Class FakeClock

core/src/testFixtures/java/io/grpc/internal/FakeClock.java:44–421

A manipulated clock that exports a Ticker and a ScheduledExecutorService. To simulate the locking scenario of using real executors, it never runs tasks within schedule() or execute(). Instead, you should call #runDueTasks in your test method to run all due

 * #runDueTasks} automatically.
 */
public final class FakeClock {

  private static final TaskFilter ACCEPT_ALL_FILTER = new TaskFilter() {
      @Override
      public boolean shouldAccept(Runnable command) {
        return true;
      }
    };

  private final ScheduledExecutorService scheduledExecutorService = new ScheduledExecutorImpl();

  private final PriorityBlockingQueue<ScheduledTask> scheduledTasks = new PriorityBlockingQueue<>();
  private final LinkedBlockingQueue<ScheduledTask> dueTasks = new LinkedBlockingQueue<>();

  private final Ticker ticker =
      new Ticker() {
        @Override public long read() {
          return currentTimeNanos;
        }
      };

  private final Deadline.Ticker deadlineTicker =
      new Deadline.Ticker() {
        @Override public long nanoTime() {
          return currentTimeNanos;
        }
      };

  private final Supplier<Stopwatch> stopwatchSupplier =
      new Supplier<Stopwatch>() {
        @Override public Stopwatch get() {
          return Stopwatch.createUnstarted(ticker);
        }
      };

  private final TimeProvider timeProvider =
      new TimeProvider() {
        @Override
        public long currentTimeNanos() {
          return currentTimeNanos;
        }
      };

  private long currentTimeNanos;

  public class ScheduledTask extends AbstractFuture<Void> implements ScheduledFuture<Void> {
    public final Runnable command;
    public long dueTimeNanos;

    ScheduledTask(Runnable command) {
      this.command = command;
    }

    void run() {
      command.run();
      set(null);
    }