[cells-gtk-devel] Multithreading patch, v2

[Peter Hildebrandt]

Here's a new version of my patch

http://www.washbear-network.de/peterblog/wp-content/uploads/2007/12/cells-gtk-threading-121207.patch

Again, it builds against the CVS version.

I did quite a bit of testing and I would call it "stable" for my  
purposes.  I'd appreciate if you guys could try to break it and let me  
know if you succeeded.

This patch includes an answer to the question of thread safety.  In short,  
it wraps every call to gdk/gtk in a thread-safe lock (with-gdk-threads  
...), thus creating thread safety at the lowest level while at the same  
time not blocking longer than necessary.

Cheers,
Peter

-----


The longer story (in case anyone is interested):

First and foremost, I modified with-gdk-threads to simulate a recursive  
lock, that is, if you call with-gdk-threads from within a with-gdk-thread,  
nothing bad happens (i.e. no dead lock).  Additionally, since we know that  
all callbacks from gtk-main are from within a lock, everything from the  
gtk-main thread gets a free pass (the overhead boils down to a pointer  
comparisson).

This enables us to use with-gdk-threads generously.  In other words, every  
call to a gtk/gdk library function is now automatically wrapped and can  
thus be used from any thread.  At least with test-gtk, there seems to be  
hardly any performance penalty, and it makes it ultimately easy to deal  
with threading -- just ignore it.

Additionally I fixed start-gtk-main.  Now in case it has forgotton the  
handle of the gtk-main thread, it checks the environment and reconnects if  
it finds one.  This way, a running cells-gtk even survives complete  
package recompilations etc.


Here's another bit of sample code for the repl: Hello World, interactive  
style:

;; fire up a hello world window
(start-win 'gtk-app :title "Hello World" :kids (c-in nil))

;; create a little playground
(defparameter vbox (first (push (mk-vbox :kids (c-in nil)) (kids *))))

;; make a label
(push (mk-label :text (c-in "Heyho!")) (kids vbox))

;; have some fun
(push (mk-button :label "Click me!" :on-clicked (callback (w e d) (print  
:hello-world))) (kids vbox))

;; now something exciting
(push (mk-label :text (c-in "") :md-name :counter) (kids vbox))
(push (mk-button :label "Count" :on-clicked (let ((c 0))
                                                (callback (w e d)
                                                   (setf (text (fm-other  
:counter))
                                                         (format nil "~r"  
(incf c)))))) (kids vbox))