diff options
Diffstat (limited to 'src/cache.c')
| -rw-r--r-- | src/cache.c | 155 |
1 files changed, 96 insertions, 59 deletions
diff --git a/src/cache.c b/src/cache.c index 8d15728..9bbe667 100644 --- a/src/cache.c +++ b/src/cache.c @@ -18,26 +18,48 @@ #include <stdlib.h> #include <stdint.h> +#include <stdalign.h> #include <string.h> #include <errno.h> +#include <time.h> #include <ctype.h> #include "cache.h" /** - * The cache structure is a blob of memory ('content') - * of 'count' bytes of only 'used' bytes. - * That blob containts at sequence of records of variable length - * Each records holds the following values in that given order: - * - length: 2 bytes unsigned integer LSB first, MSB second - * - hit count: 1 byte unsigned integer - * - value: 1 byte unsigned integer + * A cache item header + * + * Each item is followed by values in that given order: * - client: zero terminated string * - session: zero terminated string * - user: zero terminated string * - permission: zero terminated string * - */ +struct item +{ + /** expiration */ + time_t expire; + + /** length of the cache entry including this header */ + uint16_t length; + + /** hit indicator */ + uint8_t hit; + + /** value to store */ + int8_t value; + + /** fake ending character */ + char strings; +}; +typedef struct item item_t; + +/** + * The cache structure is a blob of memory ('content') + * of 'count' bytes of only 'used' bytes. + * That blob containts at sequence of records of variable length + */ struct cache { uint32_t used; @@ -46,12 +68,13 @@ struct cache }; static -uint32_t -lenat( +inline +item_t * +itemat( cache_t *cache, uint32_t pos ) { - return ((uint32_t)cache->content[pos]) | (((uint32_t)cache->content[pos + 1]) << 8); + return (item_t*)(&cache->content[pos]); } static @@ -62,7 +85,7 @@ drop_at( ) { uint32_t e, l; - l = lenat(cache, pos); + l = itemat(cache, pos)->length; e = pos + l; cache->used -= l; if (cache->used > e) @@ -75,13 +98,15 @@ drop_lre( cache_t *cache ) { uint32_t found = 0, iter = 0; - uint8_t hmin = 255, hint; + uint8_t hmin = 255, hit; + item_t *item; while (iter < cache->used) { - hint = cache->content[iter + 2]; - if (hint < hmin) + item = itemat(cache, iter); + hit = item->hit; + if (hit < hmin) found = iter; - iter += lenat(cache, iter); + iter += item->length; } if (found < cache->used) drop_at(cache, found); @@ -91,21 +116,23 @@ static void hit( cache_t *cache, - uint32_t pos + item_t *target ) { uint32_t iter = 0; - uint8_t hint; + uint8_t hit; + item_t *item; while (iter < cache->used) { - if (iter == pos) - hint = 255; + item = itemat(cache, iter); + if (item == target) + hit = 255; else { - hint = cache->content[iter + 2]; - if (hint) - hint--; + hit = item->hit; + if (hit) + hit--; } - cache->content[iter + 2] = hint; - iter += lenat(cache, iter); + item->hit = hit; + iter += item->length; } } @@ -135,7 +162,6 @@ cmp( return 0; } - static int match( @@ -156,7 +182,7 @@ match( } static -uint32_t +item_t* search( cache_t *cache, const char *client, @@ -164,16 +190,24 @@ search( const char *user, const char *permission ) { - char *txt; - uint32_t iter = 0; + time_t now; + item_t *item, *found; + uint32_t iter; + found = NULL; + now = time(NULL); + iter = 0; while (iter < cache->used) { - txt = (char*)&cache->content[iter + 4]; - if (match(txt, client, session, user, permission)) - return iter; - iter += lenat(cache, iter); + item = itemat(cache, iter); + if (item->expire && item->expire < now) + drop_at(cache, iter); + else { + if (match(&item->strings, client, session, user, permission)) + found = item; + iter += item->length; + } } - return iter; + return found; } int @@ -183,37 +217,40 @@ cache_put( const char *session, const char *user, const char *permission, - int value + int value, + time_t expire ) { - uint32_t pos; - size_t size, scli, sses, susr, sper; + uint16_t length; + item_t *item; + size_t size; - if (cache == NULL || value < 0 || value > 255) + if (cache == NULL || value < -128 || value > 127) return -EINVAL; - pos = search(cache, client, session, user, permission); - if (pos < cache->used) - cache->content[pos + 3] = (uint8_t)value; - else { - scli = strlen(client); - sses = strlen(session); - susr = strlen(user); - sper = strlen(permission); - size = scli + sses + susr + sper + 8; + item = search(cache, client, session, user, permission); + if (item == NULL) { + /* create an item */ + size = (size_t)(&((item_t*)0)->strings) + + strlen(client) + + strlen(session) + + strlen(user) + + strlen(permission); + size = (size + alignof(item_t) - 1) & ~(alignof(item_t) - 1); if (size > 65535) return -EINVAL; - if (size > cache->count) + length = (uint16_t)size; + if (length > cache->count) return -ENOMEM; - while(cache->used + (uint32_t)size > cache->count) + while(cache->used + length > cache->count) drop_lre(cache); - pos = cache->used; - cache->content[pos + 0] = (uint8_t)(size & 255); - cache->content[pos + 1] = (uint8_t)((size >> 8) & 255); - cache->content[pos + 2] = (uint8_t)255; - cache->content[pos + 3] = (uint8_t)value; - stpcpy(1 + stpcpy(1 + stpcpy(1 + stpcpy((char*)&cache->content[pos + 4], client), session), user), permission); + item = itemat(cache, cache->used); + item->length = length; + stpcpy(1 + stpcpy(1 + stpcpy(1 + stpcpy(&item->strings, client), session), user), permission); cache->used += (uint32_t)size; } + item->expire = expire; + item->hit = 255; + item->value = (int8_t)value; return 0; } @@ -225,12 +262,12 @@ cache_search( const char *user, const char *permission ) { - uint32_t pos; + item_t *item; - pos = search(cache, client, session, user, permission); - if (pos < cache->used) { - hit(cache, pos); - return (int)cache->content[pos + 3]; + item = search(cache, client, session, user, permission); + if (item) { + hit(cache, item); + return (int)item->value; } return -ENOENT; } |