Subnet Cache hashtable improvements

[tinc] / src / hash.h

diff --git a/src/hash.h b/src/hash.h
index 1a6ce32..45cf641 100644 (file)
--- a/src/hash.h
+++ b/src/hash.h
@@ -20,25 +20,65 @@
     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
-#include "system.h"
 
-typedef struct hash_t {
-       size_t n;
-       size_t size;
-       uint8_t *keys;
-       const void **values;
-} hash_t;
+/* Map 32 bits int onto 0..n-1, without throwing away too many bits if n is 2^8 or 2^16 */
 
-extern hash_t *hash_alloc(size_t n, size_t size) __attribute__((__malloc__));
-extern void hash_free(hash_t *);
+uint32_t modulo(uint32_t hash, size_t n);
 
-extern void hash_insert(hash_t *, const void *key, const void *value);
-extern void hash_delete(hash_t *, const void *key);
+#define HASH_SEARCH_ITERATIONS 4
 
-extern void *hash_search(const hash_t *, const void *key);
-extern void *hash_search_or_insert(hash_t *, const void *key, const void *value);
+#define hash_insert(t, ...) hash_insert_ ## t (__VA_ARGS__)
+#define hash_delete(t, ...) hash_delete_ ## t (__VA_ARGS__)
+#define hash_search(t, ...) hash_search_ ## t (__VA_ARGS__)
+#define hash_clear(t, n) hash_clear_ ## t ((n))
 
-extern void hash_clear(hash_t *);
-extern void hash_resize(hash_t *, size_t n);
+#define hash_define(t, n) \
+       typedef struct hash_ ## t { \
+               t keys[n]; \
+               const void *values[n]; \
+       } hash_ ## t; \
+       static uint32_t inline hash_modulo_ ## t(uint32_t hash) { \
+               return hash & (n - 1); \
+       } \
+       void hash_insert_ ## t (hash_ ##t *hash, const t *key, const void *value) { \
+               uint32_t i = hash_modulo_ ## t(hash_function_ ## t(key)); \
+               for(uint8_t f=0; f< (HASH_SEARCH_ITERATIONS - 1); f++){ \
+                       if(hash->values[i] == NULL || !memcmp(key, &hash->keys[i], sizeof(#t))) { \
+                               memcpy(&hash->keys[i], key, sizeof(#t)); \
+                               hash->values[i] = value; \
+                               return; \
+                       } \
+                       if(++i == n) i = 0; \
+               } \
+               /* We always pick the last slot. It's unfair. But thats life */ \
+               memcpy(&hash->keys[i], key, sizeof(#t)); \
+               hash->values[i] = value; \
+       } \
+       void *hash_search_ ## t (const hash_ ##t *hash, const t *key) { \
+               uint32_t i = hash_modulo_ ## t(hash_function_ ## t(key)); \
+               for(uint8_t f=0; f<HASH_SEARCH_ITERATIONS; f++){ \
+                       if(!memcmp(key, &hash->keys[i], sizeof(#t))) { \
+                               return (void *)hash->values[i]; \
+                       } \
+                       if(++i == n) i = 0; \
+               } \
+               return NULL; \
+       } \
+       void hash_delete_ ## t (hash_ ##t *hash, const t *key) { \
+               uint32_t i = hash_modulo_ ## t(hash_function_ ## t(key)); \
+               for(uint8_t f=0; f<HASH_SEARCH_ITERATIONS; f++){ \
+                       if(!memcmp(key, &hash->keys[i], sizeof(#t))) { \
+                               hash->values[i] = NULL; \
+                               return; \
+                       } \
+                       if(++i == n) i = 0; \
+               } \
+       } \
+       void hash_clear_ ## t(hash_ ##t *hash) { \
+               memset(hash->values, 0, n * sizeof(*hash->values)); \
+       }
+
+
+#define hash_new(t, name) static hash_ ## t name
 
 #endif