791f42c104
We have 'File' which associates a name with a file and will be used to offer an interface for the application. Posix 'Filehandles' which are managed in a 'Filehandlecache' to utilize a limited number of fd's at optimum. Internally we use 'Filedescriptor's which manage files, mapping and all kinds of metadata. Filedescriptors weak referenced by a registry and freed when the last user vanishes.
97 lines
3 KiB
C
97 lines
3 KiB
C
/*
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filehandlecache - filehandle management and caching
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Copyright (C) Lumiera.org
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2008, Christian Thaeter <ct@pipapo.org>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef LUMIERA_FILEHANDLECACHE_H
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#define LUMIERA_FILEHANDLECACHE_H
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#include "lib/error.h"
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#include "lib/mrucache.h"
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#include "lib/mutex.h"
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#include "backend/filehandle.h"
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/**
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* @file Filehandle management and caching
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* The number of filehandles a program can held open is usually limited, since we want to support
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* using a less limited number of files and closing/opening for each operation is expensive, we
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* provide a cache to keep the most frequent used files open and gracefully close/recycle unused filehandles.
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*/
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/*
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File handle cache manages file handles
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*/
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struct lumiera_filehandlecache_struct
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{
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lumiera_mrucache cache;
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int available;
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lumiera_mutex lock;
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};
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typedef struct lumiera_filehandlecache_struct lumiera_filehandlecache;
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typedef lumiera_filehandlecache* LumieraFilehandlecache;
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/**
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* Initializes a filehandle cache.
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* @param self pointer to the cache to be initialized
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* @param max_entries number how much filehandles shall be managed
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* @return self as given
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* The number of elements the cache can hold is static and should be
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* determined by sysconf (_SC_OPEN_MAX) minus some safety margin.
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*/
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LumieraFilehandlecache
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lumiera_filehandlecache_init (LumieraFilehandlecache self, int max_entries);
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/**
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* Destroy a filehandle cache.
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* @param self the cache to be destroyed
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* @return self as given to the now uninitialized! cache
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* No filehandles in the cache must be locked, this would be a fatal error.
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* The handles are closed automatically.
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*/
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LumieraFilehandlecache
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lumiera_filehandlecache_destroy (LumieraFilehandlecache self);
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/**
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* Get a fresh filehandle.
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* @param self pointer to the cache
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* @return the new filehandle
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* one must call lumiera_mutexacquirer_unlock (&lock) to free the lock on the handle when done
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*/
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LumieraFilehandle
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lumiera_filehandlecache_filehandle_acquire (LumieraFilehandlecache self);
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/**
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* Add filehande back to cache.
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* @param self pointer to the cache
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* @param handle filehandle to be put back
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*/
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void
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lumiera_filehandlecache_add (LumieraFilehandlecache self, LumieraFilehandle handle);
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/**
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*
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*/
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LumieraFilehandle
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lumiera_filehandlecache_remove (LumieraFilehandlecache self, int fd);
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#endif
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