Module: NATS::JetStream::PullSubscription

Defined in:
lib/cosmo/utils/overrides.rb

Instance Method Summary collapse

Instance Method Details

#fetch(batch = 1, params = {}) ⇒ Object

Raises:

  • (::NATS::JetStream::Error) 


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# File 'lib/cosmo/utils/overrides.rb', line 53

def fetch(batch = 1, params = {})
  raise ::NATS::JetStream::Error.new("nats: invalid batch size") if batch < 1

  t = MonotonicTime.now
  start_time = t # fixes the upstream bug -- see comment above
  timeout = params[:timeout] ||= 5
  expires = (timeout * 1_000_000_000) - 100_000
  next_req = { batch: batch }

  msgs = []
  case
  when batch == 1
    synchronize do
      unless @pending_queue.empty?
        msg = @pending_queue.pop
        @pending_size -= msg.data.size
        if JS.is_status_msg(msg)
          case msg.header["Status"]
          when JS::Status::NoMsgs then nil
          when JS::Status::RequestTimeout then nil # Skip
          else raise JS.from_msg(msg)
          end
        else
          msgs << msg
        end
      end
    end

    next_req[:expires] = expires
    if msgs.empty?
      @nc.publish(@jsi.nms, JS.next_req_to_json(next_req), @subject)
      synchronize { wait_for_msgs_cond.wait(timeout) }

      unless @pending_queue.empty?
        msg = @pending_queue.pop
        @pending_size -= msg.data.size
        msgs << msg
      end

      raise ::NATS::Timeout.new("nats: fetch timeout") if msgs.empty? && (MonotonicTime.since(t) > timeout)

      if JS.is_status_msg(msgs.first)
        msg = msgs.first
        case msg.header[JS::Header::Status]
        when JS::Status::RequestTimeout then raise NATS::Timeout.new("nats: fetch request timeout")
        else raise JS.from_msg(msgs.first)
        end
      end
    end
  when batch > 1
    synchronize do
      if batch <= @pending_queue.size
        batch.times do
          msg = @pending_queue.pop
          @pending_size -= msg.data.size
          if JS.is_status_msg(msg)
            case msg.header[JS::Header::Status]
            when JS::Status::NoMsgs, JS::Status::RequestTimeout then next
            else raise JS.from_msg(msg)
            end
          else
            msgs << msg
          end
        end
        return msgs
      end
    end

    next_req[:no_wait] = true
    @nc.publish(@jsi.nms, JS.next_req_to_json(next_req), @subject)

    start_time = MonotonicTime.now
    msg = nil

    synchronize do
      wait_for_msgs_cond.wait(timeout)
      unless @pending_queue.empty?
        msg = @pending_queue.pop
        @pending_size -= msg.data.size
      end
    end

    if !msg.nil? && JS.is_status_msg(msg)
      case msg.header[JS::Header::Status]
      when JS::Status::NoMsgs
        next_req[:expires] = expires
        next_req.delete(:no_wait)
        @nc.publish(@jsi.nms, JS.next_req_to_json(next_req), @subject)
      when JS::Status::RequestTimeout
        raise NATS::Timeout.new("nats: fetch request timeout")
      else
        raise JS.from_msg(msg)
      end
    else
      msgs << msg unless msg.nil?
    end

    duration = MonotonicTime.since(start_time)
    raise NATS::Timeout.new("nats: fetch timeout") if msgs.empty? && (duration > timeout)

    needed = batch - msgs.count
    while (needed > 0) && (MonotonicTime.since(start_time) < timeout)
      duration = MonotonicTime.since(start_time)

      synchronize do
        if @pending_queue.empty?
          deadline = timeout - duration
          wait_for_msgs_cond.wait(deadline) if deadline > 0

          duration = MonotonicTime.since(start_time)
          if msgs.empty? && @pending_queue.empty? && (duration > timeout)
            raise NATS::Timeout.new("nats: fetch timeout")
          end
        end

        unless @pending_queue.empty?
          msg = @pending_queue.pop
          @pending_size -= msg.data.size

          if JS.is_status_msg(msg)
            case msg.header[JS::Header::Status]
            when JS::Status::NoMsgs, JS::Status::RequestTimeout
              duration = MonotonicTime.since(start_time)
              if duration > timeout
                raise NATS::Timeout.new("nats: fetch timeout") if msgs.empty?

                return msgs
              end
            else
              raise JS.from_msg(msg)
            end
          else
            msgs << msg
            needed -= 1
          end
        end
      end
    end
  end

  raise ::NATS::Timeout.new("nats: fetch timeout") if msgs.empty? && (MonotonicTime.since(start_time) > timeout)

  msgs
end