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/*
* cache.c - generic cache module
* by Hirotsugu Kakugawa
* 5 Aug 1996
*/
/*
* Copyright (C) 1996, 1997 Hirotsugu Kakugawa.
* All rights reserved.
*
* This file is part of the VFlib Library. This library is free
* software; you can redistribute it and/or modify it under the terms of
* the GNU Library General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your
* option) any later version. This library is distributed in the hope
* that it will be useful, but WITHOUT ANY WARRANTY; without even the
* implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU Library General Public License for more details.
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free Software
* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include "VFlib-3_6.h"
#include "VFsys.h"
#include "cache.h"
/**
** CACHE (lru+hash)
**/
Private void *c_get_elem(VF_CACHE,void*,int);
Private void c_del_elem(VF_CACHE,void*,int);
Private void lru_move_top(VF_CACHE,VF_CACHE_ELEM);
Private void lru_put_top(VF_CACHE,VF_CACHE_ELEM);
Private VF_CACHE_ELEM lru_delete_tail(VF_CACHE);
Private void lru_unlink_elem(VF_CACHE,VF_CACHE_ELEM);
Private int c_hash(VF_CACHE,void*,int);
Private VF_CACHE_ELEM c_hash_is_interned(VF_CACHE,void*,int);
Private void c_hash_intern(VF_CACHE,VF_CACHE_ELEM,void*,int);
Private void c_hash_unintern(VF_CACHE,VF_CACHE_ELEM);
/* vf_cache_create()
* --- Creates a cache object.
*/
Public VF_CACHE
vf_cache_create (int cache_size, int hash_size,
void* (*load_func)(VF_CACHE,void*,int),
void (*unload_func)(void*))
{
int i;
VF_CACHE cache;
VF_CACHE_ELEM celem;
if (hash_size < 1)
return NULL;
ALLOC_IF_ERR(cache, struct s_vf_cache)
return NULL;
celem = NULL;
if (cache_size < 0){
cache->free_list = NULL;
} else {
ALLOCN_IF_ERR(celem, struct s_vf_cache_elem, cache_size){
vf_free(cache);
return NULL;
}
for (i = 0; i < cache_size; i++)
celem[i].h_forw = &celem[i+1];
celem[cache_size-1].h_forw = NULL;
cache->free_list = &celem[0];
}
ALLOCN_IF_ERR(cache->hash_table, struct s_vf_cache_elem, hash_size){
if (celem != NULL)
vf_free(celem);
vf_free(cache);
return NULL;
}
cache->cache_size = cache_size;
cache->hash_size = hash_size;
cache->get = c_get_elem;
cache->del = c_del_elem;
cache->load_elem = load_func;
cache->unload_elem = unload_func;
cache->lru_list.l_forw = &cache->lru_list;
cache->lru_list.l_back = &cache->lru_list;
for (i = 0; i < hash_size; i++){
cache->hash_table[i].h_forw = &cache->hash_table[i];
cache->hash_table[i].h_back = &cache->hash_table[i];
}
return cache;
}
/* c_get_elem()
* --- returns a elem. If not chached, reload it.
*/
Private void*
c_get_elem(VF_CACHE cache, void *key, int key_len)
{
VF_CACHE_ELEM ce;
void *key2;
if ((ce = c_hash_is_interned(cache, key, key_len)) != NULL){
lru_move_top(cache, ce);
return (ce->object);
}
if ((ce = cache->free_list) == NULL){
if (cache->cache_size > 0){
if ((ce = lru_delete_tail(cache)) == NULL){
fprintf(stderr, "Internal error in GET of CACHE object\n");
abort();
}
c_hash_unintern(cache, ce);
ce->h_forw = cache->free_list;
cache->free_list = ce;
if (cache->unload_elem != NULL)
(cache->unload_elem)(ce->object);
else if (ce->object != NULL)
vf_free(ce->object);
ce->object = NULL;
if (ce->key != NULL)
vf_free(ce->key);
} else {
ALLOC_IF_ERR(ce, struct s_vf_cache_elem)
return NULL;
ce->h_forw = NULL;
}
}
cache->free_list = ce->h_forw;
if ((key2 = malloc(key_len)) == NULL)
return NULL;
memcpy(key2, key, key_len);
ce->object = (cache->load_elem)(cache, key, key_len);
ce->key = key2;
ce->key_len = key_len;
c_hash_intern(cache, ce, key2, key_len);
lru_put_top(cache, ce);
return (ce->object);
}
/* c_del_elem()
* --- delete an elem.
