cleanup up cleanup at session destruction; clarify the meaning of 3 signals (DropReferences & Destroyed in libardour ; CatchDeletion in the GTK UI); clarify ownership of objects (session no longer pays attention to DropReferences for objects that it is considered to own, such as routes, sources, etc); fix up MIDI parsing and a couple of other places by correcting syntax for return of values from a boost::signals2::signal (possible danger elsewhere to be checked)

git-svn-id: svn://localhost/ardour2/branches/3.0@6389 d708f5d6-7413-0410-9779-e7cbd77b26cf

40 files changed, 176 insertions, 144 deletions

diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 59a282fe1d..ae9c1f58a5 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -570,11 +570,11 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 
 	/* named selections */
 
-	NamedSelection* named_selection_by_name (std::string name);
-	void add_named_selection (NamedSelection *);
-	void remove_named_selection (NamedSelection *);
+	boost::shared_ptr<NamedSelection> named_selection_by_name (std::string name);
+	void add_named_selection (boost::shared_ptr<NamedSelection>);
+	void remove_named_selection (boost::shared_ptr<NamedSelection>);
 
-	template<class T> void foreach_named_selection (T& obj, void (T::*func)(NamedSelection&));
+	template<class T> void foreach_named_selection (T& obj, void (T::*func)(boost::shared_ptr<NamedSelection>));
 	PBD::Signal0<void> NamedSelectionAdded;
 	PBD::Signal0<void> NamedSelectionRemoved;
 
@@ -1287,7 +1287,7 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 	/* NAMED SELECTIONS */
 
 	mutable Glib::Mutex named_selection_lock;
-	typedef std::set<NamedSelection *> NamedSelectionList;
+	typedef std::set<boost::shared_ptr<NamedSelection> > NamedSelectionList;
 	NamedSelectionList named_selections;
 
 	int load_named_selections (const XMLNode&);
diff --git a/libs/ardour/ardour/session_handle.h b/libs/ardour/ardour/session_handle.h
index 87c6fb6670..87de244e42 100644
--- a/libs/ardour/ardour/session_handle.h
+++ b/libs/ardour/ardour/session_handle.h
@@ -34,6 +34,7 @@ class SessionHandleRef : public PBD::ScopedConnectionList
   protected:
 	ARDOUR::Session&          _session;
 	virtual void session_going_away ();
+	virtual void insanity_check ();
 };
 
 class SessionHandlePtr
diff --git a/libs/ardour/audio_diskstream.cc b/libs/ardour/audio_diskstream.cc
index f8dc553ae0..fb225671e9 100644
--- a/libs/ardour/audio_diskstream.cc
+++ b/libs/ardour/audio_diskstream.cc
@@ -1505,7 +1505,7 @@ AudioDiskstream::transport_stopped (struct tm& when, time_t twhen, bool abort_ca
 				continue; /* XXX is this OK? */
 			}
 
-			region->GoingAway.connect_same_thread (*this, boost::bind (&Diskstream::remove_region_from_last_capture, this, boost::weak_ptr<Region>(region)));
+			region->DropReferences.connect_same_thread (*this, boost::bind (&Diskstream::remove_region_from_last_capture, this, boost::weak_ptr<Region>(region)));
 
 			_last_capture_regions.push_back (region);
 
diff --git a/libs/ardour/audio_playlist.cc b/libs/ardour/audio_playlist.cc
index 3379868d60..1ecba28653 100644
--- a/libs/ardour/audio_playlist.cc
+++ b/libs/ardour/audio_playlist.cc
@@ -102,10 +102,6 @@ AudioPlaylist::AudioPlaylist (boost::shared_ptr<const AudioPlaylist> other, nfra
 
 AudioPlaylist::~AudioPlaylist ()
 {
-	drop_references ();
-
-	/* drop connections to signals */
-
 	_crossfades.clear ();
 }
 
diff --git a/libs/ardour/automation_list.cc b/libs/ardour/automation_list.cc
index 3543f8b51f..3ecf3f0172 100644
--- a/libs/ardour/automation_list.cc
+++ b/libs/ardour/automation_list.cc
@@ -112,7 +112,6 @@ AutomationList::AutomationList (const XMLNode& node, Evoral::Parameter id)
 
 AutomationList::~AutomationList()
 {
-	drop_references ();
 }
 
 boost::shared_ptr<Evoral::ControlList>
diff --git a/libs/ardour/coreaudiosource.cc b/libs/ardour/coreaudiosource.cc
index bbb0d8ca89..1b3a77bc39 100644
--- a/libs/ardour/coreaudiosource.cc
+++ b/libs/ardour/coreaudiosource.cc
@@ -90,7 +90,6 @@ CoreAudioSource::init_cafile ()
 
 CoreAudioSource::~CoreAudioSource ()
 {
-	drop_references ();
 }
 
 int
diff --git a/libs/ardour/diskstream.cc b/libs/ardour/diskstream.cc
index a37323de84..7004ef1ed5 100644
--- a/libs/ardour/diskstream.cc
+++ b/libs/ardour/diskstream.cc
@@ -148,7 +148,7 @@ Diskstream::set_route (Route& r)
 	non_realtime_input_change ();
 	set_align_style_from_io ();
 
-	_route->GoingAway.connect_same_thread (*this, boost::bind (&Diskstream::route_going_away, this));
+	_route->Destroyed.connect_same_thread (*this, boost::bind (&Diskstream::route_going_away, this));
 }
 
 void
@@ -340,7 +340,7 @@ Diskstream::use_playlist (boost::shared_ptr<Playlist> playlist)
 		}
 
