Create timesync JNI for testing client (#1433)

photon-targeting/src/main/native/include/net/TimeSyncClient.h

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) Photon Vision.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <fmt/core.h>
+#include <wpinet/EventLoopRunner.h>
+#include <wpinet/UDPClient.h>
+#include <wpinet/uv/Buffer.h>
+#include <wpinet/uv/Timer.h>
+#include <wpinet/uv/Udp.h>
+
+#include <atomic>
+#include <chrono>
+#include <cstdlib>
+#include <cstring>
+#include <ctime>
+#include <functional>
+#include <iostream>
+#include <memory>
+#include <mutex>
+#include <string>
+#include <thread>
+
+#include <frc/filter/MedianFilter.h>
+#include <wpi/Logger.h>
+#include <wpi/static_circular_buffer.h>
+#include <wpi/struct/Struct.h>
+
+#include "TimeSyncStructs.h"
+#include "ntcore_cpp.h"
+
+namespace wpi {
+namespace tsp {
+
+class TimeSyncClient {
+ public:
+  struct Metadata {
+    int64_t offset{0};
+    int64_t rtt2{0};
+    size_t pingsSent{0};
+    size_t pongsReceived{0};
+    uint64_t lastPongTime{0};
+  };
+
+ private:
+  using SharedUdpPtr = std::shared_ptr<uv::Udp>;
+  using SharedTimerPtr = std::shared_ptr<uv::Timer>;
+
+  EventLoopRunner m_loopRunner{};
+
+  wpi::Logger m_logger;
+  std::function<uint64_t()> m_timeProvider;
+
+  SharedUdpPtr m_udp;
+  SharedTimerPtr m_pingTimer;
+
+  std::string m_serverIP;
+  int m_serverPort;
+
+  std::chrono::milliseconds m_loopDelay;
+
+  std::mutex m_offsetMutex;
+  Metadata m_metadata;
+
+  // We only allow the most recent ping to stay alive, so only keep track of it
+  TspPing m_lastPing;
+
+  // 30s is a reasonable guess
+  frc::MedianFilter<int64_t> m_lastOffsets{30};
+
+  void Tick();
+
+  void UdpCallback(uv::Buffer& buf, size_t nbytes, const sockaddr& sender,
+                   unsigned flags);
+
+ public:
+  TimeSyncClient(std::string_view server, int remote_port,
+                 std::chrono::milliseconds ping_delay,
+                 std::function<uint64_t()> timeProvider = nt::Now);
+
+  void Start();
+  void Stop();
+  int64_t GetOffset();
+  Metadata GetMetadata();
+};
+
+}  // namespace tsp
+}  // namespace wpi