gistfile1.rb

require 'queue'

# Simplified version of the pooling from datamapper's data_objects.
# https://github.com/datamapper/do/blob/master/data_objects/lib/data_objects/pooling.rb
class Moped::Session
  class << self
    alias new __new
  end

  @__pool_lock = Mutex.new

  def self.new(*args)
    (@__pools[args] ||= @__pool_lock.synchronize { Pool.new(self, args) }).reserve
  end

  def release
    @__pool.release(self)
  end

  class Pool
    def initialize(klass, args)
      @klass = klass
      @args = args
      @pool = Queue.new
    end

    def release(instance)
      @pool.push(instance)
    end

    def reserve
      @pool.pop(true)
    rescue ThreadError
      instance = @klass.__new(*@args)
      instance.instance_variable_set(:@__pool, self)
      instance
    end
  end
end

module Rack
  module Mongoid
    module Middleware
      class Sessions
        def initialize(app)
          @app = app
        end

        def call(env)
        ensure
          Mongoid::Threaded.sessions.each do |_, session|
            session.release
          end
        end
      end
    end
  end
end