 		_playlist->Modified.connect_same_thread (playlist_connections, boost::bind (&Diskstream::playlist_modified, this));
-		_playlist->GoingAway.connect_same_thread (playlist_connections, boost::bind (&Diskstream::playlist_deleted, this, boost::weak_ptr<Playlist>(_playlist)));
+		_playlist->DropReferences.connect_same_thread (playlist_connections, boost::bind (&Diskstream::playlist_deleted, this, boost::weak_ptr<Playlist>(_playlist)));
 		_playlist->RangesMoved.connect_same_thread (playlist_connections, boost::bind (&Diskstream::playlist_ranges_moved, this, _1));
 	}
 
diff --git a/libs/ardour/internal_send.cc b/libs/ardour/internal_send.cc
index 368eff2be4..4a4823a29f 100644
--- a/libs/ardour/internal_send.cc
+++ b/libs/ardour/internal_send.cc
@@ -43,7 +43,7 @@ InternalSend::InternalSend (Session& s, boost::shared_ptr<MuteMaster> mm, boost:
 
 	set_name (sendto->name());
 
-	_send_to->GoingAway.connect_same_thread (*this, boost::bind (&InternalSend::send_to_going_away, this));
+	_send_to->DropReferences.connect_same_thread (*this, boost::bind (&InternalSend::send_to_going_away, this));
 	_send_to->NameChanged.connect_same_thread (*this, boost::bind (&InternalSend::send_to_name_changed, this));
 }
 
diff --git a/libs/ardour/ladspa_plugin.cc b/libs/ardour/ladspa_plugin.cc
index bbd29e960e..7abcca2718 100644
--- a/libs/ardour/ladspa_plugin.cc
+++ b/libs/ardour/ladspa_plugin.cc
@@ -144,8 +144,6 @@ LadspaPlugin::~LadspaPlugin ()
 	deactivate ();
 	cleanup ();
 
-	drop_references ();
-
 	/* XXX who should close a plugin? */
 
         // dlclose (module);
diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index 6c593a869a..39bd8d75a7 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -181,8 +181,6 @@ LV2Plugin::~LV2Plugin ()
 	deactivate ();
 	cleanup ();
 
-	drop_references ();
-
 	slv2_instance_free(_instance);
 	slv2_value_free(_name);
 	slv2_value_free(_author);
diff --git a/libs/ardour/midi_diskstream.cc b/libs/ardour/midi_diskstream.cc
index 17c1404358..18d3bc5ce3 100644
--- a/libs/ardour/midi_diskstream.cc
+++ b/libs/ardour/midi_diskstream.cc
@@ -1024,7 +1024,7 @@ MidiDiskstream::transport_stopped (struct tm& /*when*/, time_t /*twhen*/, bool a
 				continue; /* XXX is this OK? */
 			}
 
-			region->GoingAway.connect_same_thread (*this, boost::bind (&Diskstream::remove_region_from_last_capture, this, boost::weak_ptr<Region>(region)));
+			region->DropReferences.connect_same_thread (*this, boost::bind (&Diskstream::remove_region_from_last_capture, this, boost::weak_ptr<Region>(region)));
 
 			_last_capture_regions.push_back (region);
 
diff --git a/libs/ardour/midi_playlist.cc b/libs/ardour/midi_playlist.cc
index a8e60ec866..789c91b236 100644
--- a/libs/ardour/midi_playlist.cc
+++ b/libs/ardour/midi_playlist.cc
@@ -71,9 +71,6 @@ MidiPlaylist::MidiPlaylist (boost::shared_ptr<const MidiPlaylist> other, nframes
 
 MidiPlaylist::~MidiPlaylist ()
 {
-	drop_references ();
-
-	/* drop connections to signals */
 }
 
 template<typename Time>
diff --git a/libs/ardour/midi_ui.cc b/libs/ardour/midi_ui.cc
index 70be1f345d..aa81ff2068 100644
--- a/libs/ardour/midi_ui.cc
+++ b/libs/ardour/midi_ui.cc
@@ -89,6 +89,8 @@ MidiControlUI::change_midi_ports ()
 bool
 MidiControlUI::midi_input_handler (IOCondition ioc, MIDI::Port* port)
 {
+	DEBUG_TRACE (DEBUG::MidiIO, string_compose ("something happend on  %1\n", port->name()));
+
 	if (ioc & ~IO_IN) {
 		return false;
 	}
diff --git a/libs/ardour/named_selection.cc b/libs/ardour/named_selection.cc
index a829c44a50..4bcc3f3b72 100644
--- a/libs/ardour/named_selection.cc
+++ b/libs/ardour/named_selection.cc
@@ -52,8 +52,6 @@ NamedSelection::NamedSelection (string n, PlaylistList& l)
 		(*i)->set_name (new_name);
 		(*i)->use();
 	}
-
-	NamedSelectionCreated (this);
 }
 
 NamedSelection::NamedSelection (Session& session, const XMLNode& node)
@@ -101,8 +99,9 @@ NamedSelection::NamedSelection (Session& session, const XMLNode& node)
 NamedSelection::~NamedSelection ()
 {
 	for (PlaylistList::iterator i = playlists.begin(); i != playlists.end(); ++i) {
-		(*i)->release ();
+		/* XXX who really owns these? us or the session? */
 		(*i)->drop_references ();
+		(*i)->release ();
 	}
 }
 
diff --git a/libs/ardour/plugin_insert.cc b/libs/ardour/plugin_insert.cc
index c2bf7f3562..a85cc1ee86 100644
--- a/libs/ardour/plugin_insert.cc
+++ b/libs/ardour/plugin_insert.cc
@@ -130,7 +130,6 @@ PluginInsert::set_count (uint32_t num)
 
 PluginInsert::~PluginInsert ()
 {
-	drop_references ();
 }
 
 void
diff --git a/libs/ardour/port_insert.cc b/libs/ardour/port_insert.cc
index 044230e1f7..dee661db41 100644
--- a/libs/ardour/port_insert.cc
+++ b/libs/ardour/port_insert.cc
@@ -61,7 +61,6 @@ PortInsert::PortInsert (Session& s, boost::shared_ptr<MuteMaster> mm, const XMLN
 
 PortInsert::~PortInsert ()
 {
-	drop_references ();
 }
 
 void
diff --git a/libs/ardour/region.cc b/libs/ardour/region.cc
index d706421c39..57d887f6a6 100644
--- a/libs/ardour/region.cc
+++ b/libs/ardour/region.cc
@@ -109,7 +109,7 @@ Region::Region (boost::shared_ptr<Source> src, nframes_t start, nframes_t length
 	_sources.push_back (src);
 	_master_sources.push_back (src);
 
