with_a_bias_for

# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 252
        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