Experiment: propagate solo-state with internal-sends

So far internal-sends were explicitly special-cased, and implicit
solo-state only was only forwarded for direct up/down-stream
connections.  ...and nobody can remember why :)

This restriction is removed, so far mainly with commenting-out
code, as experiment.

Internal sends are not only more convenient, but also required
in cases where direct connections result in ambiguous latency.

libs/ardour/ardour/internal_send.h

@@ -83,6 +83,8 @@ private:
 	void init_gain ();
 	int  use_target (boost::shared_ptr<Route>, bool update_name = true);
 	void target_io_changed ();
+
+	void propagate_solo (bool);
 };
 
 } // namespace ARDOUR

libs/ardour/internal_send.cc

@@ -73,11 +73,40 @@ InternalSend::InternalSend (Session&                      s,
 
 InternalSend::~InternalSend ()
 {
+	propagate_solo (false);
 	if (_send_to) {
 		_send_to->remove_send_from_internal_return (this);
 	}
 }
 
+void
+InternalSend::propagate_solo (bool enable)
+{
+	if (!_send_to || !_send_from) {
+		return;
+	}
+	bool from_soloed = _send_from->soloed();
+	bool to_soloed   = _send_to->soloed();
+
+	if (enable) {
+		if (from_soloed) {
+			_send_to->solo_control()->mod_solo_by_others_upstream (1);
+		}
+		if (to_soloed) {
+			_send_from->solo_control()->mod_solo_by_others_downstream (1);
+		}
+	} else {
+		if (from_soloed && _send_to->solo_control()->soloed_by_others_upstream())
+		{
+			_send_to->solo_control()->mod_solo_by_others_upstream (-1);
+		}
+		if (to_soloed && _send_from->solo_control()->soloed_by_others_downstream())
+		{
+			_send_from->solo_control()->mod_solo_by_others_downstream (-1);
+		}
+	}
+}
+
 void
 InternalSend::init_gain ()
 {
@@ -94,6 +123,7 @@ int
 InternalSend::use_target (boost::shared_ptr<Route> sendto, bool update_name)
 {
 	if (_send_to) {
+		propagate_solo (false);
 		_send_to->remove_send_from_internal_return (this);
 	}
 
@@ -101,6 +131,8 @@ InternalSend::use_target (boost::shared_ptr<Route> sendto, bool update_name)
 
 	_send_to->add_send_to_internal_return (this);
 
+	propagate_solo (true);
+
 	mixbufs.ensure_buffers (_send_to->internal_return ()->input_streams (), _session.get_block_size ());
 	mixbufs.set_count (_send_to->internal_return ()->input_streams ());
 
@@ -136,6 +168,9 @@ InternalSend::target_io_changed ()
 void
 InternalSend::send_from_going_away ()
 {
+	/* notify route while source-route is still available,
+	 * signal emission in the d'tor is too late */
+	propagate_solo (false);
 	_send_from.reset ();
 }
 

libs/ardour/route.cc

@@ -747,7 +747,7 @@ Route::push_solo_isolate_upstream (int32_t delta)
 		bool sends_only;
 		bool does_feed = feeds (*i, &sends_only);
 
-		if (does_feed && !sends_only) {
+		if (does_feed /*&& !sends_only*/) {
 			(*i)->solo_isolate_control()->mod_solo_isolated_by_upstream (delta);
 		}
 	}
@@ -759,7 +759,7 @@ Route::push_solo_upstream (int delta)
 	DEBUG_TRACE (DEBUG::Solo, string_compose("\t ... INVERT push from %1\n", _name));
 	for (FedBy::iterator i = _fed_by.begin(); i != _fed_by.end(); ++i) {
 		if (i->sends_only) {
-			continue;
+			/* continue; */
 		}
 		boost::shared_ptr<Route> sr (i->r.lock());
 		if (sr) {
@@ -3654,7 +3654,7 @@ Route::input_change_handler (IOChange change, void * /*src*/)
 				}
 				bool sends_only;
 				bool does_feed = (*i)->direct_feeds_according_to_reality (boost::dynamic_pointer_cast<Route> (shared_from_this()), &sends_only);
-				if (does_feed && !sends_only) {
+				if (does_feed /*&& !sends_only*/) {
 					if ((*i)->soloed()) {
 						++sbou;
 					}
@@ -3699,11 +3699,11 @@ Route::input_change_handler (IOChange change, void * /*src*/)
 			}
 			bool sends_only;
 			bool does_feed = feeds (*i, &sends_only);
-			if (delta <= 0 && does_feed && !sends_only) {
+			if (delta <= 0 && does_feed /*&& !sends_only*/) {
 				(*i)->solo_control()->mod_solo_by_others_upstream (delta);
 			}
 
-			if (idelta < 0 && does_feed && !sends_only) {
+			if (idelta < 0 && does_feed /*&& !sends_only*/) {
 				(*i)->solo_isolate_control()->mod_solo_isolated_by_upstream (-1);
 			}
 		}
@@ -3752,7 +3752,7 @@ Route::output_change_handler (IOChange change, void * /*src*/)
 					}
 					bool sends_only;
 					bool does_feed = direct_feeds_according_to_reality (*i, &sends_only);
-					if (does_feed && !sends_only) {
+					if (does_feed /*&& !sends_only*/) {
 						if ((*i)->soloed()) {
 							++sbod;
 							break;
@@ -3774,7 +3774,7 @@ Route::output_change_handler (IOChange change, void * /*src*/)
 					}
 					bool sends_only;
 					bool does_feed = (*i)->feeds (shared_this, &sends_only);
-					if (delta != 0 && does_feed && !sends_only) {
+					if (delta != 0 && does_feed /*&& !sends_only*/) {
 						(*i)->solo_control()->mod_solo_by_others_downstream (delta);
 					}
 				}

libs/ardour/session.cc

@@ -3702,7 +3702,7 @@ Session::route_solo_changed (bool self_solo_changed, Controllable::GroupControlD
 
 		if ((*i)->feeds (route, &via_sends_only)) {
 			DEBUG_TRACE (DEBUG::Solo, string_compose ("\tthere is a feed from %1\n", (*i)->name()));
-			if (!via_sends_only) {
+			if (true /*!via_sends_only*/) {
 				if (!route->soloed_by_others_upstream()) {
 					(*i)->solo_control()->mod_solo_by_others_downstream (delta);
 				} else {
@@ -3730,7 +3730,7 @@ Session::route_solo_changed (bool self_solo_changed, Controllable::GroupControlD
 			                                          via_sends_only,
 			                                          route->soloed_by_others_downstream(),
 			                                          route->soloed_by_others_upstream()));
-			if (!via_sends_only) {
+			if (true /*!via_sends_only*/) {
 				//NB. Triggers Invert Push, which handles soloed by downstream
 				DEBUG_TRACE (DEBUG::Solo, string_compose ("\tmod %1 by %2\n", (*i)->name(), delta));
 				(*i)->solo_control()->mod_solo_by_others_upstream (delta);