From: nobu.nokada@...
Date: 2004-12-27T10:02:44+09:00
Subject: Re: [PATCH] Long-Standing Bug in the Readline extension

Hi,

At Mon, 27 Dec 2004 09:30:16 +0900,
Brent Roman wrote in [ruby-talk:124508]:
> If Thread.critical is set when readline is invoked, readline_event() 
> will still schedule any other thread that becomes ready.  This can
> cause another thread, that was not in a critical section, to interrupt 
> one that was.  So, now we have a thread becoming "critical" 
> asynchronously.  This leads to some very weird lockups -- some of which 
> have been reported on this mailing list.

It would have to return immediately if rb_thread_critical is
set.

> I think a quick fix might be to remove the unconditional 
> rb_thread_schedule() call from readline_event.  But, a better
> fix is to remove the readline_event() function entirely.
> 
> So, how will we avoid blocking other threads during keyboard reads?
> Replace readline_event() with this:
> 
> static int
> readline_getc (ignored)
>    FILE *ignored;
> {
>    VALUE string = rb_funcall (rb_stdin, rb_intern("sysread"),
> 						1, INT2FIX(1));
>    return RSTRING(string)->ptr[0];  //single byte read
> }
> 
> 
> We redefine the function that GNU readline uses to read the input stream
> to be one based on Ruby's IO#sysread and let Ruby's own IO class
> deal with all its threading nastyness.

Do you mean to set it to rl_getc_function?

-- 
Nobu Nakada