[Haskell-cafe] Waiting for async exception (and nothing else)

David Turner dct25-561bs at mythic-beasts.com
Fri Aug 7 16:22:33 UTC 2015


Hi Robin,

Thanks for the pointer. I can't find the thread in question after a bit of
googling, but suspect you mean using System.Mem.StableName? From the docs,

Stable names are reclaimed by the runtime system when they are no longer
> needed.


which seems like it's not going to work. It does point me towards the
related Foreign.StablePtr which seems like it should do what I want.

Cheers,

David


On 6 August 2015 at 21:53, Robin Palotai <palotai.robin at gmail.com> wrote:

> You can make a stable name for the MVar which will prevent the rts from
> collecting it. Google it, there was a thread about this with Simon Marlow.
>
> Robin
>
> On Wed, Aug 5, 2015, 12:43 PM David Turner <dct25-561bs at mythic-beasts.com>
> wrote:
>
>> Hi,
>>
>> Is there an elegant way to have a thread wait for an async exception but
>> nothing else? I tend to do something like
>>
>>     forever $ threadDelay 1000000000
>>
>> but this seems like a bit of a hack. Waiting on an otherwise-unused MVar
>> or doing 'atomically retry' don't work because GHC kills them off straight
>> away.
>>
>> The context is when using an API that only has a 'withMyThingy' wrapper
>> and no explicit openMyThingy and closeMyThingy alternatives. Perhaps that's
>> an API problem and the only way to work around this is with something a bit
>> hacky?
>>
>> Cheers,
>>
>>
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>
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