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Re^5: AnyEvent: How to protect critical sections?

by Corion (Pope)
on May 17, 2011 at 21:03 UTC ( #905367=note: print w/ replies, xml ) Need Help??


in reply to Re^4: AnyEvent: How to protect critical sections?
in thread AnyEvent: How to protect critical sections?

This cannot work - if you expect ->lock() to block until the semaphore is released, how can it continue to execute the remaining code elsewhere?

I would either use a plain boolean variable, like you did in your first case, and keep the timer running:

my $critical; sub on_timer { if (! $critical) { ... }; };

... or manually restart the timer when it's allowed to restart again. The guard values returned from creating a timer allow you to conveniently stop a timer.


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Re^6: AnyEvent: How to protect critical sections?
by saintmike (Vicar) on May 17, 2011 at 21:25 UTC
    This cannot work - if you expect ->lock() to block until the semaphore is released, how can it continue to execute the remaining code elsewhere?
    The same way that $condvar->recv() blocks and lets code run elsewhere.

    Only problem: $condvar->recv() cannot be called from within a callback, according to the AnyEvent docs:

    "Note that doing a blocking wait in a callback is not supported by any event loop, that is, recursive invocation of a blocking "->recv" is not allowed,".

      Indeed, if you would need to do that, you need to use real threads (e.g. Coro) - the limitation of condvars is partially lifted under Coro.

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