From b14ce3137286d39854c9bbd798186dbc0d3308f0 Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Tue, 12 Aug 2025 18:56:24 +0200
Subject: [PATCH] Consolidate rt processor-changed signal emission

Prefer a single signal and bit flags, instead of individual signals.
This allows to call resort_route() at most once (if at all for
certain changes).

Notably Mixbus comp/gate/eq type changes can use NoProcessorChange
to only request a GUI update.
---
 libs/ardour/route.cc             | 30 +++++++++++++++++-------------
 libs/ardour/session.cc           | 11 ++---------
 libs/ardour/session_transport.cc | 12 ++++++++----
 3 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index f3c57fda89..7f341606be 100644
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -1055,6 +1055,10 @@ inline Route::PluginSetupOptions operator&= (Route::PluginSetupOptions& a, const
 	return a = static_cast<Route::PluginSetupOptions> (static_cast <int>(a) & static_cast<int> (b));
 }
 
+inline RouteProcessorChange::Type operator|= (RouteProcessorChange::Type& a, const RouteProcessorChange::Type& b) {
+	return a = static_cast<RouteProcessorChange::Type> (static_cast <int>(a) | static_cast<int> (b));
+}
+
 int
 Route::add_processors (const ProcessorList& others, std::shared_ptr<Processor> before, ProcessorStreams* err)
 {
@@ -4231,20 +4235,20 @@ void
 Route::emit_pending_signals ()
 {
 	int sig = _pending_signals.fetch_and (0);
-	if (sig & EmitMeterChanged) {
-		_meter->emit_configuration_changed();
-		meter_change (); /* EMIT SIGNAL */
-		if (sig & EmitMeterVisibilityChange) {
-		processors_changed (RouteProcessorChange (RouteProcessorChange::MeterPointChange, true)); /* EMIT SIGNAL */
-		} else {
-		processors_changed (RouteProcessorChange (RouteProcessorChange::MeterPointChange, false)); /* EMIT SIGNAL */
+
+	if (sig != 0) {
+		bool meter_viz_changed = (sig & (EmitMeterVisibilityChange | EmitMeterChanged)) == (EmitMeterVisibilityChange | EmitMeterChanged);
+		RouteProcessorChange::Type t = RouteProcessorChange::NoProcessorChange;
+		if (sig & EmitRtProcessorChange) {
+			t |= RouteProcessorChange::RealTimeChange;
 		}
-	}
-	if (sig & EmitRtProcessorChange) {
-		processors_changed (RouteProcessorChange (RouteProcessorChange::RealTimeChange)); /* EMIT SIGNAL */
-	}
-	if (sig & EmitSendReturnChange) {
-		processors_changed (RouteProcessorChange (RouteProcessorChange::SendReturnChange, false)); /* EMIT SIGNAL */
+		if (sig & EmitSendReturnChange) {
+			t |= RouteProcessorChange::SendReturnChange;
+		}
+		if (sig & EmitMeterVisibilityChange) {
+			t |= RouteProcessorChange::MeterPointChange;
+		}
+		processors_changed (RouteProcessorChange (t, meter_viz_changed));
 	}
 
 	/* this would be a job for the butler.
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 77554547c9..9b00b17062 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -8166,15 +8166,8 @@ Session::ProcessorChangeBlocker::~ProcessorChangeBlocker ()
 	if (PBD::atomic_dec_and_test (_session->_ignore_route_processor_changes)) {
 		RouteProcessorChange::Type type = (RouteProcessorChange::Type) _session->_ignored_a_processor_change.fetch_and (0);
 		if (_reconfigure_on_delete) {
-			if (type & RouteProcessorChange::GeneralChange) {
-				_session->route_processors_changed (RouteProcessorChange ());
-			} else {
-				if (type & RouteProcessorChange::MeterPointChange) {
-					_session->route_processors_changed (RouteProcessorChange (RouteProcessorChange::MeterPointChange));
-				}
-				if (type & RouteProcessorChange::RealTimeChange) {
-					_session->route_processors_changed (RouteProcessorChange (RouteProcessorChange::RealTimeChange));
-				}
+			if (type != RouteProcessorChange::NoProcessorChange) {
+				_session->route_processors_changed (type);
 			}
 		}
 	}
diff --git a/libs/ardour/session_transport.cc b/libs/ardour/session_transport.cc
index 68d8321024..7938daf323 100644
--- a/libs/ardour/session_transport.cc
+++ b/libs/ardour/session_transport.cc
@@ -1963,21 +1963,25 @@ Session::route_processors_changed (RouteProcessorChange c)
 		return;
 	}
 
-	if (c.type == RouteProcessorChange::MeterPointChange) {
-		/* sort rec-armed routes first */
+	if (c.type == RouteProcessorChange::NoProcessorChange) {
+		return;
+	}
+
+	if (c.type & RouteProcessorChange::MeterPointChange) {
+		/* sort rec-armed routes to be processed first */
 		resort_routes ();
 		set_dirty ();
 		return;
 	}
 
-	if (c.type == RouteProcessorChange::RealTimeChange) {
+	if (c.type & RouteProcessorChange::RealTimeChange) {
 		set_dirty ();
 		return;
 	}
 
 	resort_routes ();
 
-	if (c.type == RouteProcessorChange::SendReturnChange) {
+	if (c.type & RouteProcessorChange::SendReturnChange) {
 		update_latency_compensation (true, false);
 	} else {
 		update_latency_compensation (false, false);