Re: [paragui-users] Puzzled newbie question

[Alexander Pipelka]

Am Mon, 2002-04-29 um 19.43 schrieb Andrew Ford:
> &^*#&*$ Canada Post broke my trusty little smp celeron
> :(

shh..

> There are a couple of things I've been wondering
> about.
> When you're pumping things into the event queue for
> transport between widgets, isn't this introducing a
> lot of latency, and therefore taking the "snap" out of
> what should be a very responsive gui?

I think the overhead isn't too bad because it is a very responsive gui.
But you're right: things could be faster.

> I guess this
> won't be the case when we switch over to libsig++...

Right. No problem at all anymore.

> About thread safety, what happens if a user-defined
> widet does something like requests a blit or a sound
> in an event handler?  Locking every widget every time
> seems like a heavy-weight concurrency solution for a
> problem that likely won't be run into very often.  Is
> high multi-threaded performance that critical?  I
> don't think I'd want my application calling the gui
> from a large number of threads anyway.  There are
> alternatives like locking the gui for a single thread
> at a time, or optionally running the gui in its own
> thread and having asynchronous communication between
> it and the rest of the app (although this would
> probably be full of latency).  Locking isn't that
> cheap as far as I know, and having a mutex for every
> widget probably adds up to a fair amount of memory, is
> this true?

Maybe.
But i just asked myself if it's neccessary to use mutices at all!
Considering the eventqueue is thread-safe there is no need for a lock
because there will be exactly one event at once.

If the user want's to pump events to the queue from different threads
the user should introduce something like a queue-lock.

I will check that and compare performance :))

>   I'm willing to take a look at reference counters and
> make a proposal if you like (I know I still owe you
> something for PG_FileArchive, I've been meaning to get
> to it :) )

No problem at all.
But you're welcome to do so,... ;)

Alex