[wpilibc] Refactor Tracer functionality out of Watchdog class (#2456)

wpilibc/src/main/native/cpp/Tracer.cpp

@@ -0,0 +1,46 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2020 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "frc/Tracer.h"
+
+#include <wpi/Format.h>
+#include <wpi/raw_ostream.h>
+
+using namespace frc;
+
+Tracer::Tracer() { ResetTimer(); }
+
+void Tracer::ResetTimer() { m_startTime = hal::fpga_clock::now(); }
+
+void Tracer::ClearEpochs() {
+  ResetTimer();
+  m_epochs.clear();
+}
+
+void Tracer::AddEpoch(wpi::StringRef epochName) {
+  auto currentTime = hal::fpga_clock::now();
+  m_epochs[epochName] = currentTime - m_startTime;
+  m_startTime = currentTime;
+}
+
+void Tracer::PrintEpochs() {
+  using std::chrono::duration_cast;
+  using std::chrono::microseconds;
+
+  auto now = hal::fpga_clock::now();
+  if (now - m_lastEpochsPrintTime > kMinPrintPeriod) {
+    m_lastEpochsPrintTime = now;
+    for (const auto& epoch : m_epochs) {
+      wpi::outs() << '\t' << epoch.getKey() << ": "
+                  << wpi::format(
+                         "%.6f",
+                         duration_cast<microseconds>(epoch.getValue()).count() /
+                             1.0e6)
+                  << "s\n";
+    }
+  }
+}