From 911830726e5c5d91b254240e0f88ddd81d97c95d Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Mon, 23 Nov 2015 22:44:13 +0100
Subject: [PATCH] prefer recently used states.

---
 gtk2_ardour/engine_dialog.cc | 28 ++++++++++++++++++++++++++--
 gtk2_ardour/engine_dialog.h  |  5 ++++-
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/gtk2_ardour/engine_dialog.cc b/gtk2_ardour/engine_dialog.cc
index d8f35b211a..381a15b5ac 100644
--- a/gtk2_ardour/engine_dialog.cc
+++ b/gtk2_ardour/engine_dialog.cc
@@ -1630,8 +1630,6 @@ EngineControl::State
 EngineControl::get_matching_state (const string& backend)
 {
 	for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
-		// TODO use LRU for every backend and prefer the active one
-		// uniqueness is only guaranteed for backend + driver + device(s)
 		if ((*i)->backend == backend) {
 			return (*i);
 		}
@@ -1708,6 +1706,19 @@ bool EngineControl::equivalent_states (const EngineControl::State& state1,
 	return false;
 }
 
+bool
+EngineControl::state_sort_cmp (const State &a, const State &b) {
+	if (a->active) {
+		return true;
+	}
+	else if (b->active) {
+		return false;
+	}
+	else {
+		return a->lru < b->lru;
+	}
+}
+
 EngineControl::State
 EngineControl::save_state ()
 {
@@ -1716,6 +1727,7 @@ EngineControl::save_state ()
 	if (!_have_control) {
 		state = get_matching_state (backend_combo.get_active_text(), string(), string());
 		if (state) {
+			state->lru = time (NULL) ;
 			return state;
 		}
 		state.reset(new StateStruct);
@@ -1735,6 +1747,8 @@ EngineControl::save_state ()
 
 	states.push_back (state);
 
+	states.sort (state_sort_cmp);
+
 	return state;
 }
 
@@ -1754,6 +1768,7 @@ EngineControl::store_state (State state)
 	state->output_channels = get_output_channels ();
 	state->midi_option = get_midi_option ();
 	state->midi_devices = _midi_devices;
+	state->lru = time (NULL) ;
 }
 
 void
@@ -1817,6 +1832,7 @@ EngineControl::get_state ()
 			node->add_property ("output-channels", (*i)->output_channels);
 			node->add_property ("active", (*i)->active ? "yes" : "no");
 			node->add_property ("midi-option", (*i)->midi_option);
+			node->add_property ("lru", (*i)->active ? time (NULL) : (*i)->lru);
 
 			XMLNode* midi_devices = new XMLNode ("MIDIDevices");
 			for (std::vector<MidiDeviceSettings>::const_iterator p = (*i)->midi_devices.begin(); p != (*i)->midi_devices.end(); ++p) {
@@ -1980,6 +1996,10 @@ EngineControl::set_state (const XMLNode& root)
 				}
 			}
 
+			if ((prop = grandchild->property ("lru"))) {
+				state->lru = atoi (prop->value ());
+			}
+
 #if 1
 			/* remove accumulated duplicates (due to bug in ealier version)
 			 * this can be removed again before release
@@ -2016,6 +2036,8 @@ EngineControl::set_state (const XMLNode& root)
 		}
 	}
 
+	states.sort (state_sort_cmp);
+
 	for (StateList::const_iterator i = states.begin(); i != states.end(); ++i) {
 
 		if ((*i)->active) {
@@ -2414,6 +2436,8 @@ EngineControl::post_push ()
 		store_state(state);
 	}
 
+	states.sort (state_sort_cmp);
+
 	/* all off */
 
 	for (StateList::iterator i = states.begin(); i != states.end(); ++i) {
diff --git a/gtk2_ardour/engine_dialog.h b/gtk2_ardour/engine_dialog.h
index ae2128b19b..bfb094deea 100644
--- a/gtk2_ardour/engine_dialog.h
+++ b/gtk2_ardour/engine_dialog.h
@@ -217,6 +217,7 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
 	bool active;
 	std::string midi_option;
 	std::vector<MidiDeviceSettings> midi_devices;
+	time_t lru;
 
 	StateStruct()
 		: sample_rate (48000)
@@ -225,12 +226,14 @@ class EngineControl : public ArdourDialog, public PBD::ScopedConnectionList {
 		, output_latency (0)
 		, input_channels (0)
 		, output_channels (0)
-		, active (false) {}
+		, active (false)
+		, lru (0) {}
 
     };
 
     typedef boost::shared_ptr<StateStruct> State;
     typedef std::list<State> StateList;
+    static bool state_sort_cmp (const State &a, const State &b);
 
     StateList states;