/** Returns the delay in nanoseconds until the next execution, or -1L to not reschedule. */
  abstract fun runOnce(): Long

  internal fun initQueue(queue: TaskQueue) {
    if (this.queue === queue) return

    check(this.queue === null) { "task is in multiple queues" }
    this.queue = queue
  }

  override fun toString(): String = name

import java.util.Queue;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Creates queues, containing sample elements, to be tested.
 *
 * @author Jared Levy
 */
@GwtCompatible
@NullMarked
public interface TestQueueGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
  @Override
  Queue<E> create(Object... elements);

 *
 * Work within queues is not concurrent. This is equivalent to each queue having a dedicated thread
 * for its work; in practice a set of queues may share a set of threads to save resources.
 */
class TaskQueue internal constructor(
  internal val taskRunner: TaskRunner,
  internal val name: String,
) {
  internal var shutdown = false

import java.util.Queue;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Creates queues, containing sample elements, to be tested.
 *
 * @author Jared Levy
 */
@GwtCompatible
@NullMarked
public interface TestQueueGenerator<E extends @Nullable Object> extends TestCollectionGenerator<E> {
  @Override
  Queue<E> create(Object... elements);

import java.util.Collection;
import java.util.Queue;

/**
 * A non-blocking queue which automatically evicts elements from the head of the queue when
 * attempting to add new elements onto the queue and it is full. This queue orders elements FIFO
 * (first-in-first-out). This data structure is logically equivalent to a circular buffer (i.e.,
 * cyclic buffer or ring buffer).
 *

    // This dispatcher matches the original dispatch behavior of EventBus.

    /** Per-thread queue of events to dispatch. */
    @SuppressWarnings("ThreadLocalUsage") // Each Dispatcher needs its own state.
    private final ThreadLocal<Queue<Event>> queue =
        new ThreadLocal<Queue<Event>>() {
          @Override
          protected Queue<Event> initialValue() {
            return new ArrayDeque<>();
          }
        };

import java.util.LinkedList;
import java.util.Queue;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Synchronized#queue} and {@link Queues#synchronizedQueue}.
 *
 * @author Kurt Alfred Kluever
 */
@NullUnmarked
public class SynchronizedQueueTest extends TestCase {

  protected Queue<String> create() {

import java.util.LinkedList;
import java.util.Queue;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Synchronized#queue} and {@link Queues#synchronizedQueue}.
 *
 * @author Kurt Alfred Kluever
 */
@NullUnmarked
public class SynchronizedQueueTest extends TestCase {

  protected Queue<String> create() {

import java.util.LinkedList;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Synchronized#deque} and {@link Queues#synchronizedDeque}.
 *
 * @author Kurt Alfred Kluever
 */
@NullUnmarked
public class SynchronizedDequeTest extends TestCase {

  protected Deque<String> create() {
    TestDeque<String> inner = new TestDeque<>();

import java.util.Collection;
import java.util.Queue;

/**
 * A non-blocking queue which automatically evicts elements from the head of the queue when
 * attempting to add new elements onto the queue and it is full. This queue orders elements FIFO
 * (first-in-first-out). This data structure is logically equivalent to a circular buffer (i.e.,
 * cyclic buffer or ring buffer).
 *