move LatencyChanged detection from Plugin to Processor (plugin-insert)

* support all Plugin APIs (not implementation specific)
* also check for latency changes when plugins are hard en/disabled

libs/ardour/ardour/plugin.h

@@ -225,23 +225,6 @@ class LIBARDOUR_API Plugin : public PBD::StatefulDestructible, public Latent
 		return 0;
 	}
 
-	/** Emitted when a Latency Changes
-	 *
-	 * (this cannot be part of ARDOUR::Latent because
-	 * signals cannot be copy-constructed).
-	 */
-	PBD::Signal2<void,framecnt_t, framecnt_t> LatencyChanged;
-
-	/* overload Latent::set_user_latency w/signal emission */
-	virtual void set_user_latency (framecnt_t val) {
-		bool changed = val != _user_latency;
-		framecnt_t old = effective_latency ();
-		_user_latency = val;
-		if (changed) {
-			LatencyChanged (old, effective_latency ()); /* EMIT SIGNAL */
-		}
-	}
-
 	/** the max possible latency a plugin will have */
 	virtual framecnt_t max_latency () const { return 0; } // TODO = 0, require implementation
 

libs/ardour/ardour/plugin_insert.h

@@ -310,6 +310,7 @@ class LIBARDOUR_API PluginInsert : public Processor
 	boost::shared_ptr<SideChain> _sidechain;
 	uint32_t _sc_playback_latency;
 	uint32_t _sc_capture_latency;
+	uint32_t _plugin_signal_latency;
 
 	boost::weak_ptr<Plugin> _impulseAnalysisPlugin;
 
@@ -368,7 +369,7 @@ class LIBARDOUR_API PluginInsert : public Processor
 	void start_touch (uint32_t param_id);
 	void end_touch (uint32_t param_id);
 
-	void latency_changed (framecnt_t, framecnt_t);
+	void latency_changed ();
 	bool _latency_changed;
 	uint32_t _bypass_port;
 };

libs/ardour/lv2_plugin.cc

@@ -2707,9 +2707,6 @@ LV2Plugin::connect_and_run(BufferSet& bufs,
 
 	if (_latency_control_port) {
 		framecnt_t new_latency = signal_latency ();
-		if (_current_latency != new_latency) {
-			LatencyChanged (_current_latency, new_latency); /* EMIT SIGNAL */
-		}
 		_current_latency = new_latency;
 	}
 	return 0;

libs/ardour/plugin_insert.cc

@@ -69,6 +69,7 @@ PluginInsert::PluginInsert (Session& s, boost::shared_ptr<Plugin> plug)
 	: Processor (s, (plug ? plug->name() : string ("toBeRenamed")))
 	, _sc_playback_latency (0)
 	, _sc_capture_latency (0)
+	, _plugin_signal_latency (0)
 	, _signal_analysis_collected_nframes(0)
 	, _signal_analysis_collect_nframes_max(0)
 	, _configured (false)
@@ -551,6 +552,10 @@ PluginInsert::activate ()
 	}
 
 	Processor::activate ();
+	if (_plugin_signal_latency != signal_latency ()) {
+		_plugin_signal_latency = signal_latency ();
+		latency_changed ();
+	}
 }
 
 void
@@ -561,6 +566,10 @@ PluginInsert::deactivate ()
 	for (Plugins::iterator i = _plugins.begin(); i != _plugins.end(); ++i) {
 		(*i)->deactivate ();
 	}
+	if (_plugin_signal_latency != signal_latency ()) {
+		_plugin_signal_latency = signal_latency ();
+		latency_changed ();
+	}
 }
 
 void
@@ -914,6 +923,11 @@ PluginInsert::connect_and_run (BufferSet& bufs, framepos_t start, framepos_t end
 					     &_signal_analysis_outputs);
 		}
 	}
+
+	if (_plugin_signal_latency != signal_latency ()) {
+		_plugin_signal_latency = signal_latency ();
+		latency_changed ();
+	}
 }
 
 void
@@ -2699,6 +2713,9 @@ PluginInsert::describe_parameter (Evoral::Parameter param)
 ARDOUR::framecnt_t
 PluginInsert::signal_latency() const
 {
+	if (!_pending_active) {
+		return 0;
+	}
 	if (_user_latency) {
 		return _user_latency;
 	}
@@ -2878,7 +2895,6 @@ PluginInsert::add_plugin (boost::shared_ptr<Plugin> plugin)
 		plugin->ParameterChangedExternally.connect_same_thread (*this, boost::bind (&PluginInsert::parameter_changed_externally, this, _1, _2));
 		plugin->StartTouch.connect_same_thread (*this, boost::bind (&PluginInsert::start_touch, this, _1));
 		plugin->EndTouch.connect_same_thread (*this, boost::bind (&PluginInsert::end_touch, this, _1));
-		plugin->LatencyChanged.connect_same_thread (*this, boost::bind (&PluginInsert::latency_changed, this, _1, _2));
 		_custom_sinks = plugin->get_info()->n_inputs;
 		// cache sidechain port count
 		_cached_sidechain_pins.reset ();
@@ -2939,10 +2955,14 @@ PluginInsert::monitoring_changed ()
 }
 
 void
-PluginInsert::latency_changed (framecnt_t, framecnt_t)
+PluginInsert::latency_changed ()
 {
 	// this is called in RT context, LatencyChanged is emitted after run()
 	_latency_changed = true;
+#if 0 // TODO check possible deadlock in RT-context
+	// XXX This also needs a proper API not an owner() hack.
+	static_cast<Route*>(owner ())->processors_changed (RouteProcessorChange ()); /* EMIT SIGNAL */
+#endif
 }
 
 void