From: Nobuyoshi Nakada <nobu@...>
Date: 2007-05-16T11:46:16+09:00
Subject: Re: rb_yield(), semaphores and 'break'

Hi,

At Wed, 16 May 2007 11:25:05 +0900,
Pete wrote in [ruby-talk:251756]:
> Here's the sitch...  I'm working on an extension to handle real-time
> MIDI, and my concept is to have an 'each' method for the MidiIn class
> that will just feed events to a block as they arrive.  This is implemented
> by the 'each' (C++) function making the block available to a callback
> function, which is itself called by the Midi handler for each arriving
> event, and does a rb_yield().  The original function is meanwhile just
> sitting on a semaphore, and will return when that is released.

What semaphore?  ruby's or C++'s?

> This all works fine, as the semaphore can be released either by a
> particular yield return value or by a timeout, *unless* there is
> a 'break' in the invoked block.  The base problem is that -- although
> I can catch the break with an 'ensure' for instance -- the top-level
> 'each' is still sitting on the semaphore until that is released,
> but as the break has *already* popped the stack, when that function
> *does* terminate it just segfaults!

Have you tried rb_ensure()?

-- 
Nobu Nakada