A refined plan

- Clean up and improve functional interfaces used in Plans.
- Allow safely running TaskExecutor#sync* methods off-thread.
- Formalize the concept of "main thread" in task executor.
- Improve tests for main-thread plans.

src/main/java/com/jozufozu/flywheel/api/task/TaskExecutor.java

@@ -28,6 +28,8 @@ public interface TaskExecutor extends Executor {
 	 * Wait for running tasks, so long as the given condition is met
 	 * ({@link BooleanSupplier#getAsBoolean()} returns {@code true}).
 	 * <br>
+	 * If this method is called on the
+	 * <br>
 	 * This method is equivalent to {@code syncUntil(() -> !cond.getAsBoolean())}.
 	 *
 	 * @param cond The condition sync on.
@@ -48,10 +50,18 @@ public interface TaskExecutor extends Executor {
 	/**
 	 * Schedule a task to be run on the main thread.
 	 * <br>
-	 * This method may be called from any thread, but the runnable will only
-	 * be executed once somebody calls either {@link #syncPoint()} or
-	 * {@link #syncUntil(BooleanSupplier)}.
+	 * This method may be called from any thread (including the main thread),
+	 * but the runnable will <em>only</em> be executed once somebody calls
+	 * either {@link #syncPoint()} or {@link #syncUntil(BooleanSupplier)}
+	 * on this task executor's main thread.
 	 * @param runnable The task to run.
 	 */
-	void scheduleForSync(Runnable runnable);
+	void scheduleForMainThread(Runnable runnable);
+
+	/**
+	 * Check whether the current thread is this task executor's main thread.
+	 *
+	 * @return {@code true} if the current thread is the main thread.
+	 */
+	boolean isMainThread();
 }

src/main/java/com/jozufozu/flywheel/impl/task/FlwTaskExecutor.java

@@ -4,6 +4,7 @@ import org.apache.commons.lang3.concurrent.AtomicSafeInitializer;
 import org.apache.commons.lang3.concurrent.ConcurrentUtils;
 
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.mojang.blaze3d.systems.RenderSystem;
 
 public final class FlwTaskExecutor {
 	public static final boolean USE_SERIAL_EXECUTOR = System.getProperty("flw.useSerialExecutor") != null;
@@ -28,7 +29,7 @@ public final class FlwTaskExecutor {
 				return SerialTaskExecutor.INSTANCE;
 			}
 
-			ParallelTaskExecutor executor = new ParallelTaskExecutor("Flywheel");
+			ParallelTaskExecutor executor = new ParallelTaskExecutor("Flywheel", RenderSystem::isOnRenderThread);
 			executor.startWorkers();
 			return executor;
 		}

src/main/java/com/jozufozu/flywheel/impl/task/ParallelTaskExecutor.java

@@ -14,7 +14,6 @@ import org.slf4j.Logger;
 
 import com.jozufozu.flywheel.Flywheel;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
-import com.mojang.blaze3d.systems.RenderSystem;
 import com.mojang.logging.LogUtils;
 
 import net.minecraft.util.Mth;
@@ -27,6 +26,8 @@ public class ParallelTaskExecutor implements TaskExecutor {
 	private final String name;
 	private final int threadCount;
 
+	private final BooleanSupplier mainThreadQuery;
+
 	/**
 	 * If set to false, the executor will shut down.
 	 */
@@ -38,8 +39,9 @@ public class ParallelTaskExecutor implements TaskExecutor {
 	private final ThreadGroupNotifier taskNotifier = new ThreadGroupNotifier();
 	private final WaitGroup waitGroup = new WaitGroup();
 
-	public ParallelTaskExecutor(String name) {
+	public ParallelTaskExecutor(String name, BooleanSupplier mainThreadQuery) {
 		this.name = name;
+		this.mainThreadQuery = mainThreadQuery;
 		threadCount = getOptimalThreadCount();
 	}
 
@@ -116,16 +118,17 @@ public class ParallelTaskExecutor implements TaskExecutor {
 	}
 
 	@Override
-	public void scheduleForSync(Runnable runnable) {
+	public void scheduleForMainThread(Runnable runnable) {
 		if (!running.get()) {
 			throw new IllegalStateException("Executor is stopped");
 		}
 
-		if (RenderSystem.isOnRenderThread()) {
-			runnable.run();
-		} else {
-			mainThreadQueue.add(runnable);
-		}
+		mainThreadQueue.add(runnable);
+	}
+
+	@Override
+	public boolean isMainThread() {
+		return mainThreadQuery.getAsBoolean();
 	}
 
