Keep to a quota of open files by closing least recently used ones as required. Should fix #2341.

git-svn-id: svn://localhost/ardour2/branches/3.0@7101 d708f5d6-7413-0410-9779-e7cbd77b26cf

4 files changed, 136 insertions, 2 deletions

diff --git a/libs/ardour/ardour/audiosource.h b/libs/ardour/ardour/audiosource.h
index c4a6e4e475..9879c75a8d 100644
--- a/libs/ardour/ardour/audiosource.h
+++ b/libs/ardour/ardour/audiosource.h
@@ -32,6 +32,7 @@
 #include "ardour/source.h"
 #include "ardour/ardour.h"
 #include "ardour/readable.h"
+#include "ardour/file_manager.h"
 #include "pbd/stateful.h"
 #include "pbd/xml++.h"
 
@@ -140,7 +141,8 @@ class AudioSource : virtual public Source,
 				     framecnt_t frames_per_peak);
 
   private:
-	int        peakfile;
+	FdFileDescriptor* _peakfile_descriptor;
+	int        _peakfile_fd;
 	framecnt_t peak_leftover_cnt;
 	framecnt_t peak_leftover_size;
 	Sample*    peak_leftovers;
diff --git a/libs/ardour/ardour/debug.h b/libs/ardour/ardour/debug.h
index 57b66a8793..33d973389a 100644
--- a/libs/ardour/ardour/debug.h
+++ b/libs/ardour/ardour/debug.h
@@ -46,6 +46,7 @@ namespace PBD {
                 extern uint64_t MidiClock;
                 extern uint64_t Monitor;
                 extern uint64_t Solo;
+		extern uint64_t FileManager;
 	}
 }
 
diff --git a/libs/ardour/ardour/file_manager.h b/libs/ardour/ardour/file_manager.h
new file mode 100644
index 0000000000..86eb9676fa
--- /dev/null
+++ b/libs/ardour/ardour/file_manager.h
@@ -0,0 +1,128 @@
+/*
+    Copyright (C) 2010 Paul Davis
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+*/
+
+#ifndef __file_manager_h__
+#define __file_manager_h__
+
+#include <sys/types.h>
+#include <string>
+#include <map>
+#include <sndfile.h>
+#include <glibmm/thread.h>
+#include "pbd/signals.h"
+
+namespace ARDOUR {
+
+class FileManager;
+
+/** Parent class for FileDescriptors.
+ *
+ *  When a subclass is instantiated, the file it describes is added to a
+ *  list.  The FileDescriptor can be `allocated', meaning that its
+ *  file will be opened on the filesystem, and can then be `released'.
+ *  FileDescriptors are reference counted as they are allocated and
+ *  released.  When a descriptor's refcount is 0, the file on the
+ *  filesystem is eligible to be closed if necessary to free up file
+ *  handles for other files.
+ *
+ *  The upshot of all this is that Ardour can manage the number of
+ *  open files to stay within limits imposed by the operating system.
+ */
+	
+class FileDescriptor
+{
+public:
+	FileDescriptor (std::string const &, bool);
+	virtual ~FileDescriptor () {}
+
+	void release ();
+
+	/** Emitted when the file is closed */
+	PBD::Signal0<void> Closed;
+
+protected:
+
+	friend class FileManager;
+
+	/* These methods and variables must be called / accessed
+	   with a lock held on the FileManager's mutex
+	*/
+
+	/** @return false on success, true on failure */
+	virtual bool open () = 0;
+	virtual void close () = 0;
+	virtual bool is_open () const = 0;
+
+	int refcount; ///< number of active users of this file
+	double last_used; ///< monotonic time that this file was last allocated
+	std::string name; ///< filename
+	bool writeable; ///< true if it should be opened writeable, otherwise false
+
+	FileManager* manager ();
+	
+private:
+	
+	static FileManager* _manager;
+};
+
+/** FileDescriptor for a file to be opened using libsndfile */	
+class SndFileDescriptor : public FileDescriptor
+{
+public:
+	SndFileDescriptor (std::string const &, bool, SF_INFO *);
+	~SndFileDescriptor ();
+
+	SNDFILE* allocate ();
+
+private:	
+
+	friend class FileManager;
+
+	bool open ();
+	void close ();
+	bool is_open () const;
+
+	SNDFILE* _sndfile; ///< SNDFILE* pointer, or 0 if the file is closed
+	SF_INFO* _info; ///< libsndfile's info for this file
+};
+
+/** FileDescriptor for a file to be opened using POSIX open */	
+class FdFileDescriptor : public FileDescriptor
+{
+public:
+	FdFileDescriptor (std::string const &, bool, mode_t);
+	~FdFileDescriptor ();
+
+	int allocate ();
+
+private:
+
+	friend class FileManager;
+
+	bool open ();
+	void close ();
+	bool is_open () const;
+
+	int _fd; ///< file descriptor, or -1 if the file is closed
+	mode_t _mode; ///< mode to use when creating files
+};
+
+}
+
+#endif
diff --git a/libs/ardour/ardour/sndfilesource.h b/libs/ardour/ardour/sndfilesource.h
index 96f39de2c8..2338e35bb0 100644
--- a/libs/ardour/ardour/sndfilesource.h
+++ b/libs/ardour/ardour/sndfilesource.h
@@ -24,6 +24,7 @@
 
 #include "ardour/audiofilesource.h"
 #include "ardour/broadcast_info.h"
+#include "ardour/file_manager.h"
 
 namespace ARDOUR {
 
@@ -72,13 +73,14 @@ class SndFileSource : public AudioFileSource {
 	framecnt_t write_float (Sample* data, framepos_t pos, framecnt_t cnt);
 
   private:
-	SNDFILE *sf;
+	SndFileDescriptor* _descriptor;
 	SF_INFO _info;
 	BroadcastInfo *_broadcast_info;
 
 	void init_sndfile ();
 	int open();
 	int setup_broadcast_info (framepos_t when, struct tm&, time_t);
+	void file_closed ();
 
 	/* destructive */
 
@@ -100,6 +102,7 @@ class SndFileSource : public AudioFileSource {
 	framecnt_t nondestructive_write_unlocked (Sample *dst, framecnt_t cnt);
 	void handle_header_position_change ();
 	PBD::ScopedConnection header_position_connection;
+	PBD::ScopedConnection file_manager_connection;
 };
 
 } // namespace ARDOUR