add a mechanism to use existing MIDNAM info and connect to PatchesChanged in future, atomically

The atomically is with respect to the initial thread-based MIDNAM loading

2 files changed, 36 insertions, 3 deletions

diff --git a/libs/ardour/ardour/midi_patch_manager.h b/libs/ardour/ardour/midi_patch_manager.h
index b450fac2ea..1e1d262439 100644
--- a/libs/ardour/ardour/midi_patch_manager.h
+++ b/libs/ardour/ardour/midi_patch_manager.h
@@ -23,8 +23,11 @@
 #ifndef MIDI_PATCH_MANAGER_H_
 #define MIDI_PATCH_MANAGER_H_
 
+#include <glibmm/threads.h>
+
 #include "midi++/midnam_patch.h"
 
+#include "pbd/event_loop.h"
 #include "pbd/signals.h"
 #include "pbd/search_path.h"
 
@@ -147,7 +150,10 @@ public:
 	const DeviceNamesByMaker& devices_by_manufacturer() const { return _devices_by_manufacturer; }
 
 	void load_midnams_in_thread ();
-
+	void maybe_use (PBD::ScopedConnectionList& clist,
+	                PBD::EventLoop::InvalidationRecord* ir,
+	                const boost::function<void()>& slot,
+	                PBD::EventLoop* event_loop);
 private:
 	bool load_midi_name_document(const std::string& file_path);
 	bool add_midi_name_document(boost::shared_ptr<MIDINameDocument>);
@@ -164,6 +170,7 @@ private:
 	DeviceNamesByMaker                      _devices_by_manufacturer;
 	MasterDeviceNames::Models               _all_models;
 
+	Glib::Threads::Mutex _lock;
 	bool no_patch_changed_messages;
 	pthread_t _midnam_load_thread;
 	static void* _midnam_load (void *);
@@ -175,4 +182,3 @@ private:
 } // namespace MIDI
 
 #endif /* MIDI_PATCH_MANAGER_H_ */
-
diff --git a/libs/ardour/midi_patch_manager.cc b/libs/ardour/midi_patch_manager.cc
index c0bdd28419..9a5f45029b 100644
--- a/libs/ardour/midi_patch_manager.cc
+++ b/libs/ardour/midi_patch_manager.cc
@@ -265,13 +265,20 @@ MidiPatchManager::_midnam_load (void* arg)
 void
 MidiPatchManager::load_midnams ()
 {
+	/* really there's only going to be one x-thread request/signal before
+	   this thread exits but we'll say 8 just to be sure.
+	*/
+
+	PBD::notify_event_loops_about_thread_creation (pthread_self(), "midi-patch-manager", 8);
+
 	{
+		Glib::Threads::Mutex::Lock lm (_lock);
 		PBD::Unwinder<bool> npc (no_patch_changed_messages, true);
 		for (Searchpath::const_iterator i = _search_path.begin(); i != _search_path.end(); ++i) {
 			add_midnam_files_from_directory (*i);
 		}
 	}
-
+	
 	PatchesChanged (); /* EMIT SIGNAL */
 }
 
@@ -280,3 +287,23 @@ MidiPatchManager::load_midnams_in_thread ()
 {
 	pthread_create_and_store (X_("midnam"), &_midnam_load_thread, _midnam_load, this);
 }
+
+void
+MidiPatchManager::maybe_use (PBD::ScopedConnectionList& cl,
+                             PBD::EventLoop::InvalidationRecord* ir,
+                             const boost::function<void()> & midnam_info_method,
+                             PBD::EventLoop* event_loop)
+{
+	{
+		Glib::Threads::Mutex::Lock lm (_lock);
+
+		if (!_documents.empty()) {
+			/* already have documents loaded, so call closure to use them */
+			midnam_info_method ();
+		}
+
+		/* if/when they ever change, call the closure (maybe multiple times) */
+
+		PatchesChanged.connect (cl, ir, midnam_info_method, event_loop);
+	}
+}