.

Cheers,
Bob


=============
'From Squeak 2.2beta of Sept 16, 1998 on 20 January 1999 at 8:39:02 pm'!

!BlockContext methodsFor: 'scheduling' stamp: 'RAA 1/20/1999 20:38'!
toggleWith: parameterList
"Run the receiver block with alternating priorities as given by <parameterList>
this allows a process to run at high priority for best speed while dropping down
to a lower priority so that the UI does not completely die. Example:

[self doSomethingLengthy] toggleWith: {6. 600. 3. 400}
"
	| newPriority removed wait parms newProcess |
	parms _ ReadStream on: parameterList.
	newProcess _ [ 
		self value. newProcess _ nil.
	] newProcess.
	[
		newProcess priority: 4; resume.
		[newProcess isNil or: [newProcess suspendedContext isNil or:
					[newProcess isInDebugger]]] whileFalse: [
			parms atEnd ifTrue: [
				parms reset.
			].
			newPriority _ parms next.
			wait _ parms next.
			removed _ Processor remove: newProcess ifAbsent: [nil].
			removed ifNotNil: [
				newProcess offList; priority: newPriority.
				newProcess resume.
			].
			(Delay forMilliseconds: wait) wait.
		].
	] forkAt: 8.
	^newProcess! !
=============