 	/**
@@ -133,16 +136,18 @@ public class ParallelTaskExecutor implements TaskExecutor {
 	 */
 	@Override
 	public void syncPoint() {
+		boolean onMainThread = isMainThread();
 		while (true) {
-			if (syncOneTask()) {
+			if (syncOneTask(onMainThread)) {
 				// Done! Nothing left to do.
-				break;
+				return;
 			}
 		}
 	}
 
 	@Override
 	public boolean syncUntil(BooleanSupplier cond) {
+		boolean onMainThread = isMainThread();
 		while (true) {
 			if (cond.getAsBoolean()) {
 				// The condition is already true!
@@ -150,7 +155,7 @@ public class ParallelTaskExecutor implements TaskExecutor {
 				return true;
 			}
 
-			if (syncOneTask()) {
+			if (syncOneTask(onMainThread)) {
 				// Out of tasks entirely.
 				// The condition may have flipped though so return its result.
 				return cond.getAsBoolean();
@@ -161,6 +166,7 @@ public class ParallelTaskExecutor implements TaskExecutor {
 
 	@Override
 	public boolean syncWhile(BooleanSupplier cond) {
+		boolean onMainThread = isMainThread();
 		while (true) {
 			if (!cond.getAsBoolean()) {
 				// The condition is already false!
@@ -168,7 +174,7 @@ public class ParallelTaskExecutor implements TaskExecutor {
 				return true;
 			}
 
-			if (syncOneTask()) {
+			if (syncOneTask(onMainThread)) {
 				// Out of tasks entirely.
 				// The condition may have flipped though so return its result.
 				return !cond.getAsBoolean();
@@ -179,24 +185,49 @@ public class ParallelTaskExecutor implements TaskExecutor {
 	/**
 	 * Attempt to process a single task.
 	 *
+	 * @param mainThread Whether this is being called from the main thread or not.
 	 * @return {@code true} if the executor has nothing left to do.
 	 */
-	private boolean syncOneTask() {
+	private boolean syncOneTask(boolean mainThread) {
+		return mainThread ? syncOneTaskMainThread() : syncOneTaskOffThread();
+	}
+
+	private boolean syncOneTaskMainThread() {
 		Runnable task;
 		if ((task = mainThreadQueue.poll()) != null) {
 			// Prioritize main thread tasks.
 			processMainThreadTask(task);
+
+			// Check again next loop.
+			return false;
 		} else if ((task = taskQueue.pollLast()) != null) {
-			// then work on tasks from the queue.
+			// Nothing in the mainThreadQueue, work on tasks from the normal queue.
 			processTask(task);
+
+			// Check again next loop.
+			return false;
 		} else {
-			// then wait for the other threads to finish.
+			// Nothing right now, wait for the other threads to finish.
 			boolean done = waitGroup.await(10_000);
 			// If we timed-out tasks may have been added to the queue, so check again.
 			// if they didn't, we're done.
 			return done && mainThreadQueue.isEmpty();
 		}
-		return false;
+	}
+
+	private boolean syncOneTaskOffThread() {
+		Runnable task;
+		if ((task = taskQueue.pollLast()) != null) {
+			// then work on tasks from the queue.
+			processTask(task);
+			// Check again next loop.
+			return false;
+		} else {
+			// Nothing right now, wait for the other threads to finish.
+			// If we timed-out tasks may have been added to the queue, so check again.
+			// if they didn't, we're done.
+			return waitGroup.await(10_000);
+		}
 	}
 
 	private void processTask(Runnable task) {

src/main/java/com/jozufozu/flywheel/impl/task/SerialTaskExecutor.java

@@ -16,7 +16,7 @@ public class SerialTaskExecutor implements TaskExecutor {
 	}
 
 	@Override
-	public void scheduleForSync(Runnable runnable) {
+	public void scheduleForMainThread(Runnable runnable) {
 		runnable.run();
 	}
 
@@ -38,4 +38,9 @@ public class SerialTaskExecutor implements TaskExecutor {
 	public int getThreadCount() {
 		return 1;
 	}
+
+	@Override
+	public boolean isMainThread() {
+		return true;
+	}
 }

src/main/java/com/jozufozu/flywheel/impl/visualization/storage/Storage.java

@@ -59,7 +59,7 @@ public abstract class Storage<T> {
 		tickableVisuals.remove(visual);
 		dynamicVisuals.remove(visual);
 		if (plannedVisuals.remove(visual)) {
-			framePlan.clear();
+			framePlan.triggerReInitialize();
 		}
 		visual.delete();
 	}
@@ -103,8 +103,8 @@ public abstract class Storage<T> {
 		tickableVisuals.clear();
 		dynamicVisuals.clear();
 		plannedVisuals.clear();
-		framePlan.clear();
-		tickPlan.clear();
+		framePlan.triggerReInitialize();
+		tickPlan.triggerReInitialize();
 		visuals.values()
 				.forEach(Visual::delete);
 		visuals.clear();

src/main/java/com/jozufozu/flywheel/impl/visualization/storage/VisualUpdatePlan.java

