da23204bf3
This adds global exclusive advisory file locks on a per-thread basis. Only exclusive locking for a whole file is supported to setup headers etc. Finer grained locking will be handled somewhere else.
288 lines
8.8 KiB
C
288 lines
8.8 KiB
C
/*
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file.h - interface to files by filename
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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_FILE_H
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#define LUMIERA_FILE_H
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#include "lib/mutex.h"
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#include "lib/llist.h"
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#include "lib/error.h"
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//NOBUG_DECLARE_FLAG (file);
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LUMIERA_ERROR_DECLARE(FILE_CHANGED);
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LUMIERA_ERROR_DECLARE(FILE_NOMMAPINGS);
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/**
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* @file
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* File management
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* Handling Files is splitted into different classes:
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* 1. The 'lumiera_file' class which acts as interface to the outside for managing files.
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* 'lumiera_file' is addressed by the name of the file. Since files can have more than one name (hardlinks)
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* many 'lumiera_file' can point to a single 'lumiera_filedescriptor'
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* 2. The 'lumiera_filedescriptor' class which does the real work managing the file in the back.
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* 3. Since OS-filehandles are a limited resource we access the lazily as 'lumiera_filehandle' which are
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* managed in a 'lumiera_filehandlecache'
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*/
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typedef struct lumiera_file_struct lumiera_file;
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typedef lumiera_file* LumieraFile;
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#include "backend/filedescriptor.h"
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#include "backend/filehandle.h"
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#include "backend/mmapings.h"
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#include "backend/mmap.h"
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/**
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* File modes:
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* LUMIERA_FILE_READONLY existing file for reading only
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* LUMIERA_FILE_READWRITE existing file for reading and writing
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* LUMIERA_FILE_CREATE non-existing file for reading and writing
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* LUMIERA_FILE_RECREATE remove and recreated existing, file for reading and writing
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*/
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#define LUMIERA_FILE_READONLY (O_RDONLY | O_LARGEFILE | O_NOATIME)
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#define LUMIERA_FILE_READWRITE (O_RDWR | O_LARGEFILE | O_NOATIME)
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#define LUMIERA_FILE_CREATE (O_RDWR | O_LARGEFILE | O_NOATIME | O_CREAT | O_EXCL)
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#define LUMIERA_FILE_RECREATE (O_RDWR | O_LARGEFILE | O_NOATIME | O_CREAT | O_TRUNC)
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/* creat and excl flags will be masked out for descriptor lookup */
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#define LUMIERA_FILE_MASK ~(O_CREAT | O_EXCL | O_TRUNC)
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struct lumiera_file_struct
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{
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/* all files of one descriptor */
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llist node;
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char* name;
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LumieraFiledescriptor descriptor;
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};
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/**
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* Initialize a file structure.
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* @param self pointer to the file structure
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* @param name filename
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* @param flags open flags
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* @return self or NULL in case of an error
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*/
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LumieraFile
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lumiera_file_init (LumieraFile self, const char* name, int flags);
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/**
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* Destroy a file structure.
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* frees all associated resources, releases the filedescriptor etc.
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* @param self file structure to be destroyed
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* @param do_unlink if 1 then delete the file physically from disk (only the associated name)
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* @return self
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*/
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LumieraFile
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lumiera_file_destroy (LumieraFile self, int do_unlink);
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/**
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* Allocate a new file structure.
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* @param name filename
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* @param flags open flags
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* @return new file structure or NULL in case of an error
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*/
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LumieraFile
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lumiera_file_new (const char* name, int flags);
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/**
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* Frees a file structure.
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* @param self file structure to be freed
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*/
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void
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lumiera_file_delete (LumieraFile self);
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/**
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* Frees a file structure and deletes the associated file name from disk.
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* @param self file structure to be freed
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*/
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void
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lumiera_file_delete_unlink (LumieraFile self);
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/**
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* Get a POSIX filehandle for a file.
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* Filehandles are opened on demand and must be acquired for use.
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* Using filehandles is refcounted and might be nested.
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* After using them they must be released which puts them back into filehandlecache aging.
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* @param self file structure
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* @return POSIX filehandle or -1 on error, check lumiera_error() to retrieve the errorcode
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* Currently only LUMIERA_ERROR_ERRNO will be raised but this might change in future.