*/
Private void
c_del_elem(VF_CACHE cache, void *key, int key_len)
{
VF_CACHE_ELEM ce;
if ((ce = c_hash_is_interned(cache, key, key_len)) == NULL)
return;
c_hash_unintern(cache, ce);
lru_unlink_elem(cache, ce);
if (cache->unload_elem != NULL)
(cache->unload_elem)(ce->object);
else if (ce->object != NULL)
vf_free(ce->object);
ce->object = NULL;
if (cache->cache_size > 0){
ce->h_forw = cache->free_list;
cache->free_list = ce;
} else {
vf_free(ce);
}
}
Private void
lru_unlink_elem(VF_CACHE cache, VF_CACHE_ELEM ce)
{
VF_CACHE_ELEM ce_b, ce_f;
ce_b = ce->l_back;
ce_f = ce->l_forw;
ce_b->l_forw = ce_f;
ce_f->l_back = ce_b;
}
/* lru_put_top()
* --- puts an ELEM at the head of LRU list.
* The ELEM must not be in LRU list.
*/
Private void
lru_put_top(VF_CACHE cache, VF_CACHE_ELEM ce)
{
VF_CACHE_ELEM ce_f;
ce_f = cache->lru_list.l_forw;
ce->l_forw = ce_f;
ce_f->l_back = ce;
ce->l_back = &cache->lru_list;
cache->lru_list.l_forw = ce;
}
/* lru_move_top()
* --- moves an ELEM at the top of LRU list.
* ELEM must be in LRU list.
*/
Private void
lru_move_top(VF_CACHE cache, VF_CACHE_ELEM ce)
{
lru_unlink_elem(cache, ce);
lru_put_top(cache, ce);
}
Private VF_CACHE_ELEM
lru_delete_tail(VF_CACHE cache) /* NOTE: There must be at least one
ELEM in LRU list */
{
VF_CACHE_ELEM ce;
if ((ce = cache->lru_list.l_back) == &cache->lru_list)
return NULL;
lru_unlink_elem(cache, ce);
return ce;
}
Private int
c_hash(VF_CACHE cache, void *key, int key_len)
{
char *p;
int i;
unsigned int h;
h = 0;
for (i = 0, p = key; i < key_len; i++, p++)
h = (h + (unsigned int)*p) % cache->hash_size;
return h;
}
Private VF_CACHE_ELEM
c_hash_is_interned(VF_CACHE cache, void *key, int key_len)
{
int h;
VF_CACHE_ELEM ce, ce0;
h = c_hash(cache, key, key_len);
ce0 = &cache->hash_table[h];
for (ce = ce0->h_forw; ce != ce0; ce = ce->h_forw){
if ((ce->key_len == key_len) && (memcmp(ce->key, key, key_len) == 0)){
if (ce != ce0->h_forw){
c_hash_unintern(cache, ce);
c_hash_intern(cache, ce, NULL, h); /* MAGIC */
}
return ce;
}
}
return NULL;
}
Private void
c_hash_intern (VF_CACHE cache, VF_CACHE_ELEM ce, void *key, int key_len)
{
int h;
VF_CACHE_ELEM ce1;
if (key == NULL) /* MAGIC */
h = key_len;
else
h = c_hash(cache, key, key_len);
ce1 = cache->hash_table[h].h_forw;
cache->hash_table[h].h_forw = ce;
ce->h_forw = ce1;
ce1->h_back = ce;
ce->h_back = &cache->hash_table[h];
}
Private void
c_hash_unintern(VF_CACHE cache, VF_CACHE_ELEM ce)
{
VF_CACHE_ELEM ce_b, ce_f;
ce_b = ce->h_back;
ce_f = ce->h_forw;
ce_b->h_forw = ce_f;
ce_f->h_back = ce_b;
