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/* cache.c
* Copyright (c) 2011, Peter Ohler
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* - Neither the name of Peter Ohler nor the names of its contributors may be
* used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS 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 COPYRIGHT HOLDER OR 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.
*/
#include <stdlib.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <stdarg.h>
#include "cache.h"
struct _Cache {
/* The key is a length byte followed by the key as a string. If the key is longer than 254 characters then the
length is 255. The key can be for a premature value and in that case the length byte is greater than the length
of the key. */
char *key;
VALUE value;
struct _Cache *slots[16];
};
static void slot_print(Cache cache, unsigned int depth);
static char* form_key(const char *s) {
size_t len = strlen(s);
char *d = ALLOC_N(char, len + 2);
*d = (255 <= len) ? 255 : len;
memcpy(d + 1, s, len + 1);
return d;
}
void
ox_cache_new(Cache *cache) {
*cache = ALLOC(struct _Cache);
(*cache)->key = 0;
(*cache)->value = Qundef;
memset((*cache)->slots, 0, sizeof((*cache)->slots));
}
VALUE
ox_cache_get(Cache cache, const char *key, VALUE **slot, char **keyp) {
unsigned char *k = (unsigned char*)key;
Cache *cp;
for (; '\0' != *k; k++) {
cp = cache->slots + (unsigned int)(*k >> 4); /* upper 4 bits */
if (0 == *cp) {
ox_cache_new(cp);
}
cache = *cp;
cp = cache->slots + (unsigned int)(*k & 0x0F); /* lower 4 bits */
if (0 == *cp) { /* nothing on this tree so set key and value as a premature key/value pair */
ox_cache_new(cp);
cache = *cp;
cache->key = form_key(key);
break;
} else {
int depth = (int)(k - (unsigned char*)key + 1);
cache = *cp;
if ('\0' == *(k + 1)) { /* exact match */
if (0 == cache->key) { /* nothing in this spot so take it */
cache->key = form_key(key);
break;
} else if ((depth == *cache->key || 255 < depth) && 0 == strcmp(key, cache->key + 1)) { /* match */
break;
} else { /* have to move the current premature key/value deeper */
unsigned char *ck = (unsigned char*)(cache->key + depth + 1);
Cache orig = *cp;
cp = (*cp)->slots + (*ck >> 4);
ox_cache_new(cp);
cp = (*cp)->slots + (*ck & 0x0F);
ox_cache_new(cp);
(*cp)->key = cache->key;
(*cp)->value = cache->value;
orig->key = form_key(key);
orig->value = Qundef;
}
} else { /* not exact match but on the path */
if (0 != cache->key) { /* there is a key/value here already */
if (depth == *cache->key || (255 <= depth && 0 == strncmp(cache->key, key, depth) && '\0' == cache->key[depth])) { /* key belongs here */
continue;
} else {
unsigned char *ck = (unsigned char*)(cache->key + depth + 1);
Cache orig = *cp;
cp = (*cp)->slots + (*ck >> 4);
ox_cache_new(cp);
cp = (*cp)->slots + (*ck & 0x0F);
ox_cache_new(cp);
(*cp)->key = cache->key;
(*cp)->value = cache->value;
orig->key = 0;
orig->value = Qundef;
}
}
}
}
}
*slot = &cache->value;
if (0 != keyp) {
if (0 == cache->key) {
printf("*** Error: failed to set the key for %s\n", key);
*keyp = 0;
} else {
*keyp = cache->key + 1;
}
}
return cache->value;
}
void
ox_cache_print(Cache cache) {
/*printf("-------------------------------------------\n");*/
slot_print(cache, 0);
}
static void
slot_print(Cache c, unsigned int depth) {
char indent[256];
Cache *cp;
unsigned int i;
if (sizeof(indent) - 1 < depth) {
depth = ((int)sizeof(indent) - 1);
}
memset(indent, ' ', depth);
indent[depth] = '\0';
for (i = 0, cp = c->slots; i < 16; i++, cp++) {
if (0 == *cp) {
/*printf("%s%02u:\n", indent, i);*/
} else {
if (0 == (*cp)->key && Qundef == (*cp)->value) {
printf("%s%02u:\n", indent, i);
} else {
const char *vs;
const char *clas;
if (Qundef == (*cp)->value) {
vs = "undefined";
clas = "";
} else {
VALUE rs = rb_funcall2((*cp)->value, rb_intern("to_s"), 0, 0);
vs = StringValuePtr(rs);
clas = rb_class2name(rb_obj_class((*cp)->value));
}
printf("%s%02u: %s = %s (%s)\n", indent, i, (*cp)->key, vs, clas);
}
slot_print(*cp, depth + 2);
}
}
}
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