-	src->GoingAway.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(src)));
+	src->DropReferences.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(src)));
 
 	assert(_sources.size() > 0);
 	_positional_lock_style = AudioTime;
@@ -338,7 +338,6 @@ Region::Region (boost::shared_ptr<Source> src, const XMLNode& node)
 Region::~Region ()
 {
 	DEBUG_TRACE (DEBUG::Destruction, string_compose ("Region %1 destructor @ %2\n", _name, this));
-	drop_references ();
 }
 
 void
@@ -1416,7 +1415,12 @@ void
 Region::source_deleted (boost::weak_ptr<Source>)
 {
 	_sources.clear ();
-	cerr << "Send drop ref signal from region " << ' ' << this << endl;
+
+	/* this is a very special case: at least one of the region's
+	   sources has bee deleted, so invalidate all references to
+	   ourselves.
+	*/
+
 	drop_references ();
 }
 
@@ -1586,14 +1590,14 @@ Region::use_sources (SourceList const & s)
 
 	for (SourceList::const_iterator i = s.begin (); i != s.end(); ++i) {
 		_sources.push_back (*i);
-		(*i)->GoingAway.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(*i)));
+		(*i)->DropReferences.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(*i)));
 		unique_srcs.insert (*i);
 	}
 
 	for (SourceList::const_iterator i = s.begin (); i != s.end(); ++i) {
 		_master_sources.push_back (*i);
 		if (unique_srcs.find (*i) == unique_srcs.end()) {
-			(*i)->GoingAway.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(*i)));
+			(*i)->DropReferences.connect_same_thread (*this, boost::bind (&Region::source_deleted, this, boost::weak_ptr<Source>(*i)));
 		}
 	}
 }
diff --git a/libs/ardour/return.cc b/libs/ardour/return.cc
index 991c6ae7d1..c2c227769d 100644
--- a/libs/ardour/return.cc
+++ b/libs/ardour/return.cc
@@ -67,7 +67,6 @@ Return::Return (Session& s, const XMLNode& node, bool internal)
 
 Return::~Return ()
 {
-	drop_references ();
 }
 
 XMLNode&
diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index c652023e2c..09e38eaa86 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -792,6 +792,7 @@ Route::add_processor (boost::shared_ptr<Processor> processor, ProcessorList::ite
 			// XXX: do we want to emit the signal here ? change call order.
 			processor->activate ();
 		}
+
 		processor->ActiveChanged.connect_same_thread (*this, boost::bind (&Session::update_latency_compensation, &_session, false, false));
 
 		_output->set_user_latency (0);
diff --git a/libs/ardour/route_group.cc b/libs/ardour/route_group.cc
index 2f946dd620..d59ec82236 100644
--- a/libs/ardour/route_group.cc
+++ b/libs/ardour/route_group.cc
@@ -76,7 +76,7 @@ RouteGroup::add (boost::shared_ptr<Route> r)
 	routes->push_back (r);
 
 	r->join_route_group (this);
-	r->GoingAway.connect_same_thread (*this, boost::bind (&RouteGroup::remove_when_going_away, this, boost::weak_ptr<Route> (r)));
+	r->DropReferences.connect_same_thread (*this, boost::bind (&RouteGroup::remove_when_going_away, this, boost::weak_ptr<Route> (r)));
 	
 	_session.set_dirty ();
 	changed (); /* EMIT SIGNAL */
diff --git a/libs/ardour/send.cc b/libs/ardour/send.cc
index 1bb03642d0..e4fbf3efba 100644
--- a/libs/ardour/send.cc
+++ b/libs/ardour/send.cc
@@ -64,7 +64,6 @@ Send::Send (Session& s, boost::shared_ptr<MuteMaster> mm, const XMLNode& node, i
 
 Send::~Send ()
 {
-	drop_references ();
 }
 
 void
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index a062efee8d..2e48ed0215 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -388,32 +388,19 @@ Session::destroy ()
 	
 	AudioDiskstream::free_working_buffers();
 
-	DEBUG_TRACE (DEBUG::Destruction, "delete named selections\n");
-	for (NamedSelectionList::iterator i = named_selections.begin(); i != named_selections.end(); ) {
-		NamedSelectionList::iterator tmp;
+	/* tell everyone who is still standing that we're about to die */
+	drop_references ();
 
-		tmp = i;
-		++tmp;
+	/* tell everyone to drop references and delete objects as we go */
 
-		delete *i;
-		i = tmp;
-	}
+	DEBUG_TRACE (DEBUG::Destruction, "delete named selections\n");
+	named_selections.clear ();
 
 	DEBUG_TRACE (DEBUG::Destruction, "delete regions\n");
-	for (RegionList::iterator i = regions.begin(); i != regions.end(); ) {
-		RegionList::iterator tmp;
-
-		tmp = i;
-		++tmp;
-
-		boost::shared_ptr<Region> keep (i->second);
-		
-		DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for region %1 (%2); pre-ref = %3\n", i->second->name(), i->second.get(), i->second.use_count()));
+	for (RegionList::iterator i = regions.begin(); i != regions.end(); ++i) {
+		DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for region %1 ; pre-ref = %2\n", i->second->name(), i->second.use_count()));
 		i->second->drop_references ();
-		DEBUG_TRACE(DEBUG::Destruction, string_compose ("region post ref = %1\n", i->second.use_count()));
-		i = tmp;
 	}
-
 	regions.clear ();
 
 	DEBUG_TRACE (DEBUG::Destruction, "delete routes\n");
@@ -427,10 +414,12 @@ Session::destroy ()
 	{
 		RCUWriter<RouteList> writer (routes);
 		boost::shared_ptr<RouteList> r = writer.get_copy ();
+
 		for (RouteList::iterator i = r->begin(); i != r->end(); ++i) {
 			DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for route %1 ; pre-ref = %2\n", (*i)->name(), (*i).use_count()));
 			(*i)->drop_references ();
 		}
+
 		r->clear ();
 		/* writer goes out of scope and updates master */
 	}
@@ -444,28 +433,22 @@ Session::destroy ()
 			DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for diskstream %1 ; pre-ref = %2\n", (*i)->name(), (*i).use_count()));
 			(*i)->drop_references ();
 		}
+
 		dsl->clear ();
 	}
 	diskstreams.flush ();
 
