git clone ''

(ql:quickload :cl-memcached)


CL-MEMCACHED is a simple, fast & thread-safe library to interface with the memcached object caching system. It implements the Memcached TEXT protocol.

According to the home page :

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.

Tested on SBCL, CCL & CMUCL.

—– Global variables


Most commands have this as a fallback binding. Useful if we are only using one cache or if we want to bind it to a cache and then use it multiple places.


If this is true then the connection pool will be used. On SBCL this is about 3x faster.


Babel is used for encodeing/decoding the data. Memcached expects octets. Default encoding is UTF-8.

make-memcache &key (ip “”) (port 11211) (name “Memcache”) (pool-size 2)

Makes a memcached data-structure. We use this for further transactions. This has a inbuilt pool and know how to make new pool items.

mc-set key data &key (memcache *memcache*) (timeout 0) (flags 0) (noreply nil) (cas-unique nil) (mc-use-pool *mc-use-pool*)

Stores data for the key in the memcache. The parameters have same value as the memcached server commands. We have similar mc-add, mc-replace, mc-append, mc-prepend functions available.

mc-cas key data cas-unique &key (memcache *memcache*) (timeout 0) (flags 0) (noreply nil) (external-format *mc-default-encoding*) (mc-use-pool *mc-use-pool*)

This is a Check & Store operation.

mc-get keys-list &key (memcache *memcache*) (mc-use-pool *mc-use-pool*)

Returns a list of lists corresponding to responses to found keys in the keys-list.

mc-get+ key-or-list-of-keys &key (memcache *memcache*) (mc-use-pool *mc-use-pool*)

This is a wrapper around mc-get. It accepts 1 or many keys. Returns 1 or many memcache-response type structures containing all the pieces of the response.

The memcache-response structure has these slots : key, flags, bytes, cas-unique, data-raw. All the slot accessors start with mc-

mc-data response &key (external-format *mc-default-encoding*)

Takes the data-raw, which is in octets, and converts it to string using the external-format.

mc-get-value key &key (memcache *memcache*) (mc-use-pool *mc-use-pool*) (external-format *mc-default-encoding*)

A wrapper around mc-data and mc-get+. Give it a key and it gets a string value in return. Misuse is entierly the users responsibility. :)

mc-del key &key (memcache *memcache*) (noreply nil) (mc-use-pool *mc-use-pool*)

Deletes key from the cache.

mc-incr key &key (value 1) (noreply nil) (memcache *memcache*) (mc-use-pool *mc-use-pool*)

Increments key in place by value. If key not found then will return NOT_FOUND.

mc-decr key &key (value 1) (noreply nil) (memcache *memcache*) (mc-use-pool *mc-use-pool*)

Decrements key by value. If key not found then will return NOT_FOUND.

mc-touch key expiry-time &key ( noreply nil ) ( memcache *memcache* ) ( mc-use-pool *mc-use-pool* )

Change expiry time of key.

mc-flush-all &key ( delay 0 ) ( noreply nil) ( memcache *memcache* ) ( mc-use-pool *mc-use-pool* )

expires all the current keys.

mc-version &key ( memcache *memcache* ) ( mc-use-pool *mc-use-pool* )

Returns a text string with the version of the memcached server

mc-verbosity &key ( level 1 ) ( noreply nil) ( memcache *memcache* ) ( mc-use-pool *mc-use-pool* )

Sets the verbosity level of the logging output

mc-stats &key (memcache *memcache*) (noreply nil) (mc-use-pool *mc-use-pool*)

Returns a alist of the stats.

mc-stats-summary &key (memcache *memcache*)

Prints all the details from the alist. ;) Not too hot, but hey.

Example Usage for testing. ``` CL-USER> (require 'cl-memcached) NIL

CL-MEMCACHED> (in-package :cl-memcached)


CL-MEMCACHED> (setf memcache (make-memcache))

<MEMCACHED-SERVER Name:Memcache IP: Port:11211 >

CL-MEMCACHED> (mc-quick-test “foo” “bar”) Success SET Success GET NIL

CL-MEMCACHED> (mc-set “t1” “oooooooooooooooooooooo”) STORED :INTERNAL

CL-MEMCACHED> (mc-get+ “t1”)

CL-MEMCACHED> (describe *)


Slots with :INSTANCE allocation: KEY = “t1” FLAGS = “0” BYTES = 22 CAS-UNIQUE = NIL DATA-RAW = #(111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111 111.. ; No value

CL-MEMCACHED> (mc-data (mc-get+ “t1”)) “oooooooooooooooooooooo”

CL-MEMCACHED> (mc-get-value “t1”) “oooooooooooooooooooooo”


CL-MEMCACHED> (mc-incr “t3”) NOT_FOUND

CL-MEMCACHED> (mc-incr “t2”) 1 1

CL-MEMCACHED> (mc-incr “t2”) 2 1

CL-MEMCACHED> (mc-decr “t2”) 1 1


Abhijit 'quasi' Rao <>


* usocket
* split-sequence
* babel
* pooler

Note :
The is the homepage. But the version there is older and the documentation out of date. I have lost the creds, :-). Till I manage to set that right please ignore that one.

Host OS : OSX 10.8.4
Dataset: 1024 bytes (1kb) text string. Repeat 10000 times.

|——————-+——————+—————+——————+—————| | implementation | SET without pool | SET with pool | GET without pool | GET with pool | |——————-+——————+—————+——————+—————| | SBCL 1.1.10 | 4.942 | 0.713 | 4.905 | 0.690 | | CCL 1.9-r15759 | 4.711 | 0.847 | 4.506 | 0.648 | | CMUCL 20D Unicode | 4.460 | 0.970 | 4.290 | 0.810 | |——————-+——————+—————+——————+—————| | Dalli on Ruby 1.9 | | 0.957 | | 1.033 | |——————-+——————+—————+——————+—————| ``` When we do not use the pool we make a new socket connection every time.

The Ruby ‘dalli’ client, which implements the binary protocol, uses the same socket (I think) so this should be comparable with our with-pool.