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);
-unsigned int memcached_generate_hash(memcached_st *ptr, char *key, size_t key_length)
+uint32_t generate_hash(memcached_st *ptr, char *key, size_t key_length)
{
uint32_t hash= 1; /* Just here to remove compile warning */
- unsigned int x;
+ uint32_t x= 0;
+
WATCHPOINT_ASSERT(ptr->number_of_hosts);
}
WATCHPOINT_ASSERT(hash);
+ return hash;
+}
+
+unsigned int dispatch_host(memcached_st *ptr, uint32_t hash)
+{
+ switch (ptr->distribution)
+ {
+ case MEMCACHED_DISTRIBUTION_CONSISTENT:
+ case MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA:
+ {
+ int num= ptr->number_of_hosts * MEMCACHED_POINTS_PER_SERVER;
+
+ hash= hash;
+ struct continuum_item *begin, *end, *left, *right, *middle;
+ begin= left= ptr->continuum;
+ end= right= ptr->continuum + (num - 1);
+
+ while (1)
+ {
+ struct continuum_item *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_CONSISTENT_WHEEL:
+ {
+ unsigned int server_key;
+
+ server_key= hash % MEMCACHED_WHEEL_SIZE;
+
+ return ptr->wheel[server_key];
+ }
+ 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;
+ }
if (ptr->distribution == MEMCACHED_DISTRIBUTION_MODULA)
{
return hash % ptr->number_of_hosts;
}
- else
+ else if (ptr->distribution == MEMCACHED_DISTRIBUTION_CONSISTENT)
{
unsigned int server_key;
return ptr->wheel[server_key];
}
+ else if (ptr->distribution == MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA)
+ {
+ int num = ptr->number_of_hosts * MEMCACHED_POINTS_PER_SERVER;
+
+ hash = hash;
+ struct continuum_item *begin, *end, *left, *right, *middle;
+ begin = left = ptr->continuum;
+ end = right = ptr->continuum + (num - 1);
+ while(1)
+ {
+ middle = left + (right - left) / 2;
+ if(middle==end)
+ {
+ return begin->index;
+ }
+ if(middle==begin)
+ {
+ return end->index;
+ }
+ struct continuum_item *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;
+ }
+ }
+ else
+ {
+ WATCHPOINT_ASSERT(0);
+ }
+}
+
+unsigned int memcached_generate_hash(memcached_st *ptr, 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)