event_loop.cc

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/*
    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;

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 ();
}

void 
EventLoop::set_event_loop_for_thread (EventLoop* loop) 
{
        thread_event_loop.set (loop);
}

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::Threads::Mutex::Lock lm (ir->event_loop->slot_invalidation_mutex());
                for (list<BaseRequestObject*>::iterator i = ir->requests.begin(); i != ir->requests.end(); ++i) {
                        (*i)->valid = false;
                        (*i)->invalidation = 0;
                }
                delete ir;
        } 

        return 0;
}