dramatic change in logic and naming for operations related to adding a MIDI region on demand and cloning/unlinking

Existing code would cause data loss due to creation of two Source objects referring the same path, one with removable flags and one without. Careful code review suggested a variety of thinkos, function naming problems and other confusion that caused this. I have tried ot extensively comment what is going on with these operations, because it is one key area in which MIDI differs from audio: with audio, capture is the only way to add a new audio region, but for MIDI there are GUI input events that can add a new region.

12 files changed, 158 insertions, 94 deletions

diff --git a/gtk2_ardour/editor_ops.cc b/gtk2_ardour/editor_ops.cc
index 1a818f1c71..a2eae60052 100644
--- a/gtk2_ardour/editor_ops.cc
+++ b/gtk2_ardour/editor_ops.cc
@@ -4772,12 +4772,17 @@ Editor::fork_region ()
 		MidiRegionView* const mrv = dynamic_cast<MidiRegionView*>(*r);
 
 		if (mrv) {
-			boost::shared_ptr<Playlist> playlist = mrv->region()->playlist();
-			boost::shared_ptr<MidiRegion> newregion = mrv->midi_region()->clone ();
-
-			playlist->clear_changes ();
-			playlist->replace_region (mrv->region(), newregion, mrv->region()->position());
-			_session->add_command(new StatefulDiffCommand (playlist));
+			try {
+				boost::shared_ptr<Playlist> playlist = mrv->region()->playlist();
+				boost::shared_ptr<MidiSource> new_source = _session->create_midi_source_by_stealing_name (mrv->midi_view()->track());
+				boost::shared_ptr<MidiRegion> newregion = mrv->midi_region()->clone (new_source);
+				
+				playlist->clear_changes ();
+				playlist->replace_region (mrv->region(), newregion, mrv->region()->position());
+				_session->add_command(new StatefulDiffCommand (playlist));
+			} catch (...) {
+				error << string_compose (_("Could not unlink %1"), mrv->region()->name()) << endmsg;
+			}
 		}
 
 		r = tmp;
diff --git a/gtk2_ardour/midi_time_axis.cc b/gtk2_ardour/midi_time_axis.cc
index 54793d9904..aa057d98c6 100644
--- a/gtk2_ardour/midi_time_axis.cc
+++ b/gtk2_ardour/midi_time_axis.cc
@@ -1524,8 +1524,7 @@ MidiTimeAxisView::add_region (framepos_t pos, framecnt_t length, bool commit)
 
 	real_editor->snap_to (pos, 0);
 
-	boost::shared_ptr<Source> src = _session->create_midi_source_for_session (
-		view()->trackview().track().get(), view()->trackview().track()->name());
+	boost::shared_ptr<Source> src = _session->create_midi_source_by_stealing_name (view()->trackview().track());
 	PropertyList plist;
 
 	plist.add (ARDOUR::Properties::start, 0);
diff --git a/libs/ardour/ardour/audiofilesource.h b/libs/ardour/ardour/audiofilesource.h
index c5fd7b3af2..9be8d6ce45 100644
--- a/libs/ardour/ardour/audiofilesource.h
+++ b/libs/ardour/ardour/audiofilesource.h
@@ -39,10 +39,6 @@ class AudioFileSource : public AudioSource, public FileSource {
 public:
 	virtual ~AudioFileSource ();
 
-	bool set_name (const std::string& newname) {
-		return (set_source_name(newname, destructive()) == 0);
-	}
-
 	std::string peak_path (std::string audio_path);
 	std::string find_broken_peakfile (std::string missing_peak_path,
 	                                  std::string audio_path);
diff --git a/libs/ardour/ardour/midi_region.h b/libs/ardour/ardour/midi_region.h
index daca7a243d..91e048c03e 100644
--- a/libs/ardour/ardour/midi_region.h
+++ b/libs/ardour/ardour/midi_region.h
@@ -63,6 +63,7 @@ class MidiRegion : public Region
 	~MidiRegion();
 
