Re: [RFA] Make continuations per-thread.

[Vladimir Prus <vladimir@codesourcery.com>]

On Friday 02 May 2008 17:23:37 Daniel Jacobowitz wrote:
> On Fri, May 02, 2008 at 12:34:11PM +0100, Pedro Alves wrote:
> > to not make it centralized.  This is one of the things that gets much
> > better looking when we switch completelly to always-a-thread, and
> > get rid of context-switching.  I'm introducing another variable, instead of
> 
> So maybe we should do that in the FSF tree before the attached patch -
> is that feasible?
> 
> On Fri, May 02, 2008 at 03:51:10PM +0400, Vladimir Prus wrote:
> > This is only for intermediate continations. For ordinary continuations, not
> > running them when we hit a breakpoint in another thread is desirable. Why should
> > a breakpoint in some other thread abort "finish"? Note that in current gdb,
> > hitting a breakpoint in unrelated thread does not abort "next" -- say we
> > did next, inserted step resume breakpoint, and then hit breakpoint in some other
> > thread. Then, the step resume breakpoint will not be removed. If we decide to
> > continue the program, we'll eventually hit it. 
> > 
> > I don't see any problem with continuations been kept for a given thread
> > for a long time. It's not an unbounded amount of continuations -- if we get an
> > event in this thread, continuation will run, and if we don't get an event,
> > we won't add any futher continuations.
> 
> In non-stop mode, the continuation will run the first time that thread
> stops because threads only stop when there is an event.  But in
> all-stop mode the thread will be stopped with its continuations not
> yet run.
> 
> [Current thread is 1]
> finish
> [Switching to thread 2]
> Breakpoint at....
> thread 1
> finish
> 
> Now thread 1 has two finish continuations and they're at different
> threads... is it going to do something sensible?  What's sensible?

I think the sensible behaviour is the same as for "next" -- abort
whatever the operation we were doing. This means that we have to wipe
continuation inside 'proceed'. I can adjust the patch this way, but
does it make sense to you?

- Volodya