module ActiveRecord::ConnectionAdapters::ConnectionPool::BiasableQueue

def with_a_bias_for(thread)
  previous_cond = nil
  new_cond      = nil
  synchronize do
    previous_cond = @cond
    @cond = new_cond = BiasedConditionVariable.new(@lock, @cond, thread)
  end
  yield
ensure
  synchronize do
    @cond = previous_cond if previous_cond
    new_cond.broadcast_on_biased if new_cond # wake up any remaining sleepers
  end
end