From: Patrick Hurley <phurley@...>
Date: 2006-06-20T20:28:32+09:00
Subject: Re: C Threads and Ruby

On 6/20/06, Kroeger, Simon (ext) <simon.kroeger.ext@siemens.com> wrote:
> Hi,
>
> i know the ruby interpreter isn't thread safe and
> it's not a good idea to call rb_* functions from more
> than one thread.
>
> Nevertheless, is there a way to signal the interpreter
> that i would like him to call one of my functions in a
> c extension? (from another thread)
>
> The only way i figured out so far would be to create a
> pipe, let a ruby thread sleep on the fd and put a byte
> in the queue from c the wake the thread. (good, bad, ugly?)
>
> cheers
>
> Simon
>
>

It depends what you are trying to do. I just worked up a patch to
win32-service, that does this by creating a ruby thread in the C
extension that polls against a simple integer guarded by a mutex --
when an event occurs it is signaled there and the correct call back is
spun off in yet another ruby thread. I was worried this would be
"expensive", but the rb_thread_polling method, worked like a charm.

This idea could be easily extended to allow for an event queue that
was filled by a native C thread and processed by a ruby thread. Note
that calling any rb_XXXX from anything other than the "ruby thread" is
a really bad idea.

pth