Floss An implementation of the

on top of Celluloid # An implementation of the Raft consensus algorithm on top of Celluloid

Installation Add this line to your application's Gemfile:

ruby gem floss

And then execute:

bash $ bundle

Or install it yourself as:

bash $ gem install floss

#

Usage

We're going to implement a distributed counter. While not very useful, it's a good enough demonstration of what you can do with this library. Let's start with the counter service. It accepts three commands, get, reset and increase. The first simply returns the current count, the second sets the count to zero and the third changes the current count, optionally by a given amount.

ruby class Counter attr_accessor :count def initialize self.count = 0 end def get count end def reset self.count = 0 end def increase(amount = 1) self.count + = amount end end

To increase reliability of your counter, you decide to distribute it across multiple machines. This is where floss comes into play. To simplify this demonstration, we're going to start multiple nodes in the same process.

ruby addresses = [10001, 10002, 10003].map { |port| "tcp://127.0.0.1:#{port}" } $nodes = addresses.size.times.map do |i| combination = addresses.rotate(i) options = {id: combination.first, peers: combination[1-1]} Floss::Proxy.new (Counter.new, options) end # Give your nodes some time to start up. $nodes.each(&:wait_until_ready)

Now we're ready to play with our distributed counter.

ruby def random_node; $nodes.sample; end random_node.get # => 0 random_node.increase # => 1 random_node.get # => 1

That was easy wasn't it? Let's see what happens if the cluster is damaged.

ruby #Terminate a random node in the cluster doomed_node = $nodes.delete (random_node) doomed_node_id = doomed_node.id doomed_node.terminate random_node.increase # => 2

Your cluster still works. If you'd kill another one, executing a command would result in an error because insufficient nodes are available to ensure your system(s) consistency.

Contributing

Fork it Create your feature branch

git checkout
-b my-new-feature`
Commit your changes
  git
commit 
  -am 
 Added
 some 
feature Push to 
the branch 
git push
origin my-new-feature  
```` Create new Pull Request