 	boost::shared_ptr<MidiRegion> clone (std::string path = std::string()) const;
+	boost::shared_ptr<MidiRegion> clone (boost::shared_ptr<MidiSource>) const;
 
 	boost::shared_ptr<MidiSource> midi_source (uint32_t n=0) const;
 
diff --git a/libs/ardour/ardour/midi_source.h b/libs/ardour/ardour/midi_source.h
index a5aac8859b..6a21c03856 100644
--- a/libs/ardour/ardour/midi_source.h
+++ b/libs/ardour/ardour/midi_source.h
@@ -48,9 +48,21 @@ class MidiSource : virtual public Source, public boost::enable_shared_from_this<
 	MidiSource (Session& session, const XMLNode&);
 	virtual ~MidiSource ();
 
-	boost::shared_ptr<MidiSource> clone (const std::string& path,
-					     Evoral::MusicalTime begin = Evoral::MinMusicalTime,
-	                                     Evoral::MusicalTime end = Evoral::MaxMusicalTime);
+	/** Write the data in the given time range to another MidiSource
+	 * \param newsrc MidiSource to which data will be written. Should be a
+	 *        new, empty source. If it already has contents, the results are
+	 *        undefined. Source must be writable.
+	 *
+	 * \param begin time of earliest event that can be written.
+	 * \param end time of latest event that can be written.
+	 *
+	 * Returns zero on success, non-zero if the write failed for any
+	 * reason.
+	 *
+	 */
+	int write_to (boost::shared_ptr<MidiSource> newsrc,
+		      Evoral::MusicalTime begin = Evoral::MinMusicalTime,
+		      Evoral::MusicalTime end = Evoral::MaxMusicalTime);
 
 	/** Read the data in a given time range from the MIDI source.
 	 * All time stamps in parameters are in audio frames (even if the source has tempo time).
diff --git a/libs/ardour/ardour/session.h b/libs/ardour/ardour/session.h
index 09421a580b..07c6210833 100644
--- a/libs/ardour/ardour/session.h
+++ b/libs/ardour/ardour/session.h
@@ -194,7 +194,7 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 
 	std::string peak_path (std::string) const;
 
-	std::string change_source_path_by_name (std::string oldpath, std::string oldname, std::string newname, bool destructive);
+	std::string generate_new_source_path_from_name (std::string oldpath, std::string oldname, std::string newname, bool destructive);
 
 	std::string peak_path_from_audio_path (std::string) const;
 	std::string new_audio_source_name (const std::string&, uint32_t nchans, uint32_t chan, bool destructive);
@@ -582,11 +582,12 @@ class Session : public PBD::StatefulDestructible, public PBD::ScopedConnectionLi
 	boost::shared_ptr<AudioFileSource> create_audio_source_for_session (
 		size_t, std::string const &, uint32_t, bool destructive);
 
-	boost::shared_ptr<MidiSource> create_midi_source_for_session (
-		Track*, std::string const &);
+	boost::shared_ptr<MidiSource> create_midi_source_for_session (std::string const &);
+	boost::shared_ptr<MidiSource> create_midi_source_by_stealing_name (boost::shared_ptr<Track>);
 
 	boost::shared_ptr<Source> source_by_id (const PBD::ID&);
-	boost::shared_ptr<Source> source_by_path_and_channel (const std::string&, uint16_t);
+	boost::shared_ptr<AudioFileSource> source_by_path_and_channel (const std::string&, uint16_t) const;
+	boost::shared_ptr<MidiSource> source_by_path (const std::string&) const;
 	uint32_t count_sources_by_origin (const std::string&);
 
 	void add_playlist (boost::shared_ptr<Playlist>, bool unused = false);
diff --git a/libs/ardour/ardour/smf_source.h b/libs/ardour/ardour/smf_source.h
index e422d37f62..e0c5a9c6e8 100644
--- a/libs/ardour/ardour/smf_source.h
+++ b/libs/ardour/ardour/smf_source.h
@@ -49,8 +49,6 @@ public:
 		return safe_midi_file_extension(path);
 	}
 
