On 19/11/2014 23:07, Ganesh Sittampalam wrote:

On 13/11/2014 10:44, Simon Marlow wrote:

On 13/11/2014 07:47, Merijn Verstraaten wrote:

A new version would look like:

bracket before after thing =
    mask $ \restore -> do
      let atomicAfter = uninterruptibleMask . after
      a <- before
      r <- restore (thing a) `onException` atomicAfter a
      _ <- atomicAfter a
      return r

Slightly different versions are possible and the other relevant
bracketing functions mentioned in this thread can be treated similarly.

Since we would need this for catch too, the sensible thing to do (if we
decide to go ahead with this) would be to change the implementation of
catch in the RTS from masking the exception handler to
uninterruptibleMask.  That would mean that at least for catch there
would be no additional overhead, and it would make the modifications to
the other operations simpler in some cases.

If this isn't done in the RTS, is there a possibility of an async
exception slipping in between the exception handler starting and the
uninterruptibleMask starting?

No, because the exception handler is masked.

Cheers,
Simon

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