static uint32_t FNV_32_PRIME= 16777619;
/* Prototypes */
-static uint32_t internal_generate_hash(char *key, size_t key_length);
-static uint32_t internal_generate_md5(char *key, size_t key_length);
-static uint32_t internal_generate_ketama_md5(char *key, size_t key_length);
+static uint32_t internal_generate_hash(const char *key, size_t key_length);
+static uint32_t internal_generate_md5(const char *key, size_t key_length);
-unsigned int memcached_generate_hash(memcached_st *ptr, char *key, size_t key_length)
+uint32_t generate_hash_value(const char *key, size_t key_length, memcached_hash hash_algorithm)
{
uint32_t hash= 1; /* Just here to remove compile warning */
- unsigned int x;
+ uint32_t x= 0;
- WATCHPOINT_ASSERT(ptr->number_of_hosts);
-
- if (ptr->number_of_hosts == 1)
- return 0;
-
- switch (ptr->hash)
+ switch (hash_algorithm)
{
case MEMCACHED_HASH_DEFAULT:
hash= internal_generate_hash(key, key_length);
}
}
break;
- case MEMCACHED_HASH_KETAMA:
- {
- hash= internal_generate_ketama_md5(key, key_length);
- break;
- }
case MEMCACHED_HASH_HSIEH:
{
hash= hsieh_hash(key, key_length);
break;
}
}
+ return hash;
+}
+
+uint32_t generate_hash(memcached_st *ptr, const char *key, size_t key_length)
+{
+ uint32_t hash= 1; /* Just here to remove compile warning */
+
+
+ WATCHPOINT_ASSERT(ptr->number_of_hosts);
+
+ if (ptr->number_of_hosts == 1)
+ return 0;
+ hash= generate_hash_value(key, key_length, ptr->hash);
WATCHPOINT_ASSERT(hash);
+ return hash;
+}
- if (ptr->distribution == MEMCACHED_DISTRIBUTION_MODULA)
+unsigned int dispatch_host(memcached_st *ptr, uint32_t hash)
+{
+ switch (ptr->distribution)
{
+ case MEMCACHED_DISTRIBUTION_CONSISTENT:
+ case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA:
+ {
+ uint32_t num= ptr->continuum_points_counter;
+ WATCHPOINT_ASSERT(ptr->continuum);
+
+ hash= hash;
+ memcached_continuum_item_st *begin, *end, *left, *right, *middle;
+ begin= left= ptr->continuum;
+ end= right= ptr->continuum + (num - 1);
+
+ while (1)
+ {
+ memcached_continuum_item_st *rmiddle;
+
+ middle = left + (right - left) / 2;
+
+ if (middle==end)
+ return begin->index;
+
+ if (middle==begin)
+ return end->index;
+
+ rmiddle = middle+1;
+
+ if (hash<rmiddle->value && hash>=middle->value)
+ return middle->index;
+
+ if (middle->value < hash)
+ left = middle + 1;
+ else if (middle->value > hash)
+ right = middle - 1;
+
+ if (left>right)
+ return left->index;
+ }
+ }
+ break;
+ case MEMCACHED_DISTRIBUTION_MODULA:
+ return hash % ptr->number_of_hosts;
+ default:
+ WATCHPOINT_ASSERT(0); /* We have added a distribution without extending the logic */
return hash % ptr->number_of_hosts;
}
- else
- {
- unsigned int server_key;
- server_key= hash % MEMCACHED_WHEEL_SIZE;
+ WATCHPOINT_ASSERT(0); /* We should never reach here */
+ return 0;
+}
- return ptr->wheel[server_key];
- }
+/*
+ One day make this public, and have it return the actual memcached_server_st
+ to the calling application.
+*/
+uint32_t memcached_generate_hash(memcached_st *ptr, const char *key, size_t key_length)
+{
+ uint32_t hash= 1; /* Just here to remove compile warning */
+
+ WATCHPOINT_ASSERT(ptr->number_of_hosts);
+
+ if (ptr->number_of_hosts == 1)
+ return 0;
+
+ hash = generate_hash(ptr, key, key_length);
+
+ WATCHPOINT_ASSERT(hash);
+
+ return dispatch_host(ptr, hash);
}
-static uint32_t internal_generate_hash(char *key, size_t key_length)
+static uint32_t internal_generate_hash(const char *key, size_t key_length)
{
- char *ptr= key;
+ const char *ptr= key;
uint32_t value= 0;
while (--key_length)
return value == 0 ? 1 : value;
}
-static uint32_t internal_generate_md5(char *key, size_t key_length)
-{
- unsigned char results[16];
-
- md5_signature((unsigned char*)key, (unsigned int)key_length, results);
-
- return (uint32_t)(( results[3] << 24 )
- | ( results[2] << 16 )
- | ( results[1] << 8 )
- | results[0] );
-}
-
-static uint32_t internal_generate_ketama_md5(char *key, size_t key_length)
+static uint32_t internal_generate_md5(const char *key, size_t key_length)
{
unsigned char results[16];