-	bool set_name (const std::string& newname) { return (set_source_name(newname, false) == 0); }
-
 	void append_event_unlocked_beats (const Evoral::Event<Evoral::MusicalTime>& ev);
 	void append_event_unlocked_frames (const Evoral::Event<framepos_t>& ev, framepos_t source_start);
 
diff --git a/libs/ardour/file_source.cc b/libs/ardour/file_source.cc
index de7365962f..df9fa13e3c 100644
--- a/libs/ardour/file_source.cc
+++ b/libs/ardour/file_source.cc
@@ -529,7 +529,7 @@ FileSource::set_source_name (const string& newname, bool destructive)
 {
 	Glib::Threads::Mutex::Lock lm (_lock);
 	string oldpath = _path;
-	string newpath = _session.change_source_path_by_name (oldpath, _name, newname, destructive);
+	string newpath = _session.generate_new_source_path_from_name (oldpath, _name, newname, destructive);
 
 	if (newpath.empty()) {
 		error << string_compose (_("programming error: %1"), "cannot generate a changed file path") << endmsg;
diff --git a/libs/ardour/midi_diskstream.cc b/libs/ardour/midi_diskstream.cc
index eeabdcb728..21b5aa0a34 100644
--- a/libs/ardour/midi_diskstream.cc
+++ b/libs/ardour/midi_diskstream.cc
@@ -1199,7 +1199,7 @@ MidiDiskstream::use_new_write_source (uint32_t n)
 
 	try {
 		_write_source = boost::dynamic_pointer_cast<SMFSource>(
-			_session.create_midi_source_for_session (0, name ()));
+			_session.create_midi_source_for_session (name ()));
 
 		if (!_write_source) {
 			throw failed_constructor();
@@ -1224,13 +1224,19 @@ MidiDiskstream::use_new_write_source (uint32_t n)
 std::string
 MidiDiskstream::steal_write_source_name ()
 {
-	std::string our_new_name = _session.new_midi_source_name (_write_source->name());
-	std::string our_old_name = _write_source->name();
-	
-	if (_write_source->set_source_name (our_new_name, false)) {
+	string our_old_name = _write_source->name();
+
+	/* this will bump the name of the current write source to the next one
+	 * (e.g. "MIDI 1-1" gets renamed to "MIDI 1-2"), thus leaving the
+	 * current write source name (e.g. "MIDI 1-1" available). See the
+	 * comments in Session::create_midi_source_for_track() about why we do
+	 * this.
+	 */
+
+	if (_write_source->set_source_name (name(), false)) {
 		return string();
 	}
-
+	
 	return our_old_name;
 }
 
diff --git a/libs/ardour/midi_region.cc b/libs/ardour/midi_region.cc
index 8509e55f97..e7298e7526 100644
--- a/libs/ardour/midi_region.cc
+++ b/libs/ardour/midi_region.cc
@@ -25,6 +25,8 @@
 #include <set>
 
 #include <glibmm/threads.h>
+#include <glibmm/fileutils.h>
+#include <glibmm/miscutils.h>
 
 #include "pbd/xml++.h"
 #include "pbd/basename.h"
@@ -36,6 +38,7 @@
 #include "ardour/midi_source.h"
 #include "ardour/region_factory.h"
 #include "ardour/session.h"
+#include "ardour/source_factory.h"
 #include "ardour/tempo.h"
 #include "ardour/types.h"
 
@@ -127,15 +130,30 @@ MidiRegion::~MidiRegion ()
 boost::shared_ptr<MidiRegion>
 MidiRegion::clone (string path) const
 {
+	boost::shared_ptr<MidiSource> newsrc;
+
+	/* caller must check for pre-existing file */
+	assert (!Glib::file_test (path, Glib::FILE_TEST_EXISTS));
+	newsrc = boost::dynamic_pointer_cast<MidiSource>(
+		SourceFactory::createWritable(DataType::MIDI, _session,
+					      path, false, _session.frame_rate()));
+	return clone (newsrc);
+}
+
+boost::shared_ptr<MidiRegion>
+MidiRegion::clone (boost::shared_ptr<MidiSource> newsrc) const
+{
 	BeatsFramesConverter bfc (_session.tempo_map(), _position);
 	Evoral::MusicalTime const bbegin = bfc.from (_start);
 	Evoral::MusicalTime const bend = bfc.from (_start + _length);
 
