Coming from Squeak, I'm used to its class libraryand I didn't find any
equivalent of the UUID and Monitor classes.
UUID is implemented as part of the platform layer of Magritte, though
with the time-based UUIDv1 algorithm if I remember correctly.
I think if you're using only Monitor>>#critical: the equivalent is
RecursionLock. For more complicated stuff, Semaphore has additional
methods #notify (like #signal, but never increment the count above 0)
and #notifyAll (to wake up all processes). For example, this example of
Squeak monitors
BoundedCounter>>dec
monitor critical: [
monitor waitUntil: [value > self lowerBound].
value = self upperBound ifTrue: [monitor signalAll].
value _ value - 1].
BoundedCounter>>inc
monitor critical: [
monitor waitUntil: [value < self upperBound].
value = self lowerBound ifTrue: [monitor signalAll].
value _ value + 1].
could be written like this:
BoundedCounter>>initialize
mutex := RecursionLock new.
condition := Semaphore new.
BoundedCounter>>dec
| oldValue |
[mutex critical: [
value > self lowerBound ifTrue: [
value = self upperBound ifTrue: [condition notifyAll].
value _ value - 1. ^self]].
condition wait] repeat
BoundedCounter>>inc
[mutex critical: [
value < self upperBound ifTrue: [
value = self lowerBound ifTrue: [condition notifyAll].
value _ value + 1. ^self]].
condition wait] repeat
(I'm pretty sure that the Monitor class in Squeak has race conditions
that may leave the monitor in an unstable state if the involved
processes are terminated; see the complications in
Semaphore>>#critical:. That's why I never got to implementing it in GNU
Smalltalk).
Paolo
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