memcached
An interface to the libmemcached C client.
== License
Copyright 2009 Cloudburst, LLC. Licensed under the AFL 3. See the included LICENSE file. Portions copyright 2007-2009 TangentOrg, Brian Aker, licensed under the BSD license, and used with permission.
The public certificate for this gem is here[http://rubyforge.org/frs/download.php/25331/evan_weaver-original-public_cert.pem].
If you use this software, please {make a donation}[http://blog.evanweaver.com/donate/], or {recommend Evan}[http://www.workingwithrails.com/person/7739-evan-weaver] at Working with Rails.
== Features
* clean API
* robust access to all memcached features
* multiple hashing modes, including consistent hashing
* ludicrous speed, including optional non-blocking IO
The <b>memcached</b> library wraps the pure-C libmemcached client via SWIG.
== Installation
You need Ruby 1.8.7 or Ruby 1.9.1. Other versions may work, but are not guaranteed. You also need {memcached itself}[http://www.danga.com/memcached/] if you want to test against a local server.
Install the gem:
sudo gem install memcached --no-rdoc --no-ri
== Usage
Start a local networked memcached server:
$ memcached -p 11211 &
Now, in Ruby, require the library and instantiate a Memcached object at a global level:
require 'memcached'
$cache = Memcached.new("localhost:11211")
Now you can set things and get things:
value = 'hello'
$cache.set 'test', value
$cache.get 'test' #=> "hello"
You can set with an expiration timeout:
value = 'hello'
$cache.set 'test', value, 1
sleep(2)
$cache.get 'test' #=> raises Memcached::NotFound
You can get multiple values at once:
value = 'hello'
$cache.set 'test', value
$cache.set 'test2', value
$cache.get ['test', 'test2', 'missing']
#=> {"test" => "hello", "test2" => "hello"}
You can set a counter and increment it:
start = 1
$cache.set 'counter', start, 0, false
$cache.increment 'counter' #=> 2
$cache.increment 'counter' #=> 3
$cache.get('counter', false).to_i #=> 3
You can get some server stats:
$cache.stats #=> {..., :bytes_written=>[62], :version=>["1.2.4"] ...}
Note that the API is not the same as that of <b>Ruby-MemCache</b> or <b>memcache-client</b>. In particular, <tt>nil</tt> is a valid record value. Memcached#get does not return <tt>nil</tt> on failure, rather it raises <b>Memcached::NotFound</b>. This is consistent with the behavior of memcached itself. For example:
$cache.set 'test', nil
$cache.get 'test' #=> nil
$cache.delete 'test'
$cache.get 'test' #=> raises Memcached::NotFound
== Legacy applications
There is a compatibility wrapper for legacy applications called Memcached::Rails.
== Threading
<b>memcached</b> is threadsafe, but each thread requires its own Memcached instance. Create a global Memcached, and then call Memcached#clone each time you spawn a thread.
thread = Thread.new do
cache = $cache.clone
# Perform operations on cache, not $cache
cache.set 'example', 1
cache.get 'example'
end
# Join the thread so that exceptions don't get lost
thread.join
== Benchmarks
<b>memcached</b> is up to 10x faster than <b>memcache-client</b>. See BENCHMARKS[link:files/BENCHMARKS.html] for details.
== Reporting problems
The support forum is here[http://rubyforge.org/forum/forum.php?forum_id=20894].
Patches and contributions are very welcome. Please note that contributors are required to assign copyright for their additions to Cloudburst, LLC.
== Further resources
* {Memcached wiki}[http://www.socialtext.net/memcached/index.cgi]
* {Libmemcached homepage}[http://tangent.org/552/libmemcached.html]