-	boost::shared_ptr<MidiSource> ms = midi_source(0)->clone (path, bbegin, bend);
+	if (midi_source(0)->write_to (newsrc, bbegin, bend)) {
+		return boost::shared_ptr<MidiRegion> ();
+	}
 
 	PropertyList plist;
 
-	plist.add (Properties::name, PBD::basename_nosuffix (ms->name()));
+	plist.add (Properties::name, PBD::basename_nosuffix (newsrc->name()));
 	plist.add (Properties::whole_file, true);
 	plist.add (Properties::start, _start);
 	plist.add (Properties::start_beats, _start_beats);
@@ -143,7 +161,7 @@ MidiRegion::clone (string path) const
 	plist.add (Properties::length_beats, _length_beats);
 	plist.add (Properties::layer, 0);
 
-	return boost::dynamic_pointer_cast<MidiRegion> (RegionFactory::create (ms, plist, true));
+	return boost::dynamic_pointer_cast<MidiRegion> (RegionFactory::create (newsrc, plist, true));
 }
 
 void
diff --git a/libs/ardour/midi_source.cc b/libs/ardour/midi_source.cc
index ed9aa9ddba..880bad1c24 100644
--- a/libs/ardour/midi_source.cc
+++ b/libs/ardour/midi_source.cc
@@ -333,29 +333,9 @@ MidiSource::mark_streaming_write_completed ()
 	mark_midi_streaming_write_completed (Evoral::Sequence<Evoral::MusicalTime>::DeleteStuckNotes);
 }
 
-boost::shared_ptr<MidiSource>
-MidiSource::clone (const string& path, Evoral::MusicalTime begin, Evoral::MusicalTime end)
+int
+MidiSource::write_to (boost::shared_ptr<MidiSource> newsrc, Evoral::MusicalTime begin, Evoral::MusicalTime end)
 {
-	string newpath;
-
-	/* get a new name for the MIDI file we're going to write to
-	 */
-	
-	if (path.empty()) {
-		string newname = PBD::basename_nosuffix(_name.val());
-		newname = bump_name_once (newname, '-');
-		newname += ".mid";
-		newpath = _session.new_source_path_from_name (DataType::MIDI, newname);
-	} else {
-		/* caller must check for pre-existing file */
-		assert (!Glib::file_test (path, Glib::FILE_TEST_EXISTS));
-		newpath = path;
-	}
-
-	boost::shared_ptr<MidiSource> newsrc = boost::dynamic_pointer_cast<MidiSource>(
-		SourceFactory::createWritable(DataType::MIDI, _session,
-		                              newpath, false, _session.frame_rate()));
-
 	newsrc->set_timeline_position(_timeline_position);
 	newsrc->copy_interpolation_from (this);
 	newsrc->copy_automation_state_from (this);
@@ -368,7 +348,7 @@ MidiSource::clone (const string& path, Evoral::MusicalTime begin, Evoral::Musica
 		}
 	} else {
 		error << string_compose (_("programming error: %1"), X_("no model for MidiSource during ::clone()"));
-		return boost::shared_ptr<MidiSource>();
+		return -1;
 	}
 
 	newsrc->flush_midi();
@@ -385,7 +365,7 @@ MidiSource::clone (const string& path, Evoral::MusicalTime begin, Evoral::Musica
 
 	boost::dynamic_pointer_cast<FileSource> (newsrc)->prevent_deletion ();
 
-	return newsrc;
+	return 0;
 }
 
 void
diff --git a/libs/ardour/session.cc b/libs/ardour/session.cc
index 0bb2242b6c..cf1487c28c 100644
--- a/libs/ardour/session.cc
+++ b/libs/ardour/session.cc
@@ -3304,12 +3304,16 @@ Session::source_by_id (const PBD::ID& id)
 	return source;
 }
 
