memcached_behavior_set

MEMCACHED_BEHAVIOR_SET(3)         libmemcached         MEMCACHED_BEHAVIOR_SET(3)



NAME
       memcached_behavior_set - libmemcached Documentation

       Manipulate the behavior of a memcached_st structure.

SYNOPSIS
       #include <libmemcached/memcached.h>

       memcached_behavior_t

       uint64_t memcached_behavior_get(memcached_st *ptr,
       memcached_behavior_t flag)

       memcached_return_t memcached_behavior_set(memcached_st *ptr,
       memcached_behavior_t flag, uint64_t data)

       Compile and link with -lmemcached

DESCRIPTION
       libmemcached(3) behavior can be modified by using
       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_USE_UDP

       Causes libmemcached(3) to use the UDP transport when communicating with a
       memcached server. Not all I/O operations are testsed when this behavior
       is enababled. The following operations will return
       MEMCACHED_NOT_SUPPORTED when executed with the MEMCACHED_BEHAVIOR_USE_UDP
       enabled: memcached_version(), memcached_stat(), memcached_get(),
       memcached_get_by_key(), memcached_mget(), memcached_mget_by_key(),
       memcached_fetch(), memcached_fetch_result(), memcached_fetch_execute().

       All other operations are testsed but are executed in a 'fire-and-forget'
       mode, in which once the client has executed the operation, no attempt
       will be made to ensure the operation has been received and acted on by
       the server.

       libmemcached(3) does not allow TCP and UDP servers to be shared within
       the same libmemached(3) client 'instance'. An attempt to add a TCP server
       when this behavior is enabled will result in a
       MEMCACHED_INVALID_HOST_PROTOCOL, as will attempting to add a UDP server
       when this behavior has not been enabled.

       MEMCACHED_BEHAVIOR_NO_BLOCK

       Causes libmemcached(3) to use asychronous IO. This is the fastest
       transport available for storage functions.

       MEMCACHED_BEHAVIOR_SND_TIMEOUT

       This sets the microsecond behavior of the socket against the SO_SNDTIMEO
       flag.  In cases where you cannot use non-blocking IO this will allow you
       to still have timeouts on the sending of data.

       MEMCACHED_BEHAVIOR_RCV_TIMEOUT

       This sets the microsecond behavior of the socket against the SO_RCVTIMEO
       flag.

       In cases where you cannot use non-blocking IO this will allow you to
       still have timeouts on the reading of data.

       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, MEMCACHED_HASH_FNV1A_32, MEMCACHED_HASH_JENKINS,
       MEMCACHED_HASH_HSIEH, and MEMCACHED_HASH_MURMUR.

       Each hash has it's advantages and it's weaknesses. If you don't know or
       don't care, just go with the default.

       Support for MEMCACHED_HASH_HSIEH is a compile time option that is
       disabled by default. To enable tests for this hashing algorithm,
       configure and build libmemcached with the --enable-hash_hsieh.

       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

       Deprecated since version 0.46(?): DNS lookups are now always cached until
       an error occurs with the server.

       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_KETAMA_WEIGHTED
              Sets the default distribution to
              MEMCACHED_DISTRIBUTION_CONSISTENT_KETAMA with the weighted tests.
              and the hash to MEMCACHED_HASH_MD5.

       MEMCACHED_BEHAVIOR_KETAMA_HASH

       Sets the hashing algorithm for host mapping on continuum. 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.

       MEMCACHED_BEHAVIOR_KETAMA_COMPAT

       Sets the compatibility mode. The value can be set to either
       MEMCACHED_KETAMA_COMPAT_LIBMEMCACHED (this is the default) or
       MEMCACHED_KETAMA_COMPAT_SPY to be compatible with the SPY Memcached
       client for Java.

       MEMCACHED_BEHAVIOR_POLL_TIMEOUT

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

       MEMCACHED_BEHAVIOR_USER_DATA

       Deprecated since version <: 0.30

       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 in milliseconds. Specifying -1 means an infinite timeā€out.

       MEMCACHED_BEHAVIOR_BINARY_PROTOCOL

       Enable the use of the binary protocol. Please note that you cannot toggle
       this flag on an open connection.

       MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT

       Set this value to enable the server be removed after continuous
       MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT times connection failure.

