Memcached is a distributed memory caching system for uninterpreted arrays of bytes.
clients access data
data as key value pairs
key is a string (250 B limit)
value is array of bytes (1 MB limit)
client side compression supported
servers cache data
standardized protocols
can use TCP or UDP
transparent binary protocol
text protocol limits keys and values
servers do not know each other
server selected by client side hashing
least recently used strategy for eviction
// Initialization of memcache client.
mem = new Memcache ()
mem.add_server ("10.0.0.1:12345")
mem.add_server ("10.0.0.2:12345")
mem.add_server ("10.0.0.3:12345")
// Construct key for database query. sql = "SELECT * FROM user WHERE name = ?" key = "SQL:" + hash (sql) + name // Try to fetch value from memcache. if (defined (result = mem.get (key))) return (result) // Fetch value from database and populate memcache otherwise. result = execute_query (sql, name) mem.set (key, result, lifetime) return (result)
// Example adjusted from documentation, see references.
getting and setting values of keys
atomic setting of values for new keys
incrementing and decrementing of integer values
invalidating values by keys
The Memcached Website. http://www.memcached.org