-boost::shared_ptr<Source>
-Session::source_by_path_and_channel (const string& path, uint16_t chn)
+boost::shared_ptr<AudioFileSource>
+Session::source_by_path_and_channel (const string& path, uint16_t chn) const
 {
+	/* Restricted to audio files because only audio sources have channel
+	   as a property.
+	*/
+
 	Glib::Threads::Mutex::Lock lm (source_lock);
 
-	for (SourceMap::iterator i = sources.begin(); i != sources.end(); ++i) {
+	for (SourceMap::const_iterator i = sources.begin(); i != sources.end(); ++i) {
 		boost::shared_ptr<AudioFileSource> afs
 			= boost::dynamic_pointer_cast<AudioFileSource>(i->second);
 
@@ -3317,7 +3321,31 @@ Session::source_by_path_and_channel (const string& path, uint16_t chn)
 			return afs;
 		}
 	}
-	return boost::shared_ptr<Source>();
+
+	return boost::shared_ptr<AudioFileSource>();
+}
+
+boost::shared_ptr<MidiSource>
+Session::source_by_path (const std::string& path) const
+{
+	/* Restricted to MIDI files because audio sources require a channel
+	   for unique identification, in addition to a path.
+	*/
+
+	Glib::Threads::Mutex::Lock lm (source_lock);
+
+	for (SourceMap::const_iterator s = sources.begin(); s != sources.end(); ++s) {
+		boost::shared_ptr<MidiSource> ms
+			= boost::dynamic_pointer_cast<MidiSource>(s->second);
+		boost::shared_ptr<FileSource> fs
+			= boost::dynamic_pointer_cast<FileSource>(s->second);
+		
+		if (ms && fs && fs->path() == path) {
+			return ms;
+		}
+	}
+
+	return boost::shared_ptr<MidiSource>();
 }
 
 uint32_t
@@ -3338,9 +3366,8 @@ Session::count_sources_by_origin (const string& path)
 	return cnt;
 }
 
-
 string
-Session::change_source_path_by_name (string path, string oldname, string newname, bool destructive)
+Session::generate_new_source_path_from_name (string path, string oldname, string newname, bool destructive)
 {
 	string look_for;
 	string old_basename = PBD::basename_nosuffix (oldname);
@@ -3427,7 +3454,9 @@ Session::change_source_path_by_name (string path, string oldname, string newname
 
 			if (!matching_unsuffixed_filename_exists_in (dir, buf)) {
 				path = Glib::build_filename (dir, buf);
-				break;
+				if (!source_by_path (path)) {
+					break;
+				}
 			}
 
 			path = "";
@@ -3575,17 +3604,18 @@ Session::create_audio_source_for_session (size_t n_chans, string const & n, uint
 		SourceFactory::createWritable (DataType::AUDIO, *this, path, destructive, frame_rate()));
 }
 
-/** Return a unique name based on \a base for a new internal MIDI source */
+/** Return a unique name based on \a owner_name for a new internal MIDI source */
 string
-Session::new_midi_source_name (const string& base)
+Session::new_midi_source_name (const string& owner_name)
 {
 	uint32_t cnt;
 	char buf[PATH_MAX+1];
 	const uint32_t limit = 10000;
 	string legalized;
+	string possible_name;
 
 	buf[0] = '\0';
-	legalized = legalize_for_path (base);
+	legalized = legalize_for_path (owner_name);
 
 	// Find a "version" of the file name that doesn't exist in any of the possible directories.
 