 	DEBUG_TRACE (DEBUG::Destruction, "delete sources\n");
-	for (SourceMap::iterator i = sources.begin(); i != sources.end(); ) {
-		SourceMap::iterator tmp;
-
-		tmp = i;
-		++tmp;
-
+	for (SourceMap::iterator i = sources.begin(); i != sources.end(); ++i) {
 		DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for source %1 ; pre-ref = %2\n", i->second->path(), i->second.use_count()));
 		i->second->drop_references ();
-
-		i = tmp;
 	}
 
 	sources.clear ();
 
-
 	DEBUG_TRACE (DEBUG::Destruction, "delete route groups\n");
 	for (list<RouteGroup *>::iterator i = _route_groups.begin(); i != _route_groups.end(); ++i) {
+		
 		delete *i;
 	}
 
@@ -476,10 +459,6 @@ Session::destroy ()
 	/* not strictly necessary, but doing it here allows the shared_ptr debugging to work */
 	playlists.reset ();
 
-	/* tell everyone who is still standing that we're about to die */
-
-	drop_references ();
-
 	boost_debug_list_ptrs ();
 
 	DEBUG_TRACE (DEBUG::Destruction, "Session::destroy() done\n");
@@ -2813,8 +2792,6 @@ Session::add_regions (vector<boost::shared_ptr<Region> >& new_regions)
 			}
 
 			region->StateChanged.connect_same_thread (*this, boost::bind (&Session::region_changed, this, _1, boost::weak_ptr<Region>(region)));
-			region->GoingAway.connect_same_thread (*this, boost::bind (&Session::remove_region, this, boost::weak_ptr<Region>(region)));
-
 			update_region_name_map (region);
 		}
 
@@ -3001,7 +2978,6 @@ Session::add_source (boost::shared_ptr<Source> source)
 	}
 
 	if (result.second) {
-		source->GoingAway.connect_same_thread (*this, boost::bind (&Session::remove_source, this, boost::weak_ptr<Source> (source)));
 		set_dirty();
 	}
 
@@ -3390,10 +3366,7 @@ Session::add_playlist (boost::shared_ptr<Playlist> playlist, bool unused)
 		return;
 	}
 
-	bool existing = playlists->add (playlist);
-	if (!existing) {
-		playlist->GoingAway.connect_same_thread (*this, boost::bind (&Session::remove_playlist, this, boost::weak_ptr<Playlist>(playlist)));
-	}
+	playlists->add (playlist);
 
 	if (unused) {
 		playlist->release();
@@ -3566,7 +3539,11 @@ Session::graph_reordered ()
 void
 Session::add_processor (Processor* processor)
 {
-	processor->GoingAway.connect_same_thread (*this, boost::bind (&Session::remove_processor, this, processor));
+	/* Session does not own Processors (they belong to a Route) but we do want to track
+	   the arrival and departure of port inserts, sends and returns for naming
+	   purposes.
+	*/
+	processor->DropReferences.connect_same_thread (*this, boost::bind (&Session::remove_processor, this, processor));
 	set_dirty();
 }
 
@@ -3810,37 +3787,33 @@ Session::mark_insert_id (uint32_t id)
 
 /* Named Selection management */
 
-NamedSelection *
+boost::shared_ptr<NamedSelection>
 Session::named_selection_by_name (string name)
 {
 	Glib::Mutex::Lock lm (named_selection_lock);
 	for (NamedSelectionList::iterator i = named_selections.begin(); i != named_selections.end(); ++i) {
 		if ((*i)->name == name) {
-			return* i;
+			return *i;
 		}
 	}
-	return 0;
+	return boost::shared_ptr<NamedSelection>();
 }
 
 void
-Session::add_named_selection (NamedSelection* named_selection)
+Session::add_named_selection (boost::shared_ptr<NamedSelection> named_selection)
 {
 	{
 		Glib::Mutex::Lock lm (named_selection_lock);
 		named_selections.insert (named_selections.begin(), named_selection);
 	}
 
-	for (list<boost::shared_ptr<Playlist> >::iterator i = named_selection->playlists.begin(); i != named_selection->playlists.end(); ++i) {
-		add_playlist (*i);
-	}
-
 	set_dirty();
 
 	NamedSelectionAdded (); /* EMIT SIGNAL */
 }
 
 void
-Session::remove_named_selection (NamedSelection* named_selection)
+Session::remove_named_selection (boost::shared_ptr<NamedSelection> named_selection)
 {
 	bool removed = false;
 
@@ -3850,7 +3823,6 @@ Session::remove_named_selection (NamedSelection* named_selection)
 		NamedSelectionList::iterator i = find (named_selections.begin(), named_selections.end(), named_selection);
 
 		if (i != named_selections.end()) {
-			delete (*i);
 			named_selections.erase (i);
 			set_dirty();
 			removed = true;
@@ -4186,6 +4158,10 @@ Session::compute_initial_length ()
 void
 Session::sync_order_keys (std::string const & base)
 {
+	if (deletion_in_progress()) {
+		return;
+	}
+
 	if (!Config->get_sync_all_route_ordering()) {
 		/* leave order keys as they are */
 		return;
diff --git a/libs/ardour/session_handle.cc b/libs/ardour/session_handle.cc
index 1cd78c8aac..36515505ac 100644
--- a/libs/ardour/session_handle.cc
+++ b/libs/ardour/session_handle.cc
@@ -32,7 +32,7 @@ SessionHandlePtr::SessionHandlePtr (Session* s)
 	: _session (s) 
 {
 	if (_session) {
-		_session->GoingAway.connect_same_thread (_session_connections, boost::bind (&SessionHandlePtr::session_going_away, this));
+		_session->DropReferences.connect_same_thread (_session_connections, boost::bind (&SessionHandlePtr::session_going_away, this));
 	}
 }	
 
