[commands] Add interruptor parameter to onCommandInterrupt callbacks (#5461)

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/CommandScheduler.java

@@ -28,8 +28,10 @@ import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.WeakHashMap;
+import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 
 /**
@@ -57,6 +59,8 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
     return instance;
   }
 
+  private static final Optional<Command> kNoInterruptor = Optional.empty();
+
   private final Set<Command> m_composedCommands = Collections.newSetFromMap(new WeakHashMap<>());
 
   // A set of the currently-running commands.
@@ -79,14 +83,15 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
   // Lists of user-supplied actions to be executed on scheduling events for every command.
   private final List<Consumer<Command>> m_initActions = new ArrayList<>();
   private final List<Consumer<Command>> m_executeActions = new ArrayList<>();
-  private final List<Consumer<Command>> m_interruptActions = new ArrayList<>();
+  private final List<BiConsumer<Command, Optional<Command>>> m_interruptActions = new ArrayList<>();
   private final List<Consumer<Command>> m_finishActions = new ArrayList<>();
 
   // Flag and queues for avoiding ConcurrentModificationException if commands are
   // scheduled/canceled during run
   private boolean m_inRunLoop;
   private final Set<Command> m_toSchedule = new LinkedHashSet<>();
-  private final List<Command> m_toCancel = new ArrayList<>();
+  private final List<Command> m_toCancelCommands = new ArrayList<>();
+  private final List<Optional<Command>> m_toCancelInterruptors = new ArrayList<>();
 
   private final Watchdog m_watchdog = new Watchdog(TimedRobot.kDefaultPeriod, () -> {});
 
@@ -211,7 +216,7 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
       for (Subsystem requirement : requirements) {
         Command requiring = requiring(requirement);
         if (requiring != null) {
-          cancel(requiring);
+          cancel(requiring, Optional.of(command));
         }
       }
       initCommand(command, requirements);
@@ -272,8 +277,8 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
 
       if (!command.runsWhenDisabled() && RobotState.isDisabled()) {
         command.end(true);
-        for (Consumer<Command> action : m_interruptActions) {
-          action.accept(command);
+        for (BiConsumer<Command, Optional<Command>> action : m_interruptActions) {
+          action.accept(command, kNoInterruptor);
         }
         m_requirements.keySet().removeAll(command.getRequirements());
         iterator.remove();
@@ -304,12 +309,13 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
       schedule(command);
     }
 
-    for (Command command : m_toCancel) {
-      cancel(command);
+    for (int i = 0; i < m_toCancelCommands.size(); i++) {
+      cancel(m_toCancelCommands.get(i), m_toCancelInterruptors.get(i));
     }
 
     m_toSchedule.clear();
-    m_toCancel.clear();
+    m_toCancelCommands.clear();
+    m_toCancelInterruptors.clear();
 
     // Add default commands for un-required registered subsystems.
     for (Map.Entry<Subsystem, Command> subsystemCommand : m_subsystems.entrySet()) {
@@ -440,28 +446,42 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
    * @param commands the commands to cancel
    */
   public void cancel(Command... commands) {
+    for (Command command : commands) {
+      cancel(command, kNoInterruptor);
+    }
+  }
+
+  /**
+   * Cancels a command. The scheduler will only call {@link Command#end(boolean)} method of the
+   * canceled command with {@code true}, indicating they were canceled (as opposed to finishing
+   * normally).
+   *
+   * <p>Commands will be canceled regardless of {@link InterruptionBehavior interruption behavior}.
+   *
+   * @param command the command to cancel
+   * @param interruptor the interrupting command, if any
+   */
+  private void cancel(Command command, Optional<Command> interruptor) {
+    if (command == null) {
+      DriverStation.reportWarning("Tried to cancel a null command", true);
+      return;
+    }
     if (m_inRunLoop) {
-      m_toCancel.addAll(List.of(commands));
+      m_toCancelCommands.add(command);
+      m_toCancelInterruptors.add(interruptor);
+      return;
+    }
+    if (!isScheduled(command)) {
       return;
     }
 
-    for (Command command : commands) {
-      if (command == null) {
-        DriverStation.reportWarning("Tried to cancel a null command", true);
-        continue;
-      }
-      if (!isScheduled(command)) {
-        continue;
-      }
-
-      m_scheduledCommands.remove(command);
-      m_requirements.keySet().removeAll(command.getRequirements());
-      command.end(true);
-      for (Consumer<Command> action : m_interruptActions) {
-        action.accept(command);
-      }
-      m_watchdog.addEpoch(command.getName() + ".end(true)");
+    m_scheduledCommands.remove(command);
+    m_requirements.keySet().removeAll(command.getRequirements());
+    command.end(true);
+    for (BiConsumer<Command, Optional<Command>> action : m_interruptActions) {
+      action.accept(command, interruptor);
     }
+    m_watchdog.addEpoch(command.getName() + ".end(true)");
   }
 