@@ -3597,12 +3627,17 @@ Session::new_midi_source_name (const string& base)
 		for (i = session_dirs.begin(); i != session_dirs.end(); ++i) {
 
 			SessionDirectory sdir((*i).path);
+			
+			snprintf (buf, sizeof(buf), "%s-%u.mid", legalized.c_str(), cnt);
+			possible_name = buf;
 
-			std::string p = Glib::build_filename (sdir.midi_path(), legalized);
-
-			snprintf (buf, sizeof(buf), "%s-%u.mid", p.c_str(), cnt);
+			std::string possible_path = Glib::build_filename (sdir.midi_path(), possible_name);
+			
+			if (Glib::file_test (possible_path, Glib::FILE_TEST_EXISTS)) {
+				existing++;
+			}
 
-			if (Glib::file_test (buf, Glib::FILE_TEST_EXISTS)) {
+			if (source_by_path (possible_path)) {
 				existing++;
 			}
 		}
@@ -3614,49 +3649,62 @@ Session::new_midi_source_name (const string& base)
 		if (cnt > limit) {
 			error << string_compose(
 					_("There are already %1 recordings for %2, which I consider too many."),
-					limit, base) << endmsg;
+					limit, owner_name) << endmsg;
 			destroy ();
 			throw failed_constructor();
 		}
 	}
 
-	return Glib::path_get_basename(buf);
+	return possible_name;
 }
 
 
 /** Create a new within-session MIDI source */
 boost::shared_ptr<MidiSource>
-Session::create_midi_source_for_session (Track* track, string const & n)
+Session::create_midi_source_for_session (string const & basic_name)
 {
 	std::string name;
 
-	if (track) {
-		/* the caller passes in the track the source will be used in,
-		   so that we can keep the numbering sane. 
-		   
-		   Rationale: a track with the name "Foo" that has had N
-		   captures carried out so far will already have a write source
-		   named "Foo-N+1.mid" waiting to be used for the next capture.
-
-		   If we call new_midi_source_name() we will get "Foo-N+2". But
-		   there is no region corresponding to "Foo-N+1", so when
-		   "Foo-N+2" appears in the track, the gap presents the user
-		   with odd behaviour - why did it skip past Foo-N+1?
+	if (name.empty()) {
+		name = new_midi_source_name (basic_name);
+	}
 
-		   We could explain this to the user in some odd way, but
-		   instead we rename "Foo-N+1.mid" as "Foo-N+2.mid", and then
-		   use "Foo-N+1" here.
+	const string path = new_source_path_from_name (DataType::MIDI, name);
 
-		   If that attempted rename fails, we get "Foo-N+2.mid" anyway.
-		*/
+	return boost::dynamic_pointer_cast<SMFSource> (
+		SourceFactory::createWritable (
+			DataType::MIDI, *this, path, false, frame_rate()));
+}
 
-		MidiTrack* mt = dynamic_cast<MidiTrack*> (track);
-		assert (mt);
-		name = track->steal_write_source_name ();
-	}
+/** Create a new within-session MIDI source */
+boost::shared_ptr<MidiSource>
+Session::create_midi_source_by_stealing_name (boost::shared_ptr<Track> track)
+{
+	/* the caller passes in the track the source will be used in,
+	   so that we can keep the numbering sane. 
+	   
+	   Rationale: a track with the name "Foo" that has had N
+	   captures carried out so far will ALREADY have a write source
+	   named "Foo-N+1.mid" waiting to be used for the next capture.
+	   
+	   If we call new_midi_source_name() we will get "Foo-N+2". But
+	   there is no region corresponding to "Foo-N+1", so when
+	   "Foo-N+2" appears in the track, the gap presents the user
+	   with odd behaviour - why did it skip past Foo-N+1?
+	   
+	   We could explain this to the user in some odd way, but
+	   instead we rename "Foo-N+1.mid" as "Foo-N+2.mid", and then
+	   use "Foo-N+1" here.
+	   
+	   If that attempted rename fails, we get "Foo-N+2.mid" anyway.
+	*/
+	
+	boost::shared_ptr<MidiTrack> mt = boost::dynamic_pointer_cast<MidiTrack> (track);
+	assert (mt);
+	std::string name = track->steal_write_source_name ();
 
 	if (name.empty()) {
-		name = new_midi_source_name (n);
+		return boost::shared_ptr<MidiSource>();
 	}
 
 	const string path = new_source_path_from_name (DataType::MIDI, name);