def read(tuple, sec=nil)
      template = WaitTemplateEntry.new(self, tuple, sec)
      yield(template) if block_given?
      synchronize do
        entry = @bag.find(template)
        return entry.value if entry
        raise RequestExpiredError if template.expired?

        begin
          @read_waiter.push(template)
          start_keeper if template.expires
          template.wait
          raise RequestCanceledError if template.canceled?
          raise RequestExpiredError if template.expired?
          return template.found
        ensure
          @read_waiter.delete(template)
        end
      end
    end
def read(tuple, sec=nil)
      template = WaitTemplateEntry.new(self, tuple, sec)
      yield(template) if block_given?
      synchronize do
        entry = @bag.find(template)
        return entry.value if entry
        raise RequestExpiredError if template.expired?

        begin
          @read_waiter.push(template)
          start_keeper if template.expires
          template.wait
          raise RequestCanceledError if template.canceled?
          raise RequestExpiredError if template.expired?
          return template.found
        ensure
          @read_waiter.delete(template)
        end
      end
    end
Reads +tuple+, but does not remove it.