[Haskell-cafe] Fwd: Safe TCP accept loop

[Ömer Sinan Ağacan]

Hi Sumit,

> Does this method of handling an accept loop still need masking of async
> exceptions

You need to mask async exceptions between `accept()` and cleanup action
registration, because an exception in between these operations will cause the
socket to leak.

You can take a look at warp's accept loop:

https://github.com/yesodweb/wai/blob/master/warp/Network/Wai/Handler/Warp/Run.hs#L211

Hope this helps,

Ömer

2017-10-24 2:08 GMT+03:00 Sumit Raja <sumitraja at gmail.com>:
> Hi,
>
> I sent this to beginners but got no responses so I'm hoping someone
> here can help. I’ve looked at
> https://wiki.haskell.org/Concurrency_demos/Graceful_exit and used(2)
> Using throwTo without the use of block and unblock. It runs on 8.2.1
> with my limited testing. I can’t find out much about what the  > 7.x
> GHC replacement for block/unblock is other than mask. What does the
> unblock do in acceptConnections'?
>
> Does this method of handling an accept loop still need masking of
> async exceptions ? If so where does this need to be done?
>
> I've got a version with async running for my specific application
> (https://bitbucket.org/sumitraja/hvrr/src/6927216597a35a9a0d7f2e55cca83fa5b7279ee0/hvrr-comms/src/Network/VRR/Server/TCP/TCPAcceptLoop.hs)
> but I don't know if I need to unmask at any point so was hoping for
> some guidance.
>
>
> Thanks
>
>
>
> Sumit
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