@@ -47,7 +47,7 @@ SessionHandlePtr::set_session (Session* s)
 
 	if (s) {
 		_session = s;
-		_session->GoingAway.connect_same_thread (_session_connections, boost::bind (&SessionHandlePtr::session_going_away, this));
+		_session->DropReferences.connect_same_thread (_session_connections, boost::bind (&SessionHandlePtr::session_going_away, this));
 	}
 }
 
@@ -63,11 +63,19 @@ SessionHandlePtr::session_going_away ()
 SessionHandleRef::SessionHandleRef (Session& s)
 	: _session (s) 
 {
-	_session.GoingAway.connect_same_thread (*this, boost::bind (&SessionHandleRef::session_going_away, this));
+	_session.DropReferences.connect_same_thread (*this, boost::bind (&SessionHandleRef::session_going_away, this));
+	_session.Destroyed.connect_same_thread (*this, boost::bind (&SessionHandleRef::insanity_check, this));
 }	
 
 void
 SessionHandleRef::session_going_away ()
 {
-	error << string_compose (_("programming error: %1"), "SessionHandleRef exists across sesssion deletion!") << endmsg;
+	/* a handleRef is allowed to exist at the time of DropReferences, but not at the time of Destroyed
+	 */
+}
+
+void
+SessionHandleRef::insanity_check ()
+{
+	cerr << string_compose (_("programming error: %1"), "SessionHandleRef exists across sesssion deletion!") << endl;
 }
diff --git a/libs/ardour/session_playlists.cc b/libs/ardour/session_playlists.cc
index 238bd72404..17ed6a4e30 100644
--- a/libs/ardour/session_playlists.cc
+++ b/libs/ardour/session_playlists.cc
@@ -43,6 +43,7 @@ SessionPlaylists::~SessionPlaylists ()
 		++tmp;
 
 		DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for used playlist %1 ; pre-ref = %2\n", (*i)->name(), (*i).use_count()));
+		boost::shared_ptr<Playlist> keeper (*i);
 		(*i)->drop_references ();
 
 		i = tmp;
@@ -56,6 +57,7 @@ SessionPlaylists::~SessionPlaylists ()
 		++tmp;
 
 		DEBUG_TRACE(DEBUG::Destruction, string_compose ("Dropping for unused playlist %1 ; pre-ref = %2\n", (*i)->name(), (*i).use_count()));
+		boost::shared_ptr<Playlist> keeper (*i);
 		(*i)->drop_references ();
 
 		i = tmp;
@@ -291,6 +293,7 @@ SessionPlaylists::maybe_delete_unused (boost::function<int(boost::shared_ptr<Pla
 	/* now delete any that were marked for deletion */
 
 	for (vector<boost::shared_ptr<Playlist> >::iterator x = playlists_tbd.begin(); x != playlists_tbd.end(); ++x) {
+		boost::shared_ptr<Playlist> keeper (*x);
 		(*x)->drop_references ();
 	}
 
diff --git a/libs/ardour/session_state.cc b/libs/ardour/session_state.cc
index 2248663478..1742feaab1 100644
--- a/libs/ardour/session_state.cc
+++ b/libs/ardour/session_state.cc
@@ -274,7 +274,6 @@ Session::first_stage_init (string fullpath, string snapshot_name)
 	SourceFactory::SourceCreated.connect_same_thread (*this, boost::bind (&Session::add_source, this, _1));
 	PlaylistFactory::PlaylistCreated.connect_same_thread (*this, boost::bind (&Session::add_playlist, this, _1, _2));
 	Processor::ProcessorCreated.connect_same_thread (*this, boost::bind (&Session::add_processor, this, _1));
-	NamedSelection::NamedSelectionCreated.connect_same_thread (*this, boost::bind (&Session::add_named_selection, this, _1));
 	AutomationList::AutomationListCreated.connect_same_thread (*this, boost::bind (&Session::add_automation_list, this, _1));
 	Controllable::Destroyed.connect_same_thread (*this, boost::bind (&Session::remove_controllable, this, _1));
 	IO::PortCountChanged.connect_same_thread (*this, boost::bind (&Session::ensure_buffers, this, _1));
@@ -789,7 +788,7 @@ Session::load_state (string snapshot_name)
 
 		/* there is pending state from a crashed capture attempt */
 
-		if (AskAboutPendingState()) {
+		if (*AskAboutPendingState()) {
 			state_was_pending = true;
 		}
 	}
@@ -1126,7 +1125,7 @@ Session::set_state (const XMLNode& node, int version)
 		_nominal_frame_rate = atoi (prop->value());
 
 		if (_nominal_frame_rate != _current_frame_rate) {
-			if (AskAboutSampleRateMismatch (_nominal_frame_rate, _current_frame_rate)) {
+			if (*AskAboutSampleRateMismatch (_nominal_frame_rate, _current_frame_rate)) {
 				return -1;
 			}
 		}
diff --git a/libs/ardour/sndfilesource.cc b/libs/ardour/sndfilesource.cc
index 185cb15e79..d9d428a4cb 100644
--- a/libs/ardour/sndfilesource.cc
+++ b/libs/ardour/sndfilesource.cc
@@ -246,8 +246,6 @@ SndFileSource::open ()
 
 SndFileSource::~SndFileSource ()
 {
-	drop_references ();
-
 	if (sf) {
 		sf_close (sf);
 		sf = 0;
diff --git a/libs/ardour/vst_plugin.cc b/libs/ardour/vst_plugin.cc
index ee3ebd2ee3..80631ac840 100644
--- a/libs/ardour/vst_plugin.cc
+++ b/libs/ardour/vst_plugin.cc
@@ -102,7 +102,6 @@ VSTPlugin::VSTPlugin (const VSTPlugin &other)
 VSTPlugin::~VSTPlugin ()
 {
 	deactivate ();
-	drop_references ();
 	fst_close (_fst);
 }
 
diff --git a/libs/gtkmm2ext/gtk_ui.cc b/libs/gtkmm2ext/gtk_ui.cc
index 38512d70f5..318dedd1fc 100644
--- a/libs/gtkmm2ext/gtk_ui.cc
+++ b/libs/gtkmm2ext/gtk_ui.cc
@@ -359,7 +359,11 @@ UI::do_request (UIRequest* req)
 		do_quit ();
 