@@ -47,7 +47,7 @@ public class VisualUpdatePlan<C> implements SimplyComposedPlan<C> {
 		return plan;
 	}
 
-	public void clear() {
+	public void triggerReInitialize() {
 		plan = UnitPlan.of();
 		initialized = false;
 	}

src/main/java/com/jozufozu/flywheel/lib/task/ContextConsumer.java

@@ -1,13 +0,0 @@
-package com.jozufozu.flywheel.lib.task;
-
-import com.jozufozu.flywheel.api.task.Plan;
-
-/**
- * A consumer like interface for use with {@link Plan}s.
- *
- * @param <C> The context type.
- */
-@FunctionalInterface
-public interface ContextConsumer<C> {
-	void accept(C context);
-}

src/main/java/com/jozufozu/flywheel/lib/task/ContextFunction.java

@@ -1,13 +0,0 @@
-package com.jozufozu.flywheel.lib.task;
-
-import com.jozufozu.flywheel.api.task.Plan;
-
-/**
- * A function like interface for use with {@link Plan}s.
- * @param <C> The context type.
- * @param <R> The return type.
- */
-@FunctionalInterface
-public interface ContextFunction<C, R> {
-	R apply(C context);
-}

src/main/java/com/jozufozu/flywheel/lib/task/ContextRunnable.java

@@ -1,16 +0,0 @@
-package com.jozufozu.flywheel.lib.task;
-
-/**
- * A {@link ContextConsumer} that ignores the context object.
- *
- * @param <C> The context type.
- */
-@FunctionalInterface
-public interface ContextRunnable<C> extends ContextConsumer<C> {
-	void run();
-
-	@Override
-	default void accept(C ignored) {
-		run();
-	}
-}

src/main/java/com/jozufozu/flywheel/lib/task/ContextSupplier.java

@@ -1,17 +0,0 @@
-package com.jozufozu.flywheel.lib.task;
-
-/**
- * A {@link ContextFunction} that ignores the context object.
- *
- * @param <C> The context type.
- * @param <R> The return type.
- */
-@FunctionalInterface
-public interface ContextSupplier<C, R> extends ContextFunction<C, R> {
-	R get();
-
-	@Override
-	default R apply(C ignored) {
-		return get();
-	}
-}

src/main/java/com/jozufozu/flywheel/lib/task/DynamicNestedPlan.java

@@ -4,6 +4,7 @@ import java.util.Collection;
 
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.SupplierWithContext;
 
 /**
  * A plan that executes many other plans provided dynamically.
@@ -11,18 +12,19 @@ import com.jozufozu.flywheel.api.task.TaskExecutor;
  * @param plans A function to get a collection of plans based on the context.
  * @param <C>   The type of the context object.
  */
-public record DynamicNestedPlan<C>(ContextFunction<C, Collection<? extends Plan<C>>> plans) implements SimplyComposedPlan<C> {
-	public static <C> Plan<C> of(ContextSupplier<C, Collection<? extends Plan<C>>> supplier) {
+public record DynamicNestedPlan<C>(
+		SupplierWithContext<C, Collection<? extends Plan<C>>> plans) implements SimplyComposedPlan<C> {
+	public static <C> Plan<C> of(SupplierWithContext.Ignored<C, Collection<? extends Plan<C>>> supplier) {
 		return new DynamicNestedPlan<>(supplier);
 	}
 
-	public static <C> Plan<C> of(ContextFunction<C, Collection<? extends Plan<C>>> function) {
-		return new DynamicNestedPlan<>(function);
+	public static <C> Plan<C> of(SupplierWithContext<C, Collection<? extends Plan<C>>> supplier) {
+		return new DynamicNestedPlan<>(supplier);
 	}
 
 	@Override
 	public void execute(TaskExecutor taskExecutor, C context, Runnable onCompletion) {
-		var plans = this.plans.apply(context);
+		var plans = this.plans.get(context);
 
 		if (plans.isEmpty()) {
 			onCompletion.run();

src/main/java/com/jozufozu/flywheel/lib/task/ForEachPlan.java

@@ -1,12 +1,11 @@
 package com.jozufozu.flywheel.lib.task;
 
 import java.util.List;
-import java.util.function.BiConsumer;
-import java.util.function.Consumer;
-import java.util.function.Supplier;
 
