class ActiveRecord::ConnectionAdapters::ConnectionPool

def _fibered_mutex
  @fibered_mutex ||= EM::Synchrony::Thread::Mutex.new
end

def connection
  _fibered_mutex.synchronize do
    @thread_cached_conns[connection_cache_key(Thread.current)] ||= checkout
  end
end

def connection
  _fibered_mutex.synchronize do
    @reserved_connections[current_connection_id] ||= checkout
  end
end