[Haskell-cafe] Concurrency strategy for 2 threads and rare events

[Edward Amsden]

If you only need one structure for communication (e.g. neither thread
needs to lock multiple things) you might consider using an IORef, and
writing/polling it with atomicModifyIORef. It's cheaper than an MVar
for the case where you don't need to lock multiple threads.

On Wed, Feb 8, 2012 at 2:45 PM, JP Moresmau <jpmoresmau at gmail.com> wrote:
> No, I meant they seem to be mainly for the use case where the reading
> thread blocks for more input, and maybe there's a simpler/more
> efficient way to quickly check if an event has occurred, that's all.
> If there isn't then a MVar it will be.
>
> JP
>
> On Wed, Feb 8, 2012 at 7:35 PM, Yves Parès <yves.pares at gmail.com> wrote:
>> Why do you think it's a lot? MVar are a teeny tiny and convenient primitive
>> of communication, and I don't see why they wouldn't suit your need.
>> Sure a throwTo would do the trick... But they're is "do the trick" and "do
>> the job", you see?
>>
>> Using STM and TVars *would* be kind of overkill.
>>
>>
>> 2012/2/8 JP Moresmau <jpmoresmau at gmail.com>
>>>
>>> Hello, I'm wondering what's the best strategy to use in the following
>>> scenario:
>>> - 2 threads
>>>  - One perform some work that will take time, possibly go on forever
>>>  - Another waits for user input (like commands from the keyboard)
>>> that affects thread 1 (causing it to stop, in the simplest case)
>>>
>>> I've read a bit on MVar and channels, but they seem to be a lot for
>>> cases where the reading thread block for input. In my case, I expect
>>> to have "something" that thread 2 updates when an event occur, and
>>> thread 1 checks it regularly. So thread 1 should not block, but should
>>> check "is there something" and there is, act on it, otherwise continue
>>> doing what it was currently doing. I suppose I could just tryTakeMVar
>>> on a MVar, but is there something more adapted to my needs?
>>>
>>> Thanks!
>>>
>>> --
>>> JP Moresmau
>>> http://jpmoresmau.blogspot.com/
>>>
>>> _______________________________________________
>>> Haskell-Cafe mailing list
>>> Haskell-Cafe at haskell.org
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>>
>>
>
>
>
> --
> JP Moresmau
> http://jpmoresmau.blogspot.com/
>
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-- 
Edward Amsden
Student
Computer Science
Rochester Institute of Technology
www.edwardamsden.com