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.ConsumerWithContext;
+import com.jozufozu.flywheel.lib.task.functional.SupplierWithContext;
 
 /**
  * A plan that executes code on each element of a provided list.
@@ -18,17 +17,26 @@ import com.jozufozu.flywheel.api.task.TaskExecutor;
  * @param <T>          The type of the list elements.
  * @param <C>          The type of the context object.
  */
-public record ForEachPlan<T, C>(Supplier<List<T>> listSupplier, BiConsumer<T, C> action) implements SimplyComposedPlan<C> {
-	public static <T, C> Plan<C> of(Supplier<List<T>> iterable, BiConsumer<T, C> forEach) {
+public record ForEachPlan<T, C>(SupplierWithContext<C, List<T>> listSupplier,
+								ConsumerWithContext<T, C> action) implements SimplyComposedPlan<C> {
+	public static <T, C> Plan<C> of(SupplierWithContext<C, List<T>> iterable, ConsumerWithContext<T, C> forEach) {
 		return new ForEachPlan<>(iterable, forEach);
 	}
 
-	public static <T, C> Plan<C> of(Supplier<List<T>> iterable, Consumer<T> forEach) {
-		return of(iterable, (t, c) -> forEach.accept(t));
+	public static <T, C> Plan<C> of(SupplierWithContext<C, List<T>> iterable, ConsumerWithContext.Ignored<T, C> forEach) {
+		return new ForEachPlan<>(iterable, forEach);
+	}
+
+	public static <T, C> Plan<C> of(SupplierWithContext.Ignored<C, List<T>> iterable, ConsumerWithContext<T, C> forEach) {
+		return new ForEachPlan<>(iterable, forEach);
+	}
+
+	public static <T, C> Plan<C> of(SupplierWithContext.Ignored<C, List<T>> iterable, ConsumerWithContext.Ignored<T, C> forEach) {
+		return new ForEachPlan<>(iterable, forEach);
 	}
 
 	@Override
 	public void execute(TaskExecutor taskExecutor, C context, Runnable onCompletion) {
-		taskExecutor.execute(() -> PlanUtil.distribute(taskExecutor, context, onCompletion, listSupplier.get(), action));
+		taskExecutor.execute(() -> PlanUtil.distribute(taskExecutor, context, onCompletion, listSupplier.get(context), action));
 	}
 }

src/main/java/com/jozufozu/flywheel/lib/task/ForEachSlicePlan.java

@@ -1,11 +1,11 @@
 package com.jozufozu.flywheel.lib.task;
 
 import java.util.List;
-import java.util.function.BiConsumer;
-import java.util.function.Supplier;
 
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.ConsumerWithContext;
+import com.jozufozu.flywheel.lib.task.functional.SupplierWithContext;
 
 /**
  * A plan that executes code over many slices of a provided list.
@@ -17,14 +17,26 @@ import com.jozufozu.flywheel.api.task.TaskExecutor;
  * @param <T>          The type of the list elements.
  * @param <C>          The type of the context object.
  */
-public record ForEachSlicePlan<T, C>(Supplier<List<T>> listSupplier,
-									 BiConsumer<List<T>, C> action) implements SimplyComposedPlan<C> {
-	public static <T, C> Plan<C> of(Supplier<List<T>> iterable, BiConsumer<List<T>, C> forEach) {
+public record ForEachSlicePlan<T, C>(SupplierWithContext<C, List<T>> listSupplier,
+									 ConsumerWithContext<List<T>, C> action) implements SimplyComposedPlan<C> {
+	public static <T, C> Plan<C> of(SupplierWithContext<C, List<T>> iterable, ConsumerWithContext<List<T>, C> forEach) {
+		return new ForEachSlicePlan<>(iterable, forEach);
+	}
+
+	public static <T, C> Plan<C> of(SupplierWithContext<C, List<T>> iterable, ConsumerWithContext.Ignored<List<T>, C> forEach) {
+		return new ForEachSlicePlan<>(iterable, forEach);
+	}
+
+	public static <T, C> Plan<C> of(SupplierWithContext.Ignored<C, List<T>> iterable, ConsumerWithContext<List<T>, C> forEach) {
+		return new ForEachSlicePlan<>(iterable, forEach);
+	}
+
+	public static <T, C> Plan<C> of(SupplierWithContext.Ignored<C, List<T>> iterable, ConsumerWithContext.Ignored<List<T>, C> forEach) {
 		return new ForEachSlicePlan<>(iterable, forEach);
 	}
 
