[chuck-users] implementing a "wait for signal with timeout"

Robert Poor rdpoor at gmail.com
Mon Jun 8 17:45:36 EDT 2009

So as presaged, this is a schematic of how I've implemented "wait for  
signal or timeout".

First, I have a "PermaShred" class: a call to:


calls a do_process() function (which you subclass) in its own thread,  
er, shred.  When your do_process() function returns, the shred is  
returned to a resource pool, making it available to the next call to  
PermaShred.run_process().  That's my basic mechanism for not leaking  

To build wait_for_signal_or_timeout(event E, time T) functionality, I  
spawn, er, spork a PermaShred "watchdog" that waits until time T  
arrives, and then does a E.broadcast().  In the meantime, the caller  
simply blocks on event E.  As a result, the caller will return if  
anyone does a broadcast on E OR if the watchdog process times out.

It's a bit convoluted -- among other nuances, the watchdog shred needs  
to be careful about signaling after the caller has moved on -- but it  
does the job.  And it doesn't leak memory after an initial pool of  
PermaShred objects have been allocated.

If anyone wants to see the code, let me know.

- Rob

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