NAME

memcached_behavior_get memcached_behavior_set

LIBRARY

C Client Library for memcached (libmemcached, -lmemcached)

SYNOPSIS

#include <memcached.h>

uint64_t
  memcached_behavior_get (memcached_st *ptr,
                          memcached_behavior flag);

memcached_return
  memcached_behavior_set (memcached_st *ptr,
                          memcached_behavior flag,
                          uint64_t data);

DESCRIPTION

libmemcached(3) behavior can be modified by use memcached_behavior_set(). Default behavior is the library strives to be quick and accurate. Some behavior, while being faster, can also result in not entirely accurate behavior (for instance, memcached_set() will always respond with MEMCACHED_SUCCESS).

memcached_behavior_get() takes a behavior flag and returns whether or not that behavior is currently enabled in the client.

memcached_behavior_set() changes the value of a particular option of the client. It takes both a flag (listed below) and a value. For simple on or off options you just need to pass in a value of 1. Calls to memcached_behavior_set() will flush and reset all connections.

MEMCACHED_BEHAVIOR_NO_BLOCK

Causes libmemcached(3) to use asychronous IO. This is the fastest transport available for storage functions. For read operations it is currently similar in performance to the non-blocking method (this is being looked into).

MEMCACHED_BEHAVIOR_TCP_NODELAY

Turns on the no-delay feature for connecting sockets (may be faster in some environments).

MEMCACHED_BEHAVIOR_HASH

Makes the default hashing algorithm for keys use MD5. The value can be set to either MEMCACHED_HASH_DEFAULT, MEMCACHED_HASH_MD5, MEMCACHED_HASH_CRC, MEMCACHED_HASH_FNV1_64, MEMCACHED_HASH_FNV1A_64, MEMCACHED_HASH_FNV1_32, and MEMCACHED_HASH_FNV1A_32. The behavior for all hashes but MEMCACHED_HASH_DEFAULT is identitical to the Java driver written by Dustin Sallings.

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.

MEMCACHED_BEHAVIOR_CACHE_LOOKUPS

Memcached can cache named lookups so that DNS lookups are made only once.

MEMCACHED_BEHAVIOR_SUPPORT_CAS

Support CAS operations (this is not enabled by default at this point in the server since it imposes a slight performance penalty).

MEMCACHED_BEHAVIOR_KETAMA

Sets the default distribution to MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA and the hash to MEMCACHED_HASH_MD5.

MEMCACHED_BEHAVIOR_POLL_TIMEOUT

Modify the timeout value that is used by poll(). The default value is -1. An signed int pointer must be passed to memcached_behavior_set() to change this value. For memcached_behavior_get() a signed int value will be cast and returned as the unsigned long long.

MEMCACHED_BEHAVIOR_USER_DATA

This allows you to store a pointer to a specifc piece of data. This can be retrieved from inside of memcached_fetch_execute(). Cloning a memcached_st

will copy the pointer to the clone. This was deprecated in 0.14 in favor of memcached_callback_set(3). This will be removed in 0.15.

MEMCACHED_BEHAVIOR_BUFFER_REQUESTS

Enabling buffered IO causes commands to "buffer" instead of being sent. Any action that gets data causes this buffer to be be sent to the remote connection. Quiting the connection or closing down the connection will also cause the buffered data to be pushed to the remote connection.

MEMCACHED_BEHAVIOR_VERIFY_KEY

Enabling this will cause libmemcached(3) to test all keys to verify that they are valid keys.

MEMCACHED_BEHAVIOR_SORT_HOSTS

Enabling this will cause hosts that are added to be placed in the host list in sorted order. This will defeat consisten hashing.

MEMCACHED_BEHAVIOR_CONNECT_TIMEOUT

In non-blocking mode this changes the value of the timeout during socket connection.

RETURN

memcached_behavior_get() returns either the current value of the get, or 0 or 1 on simple flag behaviors (1 being enabled). memcached_behavior_set() returns failure or success.

NOTES

memcached_behavior_set() in version .17 was changed from taking a pointer to data value, to taking a uin64_t.

HOME

To find out more information please check: http://tangent.org/552/libmemcached.html

AUTHOR

Brian Aker, <brian@tangent.org>

SEE ALSO

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