 	@Override
 	public void execute(TaskExecutor taskExecutor, C context, Runnable onCompletion) {
-		taskExecutor.execute(() -> PlanUtil.distributeSlices(taskExecutor, context, onCompletion, listSupplier.get(), action));
+		taskExecutor.execute(() -> PlanUtil.distributeSlices(taskExecutor, context, onCompletion, listSupplier.get(context), action));
 	}
 }

src/main/java/com/jozufozu/flywheel/lib/task/IfElsePlan.java

@@ -1,9 +1,8 @@
 package com.jozufozu.flywheel.lib.task;
 
-import java.util.function.Predicate;
-
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.BooleanSupplierWithContext;
 
 /**
  * Executes one plan or another, depending on a dynamically evaluated condition.
@@ -12,14 +11,19 @@ import com.jozufozu.flywheel.api.task.TaskExecutor;
  * @param onFalse The plan to execute if the condition is false.
  * @param <C> The type of the context object.
  */
-public record IfElsePlan<C>(Predicate<C> condition, Plan<C> onTrue, Plan<C> onFalse) implements SimplyComposedPlan<C> {
-	public static <C> Builder<C> on(Predicate<C> condition) {
+public record IfElsePlan<C>(BooleanSupplierWithContext<C> condition, Plan<C> onTrue,
+							Plan<C> onFalse) implements SimplyComposedPlan<C> {
+	public static <C> Builder<C> on(BooleanSupplierWithContext<C> condition) {
+		return new Builder<>(condition);
+	}
+
+	public static <C> Builder<C> on(BooleanSupplierWithContext.Ignored<C> condition) {
 		return new Builder<>(condition);
 	}
 
 	@Override
 	public void execute(TaskExecutor taskExecutor, C context, Runnable onCompletion) {
-		if (condition.test(context)) {
+		if (condition.getAsBoolean(context)) {
 			onTrue.execute(taskExecutor, context, onCompletion);
 		} else {
 			onFalse.execute(taskExecutor, context, onCompletion);
@@ -40,11 +44,11 @@ public record IfElsePlan<C>(Predicate<C> condition, Plan<C> onTrue, Plan<C> onFa
 	}
 
 	public static class Builder<C> {
-		private final Predicate<C> condition;
+		private final BooleanSupplierWithContext<C> condition;
 		private Plan<C> onTrue = UnitPlan.of();
 		private Plan<C> onFalse = UnitPlan.of();
 
-		public Builder(Predicate<C> condition) {
+		public Builder(BooleanSupplierWithContext<C> condition) {
 			this.condition = condition;
 		}
 

src/main/java/com/jozufozu/flywheel/lib/task/MapContextPlan.java

@@ -1,12 +1,15 @@
 package com.jozufozu.flywheel.lib.task;
 
-import java.util.function.Function;
-
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.SupplierWithContext;
 
-public record MapContextPlan<C, D>(Function<C, D> map, Plan<D> plan) implements SimplyComposedPlan<C> {
-	public static <C, D> Builder<C, D> map(Function<C, D> map) {
+public record MapContextPlan<C, D>(SupplierWithContext<C, D> map, Plan<D> plan) implements SimplyComposedPlan<C> {
+	public static <C, D> Builder<C, D> map(SupplierWithContext<C, D> map) {
+		return new Builder<>(map);
+	}
+
+	public static <C, D> Builder<C, D> get(SupplierWithContext.Ignored<C, D> map) {
 		return new Builder<>(map);
 	}
 
@@ -28,9 +31,9 @@ public record MapContextPlan<C, D>(Function<C, D> map, Plan<D> plan) implements
 	}
 
 	public static class Builder<C, D> {
-		private final Function<C, D> map;
+		private final SupplierWithContext<C, D> map;
 
-		public Builder(Function<C, D> map) {
+		public Builder(SupplierWithContext<C, D> map) {
 			this.map = map;
 		}
 

src/main/java/com/jozufozu/flywheel/lib/task/NestedPlan.java

@@ -7,6 +7,7 @@ import java.util.List;
 import com.google.common.collect.ImmutableList;
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.RunnableWithContext;
 
 public record NestedPlan<C>(List<Plan<C>> parallelPlans) implements SimplyComposedPlan<C> {
 	@SafeVarargs
@@ -54,7 +55,7 @@ public record NestedPlan<C>(List<Plan<C>> parallelPlans) implements SimplyCompos
 					.simplify();
 		}
 
