Add loop timing to IterativeRobot and TimedRobot (#781)

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

@@ -20,7 +20,14 @@ import edu.wpi.first.wpilibj.hal.HAL;
  * the driver station.
  */
 public class IterativeRobot extends IterativeRobotBase {
+  private static final double kPacketPeriod = 0.02;
+
+  /**
+   * Create a new IterativeRobot.
+   */
   public IterativeRobot() {
+    super(kPacketPeriod);
+
     HAL.report(tResourceType.kResourceType_Framework, tInstances.kFramework_Iterative);
   }
 

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

@@ -42,6 +42,8 @@ import edu.wpi.first.wpilibj.smartdashboard.SmartDashboard;
  */
 @SuppressWarnings("PMD.TooManyMethods")
 public abstract class IterativeRobotBase extends RobotBase {
+  protected double m_period;
+
   private enum Mode {
     kNone,
     kDisabled,
@@ -51,6 +53,17 @@ public abstract class IterativeRobotBase extends RobotBase {
   }
 
   private Mode m_lastMode = Mode.kNone;
+  private final Watchdog m_watchdog;
+
+  /**
+   * Constructor for IterativeRobotBase.
+   *
+   * @param period Period in seconds.
+   */
+  protected IterativeRobotBase(double period) {
+    m_period = period;
+    m_watchdog = new Watchdog(period, this::printLoopOverrunMessage);
+  }
 
   /**
    * Provide an alternate "main loop" via startCompetition().
@@ -179,53 +192,77 @@ public abstract class IterativeRobotBase extends RobotBase {
   }
 
   protected void loopFunc() {
+    m_watchdog.reset();
+
     // Call the appropriate function depending upon the current robot mode
     if (isDisabled()) {
-      // call DisabledInit() if we are now just entering disabled mode from
-      // either a different mode or from power-on
+      // Call DisabledInit() if we are now just entering disabled mode from either a different mode
+      // or from power-on.
       if (m_lastMode != Mode.kDisabled) {
         LiveWindow.setEnabled(false);
         disabledInit();
+        m_watchdog.addEpoch("disabledInit()");
         m_lastMode = Mode.kDisabled;
       }
+
       HAL.observeUserProgramDisabled();
       disabledPeriodic();
+      m_watchdog.addEpoch("disablePeroidic()");
     } else if (isAutonomous()) {
-      // call Autonomous_Init() if this is the first time
-      // we've entered autonomous_mode
+      // Call AutonomousInit() if we are now just entering autonomous mode from either a different
+      // mode or from power-on.
       if (m_lastMode != Mode.kAutonomous) {
         LiveWindow.setEnabled(false);
-        // KBS NOTE: old code reset all PWMs and relays to "safe values"
-        // whenever entering autonomous mode, before calling
-        // "Autonomous_Init()"
         autonomousInit();
+        m_watchdog.addEpoch("autonomousInit()");
         m_lastMode = Mode.kAutonomous;
       }
+
       HAL.observeUserProgramAutonomous();
       autonomousPeriodic();
+      m_watchdog.addEpoch("autonomousPeriodic()");
     } else if (isOperatorControl()) {
-      // call Teleop_Init() if this is the first time
-      // we've entered teleop_mode
+      // Call TeleopInit() if we are now just entering teleop mode from either a different mode or
+      // from power-on.
       if (m_lastMode != Mode.kTeleop) {
         LiveWindow.setEnabled(false);
         teleopInit();
+        m_watchdog.addEpoch("teleopInit()");
         m_lastMode = Mode.kTeleop;
       }
+
       HAL.observeUserProgramTeleop();
       teleopPeriodic();
+      m_watchdog.addEpoch("teleopPeriodic()");
     } else {
-      // call TestInit() if we are now just entering test mode from either
-      // a different mode or from power-on
+      // Call TestInit() if we are now just entering test mode from either a different mode or from
+      // power-on.
       if (m_lastMode != Mode.kTest) {
         LiveWindow.setEnabled(true);
         testInit();
+        m_watchdog.addEpoch("testInit()");
         m_lastMode = Mode.kTest;
       }
+
       HAL.observeUserProgramTest();
       testPeriodic();
+      m_watchdog.addEpoch("testPeriodic()");
     }
+
     robotPeriodic();
+    m_watchdog.addEpoch("robotPeriodic()");
+    m_watchdog.disable();
     SmartDashboard.updateValues();
+
     LiveWindow.updateValues();
+
+    // Warn on loop time overruns
+    if (m_watchdog.isExpired()) {
+      m_watchdog.printEpochs();
+    }
+  }
+
+  private void printLoopOverrunMessage() {
+    DriverStation.reportWarning("Loop time of " + m_period + "s overrun\n", false);
   }
 }

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

@@ -22,9 +22,6 @@ import edu.wpi.first.wpilibj.hal.NotifierJNI;
 public class TimedRobot extends IterativeRobotBase {
   public static final double kDefaultPeriod = 0.02;
 
