added units to docs and netwrok tables

wpilibc/src/main/native/cpp/TimedRobot.cpp

@@ -62,7 +62,7 @@ void TimedRobot::StartCompetition() {
     while (m_callbacks.top().expirationTime <= currentTime) {
       callback = m_callbacks.pop();
 
-      callback.func();
+      callback();
 
       callback.expirationTime +=
           callback.period + (currentTime - callback.expirationTime) /
@@ -79,7 +79,7 @@ void TimedRobot::EndCompetition() {
 
 TimedRobot::TimedRobot(units::second_t period) : IterativeRobotBase(period) {
   m_startTime = std::chrono::microseconds{RobotController::GetFPGATime()};
-  AddPeriodic([=, this] { LoopFunc(); }, "RobotMain", period);
+  AddPeriodic([=, this] { LoopFunc(); }, "", period);
 
   int32_t status = 0;
   m_notifier = HAL_InitializeNotifier(&status);

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

@@ -28,11 +28,19 @@ using namespace frc;
 std::atomic<bool> singleThreadedMode = false;
 std::atomic<bool> anyTracesStarted = false;
 
+void PostUnits() {
+  auto table = nt::NetworkTableInstance::GetDefault().GetTable("/Tracer");
+  table->GetEntry("TimingUnits").SetString("Milliseconds", 0);
+}
+
 Tracer::TracerState::TracerState() {
   if (singleThreadedMode && anyTracesStarted) {
     FRC_ReportWarning("Cannot start a new trace in single-threaded mode");
     m_disabled = true;
   }
+  if (!anyTracesStarted) {
+    PostUnits();
+  }
   auto inst = nt::NetworkTableInstance::GetDefault();
   m_rootTable = inst.GetTable(fmt::format(
       "/Tracer/{}", std::hash<std::thread::id>{}(std::this_thread::get_id())));

wpilibc/src/main/native/include/frc/TimedRobot.h

@@ -99,7 +99,7 @@ class TimedRobot : public IterativeRobotBase {
   class Callback {
    public:
     std::function<void()> func;
-    frc::Tracer::SubstitutiveTracer tracer;
+    std::optional<frc::Tracer::SubstitutiveTracer> tracer;
     std::chrono::microseconds period;
     std::chrono::microseconds expirationTime;
 
@@ -115,13 +115,31 @@ class TimedRobot : public IterativeRobotBase {
              std::chrono::microseconds startTime,
              std::chrono::microseconds period, std::chrono::microseconds offset)
         : func{std::move(func)},
-          tracer{frc::Tracer::SubstitutiveTracer{name}},
           period{period},
           expirationTime(
               startTime + offset + period +
               (std::chrono::microseconds{frc::RobotController::GetFPGATime()} -
                startTime) /
-                  period * period) {}
+                  period * period) {
+      if (!name.empty()) {
+        tracer.emplace(name);
+      } else {
+        tracer = std::nullopt;
+      }
+    }
+
+    /**
+     * Call the callback function.
+     */
+    void operator()() {
+      if (tracer.has_value()) {
+        tracer->SubIn();
+      }
+      func();
+      if (tracer.has_value()) {
+        tracer->SubOut();
+      }
+    }
 
     bool operator>(const Callback& rhs) const {
       return expirationTime > rhs.expirationTime;

wpilibc/src/main/native/include/frc/Tracer.h

@@ -25,12 +25,9 @@ class raw_ostream;
 
 namespace frc {
 /**
- * A class for keeping track of how much time it takes for different parts of
- * code to execute. This is done with epochs, that are added to calls to
- * AddEpoch() and can be printed with a call to PrintEpochs().
- *
- * Epochs are a way to partition the time elapsed so that when overruns occur,
- * one can determine which parts of an operation consumed the most time.
+ * A Utility class for tracing code execution time. Will put info to
+ * NetworkTables under the "Tracer" table. The times outputted by the {@link
+ * Tracer} are in milliseconds.
  */
 class Tracer {
  public:

wpilibj/src/main/java/edu/wpi/first/wpilibj/TimedRobot.java

@@ -13,6 +13,8 @@
 import edu.wpi.first.hal.NotifierJNI;
 import edu.wpi.first.units.measure.Time;
 import edu.wpi.first.wpilibj.Tracer.SubstitutiveTracer;
+
+import java.util.Optional;
 import java.util.PriorityQueue;
 
 /**
@@ -32,7 +34,7 @@ static class Callback implements Comparable<Callback> {
      * The tracer to use for this callback. This allows callbacks to appear in their own tracer
      * table separate from the main RobotLoop tracer table.
      */
-    public SubstitutiveTracer m_tracerSub;
+    public Optional<SubstitutiveTracer> m_tracerSub;
 
     /** The period at which to run the callback in microseconds. */
     public long m_period;
@@ -53,7 +55,7 @@ static class Callback implements Comparable<Callback> {
      */
     Callback(Runnable func, String name, long startTimeUs, long periodUs, long offsetUs) {
       this.m_func = func;
-      this.m_tracerSub = new SubstitutiveTracer(name);
+      this.m_tracerSub = Optional.ofNullable(name).map(SubstitutiveTracer::new);
       this.m_period = periodUs;
       this.m_expirationTime =
           startTimeUs
@@ -63,7 +65,10 @@ static class Callback implements Comparable<Callback> {
     }
 
     void call() {
-      m_tracerSub.subWith(m_func);
+      m_tracerSub.ifPresentOrElse(
+          tracer -> tracer.subWith(m_func),
+          m_func
+      );
     }
 
     @Override
@@ -108,7 +113,7 @@ protected TimedRobot() {
   protected TimedRobot(double period) {
     super(period);
     m_startTimeUs = RobotController.getFPGATime();
-    addPeriodic(this::loopFunc, "RobotMain", period);
+    addPeriodic(this::loopFunc, null, period);
     NotifierJNI.setNotifierName(m_notifier, "TimedRobot");
 
     HAL.report(tResourceType.kResourceType_Framework, tInstances.kFramework_Timed);

wpilibj/src/main/java/edu/wpi/first/wpilibj/Tracer.java

@@ -17,7 +17,7 @@
 
 /**
  * A Utility class for tracing code execution time. Will put info to NetworkTables under the
- * "Tracer" table.
+ * "Tracer" table. The times outputted by the {@link Tracer} are in milliseconds.
  *
  * <p>Example inside {@code Robot.java}
  *
@@ -117,7 +117,9 @@ private TracerState(String name, boolean threadLocalConstruction) {
             true);
         this.m_disabled = true;
       }
-      anyTracesStarted.set(true);
+      if (!anyTracesStarted.get()) {
+        postUnits();
+      }
       if (name == null) {
         this.m_rootTable = NetworkTableInstance.getDefault().getTable("Tracer");
       } else {
@@ -211,7 +213,15 @@ private void endCycle() {
             return new TracerState(Thread.currentThread().getName(), true);
           });
 
+  private static void postUnits() {
+    NetworkTableInstance.getDefault()
+        .getTable("Tracer")
+        .getEntry("TimingUnits")
+        .setString("Milliseconds");
+  }
+
   private static void startTraceInner(final String name, final TracerState state) {
+    anyTracesStarted.set(true);
     String stack = state.appendTraceStack(name);
     if (state.m_disabled) {
       return;
@@ -285,6 +295,7 @@ public static void disableGcLoggingForCurrentThread() {
    *
    * <p>This function should be called before any traces are started.
    */
+  @SuppressWarnings("unused")
   public static void enableSingleThreadedMode() {
     if (anyTracesStarted.get()) {
       DriverStation.reportError(