[datalog] Move all DataLog functionality to new datalog library (#7641)

Currently the major DataLog backend API (reading and writing) is split between wpiutil and glass. In the interest of allowing code that wants to use these APIs to not need to link to glass and declutter wpiutil, all of those APIs are moved to a new library named "datalog".

Signed-off-by: Jade Turner <spacey-sooty@proton.me>
Co-authored-by: Jade Turner <spacey-sooty@proton.me>
Co-authored-by: Gold856 <117957790+Gold856@users.noreply.github.com>

datalog/examples/writelog/writelog.cpp

@@ -0,0 +1,83 @@
+// 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.
+
+#include <chrono>
+#include <numeric>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <wpi/print.h>
+
+#include "wpi/datalog/DataLogBackgroundWriter.h"
+
+int main(int argc, char** argv) {
+  using std::chrono::duration_cast;
+  using std::chrono::high_resolution_clock;
+  using std::chrono::microseconds;
+
+  int kNumRuns = 10;
+
+  if (argc == 2) {
+    kNumRuns = std::stoi(argv[1]);
+  }
+
+  wpi::log::DataLogBackgroundWriter log;
+  log.SetFilename("test.wpilog");
+
+  auto testVec =
+      std::vector<std::pair<std::string, void (*)(wpi::log::DataLog&)>>();
+
+  testVec.push_back({"50 double append", [](auto& log) {
+                       wpi::log::DoubleLogEntry entry{log, "fifty", 1};
+                       for (int i = 0; i < 50; ++i) {
+                         entry.Append(1.3 * i, 20000 * i);
+                       }
+                     }});
+#if 0
+  testVec.push_back({"500k double append", [](auto& log) {
+                       wpi::log::DoubleLogEntry entry{log, "500k", 1};
+                       for (uint64_t i = 0; i < 500000; ++i) {
+                         entry.Append(1.3 * i, 20000 * i);
+                       }
+                     }});
+#endif
+  testVec.push_back({"50 string append", [](auto& log) {
+                       wpi::log::StringLogEntry entry{log, "string", 1};
+                       for (int i = 0; i < 50; ++i) {
+                         entry.Append("hello", 20000 * i);
+                       }
+                     }});
+
+  testVec.push_back({"Double array append", [](auto& log) {
+                       wpi::log::DoubleArrayLogEntry entry{log, "double_array",
+                                                           1};
+                       entry.Append({1, 2, 3}, 20000);
+                       entry.Append({4, 5}, 30000);
+                     }});
+
+  testVec.push_back({"String array append", [](auto& log) {
+                       wpi::log::StringArrayLogEntry entry{log, "string_array",
+                                                           1};
+                       entry.Append({"Hello", "World"}, 20000);
+                       entry.Append({"This", "Is", "Fun"}, 30000);
+                     }});
+
+  for (const auto& [name, fn] : testVec) {
+    auto resVec = std::vector<microseconds::rep>();
+    wpi::print("{}: ", name);
+
+    for (int i = 0; i < kNumRuns; ++i) {
+      auto start = high_resolution_clock::now();
+      fn(log);
+      auto stop = high_resolution_clock::now();
+      resVec.push_back(duration_cast<microseconds>(stop - start).count());
+    }
+
+    wpi::print("{}us\n",
+               std::accumulate(resVec.begin(), resVec.end(), 0) / kNumRuns);
+  }
+
+  return EXIT_SUCCESS;
+}