[Vm-dev] Unexpected #resume behavior

[Jaromir Matas]

Hi Eliot, all,

I'm baffled by this example:

p := [Semaphore new wait] fork.
Processor yield.
p resume explore

I expected to get an error but the process just gets out of the semaphore and finishes happily.

#resume comment says:
                Primitive. Allow the process that the receiver represents to continue. Put
                 the receiver in line to become the activeProcess.  *Fail if the receiver is
                 already waiting in a queue (in a Semaphore or ProcessScheduler)*.  Fail if
                the receiver's suspendedContext is not a context.

The following works as expected - p sits at the semaphore:

p := [Semaphore new wait] fork.
Processor yield.
p explore

This works as well (with the new VM) - p backs up and sits before the wait:

p := [Semaphore new wait] fork.
Processor yield.
p suspend.
p explore

And this works too indeed - p sits at the semaphore again after suspend.

p := [Semaphore new wait] fork.
Processor yield.
p suspend.
p resume explore


Is this a bug? Or is the comment just outdated?

I've been trying to figure out possible ways how to prevent resuming a process being terminated (other than setting its suspendedContext to nil) and this unexpected behavior gave me a real hard time :)

Many thanks for your help.

Best regards,
Jaromir
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