Rack middleware to lock v8

lock_v8.rb

##
# Rack middleware which synchronizes access to an
# in-process v8 engine embedded with The Ruby Racer
#
class LockV8
  def initialize(app)
    @app = app
  end

  # Grabs the V8 GIL for the duration of this request.
  #
  # The current implentation of Locker() is naive and
  # does not catch any exceptions inside the passed in
  # block. Instead, manually manage the exceptions and
  # return value outside of the critical section.
  #
  # Locking will be made more robust in future versions.
  def call(*args)
    result = nil
    err = nil
    V8::C::Locker() do
      begin
        result = @app.call(*args)
      rescue Exception => e
        err = e
      end
    end
    raise err if err
    return result
  end
end