Re: thread cancellation, take 2

[Ludovic Courtès]

Hi,

"Julian Graham" <address@hidden> writes:

> What's useful about this is that you can have several resources at
> different levels of nesting that need to be cleaned up at cancellation
> time, but you only need to worry about pushing and popping handlers
> within your own scope.  If people feel that managing the entire list
> at once is more Scheme-y, though, I can change it.

I find it more elegant to use closures to that end.  I.e., when
installing a handler, you'd write something like this:

  (let ((cleanup (thread-cleanup-procedure (current-thread))))
    (set-thread-cleanup-procedure! (current-thread)
                                   (lambda ()
                                     ;; invoke previous handler
                                     (if (procedure? cleanup)
                                         (cleanup))
                                     ;; clean up...
                                     )))

There's a race here in case multiple threads try to change the cleanup
procedure associated with that particular thread at the same time, but I
suppose it is not an issue in practice.

> Great -- I'll deal with the paperwork, add tests, and clean up the
> code as you've suggested.  I'll send the revisions to you offline, if
> that's okay.

Please post updated patches on the list as well so others get a chance
to review them.

Thanks!

Ludovic.