 	} else if (req->type == CallSlot) {
-
+#ifndef NDEBUG
+		if (getenv ("DEBUG_THREADED_SIGNALS")) {
+			cerr << "call slot for " << name() << endl;
+		}
+#endif
 		req->the_slot ();
 
 	} else if (req->type == TouchDisplay) {
diff --git a/libs/midi++2/parser.cc b/libs/midi++2/parser.cc
index af9cfafaca..60a321cefb 100644
--- a/libs/midi++2/parser.cc
+++ b/libs/midi++2/parser.cc
@@ -313,7 +313,6 @@ Parser::trace (bool onoff, ostream *o, const string &prefix)
 	trace_connection.disconnect ();
 
 	if (onoff) {
-		cerr << "enabling tracing for port " << _port.name() << endl;
 		trace_stream = o;
 		trace_prefix = prefix;
 		any.connect_same_thread (trace_connection, boost::bind (&Parser::trace_event, this, _1, _2, _3));
@@ -402,8 +401,9 @@ Parser::scanner (unsigned char inbyte)
 	 * an EOX.  Actually, since EOX is a status byte, this
 	 * code ALWAYS handles the end of a VARIABLELENGTH message.
 	 */
-	
+
 	if (state == VARIABLELENGTH && statusbit)  {
+
 		/* The message has ended, so process it */
 
 		/* add EOX to any sysex message */
@@ -419,7 +419,7 @@ Parser::scanner (unsigned char inbyte)
 		}
 		cerr << dec << endl;
 #endif
-		if (msgindex > 0 && edit (msgbuf, msgindex) >= 0) {
+		if (msgindex > 0 && (edit.empty() || !(*edit (msgbuf, msgindex) >= 0))) {
 			if (!possible_mmc (msgbuf, msgindex) || _mmc_forward) {
 				if (!possible_mtc (msgbuf, msgindex) || _mtc_forward) {
 					if (!_offline) {
@@ -429,7 +429,7 @@ Parser::scanner (unsigned char inbyte)
 			}
 			if (!_offline) {
 				any (*this, msgbuf, msgindex);
-			}
+			} 
 		}
 	}
 	
@@ -490,8 +490,7 @@ Parser::scanner (unsigned char inbyte)
 		
 	case NEEDONEBYTE:
 		/* We've completed a 1 or 2 byte message. */
-		
-		if (edit (msgbuf, msgindex) == 0) {
+		if (edit.empty() || !(*edit (msgbuf, msgindex) == 0)) {
 			
 			/* message not cancelled by an editor */
 			
diff --git a/libs/pbd/controllable.cc b/libs/pbd/controllable.cc
index d751c3c80b..be487a0a87 100644
--- a/libs/pbd/controllable.cc
+++ b/libs/pbd/controllable.cc
@@ -62,23 +62,23 @@ Controllable::add (Controllable& ctl)
 
 	/* Controllable::remove() is static - no need to manage this connection */
 
-	ctl.GoingAway.connect_same_thread (registry_connections, boost::bind (&Controllable::remove, ref (ctl)));
+	ctl.DropReferences.connect_same_thread (registry_connections, boost::bind (&Controllable::remove, &ctl));
 }
 
 void
-Controllable::remove (Controllable& ctl)
+Controllable::remove (Controllable* ctl)
 {
 	Glib::RWLock::WriterLock lm (registry_lock);
 
 	for (Controllables::iterator i = registry.begin(); i != registry.end(); ++i) {
-		if ((*i) == &ctl) {
+		if ((*i) == ctl) {
 			registry.erase (i);
 			break;
 		}
 	}
 
-	if (!ctl.uri().empty()) {
-		ControllablesByURI::iterator i = registry_by_uri.find (ctl.uri());
+	if (!ctl->uri().empty()) {
+		ControllablesByURI::iterator i = registry_by_uri.find (ctl->uri());
 		if (i != registry_by_uri.end()) {
 			registry_by_uri.erase (i);
 		}
diff --git a/libs/pbd/pbd/abstract_ui.cc b/libs/pbd/pbd/abstract_ui.cc
index 98ef094a00..cc7010a415 100644
--- a/libs/pbd/pbd/abstract_ui.cc
+++ b/libs/pbd/pbd/abstract_ui.cc
@@ -1,4 +1,5 @@
 #include <unistd.h>
+#include <iostream>
 
 #include "pbd/stacktrace.h"
 #include "pbd/abstract_ui.h"
@@ -9,11 +10,22 @@
 
 using namespace std;
 
+static void do_not_delete_the_request_buffer (void*) { }
+
+template<typename R>
+Glib::StaticPrivate<typename AbstractUI<R>::RequestBuffer> AbstractUI<R>::per_thread_request_buffer;
+
 template <typename RequestObject>
 AbstractUI<RequestObject>::AbstractUI (const string& name)
 	: BaseUI (name)
 {
-	PBD::ThreadCreatedWithRequestSize.connect (mem_fun (*this, &AbstractUI<RequestObject>::register_thread));
+	void (AbstractUI<RequestObject>::*pmf)(string,pthread_t,string,uint32_t) = &AbstractUI<RequestObject>::register_thread;
+
+	/* better to make this connect a handler that runs in the UI event loop but the syntax seems hard, and 
+	   register_thread() is thread safe anyway.
+	*/
+
+	PBD::ThreadCreatedWithRequestSize.connect_same_thread (new_thread_connection, boost::bind (pmf, this, _1, _2, _3, _4));
 }
 
 template <typename RequestObject> void
@@ -30,7 +42,7 @@ AbstractUI<RequestObject>::register_thread (string target_gui, pthread_t thread_
 		request_buffers[thread_id] = b;
 	}
 
