On Mon, Jun 14, 2010 at 11:20 PM, Don Stewart <d...@galois.com> wrote: > > v.dijk.bas: >> Hello, >> >> I've a short question about interruptible operations. In the following >> program is it possible for 'putMVar' to re-throw asynchronous >> exceptions even when asynchronous exception are blocked/masked? >> >> newEmptyMVar >>= \mv -> block $ putMVar mv x >> >> The documentation in Control.Exception about interruptible >> operations[1] confused me: >> >> "Some operations are interruptible, which means that they can receive >> asynchronous exceptions even in the scope of a block. Any function >> which may itself block is defined as interruptible..." >> > > I think the best definition of interruptible is in this paper: > > www.haskell.org/~simonmar/papers/async.pdf > > Section 5.3 >
Thanks for the link Don! Next time I will re-read the paper before asking ;-) The definition makes it clear indeed: "Any operation which may need to wait indefinitely for a resource (e.g., takeMVar) may receive asynchronous exceptions even within an enclosing block, BUT ONLY WHILE THE RESOURCE IS UNAVAILABLE" So I guess I can update my threads package to use MVars again. Nice! because they were a bit faster in an informal benchmark I performed some time ago. A later quote from 5.3 emphasizes the definition even more: "...an interruptible operation cannot be interrupted if the resource it is attempting to acquire is always available..." The following darcs patch makes the definition of interruptibility in the documentation in Control.Exception a bit clearer in this regard: http://bifunctor.homelinux.net/~bas/doc-interruptibility.dpatch Regards, Bas _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
