[Haskell-cafe] STM, IO and event loops

Joel Reymont joelr1 at gmail.com
Sun Nov 27 06:12:23 EST 2005


I'm trying to build an event-driven system that includes multiple  
event channels. I would have one channel for network events and  
another one for events sent by other threads. I would like to use STM  
and `orElse` to poll the various event channels.

Is there a reasonably safe way to do this with STM and IO?

The network side of things currently times out after a given number  
of seconds if no input is available but can also throw exceptions.  
I'm having a hard time figuring out how to wrap this in STM.

There's another alternative that I can think of...

My poker bots are launched in separate threads but do not talk to  
each other right now. They just receive events from the network. I  
would like a poker bot to tell others to stop playing and exit, for  
example. I guess I could build poker bots with an event loop that  
reads from a TChan but... I would then need twice as many threads  
since each bot has a socket associated with it and one thread per bot  
would need to read from the socket and push events into the TChan.

Are there any facilities in Haskell that can poll a set of 10k  
descriptors and retrieve input from the first available?

I don't know if I should be concerned with launching 20k threads vs.  
10k threads but it seems that disassociating bots from the network  
has some positive effects. I could compose packets by hand in the  
interpreter and feed them to the TChan by hand to test individual  
bots, for example.

Any advice is appreciated!

	Thanks, Joel


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