}
/**
** HASH TABLE
**
** 1. A hash table object is created by the following function:
** FUNC: vf_hash_create(int hash_size)
** --- Caller must specify the size of hash table. This hash object
** uses `chaining' to store data objects: the hash table can store
** any number of data objects (more than hash_size).
** 2. A data object is stored in hash table by the PUT method.
** FUNC: (HASH_OBJ->put)(HASH_OBJ, DATA_OBJ, KEY, KEY_LENGTH)
** --- A data object, DATA_OBJ, is stored with specifying its
** KEY and KEY_LENGTH, the length (in byte) of the KEY.
** This method does not return any value. If the same data object
** in the sense of KEY and KEY_LENGTH exists in the HASH_OBJ,
** the object is not newly interned and link count is increased.
** 3. Stored data object is extracted by the GET method.
** FUNC: (TABLE_OBJ->get)(HASH, KEY, KEY_ID)
** --- This extracts a data object whose key and key length matches
** KEY and KEY_LENGTH. If NULL is returned, it implies that
** such data is not interned.
** 4. Stored data object can be deleted from the hash table by DEL method.
** FUNC: (TABLE_OBJ->del)(HASH_OBJ, KEY, KEY_ID)
** --- This delets a data object whose key and key length matches
** KEY and KEY_LENGTH. If its link count is more than one,
** the link count is decremented by one and the object is not
** deleted.
**/
Private void* h_hash_put_object(VF_HASH,void*,void*,int);
Private void* h_hash_get_object(VF_HASH,void*,int);
Private void h_hash_del_object(VF_HASH,void*,int);
Private int h_hash(VF_HASH,void*,int);
Private void h_hash_intern(VF_HASH,VF_HASH_ELEM,void*,int);
Private void h_hash_unintern(VF_HASH,VF_HASH_ELEM);
/* vf_hash_create()
* --- Creates a hash table object.
*/
Public VF_HASH
vf_hash_create (int hash_size)
{
int i;
VF_HASH hash;
if ((hash_size < 1)
|| ((hash = (VF_HASH)calloc(1, sizeof(struct s_vf_hash))) == NULL))
return NULL;
hash->table = (VF_HASH_ELEM)calloc(hash_size, sizeof(struct s_vf_hash_elem));
if (hash->table == NULL){
vf_free(hash);
return NULL;
}
hash->hash_size = hash_size;
hash->put = h_hash_put_object;
hash->get = h_hash_get_object;
hash->del = h_hash_del_object;
for (i = 0; i < hash_size; i++){
hash->table[i].h_forw = &hash->table[i];
hash->table[i].h_back = &hash->table[i];
}
return hash;
}
Private void*
h_hash_get_object(VF_HASH hash, void *key, int key_len)
{
int h;
VF_HASH_ELEM he, he0;
h = h_hash(hash, key, key_len);
he0 = &hash->table[h];
for (he = he0->h_forw; he != he0; he = he->h_forw)
if ((he->key_len == key_len) && (memcmp(he->key, key, key_len) == 0)){
if (he != he0->h_forw){ /* move top if it is not top */
h_hash_unintern(hash, he);
h_hash_intern(hash, he, NULL, h); /* MAGIC */
}
return he->object;
}
return NULL;
}
Private void*
h_hash_put_object(VF_HASH hash, void* object, void *key, int key_len)
{
VF_HASH_ELEM he;
void *key2;
if ((he = h_hash_get_object(hash, key, key_len)) != NULL){
++he->link_cnt;
return he->object;
}
he = (VF_HASH_ELEM)calloc(1, sizeof(struct s_vf_hash_elem));
key2 = calloc(1, key_len);
if ((he == NULL) || (key2 == NULL))
return NULL;
memcpy(key2, key, key_len);
he->link_cnt = 1;
he->object = object;
he->key = key2;
he->key_len = key_len;
h_hash_intern(hash, he, key2, key_len);
return he->object;
}
Private void
h_hash_del_object(VF_HASH hash, void *key, int key_len)
{
VF_HASH_ELEM he;
if ((he = h_hash_get_object(hash, key, key_len)) == NULL)
return; /* not interned */
if (--he->link_cnt > 0)
return;
h_hash_unintern(hash, he);
if (he->key != NULL)
vf_free(he->key);
vf_free(he);
}
Private void
h_hash_intern (VF_HASH hash, VF_HASH_ELEM he, void *key, int key_len)
{
int h;
VF_HASH_ELEM he1;
if (key == NULL) /* MAGIC */
h = key_len;
else
h = h_hash(hash, key, key_len);
he1 = hash->table[h].h_forw;
hash->table[h].h_forw = he;
he->h_forw = he1;
he1->h_back = he;
he->h_back = &hash->table[h];
}
Private void
h_hash_unintern(VF_HASH hash, VF_HASH_ELEM he)
{
VF_HASH_ELEM he_b, he_f;
he_b = he->h_back;
he_f = he->h_forw;
he_b->h_forw = he_f;
he_f->h_back = he_b;
}
Private int
h_hash(VF_HASH hash, void *key, int key_len)
{
char *p;
int i;
unsigned int h;
h = 0;
for (i = 0, p = key; i < key_len; i++, p++)
h = h + (unsigned int)*p;
return (h % hash->hash_size);
