[Haskell-cafe] STM, orElse and timed read from a channel

[Tomasz Zielonka]

On Mon, Nov 28, 2005 at 11:27:46PM +0000, Joel Reymont wrote:
> Folks,
> 
> How would you implement a timed read from a channel with STM? I would  
> like to return Timeout if nothing was read from a TChan in X ms.
> 
> Is this a basic two-thread timeout implementation or is there a more  
> elegant way of implementing this using `orElse`?

Here is a basic two-thread implementation:
  http://www.haskell.org/pipermail/haskell-cafe/2005-January/008303.html

The other approach I see is to create a TVar that would be updated with
current time every 0.1 s (or something like that), but that would
be rather inefficient.

You could also create a time-out manager thread (with a priority queue,
etc), so you don't have to spawn a thread for every timeout.

Best regards
Tomasz

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