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* Opening files can fail for many reasons and at any time!
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*/
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int
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lumiera_file_handle_acquire (LumieraFile self);
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/**
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* Put filehandle back into cache aging.
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* @param self file which handle to be released
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*/
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void
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lumiera_file_handle_release (LumieraFile self);
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/**
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* acquire a mmap which covers the given range
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* @param self file from where the mmap shall be acquired
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* @param start begin of the required range
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* @param size requested size
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* @return MMap object covering the requested range or NULL on error
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* note: the chunksize for the file must be set prior accessing mmaps
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*/
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LumieraMMap
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lumiera_file_mmap_acquire (LumieraFile self, off_t start, size_t size);
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/**
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* release a previously acquired MMap object
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* @param self file to which the map belongs
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* @param map object to be released
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*/
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void
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lumiera_file_release_mmap (LumieraFile self, LumieraMMap map);
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/**
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* helper macro for acquireing and releasing maped regions
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* @param nobugflag yet unused
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* @param file the file from from where to acquire the mapped region
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* @param start the start offset for the mmaped region
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* @param size the length of the requested block
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* @param addr name of a void* variable pointing to the requested memory
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*/
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#define LUMIERA_FILE_MMAP_SECTION(nobugflag, file, start, size, addr) \
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for (LumieraMMap map_##__LINE__ = \
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lumiera_file_mmap_acquire (file, start, size); \
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map_##__LINE__; \
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({ \
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lumiera_file_release_mmap (file, map_##__LINE__); \
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map_##__LINE__ = NULL; \
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})) \
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for (void* addr = lumiera_mmap_address (map_##__LINE__, start); \
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addr; \
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addr = NULL)
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/**
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* Query the underlying mmapings object from a file
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* The MMapings only exists after a chunksize got set with lumiera_file_chunksize_set()
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* @param self the file to query
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* @return Handle to the MMapings object or NULL on error (setting the error state)
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*/
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LumieraMMapings
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lumiera_file_mmapings (LumieraFile self);
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/**
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* Query the flags effective for a file
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* @param self the file to query
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* @return flags
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*/
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int
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lumiera_file_checkflags (LumieraFile self, int flags);
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/**
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* Set the chunksize for mapping operations
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* can only set once for a filedescriptor, subsequent calls are no-ops
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* @param chunksize allocation/mmaping granularity, must be 2's exponent of pagesize
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* @param bias offset to shift chunks, used for stepping over a header for example.
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* @return the effective chunksize used for the file
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*/
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size_t
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lumiera_file_set_chunksize_bias (LumieraFile self, size_t chunksize, size_t bias);
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/**
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* Get the chunksize for mapping operations
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* @return the effective chunksize used for the file
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*/
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size_t
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lumiera_file_chunksize_get (LumieraFile self);
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/**
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* Get the bias for mapping operations
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* @return the effective bias used for the file
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*/
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size_t
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lumiera_file_bias_get (LumieraFile self);
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/**
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* Place and remove locks on a file
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* This locks are per thread and lock the file across multiple lumiera processes
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* (or any other programm which repects advisory file locking).
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* Only exclusive locks over the whole file are supported for initially accessing
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* a file, other locking is done somewhere else.
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*/
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LumieraFile
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lumiera_file_rdlock (LumieraFile self);
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LumieraFile
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lumiera_file_wrlock (LumieraFile self);
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LumieraFile
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lumiera_file_unlock (LumieraFile self);
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#define LUMIERA_FILE_RDLOCK_SECTION(nobugflag, file) \
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for (LumieraFile filelock_##__LINE__ = \
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lumiera_file_rdlock (file); \
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filelock_##__LINE__; \
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({ \
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lumiera_file_unlock (filelock_##__LINE__); \
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filelock_##__LINE__ = NULL; \
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}))
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#define LUMIERA_FILE_WRLOCK_SECTION(nobugflag, file) \
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for (LumieraFile filelock_##__LINE__ = \
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lumiera_file_wrlock (file); \
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filelock_##__LINE__; \
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({ \
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lumiera_file_unlock (filelock_##__LINE__); \
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filelock_##__LINE__ = NULL; \
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}))
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#endif
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/*
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// Local Variables:
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// mode: C
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// c-file-style: "gnu"
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// indent-tabs-mode: nil
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// End:
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*/
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