}
/**
** TABLE
**
** 1. A table object is created by the following function:
** FUNC: vf_table_create(void)
** --- Table size is need not be specified. It autoatically
** and dynammically allocates memory for table memory.
** 2. A table object stores data object.
** FUNC: (TABLE_OBJ->put_obj)(TABLE_OBJ, DATA_OBJ, KEY, KEY_LENGTH)
** --- A data object, DATA_OBJ, is stored with specifying its
** KEY and KEY_LENGTH, the length (in byte) of the KEY.
** This method returns an ID (a non-negative integer) for the
** DATA_OBJ. If -1 is returned, some error occured internnaly.
** ID is used to extract DATA_OBJ. If the same data object
** in the sense of KEY and KEY_LENGTH exists in the TABLE,
** the object is not newly interned and link count is increased.
** 3. Stored data object is extracted by two ways: by ID and by KEY.
** 3.1 Data extraction by ID.
** FUNC: (TABLE_OBJ->get_obj_by_id)(TABLE_OBJ, ID)
** --- Extract a data object whose id is ID. If NULL is returned,
** ID is wrong (i.e., such data is not interned).
** 3.2 Data extraction by KEY.
** FUNC: (TABLE_OBJ->get_obj_by_key)(TABLE_OBJ, KEY, KEY_LENGTH)
** --- Extract a data object whose key and key length are KEY
** and KEY_LENGTH. If NULL is returned, such data is not interned.
** 4. Stored data object can be deleted from the table by two ways:
** by ID and by KEY.
** 4.1 Data deletion by ID.
** FUNC: (TABLE_OBJ->del_obj_by_id)(TABLE_OBJ, ID)
** --- Delete a data object from the TABLE whose id is ID. Precisely,
** it decreases the link count of the data item. If it is
** zero, the data object is deleted from the TABLE.
** 4.2 Data deletion by KEY.
** FUNC: (TABLE_OBJ->del_obj_by_key)(TABLE_OBJ, KEY, KEY_LENGTH)
** --- Delete a data object whose key and key length are KEY
** and KEY_LENGTH. Precisely, it decreases the link count
** of the data item. If it is
** zero, the data object is deleted from the TABLE.
** 5. Obtaining data ID
** 5.1 Obtain data ID by KEY and KEY_LENGTH.
** FUNC: (TABLE_OBJ->get_id_by_key)(TABLE_OBJ, KEY, KEY_LENGTH)
** --- Return an ID whose key and key length are KEY and KEY_LENGTH.
** 5.2 Obtain data ID by DATA
** FUNC: (TABLE_OBJ->get_id_by_obj)(TABLE_OBJ, DATA)
** --- Return an ID for the DATA.
** 6. Incrementing link count.
** FUNC: (TABLE_OBJ->link_by_id)(TABLE_OBJ, ID)
** --- Increment link count of an entry ID.
** 7. Decrementing link count.
** FUNC: (TABLE_OBJ->unlink_by_id)(TABLE_OBJ, ID)
** --- Decrement link count of an entry ID. If link count becomes zero,
** the entry is deleted from the table.
** 8. The number of elements in the TABLE object can be checked.
** FUNC: (TABLE_OBJ->get_nelements)(TABLE_OBJ)
** --- Return the number of elements in the TABLE.
**
**/
Private int table_put_obj(VF_TABLE,void*,void*,int);
