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File Content: `gdcache.h`

/*
 * gdcache.h
 *
 * Caches of pointers to user structs in which the least-recently-used
 * element is replaced in the event of a cache miss after the cache has
 * reached a given size.
 *
 * John Ellson  (ellson@graphviz.org)  Oct 31, 1997
 *
 * Test this with:
 *		 gcc -o gdcache -g -Wall -DTEST gdcache.c
 *
 * The cache is implemented by a singly-linked list of elements
 * each containing a pointer to a user struct that is being managed by
 * the cache.
 *
 * The head structure has a pointer to the most-recently-used
 * element, and elements are moved to this position in the list each
 * time they are used.  The head also contains pointers to three
 * user defined functions:
 *		- a function to test if a cached userdata matches some keydata
 *		- a function to provide a new userdata struct to the cache
 *          if there has been a cache miss.
 *		- a function to release a userdata struct when it is
 *          no longer being managed by the cache
 *
 * In the event of a cache miss the cache is allowed to grow up to
 * a specified maximum size.  After the maximum size is reached then
 * the least-recently-used element is discarded to make room for the
 * new.  The most-recently-returned value is always left at the
 * beginning of the list after retrieval.
 *
 * In the current implementation the cache is traversed by a linear
 * search from most-recent to least-recent.  This linear search
 * probably limits the usefulness of this implementation to cache
 * sizes of a few tens of elements.
 */

/*********************************************************/
/* header                                                */
/*********************************************************/

#include <stdlib.h>
#if (!defined(__OpenBSD__)) && HAVE_MALLOC_H
 #include <malloc.h>
#endif
#ifndef NULL
#define NULL (void *)0
#endif

/* user defined function templates */
typedef int (*gdCacheTestFn_t)(void *userdata, void *keydata);
typedef void *(*gdCacheFetchFn_t)(char **error, void *keydata);
typedef void (*gdCacheReleaseFn_t)(void *userdata);

/* element structure */
typedef struct gdCache_element_s gdCache_element_t;
struct gdCache_element_s {
	gdCache_element_t	*next;
	void			*userdata;
};

/* head structure */
typedef struct gdCache_head_s gdCache_head_t;
struct gdCache_head_s {
	gdCache_element_t	*mru;
	int					size;
	char				*error;
	gdCacheTestFn_t		gdCacheTest;
	gdCacheFetchFn_t	gdCacheFetch;
	gdCacheReleaseFn_t	gdCacheRelease;
};

/* function templates */
gdCache_head_t *
gdCacheCreate(
	int					size,
	gdCacheTestFn_t		gdCacheTest,
	gdCacheFetchFn_t	gdCacheFetch,
	gdCacheReleaseFn_t	gdCacheRelease );

void
gdCacheDelete( gdCache_head_t *head );

void *
gdCacheGet( gdCache_head_t *head, void *keydata );

Name	Size	Permission
gd.h	32783 bytes	0644
gd_intern.h	261 bytes	0644
gd_io.h	963 bytes	0644
gdcache.h	2740 bytes	0644
gdfontg.h	529 bytes	0644
gdfontl.h	527 bytes	0644
gdfontmb.h	495 bytes	0644
gdfonts.h	491 bytes	0644
gdfontt.h	522 bytes	0644
gdhelpers.h	1350 bytes	0644
jisx0208.h	71350 bytes	0644
wbmp.h	1283 bytes	0644

File Content: gdcache.h

File Content: `gdcache.h`