RE: [boost] Boost.Thread request: event object

From: Hurd, Matthew (hurdm_at_[hidden])
Date: 2004-01-26 16:50:12

> On Behalf Of Sean Kelly
> Sent: Tuesday, 27 January 2004 8:08 AM
> To: Boost mailing list
> Subject: Re: [boost] Boost.Thread request: event object
> 
> On Mon, 26 Jan 2004, Daryle Walker wrote:
> >
> > On 1/25/04 5:28 PM, "Matthew Hurd" <matt_at_[hidden]> wrote:
> >
> > [SNIP]
> > > But it does look neat.
> > >
> > > if (lock lk(guard_,t))
> > >
> > > and would release automagically as the if scope rolls out.  I'm
> warming to
> > > it.
> > >
> > > if (lock lk(guard_,false), lk.acquire_timed(t) )
> > >
> > > would do the trick if it was valid c++, but I'm pretty sure it
isn't.
> >
> > You're right, you CANNOT do:
> >
> > if ( Type  Object1( XXX ) )  // possibly with ", Object2( YYY )",
etc.
> >
> > You can only do
> >
> > if ( Type  Object = Whatever )
> >
> > or the "scoping in advance" trick you already showed.
> 
> It looks like we're moving towards a shared_ptr type design for this
lock
> object.  But the simple cases still work:
> 
> if( lock l = guard )
> 
> or:
> 
> if( lock l = lock(guard,t))
> 
> or better yet:
> 
> if( lock const& l = lock(guard,t))

I like this last one, though I suspect I'll end up with 

        if (lock lk(guard,t))

in my code as it will be the first thing I'll think of.

Not sure I understand where we are with events:

Can we wrap the acceptance of events from the OS, win32 in particular,
into a scoped acquisition without introducing race or performance
problems?

I'm not suggesting an event mechanism just being able to use the OS
efficiently.

Syntax for mutexes:

        mutex guard;

        if (lock lk(guard,t)) {

        }

Syntax for other resource offering:

        socket_event	e;
        if (lock lk(e,t)) {

        }

Lock seems a bad name.  Any good short names for an "acquirer" that
would make sense for a socket, file i/o, timer, mutex?

Under the covers on win32 the "acquirer" for the resource just uses
WaitForSingleObject.

Does this work for you?

Regards,

Matt Hurd.

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