-	per_thread_request_buffer.set (b);
+	per_thread_request_buffer.set (b, do_not_delete_the_request_buffer);
 }
 
 template <typename RequestObject> RequestObject*
@@ -143,6 +155,11 @@ template<typename RequestObject> void
 AbstractUI<RequestObject>::call_slot (const boost::function<void()>& f)
 {
 	if (caller_is_self()) {
+#ifndef NDEBUG
+		if (getenv ("DEBUG_THREADED_SIGNALS")) {
+			std::cerr << "functor called in correct thread for " << name() << " , execute ...\n";
+		}
+#endif
 		f ();
 		return;
 	}
@@ -154,6 +171,11 @@ AbstractUI<RequestObject>::call_slot (const boost::function<void()>& f)
 	}
 
 	req->the_slot = f;
+#ifndef NDEBUG
+	if (getenv ("DEBUG_THREADED_SIGNALS")) {
+		std::cerr << "functor called in wrong thread for " << name() << " (from " << pthread_name() << ") send request ...\n";
+	}
+#endif
 	send_request (req);
 }	
 
diff --git a/libs/pbd/pbd/abstract_ui.h b/libs/pbd/pbd/abstract_ui.h
index 39fe83b0fe..d04d62c463 100644
--- a/libs/pbd/pbd/abstract_ui.h
+++ b/libs/pbd/pbd/abstract_ui.h
@@ -24,12 +24,11 @@
 #include <string>
 #include <pthread.h>
 
-#include <sigc++/sigc++.h>
-
 #include <glibmm/thread.h>
 
 #include "pbd/receiver.h"
 #include "pbd/ringbufferNPT.h"
+#include "pbd/signals.h"
 #include "pbd/base_ui.h"
 
 class Touchable;
@@ -52,8 +51,8 @@ class AbstractUI : public BaseUI
 
 	Glib::Mutex request_buffer_map_lock;
 	RequestBufferMap request_buffers;
-	Glib::Private<RequestBuffer> per_thread_request_buffer;
-
+	static Glib::StaticPrivate<RequestBuffer> per_thread_request_buffer;
+	
 	Glib::Mutex               request_list_lock;
 	std::list<RequestObject*> request_list;
 	
@@ -62,6 +61,7 @@ class AbstractUI : public BaseUI
 	void send_request (RequestObject *);
 
 	virtual void do_request (RequestObject *) = 0;
+	PBD::ScopedConnection new_thread_connection;
 };
 
 #endif /* __pbd_abstract_ui_h__ */
diff --git a/libs/pbd/pbd/controllable.h b/libs/pbd/pbd/controllable.h
index d94c58d54f..28dd4b7a31 100644
--- a/libs/pbd/pbd/controllable.h
+++ b/libs/pbd/pbd/controllable.h
@@ -73,7 +73,7 @@ class Controllable : public PBD::StatefulDestructible {
 	bool        _touching;
 
 	static void add (Controllable&);
-	static void remove (Controllable&);
+	static void remove (Controllable*);
 
 	typedef std::set<PBD::Controllable*> Controllables;
 	typedef std::map<std::string,PBD::Controllable*> ControllablesByURI;
diff --git a/libs/pbd/pbd/destructible.h b/libs/pbd/pbd/destructible.h
index 8cc0113ff7..8881b45c55 100644
--- a/libs/pbd/pbd/destructible.h
+++ b/libs/pbd/pbd/destructible.h
@@ -26,14 +26,13 @@ namespace PBD {
 
 class Destructible {
   public:
-        Destructible() : refs_dropped (false){}
-	virtual ~Destructible () {}
+        Destructible() {}
+	virtual ~Destructible () { Destroyed(); }
 	
-	PBD::Signal0<void> GoingAway;
-	void drop_references () { if (!refs_dropped) { GoingAway(); } refs_dropped = true; }
+	PBD::Signal0<void> Destroyed;
+	PBD::Signal0<void> DropReferences;
 
-  private:
-	bool refs_dropped;
+	void drop_references () { DropReferences();  }
 };
 
 }
diff --git a/libs/pbd/pbd/memento_command.h b/libs/pbd/pbd/memento_command.h
index a08d3bb717..8c3d1a1870 100644
--- a/libs/pbd/pbd/memento_command.h
+++ b/libs/pbd/pbd/memento_command.h
@@ -42,7 +42,7 @@ public:
 		: obj(a_object), before(a_before), after(a_after)
 	{
 		/* if the object dies, make sure that we die and that everyone knows about it */
-		obj.GoingAway.connect_same_thread (obj_death_connection, boost::bind (&MementoCommand::object_died, this));
+		obj.Destroyed.connect_same_thread (obj_death_connection, boost::bind (&MementoCommand::object_died, this));
 	}
 
 	~MementoCommand () {
diff --git a/libs/pbd/pbd/pthread_utils.h b/libs/pbd/pbd/pthread_utils.h
index e6c5a376df..b8f99ba144 100644
--- a/libs/pbd/pbd/pthread_utils.h
+++ b/libs/pbd/pbd/pthread_utils.h
@@ -25,7 +25,7 @@
 #include <string>
 #include <stdint.h>
 
-#include <sigc++/sigc++.h>
+#include <pbd/signals.h>
 
 int  pthread_create_and_store (std::string name, pthread_t  *thread, void * (*start_routine)(void *), void * arg);
 void pthread_cancel_one (pthread_t thread);
@@ -36,10 +36,7 @@ std::string pthread_name ();
 
 namespace PBD {
 	extern void notify_gui_about_thread_creation (std::string, pthread_t, std::string, int requests = 256);
-	extern void notify_gui_about_thread_exit (pthread_t);
-
-	extern sigc::signal<void,pthread_t>                                  ThreadLeaving;
-	extern sigc::signal<void,std::string,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
+	extern PBD::Signal4<void,std::string,pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
 }
 
