tcp-over-high-latency/hltp/LatencyBuffer.rb

class LatencyBuffer

  class NotRequestedReturnLatencyError < StandardError; end

  def initialize
    @latencies = []
    @latencies_mutex = Mutex.new
    @packets = {}
    @packets_mutex = Mutex.new
  end

  def get_next_free_id
    rnd_id = Random.rand((1...(2**64)))
    id = rnd_id
    while @packets.key? id
      id += 1
      if id >= 2**64
        id = 1
      end
    end

    return id
  end

  def get_packet_id
    id = nil
    @packets_mutex.synchronize do
      id = get_next_free_id
      @packets[id] = Time.now
    end

    do_gc

    return id
  end

  def do_gc
    @packets_mutex.synchronize do
      @packets.delete_if do |id, time|
        (Time.now - time) > [2 * 60, get_latency].max
      end
    end
  end

  def receive_id_handler(id)
    time = nil
    @packets_mutex.synchronize do
      return unless @packets.key? id

      time = (Time.now - @packets[id]).to_f
      @packets.delete id
    end
    add_latency time
  end

  def add_latency(latency)
    @latencies_mutex.synchronize do
      @latencies << latency
      if @latencies.length > 12
        @latencies.shift
      end
    end
  end

  def get_latency
    return 1 if @latencies.length == 0

    @latencies_mutex.synchronize do
      latency = (@latencies.sum / @latencies.length).round(2)
      $logger.warn "Latency #{latency} is too low!" if latency < 1
      $logger.debug "Latency: #{latency}"
      return latency
    end
  end

end