Update latency compensation when sends are added or removed

Previously only adding an aux-send triggered a graph-reorder but copying
or deleting sends did nothing.

Adding/removing an aux-send may not even change the graph, but
both upstream/downstream latency can change and delaylines need to be
configured (which is done by calling update_latency_compensation with
force_whole_graph = true).

This fixes an issue with incorrect initial latency compensation after
copying a send (any later change to connections will correctly
recalculate it).

libs/ardour/ardour/types.h

@@ -703,7 +703,8 @@ struct RouteProcessorChange {
 	enum Type {
 		MeterPointChange = 0x1,
 		RealTimeChange   = 0x2,
-		GeneralChange    = 0x4
+		GeneralChange    = 0x4,
+		SendReturnChange = 0x8
 	};
 
 	RouteProcessorChange () : type (GeneralChange), meter_visibly_changed (true)

libs/ardour/route.cc

@@ -1104,6 +1104,8 @@ Route::add_processors (const ProcessorList& others, boost::shared_ptr<Processor>
 		}
 	}
 
+	bool routing_processor_added = false;
+
 	{
 		Glib::Threads::Mutex::Lock lx (AudioEngine::instance()->process_lock ());
 		Glib::Threads::RWLock::WriterLock lm (_processor_lock);
@@ -1177,6 +1179,10 @@ Route::add_processors (const ProcessorList& others, boost::shared_ptr<Processor>
 					send->output()->changed.connect_same_thread (**i, boost::bind (&Route::output_change_handler, this, _1, _2));
 				}
 			}
+
+			if (boost::dynamic_pointer_cast<InternalSend>(*i)) {
+				routing_processor_added = true;
+			}
 		}
 
 		for (ProcessorList::const_iterator i = _processors.begin(); i != _processors.end(); ++i) {
@@ -1192,7 +1198,7 @@ Route::add_processors (const ProcessorList& others, boost::shared_ptr<Processor>
 	}
 
 	reset_instrument_info ();
-	processors_changed (RouteProcessorChange ()); /* EMIT SIGNAL */
+	processors_changed (RouteProcessorChange (routing_processor_added ? RouteProcessorChange::SendReturnChange : RouteProcessorChange::GeneralChange, false)); /* EMIT SIGNAL */
 	set_processor_positions ();
 
 	if (fanout && fanout->configured ()
@@ -1465,6 +1471,8 @@ Route::remove_processor (boost::shared_ptr<Processor> processor, ProcessorStream
 		return 1;
 	}
 
+	bool routing_processor_removed = false;
+
 	processor_max_streams.reset();
 
 	{
@@ -1508,6 +1516,10 @@ Route::remove_processor (boost::shared_ptr<Processor> processor, ProcessorStream
 			lm.acquire ();
 		}
 
+		if (boost::dynamic_pointer_cast<InternalSend>(*i)) {
+			routing_processor_removed = true;
+		}
+
 		_processors.erase (i);
 
 		if (configure_processors_unlocked (err, &lm)) {
@@ -1536,7 +1548,7 @@ Route::remove_processor (boost::shared_ptr<Processor> processor, ProcessorStream
 
 	reset_instrument_info ();
 	processor->drop_references ();
-	processors_changed (RouteProcessorChange ()); /* EMIT SIGNAL */
+	processors_changed (RouteProcessorChange (routing_processor_removed ? RouteProcessorChange::SendReturnChange : RouteProcessorChange::GeneralChange, false)); /* EMIT SIGNAL */
 	set_processor_positions ();
 
 	return 0;
@@ -1648,6 +1660,8 @@ Route::remove_processors (const ProcessorList& to_be_deleted, ProcessorStreams*
 		return 1;
 	}
 
+	bool routing_processor_removed = false;
+
 	processor_max_streams.reset();
 
 	{
@@ -1692,6 +1706,10 @@ Route::remove_processors (const ProcessorList& to_be_deleted, ProcessorStreams*
 				iop->disconnect ();
 			}
 
+			if (boost::dynamic_pointer_cast<InternalSend>(processor)) {
+				routing_processor_removed = true;
+			}
+
 			deleted.push_back (processor);
 			i = _processors.erase (i);
 		}
@@ -1730,7 +1748,7 @@ Route::remove_processors (const ProcessorList& to_be_deleted, ProcessorStreams*
 	}
 
 	reset_instrument_info ();
-	processors_changed (RouteProcessorChange ()); /* EMIT SIGNAL */
+	processors_changed (RouteProcessorChange (routing_processor_removed ? RouteProcessorChange::SendReturnChange : RouteProcessorChange::GeneralChange, false)); /* EMIT SIGNAL */
 	set_processor_positions ();
 
 	return 0;

libs/ardour/session.cc

@@ -3468,8 +3468,6 @@ Session::add_internal_send (boost::shared_ptr<Route> dest, boost::shared_ptr<Pro
 	}
 
 	sender->add_aux_send (dest, before);
-
-	graph_reordered (false);
 }
 
 void

libs/ardour/session_transport.cc

@@ -1896,7 +1896,12 @@ Session::route_processors_changed (RouteProcessorChange c)
 	}
 
 	resort_routes ();
-	update_latency_compensation (false, false);
+
+	if (c.type == RouteProcessorChange::SendReturnChange) {
+		update_latency_compensation (true, false);
+	} else {
+		update_latency_compensation (false, false);
+	}
 
 	set_dirty ();
 }