Merge branch 'master' into windows

[ardour.git] / libs / pbd / event_loop.cc

diff --git a/libs/pbd/event_loop.cc b/libs/pbd/event_loop.cc
index 687dbf558e72588501555005ec2e14b002e7fa68..b6888f0f7d09b0c9e0e96dccc9f17814f476ce9d 100644 (file)
--- a/libs/pbd/event_loop.cc
+++ b/libs/pbd/event_loop.cc
@@ -1,14 +1,32 @@
-#include <iostream>
+/*
+    Copyright (C) 2012 Paul Davis 
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
 #include "pbd/event_loop.h"
 #include "pbd/stacktrace.h"
 
 using namespace PBD;
 using namespace std;
 
-Glib::StaticPrivate<EventLoop> EventLoop::thread_event_loop;
-
 static void do_not_delete_the_loop_pointer (void*) { }
 
+Glib::Threads::Private<EventLoop> EventLoop::thread_event_loop (do_not_delete_the_loop_pointer); 
+
 EventLoop* 
 EventLoop::get_event_loop_for_thread() {
        return thread_event_loop.get ();
@@ -17,27 +35,46 @@ EventLoop::get_event_loop_for_thread() {
 void 
 EventLoop::set_event_loop_for_thread (EventLoop* loop) 
 {
-       thread_event_loop.set (loop, do_not_delete_the_loop_pointer); 
+       thread_event_loop.set (loop);
 }
 
-/** Called when a sigc::trackable that was connected to using the invalidator() macro
- *  is destroyed.
- */
 void* 
 EventLoop::invalidate_request (void* data)
 {
         InvalidationRecord* ir = (InvalidationRecord*) data;
 
+       /* Some of the requests queued with an EventLoop may involve functors
+        * that make method calls to objects whose lifetime is shorter
+        * than the EventLoop's. We do not want to make those calls if the
+        * object involve has been destroyed. To prevent this, we 
+        * provide a way to invalidate those requests when the object is
+        * destroyed.
+        *
+        * An object was passed to __invalidator() which added a callback to
+        * EventLoop::invalidate_request() to its "notify when destroyed"
+        * list. __invalidator() returned an InvalidationRecord that has been
+        * to passed to this function as data.
+        *
+        * The object is currently being destroyed and so we want to
+        * mark all requests involving this object that are queued with
+        * any EventLoop as invalid. 
+        *
+        * As of April 2012, we are usign sigc::trackable as the base object
+        * used to queue calls to ::invalidate_request() to be made upon
+        * destruction, via its ::add_destroy_notify_callback() API. This is
+        * not necessarily ideal, but it is very close to precisely what we
+        * want, and many of the objects we want to do this with already
+        * inherit (indirectly) from sigc::trackable.
+        */
+       
         if (ir->event_loop) {
-               Glib::Mutex::Lock lm (ir->event_loop->slot_invalidation_mutex());
+               Glib::Threads::Mutex::Lock lm (ir->event_loop->slot_invalidation_mutex());
                for (list<BaseRequestObject*>::iterator i = ir->requests.begin(); i != ir->requests.end(); ++i) {
-                            << ir->file << ':' << ir->line
-                            << endl;
                        (*i)->valid = false;
                        (*i)->invalidation = 0;
                }
                delete ir;
-        }
+        } 
 
         return 0;
 }