   /** Cancels all commands that are currently scheduled. */
@@ -528,6 +548,19 @@ public final class CommandScheduler implements Sendable, AutoCloseable {
    * @param action the action to perform
    */
   public void onCommandInterrupt(Consumer<Command> action) {
+    requireNonNullParam(action, "action", "onCommandInterrupt");
+    m_interruptActions.add((command, interruptor) -> action.accept(command));
+  }
+
+  /**
+   * Adds an action to perform on the interruption of any command by the scheduler. The action
+   * receives the interrupted command and an Optional containing the interrupting command, or
+   * Optional.empty() if it was not canceled by a command (e.g., by {@link
+   * CommandScheduler#cancel}).
+   *
+   * @param action the action to perform
+   */
+  public void onCommandInterrupt(BiConsumer<Command, Optional<Command>> action) {
     m_interruptActions.add(requireNonNullParam(action, "action", "onCommandInterrupt"));
   }
 

wpilibNewCommands/src/main/native/cpp/frc2/command/CommandScheduler.cpp

@@ -48,7 +48,7 @@ class CommandScheduler::Impl {
   // every command.
   wpi::SmallVector<Action, 4> initActions;
   wpi::SmallVector<Action, 4> executeActions;
-  wpi::SmallVector<Action, 4> interruptActions;
+  wpi::SmallVector<InterruptAction, 4> interruptActions;
   wpi::SmallVector<Action, 4> finishActions;
 
   // Flag and queues for avoiding concurrent modification if commands are
@@ -56,7 +56,8 @@ class CommandScheduler::Impl {
 
   bool inRunLoop = false;
   wpi::SmallVector<Command*, 4> toSchedule;
-  wpi::SmallVector<Command*, 4> toCancel;
+  wpi::SmallVector<Command*, 4> toCancelCommands;
+  wpi::SmallVector<std::optional<Command*>, 4> toCancelInterruptors;
 };
 
 template <typename TMap, typename TKey>
@@ -138,7 +139,7 @@ void CommandScheduler::Schedule(Command* command) {
   if (isDisjoint || allInterruptible) {
     if (allInterruptible) {
       for (auto&& cmdToCancel : intersection) {
-        Cancel(cmdToCancel);
+        Cancel(cmdToCancel, std::make_optional(command));
       }
     }
     m_impl->scheduledCommands.insert(command);
@@ -196,7 +197,7 @@ void CommandScheduler::Run() {
   // Run scheduled commands, remove finished commands.
   for (Command* command : m_impl->scheduledCommands) {
     if (!command->RunsWhenDisabled() && frc::RobotState::IsDisabled()) {
-      Cancel(command);
+      Cancel(command, std::nullopt);
       continue;
     }
 
@@ -226,12 +227,13 @@ void CommandScheduler::Run() {
     Schedule(command);
   }
 
-  for (auto&& command : m_impl->toCancel) {
-    Cancel(command);
+  for (size_t i = 0; i < m_impl->toCancelCommands.size(); i++) {
+    Cancel(m_impl->toCancelCommands[i], m_impl->toCancelInterruptors[i]);
   }
 
   m_impl->toSchedule.clear();
-  m_impl->toCancel.clear();
+  m_impl->toCancelCommands.clear();
+  m_impl->toCancelInterruptors.clear();
 
   // Add default commands for un-required registered subsystems.
   for (auto&& subsystem : m_impl->subsystems) {
@@ -319,13 +321,15 @@ Command* CommandScheduler::GetDefaultCommand(const Subsystem* subsystem) const {
   }
 }
 
-void CommandScheduler::Cancel(Command* command) {
+void CommandScheduler::Cancel(Command* command,
+                              std::optional<Command*> interruptor) {
   if (!m_impl) {
     return;
   }
 
   if (m_impl->inRunLoop) {
-    m_impl->toCancel.emplace_back(command);
+    m_impl->toCancelCommands.emplace_back(command);
+    m_impl->toCancelInterruptors.emplace_back(interruptor);
     return;
   }
 
