2 Copyright (C) 2010 Paul Davis
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 #ifndef __pbd_file_manager_h__
21 #define __pbd_file_manager_h__
23 #include <sys/types.h>
27 #include <glibmm/thread.h>
28 #include "pbd/signals.h"
34 /** Parent class for FileDescriptors.
36 * When a subclass is instantiated, the file it describes is added to a
37 * list. The FileDescriptor can be `allocated', meaning that its
38 * file will be opened on the filesystem, and can then be `released'.
39 * FileDescriptors are reference counted as they are allocated and
40 * released. When a descriptor's refcount is 0, the file on the
41 * filesystem is eligible to be closed if necessary to free up file
42 * handles for other files.
44 * The upshot of all this is that Ardour can manage the number of
45 * open files to stay within limits imposed by the operating system.
51 FileDescriptor (std::string const &, bool);
52 virtual ~FileDescriptor () {}
54 const std::string& path() const { return _path; }
57 virtual void set_path (const std::string&);
59 /** Emitted when the file is closed */
60 PBD::Signal0<void> Closed;
64 friend class FileManager;
66 /* These methods and variables must be called / accessed
67 with a lock held on the FileManager's mutex
70 /** @return false on success, true on failure */
71 virtual bool open () = 0;
72 virtual void close () = 0;
73 virtual bool is_open () const = 0;
75 int _refcount; ///< number of active users of this file
76 double _last_used; ///< monotonic time that this file was last allocated
77 std::string _path; ///< file path
78 bool _writeable; ///< true if it should be opened writeable, otherwise false
80 FileManager* manager ();
84 static FileManager* _manager;
88 /** FileDescriptor for a file to be opened using POSIX open */
89 class FdFileDescriptor : public FileDescriptor
92 FdFileDescriptor (std::string const & file_name, bool writeable, mode_t mode);
99 friend class FileManager;
103 bool is_open () const;
105 int _fd; ///< file descriptor, or -1 if the file is closed
106 mode_t _mode; ///< mode to use when creating files
109 /** FileDescriptor for a file opened using stdio */
110 class StdioFileDescriptor : public FileDescriptor
113 StdioFileDescriptor (std::string const & file_name, std::string const & mode);
114 ~StdioFileDescriptor ();
120 friend class FileManager;
124 bool is_open () const;
131 /** Class to limit the number of files held open */
137 void add (FileDescriptor *);
138 void remove (FileDescriptor *);
140 void release (FileDescriptor *);
141 bool allocate (FileDescriptor *);
145 void close (FileDescriptor *);
147 std::list<FileDescriptor*> _files; ///< files we know about
148 Glib::Mutex _mutex; ///< mutex for _files, _open and FileDescriptor contents
149 int _open; ///< number of open files
150 int _max_open; ///< maximum number of open files