-		var simplifiedTasks = new ArrayList<ContextConsumer<C>>();
+		var simplifiedTasks = new ArrayList<RunnableWithContext<C>>();
 		var simplifiedPlans = new ArrayList<Plan<C>>();
 		var toVisit = new ArrayDeque<>(parallelPlans);
 		while (!toVisit.isEmpty()) {

src/main/java/com/jozufozu/flywheel/lib/task/SimplePlan.java

@@ -5,19 +5,20 @@ import java.util.List;
 import com.google.common.collect.ImmutableList;
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.RunnableWithContext;
 
-public record SimplePlan<C>(List<ContextConsumer<C>> parallelTasks) implements SimplyComposedPlan<C> {
+public record SimplePlan<C>(List<RunnableWithContext<C>> parallelTasks) implements SimplyComposedPlan<C> {
 	@SafeVarargs
-	public static <C> SimplePlan<C> of(ContextRunnable<C>... tasks) {
+	public static <C> SimplePlan<C> of(RunnableWithContext.Ignored<C>... tasks) {
 		return new SimplePlan<>(List.of(tasks));
 	}
 
 	@SafeVarargs
-	public static <C> SimplePlan<C> of(ContextConsumer<C>... tasks) {
+	public static <C> SimplePlan<C> of(RunnableWithContext<C>... tasks) {
 		return new SimplePlan<>(List.of(tasks));
 	}
 
-	public static <C> SimplePlan<C> of(List<ContextConsumer<C>> tasks) {
+	public static <C> SimplePlan<C> of(List<RunnableWithContext<C>> tasks) {
 		return new SimplePlan<>(tasks);
 	}
 
@@ -28,15 +29,13 @@ public record SimplePlan<C>(List<ContextConsumer<C>> parallelTasks) implements S
 			return;
 		}
 
-		taskExecutor.execute(() -> {
-			PlanUtil.distribute(taskExecutor, context, onCompletion, parallelTasks, ContextConsumer::accept);
-		});
+		taskExecutor.execute(() -> PlanUtil.distribute(taskExecutor, context, onCompletion, parallelTasks, RunnableWithContext::run));
 	}
 
 	@Override
 	public Plan<C> and(Plan<C> plan) {
 		if (plan instanceof SimplePlan<C> simple) {
-			return of(ImmutableList.<ContextConsumer<C>>builder()
+			return of(ImmutableList.<RunnableWithContext<C>>builder()
 					.addAll(parallelTasks)
 					.addAll(simple.parallelTasks)
 					.build());

src/main/java/com/jozufozu/flywheel/lib/task/SyncedPlan.java

@@ -2,20 +2,26 @@ package com.jozufozu.flywheel.lib.task;
 
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.api.task.TaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.RunnableWithContext;
 
-public record SyncedPlan<C>(ContextConsumer<C> task) implements SimplyComposedPlan<C> {
-	public static <C> Plan<C> of(ContextConsumer<C> task) {
+public record SyncedPlan<C>(RunnableWithContext<C> task) implements SimplyComposedPlan<C> {
+	public static <C> Plan<C> of(RunnableWithContext<C> task) {
 		return new SyncedPlan<>(task);
 	}
 
-	public static <C> Plan<C> of(ContextRunnable<C> task) {
+	public static <C> Plan<C> of(RunnableWithContext.Ignored<C> task) {
 		return new SyncedPlan<>(task);
 	}
 
 	@Override
 	public void execute(TaskExecutor taskExecutor, C context, Runnable onCompletion) {
-		taskExecutor.scheduleForSync(() -> {
-			task.accept(context);
+		if (taskExecutor.isMainThread()) {
+			task.run(context);
+			onCompletion.run();
+			return;
+		}
+		taskExecutor.scheduleForMainThread(() -> {
+			task.run(context);
 			onCompletion.run();
 		});
 	}

src/main/java/com/jozufozu/flywheel/lib/task/functional/BooleanSupplierWithContext.java

@@ -0,0 +1,35 @@
+package com.jozufozu.flywheel.lib.task.functional;
+
+import java.util.function.BooleanSupplier;
+import java.util.function.Predicate;
+
+/**
+ * A boolean supplier like interface for use with {@link com.jozufozu.flywheel.api.task.Plan Plans} and their contexts.
+ *
+ * @param <C> The context type.
+ */
+@FunctionalInterface
+public interface BooleanSupplierWithContext<C> extends Predicate<C> {
+	boolean getAsBoolean(C context);
+
+	@Override
+	default boolean test(C c) {
+		return getAsBoolean(c);
+	}
+
+	/**
+	 * A {@link BooleanSupplierWithContext} that ignores the context object.
+	 *
+	 * @param <C> The (ignored) context type.
+	 */
+	@FunctionalInterface
+	interface Ignored<C> extends BooleanSupplierWithContext<C>, BooleanSupplier {
+		@Override
+		boolean getAsBoolean();
+
+		@Override
+		default boolean getAsBoolean(C ignored) {
+			return getAsBoolean();
+		}
+	}
+}

