[Barrelfish-users] Timed wait on condition variable

[Georgios Varisteas]

Hi Zaheer,

The simplest way I can think of, is to use a differed event for the timeout. Check out lib/barrelfish/deferred.c and the deferred_event_register() function. You can also use it as inspiration for implementing an extension to the current conditionals variable API. The same lib contains functionality for periodic events.

cheers,
Georgios

________________________________________
From: Chothia  Zaheer [zchothia at student.ethz.ch]
Sent: Wednesday, December 19, 2012 13:53
To: barrelfish-users at lists.inf.ethz.ch
Subject: [Barrelfish-users] Timed wait on condition variable

Hello,

Crescando has a synchronized queue with the typical get/put operations, which wait on a condition variable if the queue is either empty or full.
These operations can optionally be passed a timeout.  Barrelfish's concurrency primitives don't currently support timeouts, so I am writing to enquire how this may be ported.

Conceptually it isn't too difficult to implement thread_cond_timedwait: extend the wait queues with a timeout and use an alarm to unblock the thread.  In practice though it seems this would involve quite some effort (single-shot timer mechanism, spinlocks with bounded wait).  Any thoughts or ideas on a simpler approach?

Thanks and kind regards,

--Zaheer

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