Add loop timing to IterativeRobot and TimedRobot (#781)

wpilibc/src/main/native/include/Watchdog.h

@@ -0,0 +1,92 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <functional>
+
+#include <wpi/StringMap.h>
+#include <wpi/StringRef.h>
+
+#include "Notifier.h"
+
+namespace frc {
+
+/**
+ * A class that's a wrapper around a watchdog timer.
+ *
+ * When the timer expires, a message is printed to the console and an optional
+ * user-provided callback is invoked.
+ *
+ * The watchdog is initialized disabled, so the user needs to call Enable()
+ * before use.
+ */
+class Watchdog {
+ public:
+  /**
+   * Watchdog constructor.
+   *
+   * @param timeout  The watchdog's timeout in seconds.
+   * @param callback This function is called when the timeout expires.
+   */
+  explicit Watchdog(double timeout, std::function<void()> callback = [] {});
+
+  Watchdog(const Watchdog&) = delete;
+  Watchdog& operator=(const Watchdog&) = delete;
+
+  /**
+   * Get the time in seconds since the watchdog was last fed.
+   */
+  double GetTime() const;
+
+  /**
+   * Returns true if the watchdog timer has expired.
+   */
+  bool IsExpired() const;
+
+  /**
+   * Adds time since last epoch to the list printed by PrintEpochs().
+   *
+   * @param epochName The name to associate with the epoch.
+   */
+  void AddEpoch(wpi::StringRef epochName);
+
+  /**
+   * Prints list of epochs added so far and their times.
+   */
+  void PrintEpochs();
+
+  /**
+   * Resets the watchdog timer.
+   *
+   * This also enables the timer if it was previously disabled.
+   */
+  void Reset();
+
+  /**
+   * Enables the watchdog timer.
+   */
+  void Enable();
+
+  /**
+   * Disable the watchdog.
+   */
+  void Disable();
+
+ private:
+  double m_timeout;
+  std::function<void()> m_callback;
+  Notifier m_notifier;
+
+  double m_startTime = 0.0;
+  wpi::StringMap<double> m_epochs;
+  bool m_isExpired = false;
+
+  void TimeoutFunc();
+};
+
+}  // namespace frc