Cache::Memcached - client library for memcached (memory cache daemon)

  use Cache::Memcached;

  $memd = new Cache::Memcached {
    'servers' => [ "10.0.0.15:11211", "10.0.0.15:11212",
                   "10.0.0.17:11211", [ "10.0.0.17:11211", 3 ] ],
    'debug' => 0,
    'compress_threshold' => 10_000,
  };
  $memd->set_servers($array_ref);
  $memd->set_compress_threshold(10_000);
  $memd->enable_compress(0);

  $memd->set("my_key", "Some value");
  $memd->set("object_key", { 'complex' => [ "object", 2, 4 ]});

  $val = $memd->get("my_key");
  $val = $memd->get("object_key");
  if ($val) { print $val->{'complex'}->[2]; }

  $memd->incr("key");
  $memd->decr("key");
  $memd->incr("key", 2);

This is the Perl API for memcached, a distributed memory cache daemon. More information is available at:

  http://www.danga.com/memcached/

Takes one parameter, a hashref of options. The most important key is CWservers, but that can also be set later with the CWset_servers method. The servers must be an arrayref of hosts, each of which is either a scalar of the form CW10.0.0.10:11211 or an arrayref of the former and an integer weight value. (The default weight if unspecified is 1.) It's recommended that weight values be kept as low as possible, as this module currently allocates memory for bucket distribution proportional to the total host weights. Use CWcompress_threshold to set a compression threshold, in bytes. Values larger than this threshold will be compressed by CWset and decompressed by CWget. Use CWno_rehash to disable finding a new memcached server when one goes down. Your application may or may not need this, depending on your expirations and key usage. Use CWreadonly to disable writes to backend memcached servers. Only get and get_multi will work. This is useful in bizarre debug and profiling cases only. The other useful key is CWdebug, which when set to true will produce diagnostics on STDERR.

Sets the server list this module distributes key gets and sets between. The format is an arrayref of identical form as described in the CWnew constructor. Sets the CWdebug flag. See CWnew constructor for more information. Sets the CWreadonly flag. See CWnew constructor for more information. Sets the CWno_rehash flag. See CWnew constructor for more information. Sets the compression threshold. See CWnew constructor for more information. Temporarily enable or disable compression. Has no effect if CWcompress_threshold isn't set, but has an overriding effect if it is. my CW$val = CW$memd->get($key); Retrieves a key from the memcache. Returns the value (automatically thawed with Storable, if necessary) or undef. The CW$key can optionally be an arrayref, with the first element being the hash value, if you want to avoid making this module calculate a hash value. You may prefer, for example, to keep all of a given user's objects on the same memcache server, so you could use the user's unique id as the hash value. my CW$hashref = CW$memd->get_multi(@keys); Retrieves multiple keys from the memcache doing just one query. Returns a hashref of key/value pairs that were available. This method is recommended over regular 'get' as it lowers the number of total packets flying around your network, reducing total latency, since your app doesn't have to wait for each round-trip of 'get' before sending the next one. $memd->set($key, CW$value[, CW$exptime]); Unconditionally sets a key to a given value in the memcache. Returns true if it was stored successfully. The CW$key can optionally be an arrayref, with the first element being the hash value, as described above. The CW$exptime (expiration time) defaults to never if unspecified. If you want the key to expire in memcached, pass an integer CW$exptime. If value is less than 60*60*24*30 (30 days), time is assumed to be relative from the present. If larger, it's considered an absolute Unix time. $memd->add($key, CW$value[, CW$exptime]); Like CWset, but only stores in memcache if the key doesn't already exist. $memd->replace($key, CW$value[, CW$exptime]); Like CWset, but only stores in memcache if the key already exists. The opposite of CWadd. $memd->delete($key[, CW$time]); Deletes a key. You may optionally provide an integer time value (in seconds) to tell the memcached server to block new writes to this key for that many seconds. (Sometimes useful as a hacky means to prevent races.) Returns true if key was found and deleted, and false otherwise. $memd->incr($key[, CW$value]); Sends a command to the server to atomically increment the value for CW$key by CW$value, or by 1 if CW$value is undefined. Returns undef if CW$key doesn't exist on server, otherwise it returns the new value after incrementing. Value should be zero or greater. Overflow on server is not checked. Be aware of values approaching 2**32. See decr. $memd->decr($key[, CW$value]); Like incr, but decrements. Unlike incr, underflow is checked and new values are capped at 0. If server value is 1, a decrement of 2 returns 0, not -1. $memd->stats([$keys]); Returns a hashref of statistical data regarding the memcache server(s), the CW$memd object, or both. CW$keys can be an arrayref of keys wanted, a single key wanted, or absent (in which case the default value is malloc, sizes, self, and the empty string). These keys are the values passed to the 'stats' command issued to the memcached server(s), except for 'self' which is internal to the CW$memd object. Allowed values are: The stats returned by a 'stats' command: pid, uptime, version, bytes, get_hits, etc. The stats returned by a 'stats malloc': total_alloc, arena_size, etc. The stats returned by a 'stats sizes'. The stats for the CW$memd object itself (a copy of CW$memd->{'stats'}). The stats returned by a 'stats maps'. The stats returned by a 'stats cachedump'. The stats returned by a 'stats slabs'. The stats returned by a 'stats items'. $memd->disconnect_all(); Closes all cached sockets to all memcached servers. You must do this if your program forks and the parent has used this module at all. Otherwise the children will try to use cached sockets and they'll fight (as children do) and garble the client/server protocol.

When a server goes down, this module does detect it, and re-hashes the request to the remaining servers, but the way it does it isn't very clean. The result may be that it gives up during its rehashing and refuses to get/set something it could've, had it been done right.

This module is Copyright (c) 2003 Brad Fitzpatrick. All rights reserved.

You may distribute under the terms of either the GNU General Public License or the Artistic License, as specified in the Perl README file.

This is free software. IT COMES WITHOUT WARRANTY OF ANY KIND.

See the memcached website: http://www.danga.com/memcached/

Brad Fitzpatrick <brad@danga.com>

Anatoly Vorobey <mellon@pobox.com>

Brad Whitaker <whitaker@danga.com>

Jamie McCarthy <jamie@mccarthy.vg>