[datalogtool] Add datalogtool

This is a support tool for datalog file conversion (and eventually
download/remote datalog file management).

datalogtool/src/main/native/cpp/DataLogThread.h

@@ -0,0 +1,71 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#pragma once
+
+#include <atomic>
+#include <functional>
+#include <map>
+#include <string>
+#include <string_view>
+#include <thread>
+#include <utility>
+
+#include <wpi/DataLogReader.h>
+#include <wpi/DenseMap.h>
+#include <wpi/Signal.h>
+#include <wpi/mutex.h>
+
+class DataLogThread {
+ public:
+  explicit DataLogThread(wpi::log::DataLogReader reader)
+      : m_reader{std::move(reader)}, m_thread{[=] { ReadMain(); }} {}
+  ~DataLogThread();
+
+  bool IsDone() const { return m_done; }
+  std::string_view GetBufferIdentifier() const {
+    return m_reader.GetBufferIdentifier();
+  }
+  unsigned int GetNumRecords() const { return m_numRecords; }
+  unsigned int GetNumEntries() const {
+    std::scoped_lock lock{m_mutex};
+    return m_entryNames.size();
+  }
+
+  // Passes wpi::log::StartRecordData to func
+  template <typename T>
+  void ForEachEntryName(T&& func) {
+    std::scoped_lock lock{m_mutex};
+    for (auto&& kv : m_entryNames) {
+      func(kv.second);
+    }
+  }
+
+  wpi::log::StartRecordData GetEntry(std::string_view name) const {
+    std::scoped_lock lock{m_mutex};
+    auto it = m_entryNames.find(name);
+    if (it == m_entryNames.end()) {
+      return {};
+    }
+    return it->second;
+  }
+
+  const wpi::log::DataLogReader& GetReader() const { return m_reader; }
+
+  // note: these are called on separate thread
+  wpi::sig::Signal_mt<const wpi::log::StartRecordData&> sigEntryAdded;
+  wpi::sig::Signal_mt<> sigDone;
+
+ private:
+  void ReadMain();
+
+  wpi::log::DataLogReader m_reader;
+  mutable wpi::mutex m_mutex;
+  std::atomic_bool m_active{true};
+  std::atomic_bool m_done{false};
+  std::atomic<unsigned int> m_numRecords{0};
+  std::map<std::string, wpi::log::StartRecordData, std::less<>> m_entryNames;
+  wpi::DenseMap<int, wpi::log::StartRecordData> m_entries;
+  std::thread m_thread;
+};