Top 10 ports - Introduce TopPorts class

input/topPorts.hpp

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+/**
+ * \file topPorts.hpp
+ * \brief Template class implementing the most popular ports.
+ * \author Damir Zainullin <[email protected]>
+ * \date 2024
+ */
+#pragma once
+
+#include <array>
+#include <cmath>
+#include <cstdint>
+#include <functional>
+#include <limits>
+#include <queue>
+#include <unordered_map>
+#include <unordered_set>
+
+namespace ipxp {
+/**
+ * \brief Top ports counter.
+ * \tparam TopPortsCount Number of the most popular ports to store.
+ */
+template<std::size_t TopPortsCount>
+class TopPorts {
+public:
+    /**
+     * \brief Insert a port into the top ports.
+     * \param port Port to insert.
+     */
+    void insert(uint16_t port) noexcept
+    {
+        m_port_frequencies[port]++;
+
+        if (m_ports_present.size() < TopPortsCount) {
+            m_ports_present.insert(port);
+            m_least_popuplar_top_port = find_least_popular_top_port();
+            return;
+        }
+
+        if (auto it = m_ports_present.find(port); it == m_ports_present.end()
+            && m_port_frequencies[port] > m_port_frequencies[m_least_popuplar_top_port]) {
+            m_ports_present.erase(m_least_popuplar_top_port);
+            m_least_popuplar_top_port = port;
+            m_ports_present.insert(port);
+        } else if (port == m_least_popuplar_top_port) {
+            m_least_popuplar_top_port = find_least_popular_top_port();
+        }
+    }
+
+    /**
+     * \brief Get the top ports.
+     * \return Pair of the top ports array and their count.
+     */
+    std::pair<std::array<std::pair<uint16_t, size_t>, TopPortsCount>, size_t>
+    get_top_ports() const noexcept
+    {
+        std::array<std::pair<uint16_t, size_t>, TopPortsCount> res;
+        std::transform(
+            m_ports_present.begin(),
+            m_ports_present.end(),
+            res.begin(),
+            [this](uint16_t port) { return std::make_pair(port, m_port_frequencies[port]); });
+	std::sort(res.begin(), res.begin() + m_ports_present.size(), [] (const std::pair<uint16_t, size_t>& port1, const std::pair<uint16_t, size_t>& port2){ return port1.second > port2.second;});
+        return {res, m_ports_present.size()};
+    }
+
+private:
+    uint16_t find_least_popular_top_port() const noexcept
+    {
+        return *std::min_element(
+            m_ports_present.begin(),
+            m_ports_present.end(),
+            [this](uint16_t port1, uint16_t port2) {
+                return m_port_frequencies[port1] < m_port_frequencies[port2];
+            });
+    }
+
+    std::array<std::size_t, 65536> m_port_frequencies {};
+    uint16_t m_least_popuplar_top_port {0};
+    using PortFrequencyPair = std::pair<std::size_t, uint16_t>;
+    std::priority_queue<
+        std::pair<std::size_t, uint16_t>,
+        std::vector<std::pair<std::size_t, uint16_t>>,
+        std::greater<>>
+        m_top_ports;
+    std::unordered_set<uint16_t> m_ports_present;
+};
+
+} // namespace ipxp