@@ -341,11 +345,15 @@ void CommandScheduler::Cancel(Command* command) {
   }
   command->End(true);
   for (auto&& action : m_impl->interruptActions) {
-    action(*command);
+    action(*command, interruptor);
   }
   m_watchdog.AddEpoch(command->GetName() + ".End(true)");
 }
 
+void CommandScheduler::Cancel(Command* command) {
+  Cancel(command, std::nullopt);
+}
+
 void CommandScheduler::Cancel(const CommandPtr& command) {
   Cancel(command.get());
 }
@@ -424,6 +432,14 @@ void CommandScheduler::OnCommandExecute(Action action) {
 }
 
 void CommandScheduler::OnCommandInterrupt(Action action) {
+  m_impl->interruptActions.emplace_back(
+      [action = std::move(action)](const Command& command,
+                                   const std::optional<Command*>& interruptor) {
+        action(command);
+      });
+}
+
+void CommandScheduler::OnCommandInterrupt(InterruptAction action) {
   m_impl->interruptActions.emplace_back(std::move(action));
 }
 

wpilibNewCommands/src/main/native/include/frc2/command/CommandScheduler.h

@@ -8,6 +8,7 @@
 #include <functional>
 #include <initializer_list>
 #include <memory>
+#include <optional>
 #include <span>
 #include <utility>
 
@@ -48,6 +49,8 @@ class CommandScheduler final : public wpi::Sendable,
   CommandScheduler& operator=(const CommandScheduler&) = delete;
 
   using Action = std::function<void(const Command&)>;
+  using InterruptAction =
+      std::function<void(const Command&, const std::optional<Command*>&)>;
 
   /**
    * Changes the period of the loop overrun watchdog. This should be kept in
@@ -353,6 +356,16 @@ class CommandScheduler final : public wpi::Sendable,
    */
   void OnCommandInterrupt(Action action);
 
+  /**
+   * Adds an action to perform on the interruption of any command by the
+   * scheduler. The action receives the interrupted command and an optional
+   * containing the interrupting command, or nullopt if it was not canceled by a
+   * command (e.g., by Cancel()).
+   *
+   * @param action the action to perform
+   */
+  void OnCommandInterrupt(InterruptAction action);
+
   /**
    * Adds an action to perform on the finishing of any command by the scheduler.
    *
@@ -397,6 +410,8 @@ class CommandScheduler final : public wpi::Sendable,
   void SetDefaultCommandImpl(Subsystem* subsystem,
                              std::unique_ptr<Command> command);
 
+  void Cancel(Command* command, std::optional<Command*> interruptor);
+
   class Impl;
   std::unique_ptr<Impl> m_impl;
 

wpilibNewCommands/src/test/java/edu/wpi/first/wpilibj2/command/SchedulerTest.java

@@ -6,6 +6,9 @@ package edu.wpi.first.wpilibj2.command;
 
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.concurrent.atomic.AtomicInteger;
 import org.junit.jupiter.api.Test;
@@ -43,6 +46,76 @@ class SchedulerTest extends CommandTestBase {
     }
   }
 
+  @Test
+  void schedulerInterruptNoCauseLambdaTest() {
+    try (CommandScheduler scheduler = new CommandScheduler()) {
+      AtomicInteger counter = new AtomicInteger();
+
+      scheduler.onCommandInterrupt(
+          (interrupted, cause) -> {
+            assertFalse(cause.isPresent());
+            counter.incrementAndGet();
+          });
+
+      Command command = Commands.run(() -> {});
+
+      scheduler.schedule(command);
+      scheduler.cancel(command);
+
+      assertEquals(1, counter.get());
+    }
+  }
+
+  @Test
+  void schedulerInterruptCauseLambdaTest() {
+    try (CommandScheduler scheduler = new CommandScheduler()) {
+      AtomicInteger counter = new AtomicInteger();
+
+      Subsystem subsystem = new Subsystem() {};
+      Command command = subsystem.run(() -> {});
+      Command interruptor = subsystem.runOnce(() -> {});
+
+      scheduler.onCommandInterrupt(
+          (interrupted, cause) -> {
+            assertTrue(cause.isPresent());
+            assertSame(interruptor, cause.get());
+            counter.incrementAndGet();
+          });
+
+      scheduler.schedule(command);
+      scheduler.schedule(interruptor);
+
+      assertEquals(1, counter.get());
+    }
+  }
+
+  @Test
+  void schedulerInterruptCauseLambdaInRunLoopTest() {
+    try (CommandScheduler scheduler = new CommandScheduler()) {
+      AtomicInteger counter = new AtomicInteger();
+
+      Subsystem subsystem = new Subsystem() {};
+      Command command = subsystem.run(() -> {});
+      Command interruptor = subsystem.runOnce(() -> {});
+      // This command will schedule interruptor in execute() inside the run loop
+      Command interruptorScheduler = Commands.runOnce(() -> scheduler.schedule(interruptor));
+
+      scheduler.onCommandInterrupt(
+          (interrupted, cause) -> {
+            assertTrue(cause.isPresent());
+            assertSame(interruptor, cause.get());
+            counter.incrementAndGet();
+          });
+
+      scheduler.schedule(command);
+      scheduler.schedule(interruptorScheduler);
+
+      scheduler.run();
+
+      assertEquals(1, counter.get());
+    }
+  }
+
   @Test
   void registerSubsystemTest() {
     try (CommandScheduler scheduler = new CommandScheduler()) {
@@ -87,6 +160,7 @@ class SchedulerTest extends CommandTestBase {
       AtomicInteger counter = new AtomicInteger();
 
