An EventMachine based library for interacting with the very cool Redis data store by Salvatore ‘antirez’ Sanfilippo. Modeled after eventmachine’s implementation of the memcached protocol, and influenced by Ezra Zygmuntowicz’s redis-rb library (distributed as part of Redis).

This library is only useful when used as part of an application that relies on Event Machine’s event loop. It implements an EM-based client protocol, which leverages the non-blocking nature of the EM interface to achieve significant parallelization without threads.

Implements most Redis commands (see the list of available commands here with the notable exception of MONITOR. Implements Redis Cluster by integrating antirez’s job into em-redis.

Like any Deferrable eventmachine-based protocol implementation, using EM-Redis-Cluster involves making calls and passing blocks that serve as callbacks when the call returns.

require 'em_redis_cluster'

# Cluster mode
EM.run do
  startup_nodes = [
    {:host => "127.0.0.1", :port => 7000},
    {:host => "127.0.0.1", :port => 7001},
  ]

  rc = EM::Protocols::RedisCluster.new(startup_nodes, logger: Logger.new(STDOUT), reconn_timer: 0.5)

  rc.mapped_hmset("foo", {bar: 1, timestamp: Time.now.to_s}) do |rsp|
    if rsp.is_a?(StandardError)
      # handle error
    else
      p rsp
    end
    EM.stop
  end
end

# Non-cluster mode
EM.run do
  redis = EM::Protocols::Redis.connect
  redis.errback do |code|
    puts "Error code: #{code}"
  end
  redis.set "a", "foo" do |response|
    redis.get "a" do |response|
      puts response
    end
  end
  # We get pipelining for free
  redis.set("b", "bar")
  redis.get("a") do |response|
    puts response # will be foo
  end
end

To run tests on a Redis server (currently compatible with 2.2)

rake

Because the EM::Protocol::Memcached code used Bacon for testing, test code is currently in the form of bacon specs.

• Redis (download)

sudo gem install em_redis_cluster

(The MIT License)

Copyright © 2008, 2009

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

by Jonathan Broad (http://www.relativepath.org)