Private int table_put_obj2(VF_TABLE,void*,void*,int);
Private int table_get_id_by_key(VF_TABLE,void*,int);
Private int table_get_id_by_obj(VF_TABLE,void*);
Private void *table_get_obj_by_id(VF_TABLE,int);
Private void *table_get_obj_by_key(VF_TABLE,void*,int);
Private int table_del_obj_by_id(VF_TABLE,int);
Private int table_del_obj_by_key(VF_TABLE,void*,int);
Private int table_link_by_id(VF_TABLE,int);
Private int table_unlink_by_id(VF_TABLE,int);
Private int table_get_nelements(VF_TABLE);
#ifndef VF_INIT_TABLE_SIZE
# define VF_INIT_TABLE_SIZE 16
#endif/*VF_INIT_TABLE_SIZE*/
/* vf_table_create()
* --- Creates a table object.
*/
Public VF_TABLE
vf_table_create (void)
{
VF_TABLE table;
if (VF_INIT_TABLE_SIZE < 1){
fprintf(stderr, "Internal error: Initial # of elems for TABLE\n");
abort();
}
ALLOC_IF_ERR(table, struct s_vf_table)
return NULL;
table->put = table_put_obj;
table->put2 = table_put_obj2;
table->get_id_by_key = table_get_id_by_key;
table->get_id_by_obj = table_get_id_by_obj;
table->get_obj_by_id = table_get_obj_by_id;
table->get_obj_by_key = table_get_obj_by_key;
table->del_obj_by_id = table_del_obj_by_id;
table->del_obj_by_key = table_del_obj_by_key;
table->link_by_id = table_link_by_id;
table->unlink_by_id = table_unlink_by_id;
table->get_nelements = table_get_nelements;
table->nelems = 0;
table->next_slot = 0;
table->table_size = 0;
table->table = NULL;
return table;
}
Private int
table_put_obj(VF_TABLE table, void *object, void *key, int key_len)
{
int id;
VF_TABLE_ELEM te;
if ((id = table_get_id_by_key(table, key, key_len)) >= 0){
te = &table->table[id];
++te->link_cnt;
return id;
}
return table_put_obj2(table, object, key, key_len);
}
Private int
table_put_obj2(VF_TABLE table, void *object, void *key, int key_len)
{
int id, idz, new_table_size, i;
VF_TABLE_ELEM new_table;
void *key2;
if (table->nelems == table->table_size){ /* realloc */
if (table->table_size == 0)
new_table_size = VF_INIT_TABLE_SIZE;
else
new_table_size = 2 * table->table_size;
ALLOCN_IF_ERR(new_table, struct s_vf_table_elem, new_table_size){
return -1;
}
for (i = 0; i < table->table_size; i++){
new_table[i].link_cnt = table->table[i].link_cnt;
new_table[i].object = table->table[i].object;
new_table[i].key = table->table[i].key;
new_table[i].key_len = table->table[i].key_len;
}
for (i = table->table_size; i < new_table_size; i++){
new_table[i].link_cnt = 0;
new_table[i].object = NULL;
new_table[i].key = NULL;
new_table[i].key_len = 0;
}
table->next_slot = table->table_size; /* possibly, free slot */
table->table_size = new_table_size;
if (table->table != NULL)
vf_free(table->table);
table->table = new_table;
}
id = idz = table->next_slot;
