HashedWheelTimer Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/HashedWheelTimer.java lines 85–865

public class HashedWheelTimer implements Timer {

    static final InternalLogger logger =
            InternalLoggerFactory.getInstance(HashedWheelTimer.class);

    private static final AtomicInteger INSTANCE_COUNTER = new AtomicInteger();
    private static final AtomicBoolean WARNED_TOO_MANY_INSTANCES = new AtomicBoolean();
    private static final int INSTANCE_COUNT_LIMIT = 64;
    private static final long MILLISECOND_NANOS = TimeUnit.MILLISECONDS.toNanos(1);
    private static final ResourceLeakDetector<HashedWheelTimer> leakDetector = ResourceLeakDetectorFactory.instance()
            .newResourceLeakDetector(HashedWheelTimer.class, 1);

    private static final AtomicIntegerFieldUpdater<HashedWheelTimer> WORKER_STATE_UPDATER =
            AtomicIntegerFieldUpdater.newUpdater(HashedWheelTimer.class, "workerState");

    private final ResourceLeakTracker<HashedWheelTimer> leak;
    private final Worker worker = new Worker();
    private final Thread workerThread;

    public static final int WORKER_STATE_INIT = 0;
    public static final int WORKER_STATE_STARTED = 1;
    public static final int WORKER_STATE_SHUTDOWN = 2;
    @SuppressWarnings({"unused", "FieldMayBeFinal"})
    private volatile int workerState; // 0 - init, 1 - started, 2 - shut down

    private final long tickDuration;
    private final HashedWheelBucket[] wheel;
    private final int mask;
    private final CountDownLatch startTimeInitialized = new CountDownLatch(1);
    private final Queue<HashedWheelTimeout> timeouts = PlatformDependent.newMpscQueue();
    private final Queue<HashedWheelTimeout> cancelledTimeouts = PlatformDependent.newMpscQueue();
    private final AtomicLong pendingTimeouts = new AtomicLong(0);
    private final long maxPendingTimeouts;
    private final Executor taskExecutor;

    private volatile long startTime;

    /**
     * Creates a new timer with the default thread factory
     * ({@link Executors#defaultThreadFactory()}), default tick duration, and
     * default number of ticks per wheel.
     */
    public HashedWheelTimer() {
        this(Executors.defaultThreadFactory());
    }

    /**
     * Creates a new timer with the default thread factory
     * ({@link Executors#defaultThreadFactory()}) and default number of ticks
     * per wheel.
     *
     * @param tickDuration the duration between tick
     * @param unit         the time unit of the {@code tickDuration}
     * @throws NullPointerException     if {@code unit} is {@code null}
     * @throws IllegalArgumentException if {@code tickDuration} is &lt;= 0
     */
    public HashedWheelTimer(long tickDuration, TimeUnit unit) {
        this(Executors.defaultThreadFactory(), tickDuration, unit);
    }

    /**
     * Creates a new timer with the default thread factory
     * ({@link Executors#defaultThreadFactory()}).
     *
     * @param tickDuration  the duration between tick
     * @param unit          the time unit of the {@code tickDuration}
     * @param ticksPerWheel the size of the wheel
     * @throws NullPointerException     if {@code unit} is {@code null}
     * @throws IllegalArgumentException if either of {@code tickDuration} and {@code ticksPerWheel} is &lt;= 0
     */
    public HashedWheelTimer(long tickDuration, TimeUnit unit, int ticksPerWheel) {
        this(Executors.defaultThreadFactory(), tickDuration, unit, ticksPerWheel);
    }

    /**
     * Creates a new timer with the default tick duration and default number of
     * ticks per wheel.
     *
     * @param threadFactory a {@link ThreadFactory} that creates a
     *                      background {@link Thread} which is dedicated to
     *                      {@link TimerTask} execution.