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MEMCACHED(3) libmemcached-awesome MEMCACHED(3)


memcached - libmemcached Documentation


#include <libmemcached-1.0/memcached.h>
Compile and link with -lmemcached

  • string -- configuration string
  • string_length -- length of the configuration string without any terminating zero

allocated and initialized memcached_st struct

  • option_string -- configuration string
  • length -- length of the configuration string without any terminating zero
  • error_buffer -- buffer used to store any error message
  • error_buffer_size -- available size of the error_buffer

memcached_return_t indicating success


libmemcached implements a custom language for configuring and modifying servers. By passing in an option string you can generate a memcached_st object that you can use in your application directly.

General Options:

Provide a servername to be used by the client.

Providing a weight will cause weighting to occur with all hosts with each server getting a default weight of 1.

Provide a filepath to a UNIX socket file. Providing a weight will cause weighting to occur with all hosts with each server getting a default weight of 1.

Verify that keys that are being used fit within the design of the protocol being used.


Force all connections to use the binary protocol.


Provide a configuration file to be used to load requests. Beware that by using a configuration file libmemcached will reset memcached_st based on information only contained in the file.

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT.

Set the distribution model used by the client. See memcached_behavior_set() for more details.

Set the hashing algorithm used for placing keys on servers.

When enabled the prefix key will be added to the key when determining which server to store the data in.

Enable "no reply" for all calls that support this. It is highly recommended that you use this option with the binary protocol only.

Set the number of servers that keys will be replicated to.

Select randomly the server within the replication pool to read from.

When adding new servers always calculate their distribution based on sorted naming order.

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_SUPPORT_CAS

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_USE_UDP

A namespace is a container that provides context for keys, only other requests that know the namespace can access these values. This is accomplished by prepending the namespace value to all keys.

Memcached Pool Options:

Initial size of pool.

Maximize size of the pool.

I/O Options:

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_TCP_NODELAY

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_TCP_KEEPALIVE

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_RETRY_TIMEOUT

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_SND_TIMEOUT

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_SOCKET_RECV_SIZE

See memcached_behavior_set() for MEMCACHED_BEHAVIOR_SOCKET_SEND_SIZE

Set the timeout used by poll(3).

Other Options:

Include a file in configuration. Unlike --CONFIGURE-FILE= this will not reset memcached_st.

Reset memcached_st and continue to process.

End configuration processing.

End configuration processing and throw an error.



memcached() returns a pointer to the memcached_st that was created (or initialized). On an allocation failure, it returns NULL.


const char *config_string=

" "
" "
""; memcached_st *memc= memcached(config_string, strlen(config_string)); {
// ... } memcached_free(memc);


memcached(1) libmemcached(3) memcached_strerror(3)

February 5, 2024 1.1