+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 host_index;
+ uint32_t continuum_index= 0;
+ uint32_t value;
+ memcached_server_st *list;
+ uint32_t pointer_index;
+ 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;
+ uint64_t is_ketama_weighted= 0;
+ uint64_t is_auto_ejecting= 0;
+ uint32_t points_per_server= 0;
+ uint32_t live_servers= 0;
+ struct timeval now;
+
+ if (gettimeofday(&now, NULL) != 0)
+ {
+ ptr->cached_errno = errno;
+ return MEMCACHED_ERRNO;
+ }
+
+ list = ptr->hosts;
+
+ /* count live servers (those without a retry delay set) */
+ is_auto_ejecting= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_AUTO_EJECT_HOSTS);
+ if (is_auto_ejecting)
+ {
+ live_servers= 0;
+ ptr->next_distribution_rebuild= 0;
+ for (host_index= 0; host_index < ptr->number_of_hosts; ++host_index)
+ {
+ if (list[host_index].next_retry <= now.tv_sec)
+ live_servers++;
+ else
+ {
+ if (ptr->next_distribution_rebuild == 0 || list[host_index].next_retry < ptr->next_distribution_rebuild)
+ ptr->next_distribution_rebuild= list[host_index].next_retry;
+ }
+ }
+ }
+ else
+ live_servers= ptr->number_of_hosts;
+
+ is_ketama_weighted= memcached_behavior_get(ptr, MEMCACHED_BEHAVIOR_KETAMA_WEIGHTED);
+ points_per_server= (uint32_t) (is_ketama_weighted ? MEMCACHED_POINTS_PER_SERVER_KETAMA : MEMCACHED_POINTS_PER_SERVER);
+
+ if (live_servers == 0)
+ return MEMCACHED_SUCCESS;
+
+ if (live_servers > ptr->continuum_count)
+ {
+ memcached_continuum_item_st *new_ptr;
+
+ new_ptr= ptr->call_realloc(ptr, ptr->continuum,
+ sizeof(memcached_continuum_item_st) * (live_servers + MEMCACHED_CONTINUUM_ADDITION) * points_per_server);
+
+ if (new_ptr == 0)
+ return MEMCACHED_MEMORY_ALLOCATION_FAILURE;
+
+ ptr->continuum= new_ptr;
+ ptr->continuum_count= live_servers + MEMCACHED_CONTINUUM_ADDITION;
+ }
+
+ 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;
+ }
+ if (!is_auto_ejecting || list[host_index].next_retry <= now.tv_sec)
+ total_weight += list[host_index].weight;
+ }
+ }
+
+ for (host_index = 0; host_index < ptr->number_of_hosts; ++host_index)
+ {
+ if (is_auto_ejecting && list[host_index].next_retry > now.tv_sec)
+ continue;
+
+ if (is_ketama_weighted)
+ {
+ float pct = (float)list[host_index].weight / (float)total_weight;
+ pointer_per_server= (uint32_t) ((floorf((float) (pct * MEMCACHED_POINTS_PER_SERVER_KETAMA / 4 * (float)live_servers + 0.0000000001))) * 4);
+ pointer_per_hash= 4;
+#ifdef 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
+ }
+
+
+ if (ptr->distribution == MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA_SPY)
+ {
+ for (pointer_index= 0;
+ pointer_index < pointer_per_server / pointer_per_hash;
+ pointer_index++)
+ {
+ char sort_host[MEMCACHED_MAX_HOST_SORT_LENGTH]= "";
+ size_t sort_host_length;
+
+ // Spymemcached ketema key format is: hostname/ip:port-index
+ // If hostname is not available then: /ip:port-index
+ sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
+ "/%s:%d-%d",
+ list[host_index].hostname,
+ list[host_index].port,
+ pointer_index);
+#ifdef DEBUG
+ printf("update_continuum: key is %s\n", sort_host);
+#endif
+
+ WATCHPOINT_ASSERT(sort_host_length);
+
+ if (is_ketama_weighted)
+ {
+ unsigned int i;
+ for (i = 0; i < pointer_per_hash; i++)
+ {
+ value= ketama_server_hash(sort_host, (uint32_t) sort_host_length, (int) i);
+ ptr->continuum[continuum_index].index= host_index;
+ ptr->continuum[continuum_index++].value= value;
+ }
+ }
+ else
+ {
+ value= memcached_generate_hash_value(sort_host, sort_host_length, ptr->hash_continuum);
+ ptr->continuum[continuum_index].index= host_index;
+ ptr->continuum[continuum_index++].value= value;
+ }
+ }
+ }
+ else
+ {
+ for (pointer_index= 1;
+ pointer_index <= pointer_per_server / pointer_per_hash;
+ pointer_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= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
+ "%s-%d",
+ list[host_index].hostname,
+ pointer_index - 1);
+ }
+ else
+ {
+ sort_host_length= (size_t) snprintf(sort_host, MEMCACHED_MAX_HOST_SORT_LENGTH,
+ "%s:%d-%d",
+ list[host_index].hostname,
+ list[host_index].port, pointer_index - 1);
+ }
+
+ WATCHPOINT_ASSERT(sort_host_length);
+
+ if (is_ketama_weighted)
+ {
+ unsigned int i;
+ for (i = 0; i < pointer_per_hash; i++)
+ {
+ value= ketama_server_hash(sort_host, (uint32_t) sort_host_length, (int) i);
+ ptr->continuum[continuum_index].index= host_index;
+ ptr->continuum[continuum_index++].value= value;
+ }
+ }
+ else
+ {
+ value= memcached_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 DEBUG
+ for (pointer_index= 0; ptr->number_of_hosts && pointer_index < ((live_servers * MEMCACHED_POINTS_PER_SERVER) - 1); pointer_index++)
+ {
+ WATCHPOINT_ASSERT(ptr->continuum[pointer_index].value <= ptr->continuum[pointer_index + 1].value);
+ }
+#endif
+
+ return MEMCACHED_SUCCESS;
+}
+
+