my-sequel-synchrony

A fiber-aware MySQL adapter for Sequel that works with em-synchrony. Uses the Mysql2::EM::Client client with the em-synchrony extensions.

Note: this code is in an early stage of active development and has not been battle-tested in any production environments. For now, use at your own risk, and please report any bugs you find!

Add this line to your application's Gemfile:

gem 'my-sequel-synchrony'

And then execute:

$ bundle

Or install it yourself as:

$ gem install my-sequel-synchrony

Inside an EM.synchrony block or a synchrony-enabled web server (such as sinatra-synchrony), simply create the Sequel connection as usual, and specify the :adapter => :mysql2synchrony option:

@database = Sequel.connect(
  :adapter => :mysql2synchrony,
  :hostname => ...,
  ...)

And use it just like you would normally use a Sequel database object! If you have multiple DB shards (either master/slaves, or data sharded across multiple masters), you can specify them by passing in a :servers option just like you would with any other Sequel adapter that supports sharding (see the Sequel sharding doc).

You can even run queries in parallel with FiberIterator:

require 'em-synchrony/fiber_iterator'

@shard_ids = [ :master, :slave1, :slave2 ]

# Assuming we're in a sinatra-synchrony webapp, this will run a simple "am i connected?" check
# on every shard in parallel and return 200 or 500 depending on the result.
get "/healthz" do
  shard_errors = {}
  EM::Synchrony::FiberIterator.new(@shard_ids, @shard_ids.size).each do |shard_id|
    begin
      @db.run("select 1;", :server => shard_id)
    rescue Exception => e
      shard_errors[shard_id] = e
    end
  end
  halt 200, "All DB shards ok" if shard_errors.empty?

  message = "#{shard_errors.size} DB shards had errors:\n"
  message += shard_errors.map { |shard_id, error| "#{shard_id}: #{e.message}" }.join("\n")
  halt 500, message
end

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

• Bo Chen (bochen.chen@gmail.com)
• Ilya Maykov (ivmaykov@gmail.com)