yield_shares

# File activesupport/lib/active_support/concurrency/share_lock.rb, line 171
      def yield_shares(purpose: nil, compatible: [], block_share: false)
        loose_shares = previous_wait = nil
        synchronize do
          if loose_shares = @sharing.delete(Thread.current)
            if previous_wait = @waiting[Thread.current]
              purpose = nil unless purpose == previous_wait[0]
              compatible &= previous_wait[1]
            end
            compatible |= [false] unless block_share
            @waiting[Thread.current] = [purpose, compatible]
          end

          @cv.broadcast
        end

        begin
          yield
        ensure
          synchronize do
            wait_for(:yield_shares) { @exclusive_thread && @exclusive_thread != Thread.current }

            if previous_wait
              @waiting[Thread.current] = previous_wait
            else
              @waiting.delete Thread.current
            end
            @sharing[Thread.current] = loose_shares if loose_shares
          end
        end
      end