       MEMCACHED_BEHAVIOR_IO_MSG_WATERMARK

       Set this value to tune the number of messages that may be sent before
       libmemcached should start to automatically drain the input queue. Setting
       this value to high, may cause libmemcached to deadlock (trying to send
       data, but the send will block because the input buffer in the kernel is
       full).

       MEMCACHED_BEHAVIOR_IO_BYTES_WATERMARK

       Set this value to tune the number of bytes that may be sent before
       libmemcached should start to automatically drain the input queue (need at
       least 10 IO requests sent without reading the input buffer). Setting this
       value to high, may cause libmemcached to deadlock (trying to send data,
       but the send will block because the input buffer in the kernel is full).

       MEMCACHED_BEHAVIOR_IO_KEY_PREFETCH

       The binary protocol works a bit different than the textual protocol in
       that a multiget is implemented as a pipe of single get-operations which
       are sent to the server in a chunk. If you are using large multigets from
       your application, you may improve the latency of the gets by setting this
       value so you send out the first chunk of requests when you hit the
       specified limit.  It allows the servers to start processing the requests
       to send the data back while the rest of the requests are created and sent
       to the server.

       MEMCACHED_BEHAVIOR_NOREPLY

       Set this value to specify that you really don't care about the result
       from your storage commands (set, add, replace, append, prepend).

       MEMCACHED_BEHAVIOR_NUMBER_OF_REPLICAS

       If you just want "a poor mans HA", you may specify the numbers of
       replicas libmemcached should store of each item (on different servers).
       This replication does not dedicate certain memcached servers to store the
       replicas in, but instead it will store the replicas together with all of
       the other objects (on the 'n' next servers specified in your server
       list).

       MEMCACHED_BEHAVIOR_RANDOMIZE_REPLICA_READ

       Allows randomizing the replica reads starting point. Normally the read is
       done from primary server and in case of miss the read is done from
       primary + 1, then primary + 2 all the way to 'n' replicas. If this option
       is set on the starting point of the replica reads is randomized between
       the servers.  This allows distributing read load to multiple servers with
       the expense of more write traffic.

       MEMCACHED_BEHAVIOR_CORK

       This open has been deprecated with the behavior now built and used
       appropriately on selected platforms.

       MEMCACHED_BEHAVIOR_KEEPALIVE

       Enable TCP_KEEPALIVE behavior.

       MEMCACHED_BEHAVIOR_KEEPALIVE_IDLE

       Specify time, in seconds, to mark a connection as idle. This is only
       available as an option Linux.

       MEMCACHED_BEHAVIOR_SOCKET_SEND_SIZE

       Find the current size of SO_SNDBUF. A value of 0 means either an error
       occured or no hosts were available. It is safe to assume system default
       if this occurs. If an error occurs you can checked the last cached errno
       statement to find the specific error.

       MEMCACHED_BEHAVIOR_SOCKET_RECV_SIZE

       Find the current size of SO_RCVBUF. A value of 0 means either an error
       occured or no hosts were available. It is safe to assume system default
       if this occurs. If an error occurs you can checked the last cached errno
       statement to find the specific error.

       MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT

       Deprecated since version 0.48: See
       MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS

       This number of times a host can have an error before it is disabled.


       MEMCACHED_BEHAVIOR_AUTO_EJECT_HOSTS

       Deprecated since version 0.48: See
       MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS

       If enabled any hosts which have been flagged as disabled will be removed
       from the list of servers in the memcached_st structure. This must be used
       in combination with MEMCACHED_BEHAVIOR_SERVER_FAILURE_LIMIT.


       MEMCACHED_BEHAVIOR_REMOVE_FAILED_SERVERS
              If enabled any hosts which have been flagged as disabled will be
              removed from the list of servers in the memcached_st structure.

       MEMCACHED_BEHAVIOR_RETRY_TIMEOUT

       When enabled a host which is problematic will only be checked for usage
       based on the amount of time set by this behavior. The value is in
       seconds.

       MEMCACHED_BEHAVIOR_HASH_WITH_PREFIX_KEY

       When enabled the prefix key will be added to the key when determining
       server by hash. See MEMCACHED_CALLBACK_NAMESPACE for additional
       information.

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://libmemcached.org/

SEE ALSO
       memcached(1) libmemcached(3) memcached_strerror(3)

AUTHOR
       Brian Aker

COPYRIGHT
       2011-2013, Brian Aker DataDifferential, http://datadifferential.com/



1.0.18                          February 09, 2014      MEMCACHED_BEHAVIOR_SET(3)