REFACTORING: packet reordering (#436)

closes #435

Author: PaulRalnikov

source/metrics/metrics_collector.cpp

@@ -92,7 +92,9 @@ void MetricsCollector::draw_RTT_plot(std::filesystem::path path) const {
 void MetricsCollector::draw_packet_reordering_plot(
     std::filesystem::path path) const {
     m_packet_reordering_storage.draw_on_plot(
-        path, PlotMetadata{"Time, ns", "Reordering, %", "Packet reordering"},
+        path,
+        PlotMetadata{"Time, ns", "Reordering (inversions count)",
+                     "Packet reordering"},
         flow_id_to_curve_name);
 }
 

source/metrics/packet_reordering/i_packet_reordering.hpp

@@ -3,7 +3,7 @@
 
 namespace sim {
 
-using PacketReordering = long double;
+using PacketReordering = uint64_t;
 
 // Metrics that shows degree of packet reordering
 class IPacketReordering {

source/metrics/packet_reordering/simple_packet_reordering.cpp

@@ -2,33 +2,24 @@
 
 namespace sim {
 
-SimplePacketReordering::SimplePacketReordering(long double a_smoothing_factor)
-    : m_metric_statistics(a_smoothing_factor) {}
-
-SimplePacketReordering::SimplePacketReordering(long double a_smoothing_factor,
-                                               std::size_t a_max_packets)
-    : m_max_packets(a_max_packets), m_metric_statistics(a_smoothing_factor) {}
+SimplePacketReordering::SimplePacketReordering(std::size_t a_max_packets)
+    : m_max_packets(a_max_packets), m_inversions_count(0) {}
 
 void SimplePacketReordering::add_record(PacketNum packet_num) {
-    if (!m_packet_num_set.insert(packet_num).second) {
-        // packet with same id already in set; new one ignored
-        return;
-    }
+    m_packet_num_set.insert(packet_num);
     std::size_t count_lower = m_packet_num_set.order_of_key(packet_num);
     std::size_t total_count = m_packet_num_set.size();
     std::size_t count_upper = total_count - count_lower - 1;
 
-    long double curr_metric =
-        count_upper / static_cast<long double>(total_count);
-    m_metric_statistics.add_record(curr_metric);
+    m_inversions_count += count_upper;
 
     if (m_packet_num_set.size() > m_max_packets) {
         m_packet_num_set.erase(m_packet_num_set.begin());
     }
 }
 
 PacketReordering SimplePacketReordering::value() const {
-    return m_metric_statistics.get_mean();
+    return m_inversions_count;
 }
 
 };  // namespace sim

source/metrics/packet_reordering/simple_packet_reordering.hpp

@@ -6,10 +6,7 @@
 namespace sim {
 class SimplePacketReordering : public IPacketReordering {
 public:
-    SimplePacketReordering() = default;
-    explicit SimplePacketReordering(long double a_smoothing_factor);
-    SimplePacketReordering(long double a_smoothing_factor,
-                           std::size_t a_max_packets);
+    explicit SimplePacketReordering(std::size_t a_max_packets = 1'000'000);
     ~SimplePacketReordering() = default;
 
     void add_record(PacketNum packet_num) final;
@@ -18,8 +15,8 @@ class SimplePacketReordering : public IPacketReordering {
 private:
     // maximal count of packets in m_packet_num_set
     // When m_packet_num_set.size() growth up it, the smallest element deletes
-    std::size_t m_max_packets = 1'000'000;
+    std::size_t m_max_packets;
+    uint64_t m_inversions_count;
     utils::ordered_set<PacketNum> m_packet_num_set;
-    utils::Statistics<long double> m_metric_statistics;
 };
 }  // namespace sim