-  // Prevents loop from starting if user calls setPeriod() in robotInit()
-  private boolean m_startLoop;
-
   // The C pointer to the notifier object. We don't use it directly, it is
   // just passed to the JNI bindings.
   private final int m_notifier = NotifierJNI.initializeNotifier();
@@ -32,9 +29,23 @@ public class TimedRobot extends IterativeRobotBase {
   // The absolute expiration time
   private double m_expirationTime;
 
-  private double m_period = kDefaultPeriod;
+  private double m_period;
+
+  /**
+   * Constructor for TimedRobot.
+   */
+  protected TimedRobot() {
+    this(kDefaultPeriod);
+  }
+
+  /**
+   * Constructor for TimedRobot.
+   *
+   * @param period Period in seconds.
+   */
+  protected TimedRobot(double period) {
+    super(period);
 
-  public TimedRobot() {
     // HAL.report(tResourceType.kResourceType_Framework, tInstances.kFramework_Periodic);
     HAL.report(tResourceType.kResourceType_Framework, tInstances.kFramework_Iterative);
   }
@@ -56,8 +67,6 @@ public class TimedRobot extends IterativeRobotBase {
     // Tell the DS that the robot is ready to be enabled
     HAL.observeUserProgramStarting();
 
-    m_startLoop = true;
-
     m_expirationTime = RobotController.getFPGATime() * 1e-6 + m_period;
     updateAlarm();
 
@@ -75,20 +84,6 @@ public class TimedRobot extends IterativeRobotBase {
     }
   }
 
-  /**
-   * Set time period between calls to Periodic() functions.
-   *
-   * @param period Period in seconds.
-   */
-  public void setPeriod(double period) {
-    m_period = period;
-
-    if (m_startLoop) {
-      m_expirationTime = RobotController.getFPGATime() * 1e-6 + period;
-      updateAlarm();
-    }
-  }
-
   /**
    * Get time period between calls to Periodic() functions.
    */

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

@@ -0,0 +1,122 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.wpilibj;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * A class that's a wrapper around a watchdog timer.
+ *
+ * <p>When the timer expires, a message is printed to the console and an optional user-provided
+ * callback is invoked.
+ *
+ * <p>The watchdog is initialized disabled, so the user needs to call enable() before use.
+ */
+public class Watchdog {
+  private double m_timeout;
+  private Runnable m_callback;
+  private Notifier m_notifier;
+
+  private double m_startTime;
+  @SuppressWarnings("PMD.UseConcurrentHashMap")
+  private final Map<String, Double> m_epochs = new HashMap<>();
+  boolean m_isExpired;
+
+  /**
+   * Watchdog constructor.
+   *
+   * @param timeout The watchdog's timeout in seconds.
+   */
+  public Watchdog(double timeout) {
+    this(timeout, () -> {
+    });
+  }
+
+  /**
+   * Watchdog constructor.
+   *
+   * @param timeout  The watchdog's timeout in seconds.
+   * @param callback This function is called when the timeout expires.
+   */
+  public Watchdog(double timeout, Runnable callback) {
+    m_timeout = timeout;
+    m_callback = callback;
+    m_notifier = new Notifier(this::timeoutFunc);
+    enable();
+  }
+
+  /**
+   * Get the time in seconds since the watchdog was last fed.
+   */
+  public double getTime() {
+    return Timer.getFPGATimestamp() - m_startTime;
+  }
+
+  /**
+   * Returns true if the watchdog timer has expired.
+   */
+  public boolean isExpired() {
+    return m_isExpired;
+  }
+
+  /**
+   * Adds time since last epoch to the list printed by printEpochs().
+   *
+   * @param epochName The name to associate with the epoch.
+   */
+  public void addEpoch(String epochName) {
+    double currentTime = Timer.getFPGATimestamp();
+    m_epochs.put(epochName, currentTime - m_startTime);
+    m_startTime = currentTime;
+  }
+
+  /**
+   * Prints list of epochs added so far and their times.
+   */
+  public void printEpochs() {
+    m_epochs.forEach((key, value) -> {
+      System.out.println("\t" + key + ": " + value + "s");
+    });
+  }
+
+  /**
+   * Resets the watchdog timer.
+   *
+   * <p>This also enables the timer if it was previously disabled.
+   */
+  public void reset() {
+    enable();
+  }
+
+  /**
+   * Enables the watchdog timer.
+   */
+  public void enable() {
+    m_startTime = Timer.getFPGATimestamp();
+    m_isExpired = false;
+    m_epochs.clear();
+    m_notifier.startPeriodic(m_timeout);
+  }
+
+  /**
+   * Disable the watchdog.
+   */
+  public void disable() {
+    m_notifier.stop();
+  }
+
+  private void timeoutFunc() {
+    if (!m_isExpired) {
+      System.out.println("Watchdog not fed after " + m_timeout + "s");
+      m_callback.run();
+      m_isExpired = true;
+      disable();
+    }
+  }
+}