+static uint32_t ketama_server_hash(const char *key, unsigned int key_length, int alignment)
+{
+ unsigned char results[16];
+
+ md5_signature((unsigned char*)key, key_length, results);
+ return ((uint32_t) (results[3 + alignment * 4] & 0xFF) << 24)
+ | ((uint32_t) (results[2 + alignment * 4] & 0xFF) << 16)
+ | ((uint32_t) (results[1 + alignment * 4] & 0xFF) << 8)
+ | (results[0 + alignment * 4] & 0xFF);
+}
+
+static int continuum_item_cmp(const void *t1, const void *t2)
+{
+ memcached_continuum_item_st *ct1= (memcached_continuum_item_st *)t1;
+ memcached_continuum_item_st *ct2= (memcached_continuum_item_st *)t2;
+
+ /* Why 153? Hmmm... */
+ WATCHPOINT_ASSERT(ct1->value != 153);
+ if (ct1->value == ct2->value)
+ return 0;
+ else if (ct1->value > ct2->value)
+ return 1;
+ else
+ return -1;
+}
+
+memcached_return update_continuum(memcached_st *ptr)
+{
+ uint32_t index;
+ uint32_t host_index;
+ uint32_t continuum_index= 0;
+ uint32_t value;
+ memcached_server_st *list;
+ uint32_t pointer_counter= 0;
+ uint32_t pointer_per_server= MEMCACHED_POINTS_PER_SERVER;
+ uint32_t pointer_per_hash= 1;
+ uint64_t total_weight= 0;
+ uint32_t is_ketama_weighted= 0;
+ uint32_t points_per_server= 0;
+
+ is_ketama_weighted= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED);
+ points_per_server= is_ketama_weighted ? MEMCACHED_POINTS_PER_SERVER_KETAMA : MEMCACHED_POINTS_PER_SERVER;
+
+ if (ptr->number_of_hosts == 0)
+ return MEMCACHED_SUCCESS;
+
+ if (ptr->number_of_hosts > ptr->continuum_count)
+ {
+ memcached_continuum_item_st *new_ptr;
+
+ if (ptr->call_realloc)
+ new_ptr= (memcached_continuum_item_st *)ptr->call_realloc(ptr, ptr->continuum,
+ sizeof(memcached_continuum_item_st) * (ptr->number_of_hosts + MEMCACHED_CONTINUUM_ADDITION) * points_per_server);
+ else
+ new_ptr= (memcached_continuum_item_st *)realloc(ptr->continuum,
+ sizeof(memcached_continuum_item_st) * (ptr->number_of_hosts + MEMCACHED_CONTINUUM_ADDITION) * points_per_server);
+
+ if (new_ptr == 0)
+ return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
+
+ ptr->continuum= new_ptr;
+ ptr->continuum_count= ptr->number_of_hosts + MEMCACHED_CONTINUUM_ADDITION;
+ }
+
+ list = ptr->hosts;
+
+ if (is_ketama_weighted)
+ {
+ for (host_index = 0; host_index < ptr->number_of_hosts; ++host_index)
+ {
+ if (list[host_index].weight == 0)
+ {
+ list[host_index].weight = 1;
+ }
+ total_weight += list[host_index].weight;
+ }
+ }
+
+ for (host_index = 0; host_index < ptr->number_of_hosts; ++host_index)
+ {
+ if (is_ketama_weighted)
+ {
+ float pct = (float)list[host_index].weight / (float)total_weight;
+ pointer_per_server= floorf(pct * MEMCACHED_POINTS_PER_SERVER_KETAMA / 4 * (float)(ptr->number_of_hosts) + 0.0000000001) * 4;
+ pointer_per_hash= 4;
+#ifdef HAVE_DEBUG
+ printf("ketama_weighted:%s|%d|%llu|%u\n",
+ list[host_index].hostname,
+ list[host_index].port,
+ (unsigned long long)list[host_index].weight,
+ pointer_per_server);
+#endif
+ }
+ for (index= 1; index <= pointer_per_server / pointer_per_hash; ++index)
+ {
+ char sort_host[MEMCACHED_MAX_HOST_SORT_LENGTH]= "";
+ size_t sort_host_length;
+
+ if (list[host_index].port == MEMCACHED_DEFAULT_PORT)
+ {
+ sort_host_length= snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH, "%s-%d",
+ list[host_index].hostname, index - 1);
+
+ }
+ else
+ {
+ sort_host_length= snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH, "%s:%d-%d",
+ list[host_index].hostname, list[host_index].port, index - 1);
+ }
+ WATCHPOINT_ASSERT(sort_host_length);
+
+ if (is_ketama_weighted)
+ {
+ int i;
+ for (i = 0; i < pointer_per_hash; i++)
+ {
+ value= ketama_server_hash(sort_host, sort_host_length, i);
+ ptr->continuum[continuum_index].index= host_index;
+ ptr->continuum[continuum_index++].value= value;
+ }
+ }
+ else
+ {
+ value= generate_hash_value(sort_host, sort_host_length, ptr->hash_continuum);
+ ptr->continuum[continuum_index].index= host_index;
+ ptr->continuum[continuum_index++].value= value;
+ }
+ }
+ pointer_counter+= pointer_per_server;
+ }
+
+ WATCHPOINT_ASSERT(ptr);
+ WATCHPOINT_ASSERT(ptr->continuum);
+ WATCHPOINT_ASSERT(ptr->number_of_hosts * MEMCACHED_POINTS_PER_SERVER <= MEMCACHED_CONTINUUM_SIZE);
+ ptr->continuum_points_counter= pointer_counter;
+ qsort(ptr->continuum, ptr->continuum_points_counter, sizeof(memcached_continuum_item_st), continuum_item_cmp);
+
+#ifdef HAVE_DEBUG
+ for (index= 0; ptr->number_of_hosts && index < ((ptr->number_of_hosts * MEMCACHED_POINTS_PER_SERVER) - 1); index++)
+ {
+ WATCHPOINT_ASSERT(ptr->continuum[index].value <= ptr->continuum[index + 1].value);
+ }
+#endif
+
+ return MEMCACHED_SUCCESS;
+}
+
+