src/main/java/com/jozufozu/flywheel/lib/task/functional/ConsumerWithContext.java

@@ -0,0 +1,34 @@
+package com.jozufozu.flywheel.lib.task.functional;
+
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+
+/**
+ * A consumer like interface for use with {@link com.jozufozu.flywheel.api.task.Plan Plans} and their contexts.
+ * <br>
+ * The subinterface {@link Ignored} is provided for consumers that do not need the context object.
+ *
+ * @param <T> The type to actually consume.
+ * @param <C> The context type.
+ */
+@FunctionalInterface
+public interface ConsumerWithContext<T, C> extends BiConsumer<T, C> {
+	void accept(T t, C context);
+
+	/**
+	 * A {@link ConsumerWithContext} that ignores the context object.
+	 *
+	 * @param <T> The type to actually consume.
+	 * @param <C> The (ignored) context type.
+	 */
+	@FunctionalInterface
+	interface Ignored<T, C> extends ConsumerWithContext<T, C>, Consumer<T> {
+		@Override
+		void accept(T t);
+
+		@Override
+		default void accept(T t, C ignored) {
+			accept(t);
+		}
+	}
+}

src/main/java/com/jozufozu/flywheel/lib/task/functional/RunnableWithContext.java

@@ -0,0 +1,35 @@
+package com.jozufozu.flywheel.lib.task.functional;
+
+import java.util.function.Consumer;
+
+/**
+ * A runnable like interface for use with {@link com.jozufozu.flywheel.api.task.Plan Plans} and their contexts.
+ * <br>
+ * The subinterface {@link Ignored} is provided for runnables that do not need the context object.
+ * @param <C> The context type.
+ */
+@FunctionalInterface
+public interface RunnableWithContext<C> extends Consumer<C> {
+	void run(C context);
+
+	@Override
+	default void accept(C c) {
+		run(c);
+	}
+
+	/**
+	 * A {@link RunnableWithContext} that ignores the context object.
+	 *
+	 * @param <C> The (ignored) context type.
+	 */
+	@FunctionalInterface
+	interface Ignored<C> extends RunnableWithContext<C>, Runnable {
+		@Override
+		void run();
+
+		@Override
+		default void run(C ignored) {
+			run();
+		}
+	}
+}

src/main/java/com/jozufozu/flywheel/lib/task/functional/SupplierWithContext.java

@@ -0,0 +1,38 @@
+package com.jozufozu.flywheel.lib.task.functional;
+
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+/**
+ * A supplier like interface for use with {@link com.jozufozu.flywheel.api.task.Plan Plans} and their contexts.
+ * <br>
+ * The subinterface {@link Ignored} is provided for suppliers that do not need the context object.
+ * @param <C> The context type.
+ * @param <R> The return type.
+ */
+@FunctionalInterface
+public interface SupplierWithContext<C, R> extends Function<C, R> {
+	R get(C context);
+
+	@Override
+	default R apply(C c) {
+		return get(c);
+	}
+
+	/**
+	 * A {@link SupplierWithContext} that ignores the context object.
+	 *
+	 * @param <C> The (ignored) context type.
+	 * @param <R> The return type.
+	 */
+	@FunctionalInterface
+	interface Ignored<C, R> extends SupplierWithContext<C, R>, Supplier<R> {
+		@Override
+		R get();
+
+		@Override
+		default R get(C ignored) {
+			return get();
+		}
+	}
+}

src/main/java/com/jozufozu/flywheel/lib/task/functional/package-info.java

@@ -0,0 +1,8 @@
+/**
+ * Functional interfaces accepting a context object for use with {@link com.jozufozu.flywheel.api.task.Plan Plans}.
+ * <br>
+ * Each interface in this package has a subinterface that ignores the context object. Plans then call the parent
+ * interface, but do not need to create additional closure objects to translate when the consumer wishes to ignore
+ * the context object.
+ */
+package com.jozufozu.flywheel.lib.task.functional;

src/test/java/com/jozufozu/flywheel/lib/task/PlanExecutionTest.java

@@ -5,9 +5,9 @@ import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Assertions;
-import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.RepeatedTest;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -15,22 +15,26 @@ import org.junit.jupiter.params.provider.ValueSource;
 
 import com.jozufozu.flywheel.api.task.Plan;
 import com.jozufozu.flywheel.impl.task.ParallelTaskExecutor;
+import com.jozufozu.flywheel.lib.task.functional.RunnableWithContext;
 import com.jozufozu.flywheel.lib.util.Unit;
 
 import it.unimi.dsi.fastutil.ints.IntArrayList;
 
 class PlanExecutionTest {
 
-	protected static final ParallelTaskExecutor EXECUTOR = new ParallelTaskExecutor("PlanTest");
+	protected static ParallelTaskExecutor EXECUTOR;
 
