ossp-pkg/cache/cache.c
1.2
/*
** cache - OSSP Caching Library
** Copyright (c) 2002 Ralf S. Engelschall <rse@engelschall.com>
** Copyright (c) 2002 The OSSP Project <http://www.ossp.org/>
** Copyright (c) 2002 Cable & Wireless Deutschland <http://www.cw.com/de/>
**
** This file is part of OSSP cache, a Caching library which
** can be found at http://www.ossp.org/pkg/cache/.
**
** Permission to use, copy, modify, and distribute this software for
** any purpose with or without fee is hereby granted, provided that
** the above copyright notice and this permission notice appear in all
** copies.
**
** THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHORS AND COPYRIGHT HOLDERS AND THEIR
** CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
** USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
** ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
** OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
** OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
** SUCH DAMAGE.
**
** cache.c: library implementation
*/
/* include optional Autoconf header */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
/* include system API headers */
#include <stdio.h> /* for "s[n]printf()" */
/* include own API header */
#include "cache.h"
/* boolean values */
#ifndef FALSE
#define FALSE (0)
#endif
#ifndef TRUE
#define TRUE (!FALSE)
#endif
/* forward declarations */
struct cache_st;
struct cache_obj_st;
/* type definitions */
typedef struct cache_obj_st cache_obj_t;
/* support for relative pointers (offset pointers) */
typedef long op_t;
#define VP2OP(bp,vp) \
(long)(((char *)(vp))-((char *)(bp)))
#define OP2VP(bp,op) \
(void *)(((char *)(bp))+((char *)(op)))
/* definition: top-level cache structure */
struct cache_st {
/* top level access pointers */
op_t opHash; /* pointer to hash table */
op_t opObjMRU; /* pointer to MRU object */
op_t opObjLRU; /* pointer to LRU object */
op_t opObjEmpty; /* pointer to empty object */
/* information */
int bExpireReset; /* whether expire resets on each access or is absolute */
int tExpireReset; /* the optional expire reset time */
/* sub-structure information */
op_t opKeyIndex; /* base address of key bucket index */
op_t opKeyBuckets; /* base address of key bucket pool */
int nKeyBuckets; /* number of buckets in key bucket pool */
op_t opValIndex; /* base address of key bucket index */
op_t opValBuckets; /* base address of value bucket pool */
int nValBuckets; /* number of buckets in value bucket pool */
/* statistics */
long nInserts;
long nLookups;
long nLookupsSuccess;
long nRemoves;
/* callbacks */
/* ... */
};
/* definition: cache object */
struct cache_obj_st {
int bUsed; /* used in an ongoing iteration */
op_t opHashNext; /* next object in hash table collision chain */
op_t opQueuePrev; /* previous object in LRU queue */
op_t opQueueNext; /* next object in LRU queue */
op_t opKey; /* pointer to first key segment in key index */
size_t nKey; /* size of key in bytes */
op_t opVal; /* pointer to first value segment in value index */
size_t nVal; /* size of value in bytes */
time_t tExpire; /* expire time of object */
};