       scheduler.onCommandInterrupt(command -> counter.incrementAndGet());
+      scheduler.onCommandInterrupt((command, interruptor) -> assertFalse(interruptor.isPresent()));
 
       Command command = new WaitCommand(10);
       Command command2 = new WaitCommand(10);

wpilibNewCommands/src/test/native/cpp/frc2/command/SchedulerTest.cpp

@@ -43,6 +43,74 @@ TEST_F(SchedulerTest, SchedulerLambdaInterrupt) {
   EXPECT_EQ(counter, 1);
 }
 
+TEST_F(SchedulerTest, SchedulerLambdaInterruptNoCause) {
+  CommandScheduler scheduler = GetScheduler();
+
+  int counter = 0;
+
+  scheduler.OnCommandInterrupt(
+      [&counter](const Command&, const std::optional<Command*>& interruptor) {
+        EXPECT_FALSE(interruptor);
+        counter++;
+      });
+
+  RunCommand command([] {});
+
+  scheduler.Schedule(&command);
+  scheduler.Cancel(&command);
+
+  EXPECT_EQ(1, counter);
+}
+
+TEST_F(SchedulerTest, SchedulerLambdaInterruptCause) {
+  CommandScheduler scheduler = GetScheduler();
+
+  int counter = 0;
+
+  TestSubsystem subsystem{};
+  RunCommand command([] {}, {&subsystem});
+  InstantCommand interruptor([] {}, {&subsystem});
+
+  scheduler.OnCommandInterrupt(
+      [&](const Command&, const std::optional<Command*>& cause) {
+        ASSERT_TRUE(cause);
+        EXPECT_EQ(&interruptor, *cause);
+        counter++;
+      });
+
+  scheduler.Schedule(&command);
+  scheduler.Schedule(&interruptor);
+
+  EXPECT_EQ(1, counter);
+}
+
+TEST_F(SchedulerTest, SchedulerLambdaInterruptCauseInRunLoop) {
+  CommandScheduler scheduler = GetScheduler();
+
+  int counter = 0;
+
+  TestSubsystem subsystem{};
+  RunCommand command([] {}, {&subsystem});
+  InstantCommand interruptor([] {}, {&subsystem});
+  // This command will schedule interruptor in execute() inside the run loop
+  InstantCommand interruptorScheduler(
+      [&] { scheduler.Schedule(&interruptor); });
+
+  scheduler.OnCommandInterrupt(
+      [&](const Command&, const std::optional<Command*>& cause) {
+        ASSERT_TRUE(cause);
+        EXPECT_EQ(&interruptor, *cause);
+        counter++;
+      });
+
+  scheduler.Schedule(&command);
+  scheduler.Schedule(&interruptorScheduler);
+
+  scheduler.Run();
+
+  EXPECT_EQ(1, counter);
+}
+
 TEST_F(SchedulerTest, RegisterSubsystem) {
   CommandScheduler scheduler = GetScheduler();
 
@@ -78,6 +146,10 @@ TEST_F(SchedulerTest, SchedulerCancelAll) {
   int counter = 0;
 
   scheduler.OnCommandInterrupt([&counter](const Command&) { counter++; });
+  scheduler.OnCommandInterrupt(
+      [](const Command&, const std::optional<Command*>& interruptor) {
+        EXPECT_FALSE(interruptor);
+      });
 
   scheduler.Schedule(&command);
   scheduler.Schedule(&command2);