backend/filehandlecache.h File Reference

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Detailed Description

Filehandle management and caching The number of filehandles a program can held open is usually limited, since we want to support using a less limited number of files and closing/opening for each operation is expensive, we provide a cache to keep the most frequent used files open and gracefully close/recycle unused filehandles.

The filehandlecache defined here protects all operations on the cache with a mutex.

Definition in file filehandlecache.h.

#include "lib/error.h"
#include "lib/mrucache.h"
#include "lib/mutex.h"
#include "backend/filehandle.h"

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Classes
struct	lumiera_filehandlecache_struct
Typedefs
typedef struct lumiera_filehandlecache_struct	lumiera_filehandlecache
typedef lumiera_filehandlecache *	LumieraFilehandlecache
Functions
void	lumiera_filehandlecache_checkin (LumieraFilehandle handle)
	Put a filehandle into the cache Filehandles which are checked in are subject of cache aging and might get destroyed and reused.
LumieraFilehandle	lumiera_filehandlecache_checkout (LumieraFilehandle handle)
	Remove a filehandle from cache aging Filehandles which are subject of cache aging must be checked out before they can be used.
void	lumiera_filehandlecache_delete (void)
	Delete the filehandle cache.
LumieraFilehandle	lumiera_filehandlecache_handle_acquire (LumieraFiledescriptor desc)
	Get a fresh filehandle.
void	lumiera_filehandlecache_new (int max_entries)
	Initializes the filehandle cache.

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Function Documentation

void lumiera_filehandlecache_new

(

int

max_entries

)

Initializes the filehandle cache.

Parameters:

max_entries

number how much filehandles shall be managed The number of elements the cache can hold is static and should be determined by sysconf (_SC_OPEN_MAX) minus some (big) safety margin.

Definition at line 39 of file filehandlecache.c.

References lumiera_mutex_init().

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void lumiera_filehandlecache_delete

(

void

)

Delete the filehandle cache.

No filehandles in the cache must be locked, this would be a fatal error. The handles are closed automatically.

Definition at line 53 of file filehandlecache.c.

References lumiera_free(), and lumiera_mutex_destroy().

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LumieraFilehandle lumiera_filehandlecache_handle_acquire

(

LumieraFiledescriptor

desc

)

Get a fresh filehandle.

Parameters:

self

pointer to the cache

Returns:

the new filehandle

Definition at line 67 of file filehandlecache.c.

References LUMIERA_ERROR_SET_ALERT, lumiera_mrucache_pop(), and LUMIERA_MUTEX_SECTION.

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LumieraFilehandle lumiera_filehandlecache_checkout

(

LumieraFilehandle

handle

)

Remove a filehandle from cache aging Filehandles which are subject of cache aging must be checked out before they can be used.

Parameters:

	self	the filehandlecache
	handle	the filehandle to be checked out

Definition at line 102 of file filehandlecache.c.

References lumiera_filehandle_struct::cachenode, lumiera_mrucache_checkout(), LUMIERA_MUTEX_SECTION, and lumiera_filehandle_struct::use_cnt.

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void lumiera_filehandlecache_checkin

(

LumieraFilehandle

handle

)

Put a filehandle into the cache Filehandles which are checked in are subject of cache aging and might get destroyed and reused.

Parameters:

	self	the filehandlecache
	handle	the filehandle to be checked in

Definition at line 123 of file filehandlecache.c.

References lumiera_filehandle_struct::cachenode, lumiera_mrucache_checkin(), LUMIERA_MUTEX_SECTION, and lumiera_filehandle_struct::use_cnt.

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