C/C++ Client Library for memcached¶
SYNOPSIS¶
- #include <libmemcached/memcached.h>
Compile and link with -lmemcached
libmemcached
is an open source C/C++ client library and tools for the
memcached server (http://memcached.org/). It has been designed to be light on
memory usage, thread safe, and provide full access to server side methods.
libmemcached
was designed to provide the greatest number of options to use
Memcached. Some of the features provided:
Asynchronous and Synchronous Transport Support.
Consistent Hashing and Distribution.
Tunable Hashing algorithm to match keys.
Access to large object support.
Local replication.
A complete reference guide and documentation to the API.
Tools to Manage your Memcached networks.
DESCRIPTION¶
“Memcached is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.” http://memcached.org/
libmemcached
is a small, thread-safe client library for the
memcached protocol. The code has all been written to allow
for both web and embedded usage. It handles the work behind routing
individual keys to specific servers specified by the developer (and values are
matched based on server order as supplied by the user). It implements
a modular and consistent method of object distribution.
There are multiple implemented routing and hashing methods. See the
memcached_behavior_set()
manpage for more information.
All operations are performed against a memcached_st
structure.
These structures can either be dynamically allocated or statically
allocated and then initialized by memcached_create()
. Functions have
been written in order to encapsulate the memcached_st
. It is not
recommended that you operate directly against the structure.
Nearly all functions return a memcached_return_t
value.
This value can be translated to a printable string with
memcached_strerror
.
Objects are stored on servers by hashing keys. The hash value maps the key to a particular server. All clients understand how this hashing works, so it is possibly to reliably both push data to a server and retrieve data from a server.
Group keys can be optionally used to group sets of objects with servers.
Namespaces are supported, and can be used to partition caches so that multiple applications can use the same memcached servers.
Some features of the library must be enabled through memcached_behavior_set()
.
CONSTANTS¶
A number of constants have been provided for in the library.
THREADS AND PROCESSES¶
No global variables are used in this library.
memcached_st
structures are thread-safe, but when using threads or
forked processes it is important to keep one instance of memcached_st
per process or thread. Without creating your own locking structures you can not
share a single memcached_st
. However, you can call
memcached_quit()
on a memcached_st
and then use the resulting
cloned structure.
SYSTEMTAP¶
libmemcached
can be built to support Systemtap on Linux when enabled at
compile time.
Please see stap(1) and dtrace(1) for more information about Systemtap.
CLIENT PROGRAMS¶
libmemcached
comes with a few useful client programs: