xchat-guile and threads

[Zeeshan Ali (Khattak)]

Hi all!
   I am looking back at the code i wrote[1] some years back and I
don't seem to recall why i did somethings the way i did. One thing
that i can't remember is why I am doing threads and locking in there.
Given some thought, i called reading python plugin code a bit before
writing xchat-guile so i looked at the source and found this comment:

/* Thread support
 * ==============
 *
 * The python interpreter has a global interpreter lock. Any thread
 * executing must acquire it before working with data accessible from
 * python code. Here we must also care about xchat not being
 * thread-safe. We do this by using an xchat lock, which protects
 * xchat instructions from being executed out of time (when this
 * plugin is not "active").
 *
 * When xchat calls python code:
 *   - Change the current_plugin for the executing plugin;
 *   - Release xchat lock
 *   - Acquire the global interpreter lock
 *   - Make the python call
 *   - Release the global interpreter lock
 *   - Acquire xchat lock
 *
 * When python code calls xchat:
 *   - Release the global interpreter lock
 *   - Acquire xchat lock
 *   - Restore context, if necessary
 *   - Make the xchat call
 *   - Release xchat lock
 *   - Acquire the global interpreter lock
 *
 * Inside a timer, so that individual threads have a chance to run:
 *   - Release xchat lock
 *   - Go ahead threads. Have a nice time!
 *   - Acquire xchat lock
 *
 */

  So in those very early days of my flying lessons, I might have just
assumed I need to do the same in guile plugin as well. If someone
knows some better reason I did what I did, please let me know before i
start removing all the ugly thread stuff and learning the importance
of it the hard way.

-- 
Regards,

Zeeshan Ali (Khattak)
FSF member#5124

[1] 
http://gitorious.org/projects/xchat-guile/repos/mainline/blobs/master/guile.c
     
http://gitorious.org/projects/xchat-guile/repos/mainline/blobs/master/plugin-system.scm