-	@BeforeAll
-	public static void setUp() {
+	@BeforeEach
+	public void setUp() {
+		var currentThread = Thread.currentThread();
+		EXECUTOR = new ParallelTaskExecutor("PlanTest", () -> currentThread == Thread.currentThread());
 		EXECUTOR.startWorkers();
 	}
 
-	@AfterAll
-	public static void tearDown() {
+	@AfterEach
+	public void tearDown() {
 		EXECUTOR.stopWorkers();
+		EXECUTOR = null;
 	}
 
 	@ParameterizedTest
@@ -73,12 +77,12 @@ class PlanExecutionTest {
 		var lock = new Object();
 		var sequence = new IntArrayList(8);
 
-		ContextRunnable<Unit> addOne = () -> {
+		RunnableWithContext.Ignored<Unit> addOne = () -> {
 			synchronized (lock) {
 				sequence.add(1);
 			}
 		};
-		ContextRunnable<Unit> addTwo = () -> {
+		RunnableWithContext.Ignored<Unit> addTwo = () -> {
 			synchronized (lock) {
 				sequence.add(2);
 			}
@@ -185,12 +189,26 @@ class PlanExecutionTest {
 	}
 
 	@Test
-	void mainThreadPlan() {
+	void mainThreadPlanRunsImmediately() {
 		var done = new AtomicBoolean(false);
 		var plan = SyncedPlan.of(() -> done.set(true));
 
 		plan.execute(EXECUTOR, Unit.INSTANCE);
 
+		Assertions.assertTrue(done.get());
+	}
+
+	@Test
+	void mainThreadPlanIsNotCalledOffThread() {
+		var done = new AtomicBoolean(false);
+
+		var plan = SyncedPlan.of(() -> {
+			done.set(true);
+		});
+
+		// call execute from within a worker thread
+		EXECUTOR.execute(() -> plan.execute(EXECUTOR, Unit.INSTANCE));
+
 		Assertions.assertFalse(done.get());
 
 		EXECUTOR.syncPoint();
@@ -222,16 +240,18 @@ class PlanExecutionTest {
 		var first = new NamedFlag("ready right away");
 		var second = new NamedFlag("ready after 2s");
 
-		RaisePlan.raise(first)
+		var plan = RaisePlan.raise(first)
 				.then(SimplePlan.of(() -> {
+					// sleep to add delay between raising the first flag and raising the second flag
 					try {
 						Thread.sleep(2000);
 					} catch (InterruptedException e) {
 						throw new RuntimeException(e);
 					}
 				}))
-				.then(RaisePlan.raise(second))
-				.execute(EXECUTOR, Unit.INSTANCE);
+				.then(RaisePlan.raise(second));
+
+		EXECUTOR.execute(() -> plan.execute(EXECUTOR, Unit.INSTANCE));
 
 		Assertions.assertTrue(EXECUTOR.syncUntil(first::isRaised), "First flag should be raised since we submitted a plan that raises it.");
 
@@ -260,7 +280,7 @@ class PlanExecutionTest {
 	}
 
 	public static void runAndWait(Plan<Unit> plan) {
-		new TestBarrier<Unit>(plan, Unit.INSTANCE).runAndWait();
+		new TestBarrier<>(plan, Unit.INSTANCE).runAndWait();
 	}
 
 	public static <C> void runAndWait(Plan<C> plan, C ctx) {

src/test/java/com/jozufozu/flywheel/lib/task/PlanSimplificationTest.java

@@ -4,11 +4,12 @@ import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
 import com.jozufozu.flywheel.api.task.Plan;
+import com.jozufozu.flywheel.lib.task.functional.RunnableWithContext;
 import com.jozufozu.flywheel.lib.util.Unit;
 
 public class PlanSimplificationTest {
 
-	public static final ContextRunnable<Unit> NOOP = () -> {
+	public static final RunnableWithContext.Ignored<Unit> NOOP = () -> {
 	};
 	public static final Plan<Unit> SIMPLE = SimplePlan.of(NOOP);