do {
if ((table->table[id].object == NULL) && (table->table[id].key == NULL)
&& (table->table[id].key_len == 0)){
if ((key2 = malloc(key_len)) == NULL)
return -1;
memcpy(key2, key, key_len);
table->table[id].link_cnt = 1;
table->table[id].object = object;
table->table[id].key = key2;
table->table[id].key_len = key_len;
table->next_slot = (id + 1) % table->table_size;
++table->nelems;
return id;
}
id = (id + 1) % table->table_size;
} while (id != idz);
fprintf(stderr, "Cannot happen in table_put_obj()\n");
abort();
return -1;
}
Private int
table_get_id_by_key(VF_TABLE table, void *key, int key_len)
{
int id;
VF_TABLE_ELEM te;
for (id = 0; id < table->table_size; id++){
te = &table->table[id];
if ((te->object == NULL) && (te->key == NULL) && (te->key_len == 0))
continue;
if ((te->key_len == key_len) && (memcmp(te->key, key, key_len) == 0))
return id;
}
return -1;
}
Private int
table_get_id_by_obj(VF_TABLE table, void *obj)
{
int id;
VF_TABLE_ELEM te;
if (obj == NULL)
return -1;
for (id = 0; id < table->table_size; id++){
te = &table->table[id];
if (te->object == obj)
return id;
}
return -1;
}
Private void*
table_get_obj_by_id(VF_TABLE table, int id)
{
if ((id < 0) && (table->table_size <= id))
return NULL;
if (table->table == NULL)
return NULL;
return table->table[id].object;
}
Private void*
table_get_obj_by_key(VF_TABLE table, void *key, int key_len)
{
int id;
if ((id = table_get_id_by_key(table, key, key_len)) < 0)
return NULL;
return table->table[id].object;
}
Private int
table_del_obj_by_id(VF_TABLE table, int id)
{
--table->table[id].link_cnt;
if (table->table[id].link_cnt > 0)
return table->table[id].link_cnt;
--table->nelems;
if (table->table[id].key != NULL)
vf_free(table->table[id].key);
table->table[id].object = NULL;
table->table[id].key = NULL;
table->table[id].key_len = 0;
table->table[id].link_cnt = 0;
return table->table[id].link_cnt;
}
Private int
table_del_obj_by_key(VF_TABLE table, void *key, int key_len)
{
int id;
if ((id = table_get_id_by_key(table, key, key_len)) < 0)
return -1;
return table_del_obj_by_id(table, id);
}
Private int
table_link_by_id(VF_TABLE table, int id)
{
table->table[id].link_cnt++;
return table->table[id].link_cnt;
}
Private int
table_unlink_by_id(VF_TABLE table, int id)
{
--table->table[id].link_cnt;
if (table->table[id].link_cnt <= 0){
--table->nelems;
if (table->table[id].key != NULL)
vf_free(table->table[id].key);
table->table[id].object = NULL;
table->table[id].key = NULL;
table->table[id].key_len = 0;
table->table[id].link_cnt = 0;
return 0;
}
return table->table[id].link_cnt;
}
Private int
table_get_nelements(VF_TABLE table)
{
return table->nelems;
}
/*EOF*/
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