Proposal: Add tryReadChan to Chan

[Duncan Coutts]

On Wed, 2010-12-01 at 01:28 +0100, Mitar wrote:
> Hi!
> 
> On Wed, Dec 1, 2010 at 12:37 AM, Duncan Coutts
> <duncan.coutts at googlemail.com> wrote:
> > I've not looked at it in detail, I just wanted to mention that I would
> > be nervous about accepting this unless someone like Simon Marlow reads
> > it over and decides the locking works.
> 
> I think he did?
> 
> http://hackage.haskell.org/trac/ghc/ticket/4535#comment:2

Oh sorry. When I said I've not looked at it in detail, that included not
reading the ticket, just your email :-)

> > This sort of stuff is notoriously subtle, for example Neil Mitchell is
> > convinced we have a deadlock bug in the current Chan code (without using
> > isEmptyChan), but he cannot pin it down (but using his own trivial Chan
> > impl cures the deadlock).
> 
> Can you give me a link to a test code which fails with current
> implementation of Chan? Or does this problems with pinning it down
> means that there wasn't yet simple code which would show the problem?

You can ask him, since it was some time ago when he mentioned it, but I
think narrowing it down was part of the problem.

Duncan