How to use consistent hashing in memcached c client?

Question

I am using libmemcached c client for set and get the memcache value.

  memcached_server_st *servers = NULL;
  memcached_st *memc;
  memcached_return rc;
  char *key= "keystring";
  char *value= "keyvalue";

//  memcached_server_st *memcached_servers_parse (char *server_strings);
  memc= memcached_create(NULL);

  servers= memcached_server_list_append(servers, "localhost", 5555, &rc);
  servers= memcached_server_list_append(servers, "localhost", 5566, &rc);
  rc= memcached_server_push(memc, servers);

  if (rc == MEMCACHED_SUCCESS)
    fprintf(stderr,"Added server successfully\n");
  else
    fprintf(stderr,"Couldn't add server: %s\n",memcached_strerror(memc, rc));

  rc= memcached_set(memc, key, strlen(key), value, strlen(value), (time_t)0, (uint32_t)0);

  if (rc == MEMCACHED_SUCCESS)
    fprintf(stderr,"Key stored successfully\n");
  else
    fprintf(stderr,"Couldn't store key: %s\n",memcached_strerror(memc, rc));

  return 0;

I want to use the consistent hashing algorithm for set and get the key. http://docs.libmemcached.org/memcached_behavior.html#memcached_behavior_setlink

But i don't know how to implement this.code snippets or reference links are very much appreciated.

Thanks in advance.

Answer 1

Go to the link http://docs.libmemcached.org/memcached_behavior.html#memcached_behavior_setlink You can see two method to make it.

first one
MEMCACHED_BEHAVIOR_DISTRIBUTION
Using this you can enable different means of distributing values to servers. The default method is MEMCACHED_DISTRIBUTION_MODULA. You can enable consistent hashing by setting MEMCACHED_DISTRIBUTION_CONSISTENT. Consistent hashing delivers better distribution and allows servers to be added to the cluster with minimal cache losses. Currently MEMCACHED_DISTRIBUTION_CONSISTENT is an alias for the value MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA.

second one
MEMCACHED_BEHAVIOR_KETAMA
Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA and the hash to MEMCACHED_HASH_MD5.

example

memcached_behavior_set(memc, MEMCACHED_BEHAVIOR_KETAMA, 1);