 #endif /* __pbd_pthread_utils__ */
diff --git a/libs/pbd/pbd/signals.h b/libs/pbd/pbd/signals.h
index 0b44ee8051..ffb0dcebb6 100644
--- a/libs/pbd/pbd/signals.h
+++ b/libs/pbd/pbd/signals.h
@@ -102,6 +102,8 @@ public:
     typename SignalType::result_type operator()() {
 	    return _signal ();
     }
+
+    bool empty() const { return _signal.empty(); }
     
 private:
     SignalType _signal;
@@ -144,6 +146,8 @@ public:
 	    return _signal (arg1);
     }
     
+    bool empty() const { return _signal.empty(); }
+
 private:
     SignalType _signal;
 };
@@ -184,6 +188,8 @@ public:
 	    return _signal (arg1, arg2);
     }
     
+    bool empty() const { return _signal.empty(); }
+
 private:
     SignalType _signal;
 };
@@ -224,6 +230,50 @@ public:
 	    return _signal (arg1, arg2, arg3);
     }
     
+    bool empty() const { return _signal.empty(); }
+
+private:
+    SignalType _signal;
+};
+
+template<typename R, typename A1, typename A2, typename A3, typename A4>
+class Signal4 {
+public:
+    Signal4 () {}
+    typedef boost::signals2::signal<R(A1,A2,A3,A4)> SignalType;
+
+    void connect_same_thread (ScopedConnectionList& clist, 
+		  const typename SignalType::slot_function_type& slot) {
+	    clist.add_connection (_signal.connect (slot));
+    }
+
+    void connect_same_thread (Connection& c, 
+			      const typename SignalType::slot_function_type& slot) {
+	    c = _signal.connect (slot);
+    }
+
+    static void compositor (typename boost::function<void(A1,A2,A3)> f, PBD::EventLoop* event_loop, A1 arg1, A2 arg2, A3 arg3, A4 arg4) {
+	    event_loop->call_slot (boost::bind (f, arg1, arg2, arg3, arg4));
+    }
+
+    void connect (ScopedConnectionList& clist, 
+		  const typename SignalType::slot_function_type& slot,
+		  PBD::EventLoop* event_loop) {
+	    clist.add_connection (_signal.connect (boost::bind (&compositor, slot, event_loop, _1, _2, _3, _4)));
+    }
+    
+    void connect (Connection& c, 
+		  const typename SignalType::slot_function_type& slot,
+		  PBD::EventLoop* event_loop) {
+	    c = _signal.connect (_signal.connect (boost::bind (&compositor, slot, event_loop, _1, _2, _3, _4)));
+    }
+    
+    typename SignalType::result_type operator()(A1 arg1, A2 arg2, A3 arg3, A4 arg4) {
+	    return _signal (arg1, arg2, arg3, arg4);
+    }
+    
+    bool empty() const { return _signal.empty(); }
+
 private:
     SignalType _signal;
 };
diff --git a/libs/pbd/pthread_utils.cc b/libs/pbd/pthread_utils.cc
index 495214a481..ca63603446 100644
--- a/libs/pbd/pthread_utils.cc
+++ b/libs/pbd/pthread_utils.cc
@@ -33,11 +33,9 @@ using namespace std;
 typedef std::map<string,pthread_t> ThreadMap;
 static ThreadMap all_threads;
 static pthread_mutex_t thread_map_lock = PTHREAD_MUTEX_INITIALIZER;
-static pthread_mutex_t gui_notify_lock = PTHREAD_MUTEX_INITIALIZER;
 
 namespace PBD {
-	sigc::signal<void,pthread_t>             ThreadLeaving;
-	sigc::signal<void,std::string, pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
+	PBD::Signal4<void,std::string, pthread_t,std::string,uint32_t> ThreadCreatedWithRequestSize;
 }
 
 using namespace PBD;
@@ -54,17 +52,7 @@ static int thread_creator (pthread_t* thread_id, const pthread_attr_t* attr, voi
 void
 PBD::notify_gui_about_thread_creation (std::string target_gui, pthread_t thread, std::string str, int request_count)
 {
-	pthread_mutex_lock (&gui_notify_lock);
 	ThreadCreatedWithRequestSize (target_gui, thread, str, request_count);
-	pthread_mutex_unlock (&gui_notify_lock);
-}
-
-void
-PBD::notify_gui_about_thread_exit (pthread_t thread)
-{
-	pthread_mutex_lock (&gui_notify_lock);
-	ThreadLeaving (thread);
-	pthread_mutex_unlock (&gui_notify_lock);
 }
 
 int  
diff --git a/libs/pbd/undo.cc b/libs/pbd/undo.cc
index 81e31f3a88..c3594b1658 100644
--- a/libs/pbd/undo.cc
+++ b/libs/pbd/undo.cc
@@ -83,7 +83,7 @@ UndoTransaction::add_command (Command *const action)
 	   so there is no need to manage this connection.
 	 */
 
-	action->GoingAway.connect_same_thread (*this, boost::bind (&command_death, this, action));
+	action->DropReferences.connect_same_thread (*this, boost::bind (&command_death, this, action));
 	actions.push_back (action);
 }
 
@@ -186,7 +186,7 @@ UndoHistory::add (UndoTransaction* const ut)
 {
 	uint32_t current_depth = UndoList.size();
 
-	ut->GoingAway.connect_same_thread (*this, boost::bind (&UndoHistory::remove, this, ut));
+	ut->DropReferences.connect_same_thread (*this, boost::bind (&UndoHistory::remove, this, ut));
 
 	/* if the current undo history is larger than or equal to the currently
 	   requested depth, then pop off at least 1 element to make space
diff --git a/libs/surfaces/osc/osc.cc b/libs/surfaces/osc/osc.cc
index 6054d01334..9e64667ce7 100644
--- a/libs/surfaces/osc/osc.cc
+++ b/libs/surfaces/osc/osc.cc
@@ -578,7 +578,7 @@ OSC::listen_to_route (boost::shared_ptr<Route> route, lo_address addr)
 	*/
 	
 	if (!route_exists) {
-		route->GoingAway.connect (*this, boost::bind (&OSC::drop_route, this, boost::weak_ptr<Route> (route)), this);
+		route->DropReferences.connect (*this, boost::bind (&OSC::drop_route, this, boost::weak_ptr<Route> (route)), this);
 	}
 }