Handle tempo-map changes in sync from the calling thread

This is required to collect relevent undo/redo information, notably
automation-data changes from Playlist::update_after_tempo_map_change and
DiskReader::playlist_ranges_moved.

The realtime thread should not move regions to begin with, and debug
builds woudl also assert since no undo operation was started.

gtk2_ardour/editor_markers.cc

@@ -1662,9 +1662,9 @@ Editor::toggle_tempo_type ()
 
 		XMLNode &after = tmap->get_state();
 		_session->add_command (new Temporal::TempoCommand (_("change tempo type"), &before, &after));
-		commit_reversible_command ();
 
 		TempoMap::update (tmap);
+		commit_reversible_command ();
 	}
 }
 
@@ -1696,9 +1696,9 @@ Editor::toggle_tempo_continues ()
 
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("change tempo clamp"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 }
 
 void
@@ -1729,9 +1729,9 @@ Editor::ramp_to_next_tempo ()
 
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("changed tempo ramp"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 }
 
 void

gtk2_ardour/editor_ops.cc

@@ -7462,9 +7462,9 @@ Editor::define_one_bar (timepos_t const & start, timepos_t const & end)
 	XMLNode& after (tmap->get_state());
 
 	_session->add_command (new Temporal::TempoCommand (_("set tempo from range"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 }
 
 void

gtk2_ardour/editor_tempodisplay.cc

@@ -490,9 +490,8 @@ Editor::mouse_add_new_tempo_event (timepos_t pos)
 		map->set_tempo (map->tempo_at (pos), pos);
 		XMLNode &after = map->get_state();
 		_session->add_command (new Temporal::TempoCommand (_("add tempo"), &before, &after));
-		commit_reversible_command ();
-
 		TempoMap::update (map);
+		commit_reversible_command ();
 	}
 
 	//map.dump (cerr);
@@ -533,9 +532,9 @@ Editor::mouse_add_new_meter_event (timepos_t pos)
 	map->set_meter (Meter (bpb, note_type), pos);
 
 	_session->add_command (new Temporal::TempoCommand (_("add time signature"), &before, &map->get_state()));
-	commit_reversible_command ();
 
 	TempoMap::update (map);
+	commit_reversible_command ();
 
 	//map.dump (cerr);
 }
@@ -579,9 +578,9 @@ Editor::mouse_add_bbt_marker_event (timepos_t pos)
 	map->set_bartime (bbt, marker_dialog.position(), name);
 
 	_session->add_command (new Temporal::TempoCommand (_("add BBT marker"), &before, &map->get_state()));
-	commit_reversible_command ();
 
 	TempoMap::update (map);
+	commit_reversible_command ();
 }
 
 
@@ -657,9 +656,9 @@ Editor::edit_meter_section (Temporal::MeterPoint& section)
 
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("edit time signature"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 }
 
 void
@@ -693,9 +692,9 @@ Editor::edit_bbt (MusicTimePoint& point)
 
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("edit tempo"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 }
 
 void
@@ -730,9 +729,9 @@ Editor::edit_tempo_section (TempoPoint& section)
 
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("edit tempo"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 }
 
 void
@@ -762,9 +761,9 @@ Editor::real_remove_bbt_marker (MusicTimePoint const * point)
 	tmap->remove_bartime (*point);
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("remove BBT marker"), &before, &after));
-	commit_reversible_command ();
 
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 
 	return FALSE;
 }
@@ -778,10 +777,8 @@ Editor::real_remove_tempo_marker (TempoPoint const * section)
 	tmap->remove_tempo (*section);
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("remove tempo change"), &before, &after));
-	commit_reversible_command ();
-
 	TempoMap::update (tmap);
-
+	commit_reversible_command ();
 	return FALSE;
 }
 
@@ -815,9 +812,8 @@ Editor::real_remove_meter_marker (Temporal::MeterPoint const * section)
 	tmap->remove_meter (*section);
 	XMLNode &after = tmap->get_state();
 	_session->add_command (new Temporal::TempoCommand (_("remove time signature change"), &before, &after));
-	commit_reversible_command ();
-
 	TempoMap::update (tmap);
+	commit_reversible_command ();
 
 	return FALSE;
 }

libs/ardour/audioengine.cc

@@ -292,9 +292,6 @@ AudioEngine::process_callback (pframes_t nframes)
 	Temporal::TempoMap::WritableSharedPtr current_map = Temporal::TempoMap::read ();
 	if (current_map != Temporal::TempoMap::use()) {
 		Temporal::TempoMap::set (current_map);
-		if (_session) {
-			_session->tempo_map_changed ();
-		}
 	}
 
 	/* This is for JACK, where the latency callback arrives in sync with

libs/ardour/session.cc

@@ -502,6 +502,8 @@ Session::Session (AudioEngine &eng,
 
 	IOPluginsChanged.connect_same_thread (*this, boost::bind (&Session::resort_io_plugs, this));
 
+	TempoMap::MapChanged.connect_same_thread (*this, boost::bind (&Session::tempo_map_changed, this));
+
 	emit_thread_start ();
 	auto_connect_thread_start ();
 

share/scripts/s_tempo_map.lua

@@ -13,7 +13,11 @@ function factory () return function ()
 	tm:set_tempo (Temporal.Tempo (140, 120, 4), Temporal.timepos_t (0))
 	tm:set_tempo (Temporal.Tempo (120, 80, 4), Temporal.timepos_t.from_ticks (Temporal.ticks_per_beat * 4))
 	tm:set_tempo (Temporal.Tempo (80, 80, 4), Temporal.timepos_t.from_ticks (Temporal.ticks_per_beat * 4))
+	Session:begin_reversible_command ("Change Tempo Map")
 	Temporal.TempoMap.update (tm)
+	if not Session:abort_empty_reversible_command () then
+		Session:commit_reversible_command (nil)
+	end
 	tm = nil
 
 	-- Abort Edit example