SingleThreadEventExecutor Class — netty Architecture

Source Code

common/src/main/java/io/netty/util/concurrent/SingleThreadEventExecutor.java lines 55–1371

public abstract class SingleThreadEventExecutor extends AbstractScheduledEventExecutor implements OrderedEventExecutor {

    static final int DEFAULT_MAX_PENDING_EXECUTOR_TASKS = Math.max(16,
            SystemPropertyUtil.getInt("io.netty.eventexecutor.maxPendingTasks", Integer.MAX_VALUE));

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

    private static final int ST_NOT_STARTED = 1;
    private static final int ST_SUSPENDING = 2;
    private static final int ST_SUSPENDED = 3;
    private static final int ST_STARTED = 4;
    private static final int ST_SHUTTING_DOWN = 5;
    private static final int ST_SHUTDOWN = 6;
    private static final int ST_TERMINATED = 7;

    private static final Runnable NOOP_TASK = new Runnable() {
        @Override
        public void run() {
            // Do nothing.
        }
    };

    private static final AtomicIntegerFieldUpdater<SingleThreadEventExecutor> STATE_UPDATER =
            AtomicIntegerFieldUpdater.newUpdater(SingleThreadEventExecutor.class, "state");
    private static final AtomicReferenceFieldUpdater<SingleThreadEventExecutor, ThreadProperties> PROPERTIES_UPDATER =
            AtomicReferenceFieldUpdater.newUpdater(
                    SingleThreadEventExecutor.class, ThreadProperties.class, "threadProperties");
    private static final AtomicLongFieldUpdater<SingleThreadEventExecutor> ACCUMULATED_ACTIVE_TIME_NANOS_UPDATER =
            AtomicLongFieldUpdater.newUpdater(SingleThreadEventExecutor.class, "accumulatedActiveTimeNanos");
    private static final AtomicIntegerFieldUpdater<SingleThreadEventExecutor> CONSECUTIVE_IDLE_CYCLES_UPDATER =
            AtomicIntegerFieldUpdater.newUpdater(SingleThreadEventExecutor.class, "consecutiveIdleCycles");
    private static final AtomicIntegerFieldUpdater<SingleThreadEventExecutor> CONSECUTIVE_BUSY_CYCLES_UPDATER =
            AtomicIntegerFieldUpdater.newUpdater(SingleThreadEventExecutor.class, "consecutiveBusyCycles");
    private final Queue<Runnable> taskQueue;

    private volatile Thread thread;
    @SuppressWarnings("unused")
    private volatile ThreadProperties threadProperties;
    private final Executor executor;
    private volatile boolean interrupted;

    private final Lock processingLock = new ReentrantLock();
    private final CountDownLatch threadLock = new CountDownLatch(1);
    private final Set<Runnable> shutdownHooks = new LinkedHashSet<Runnable>();
    private final boolean addTaskWakesUp;
    private final int maxPendingTasks;
    private final RejectedExecutionHandler rejectedExecutionHandler;
    private final boolean supportSuspension;

    // A running total of nanoseconds this executor has spent in an "active" state.
    private volatile long accumulatedActiveTimeNanos;
    // Timestamp of the last recorded activity (tasks + I/O).
    private volatile long lastActivityTimeNanos;
    /**
     * Tracks the number of consecutive monitor cycles this executor's
     * utilization has been below the scale-down threshold.
     */
    private volatile int consecutiveIdleCycles;

    /**
     * Tracks the number of consecutive monitor cycles this executor's
     * utilization has been above the scale-up threshold.
     */
    private volatile int consecutiveBusyCycles;
    private long lastExecutionTime;

    @SuppressWarnings({ "FieldMayBeFinal", "unused" })
    private volatile int state = ST_NOT_STARTED;

    private volatile long gracefulShutdownQuietPeriod;
    private volatile long gracefulShutdownTimeout;
    private long gracefulShutdownStartTime;

    private final Promise<?> terminationFuture = new DefaultPromise<Void>(GlobalEventExecutor.INSTANCE);

    /**
     * Create a new instance
     *
     * @param parent            the {@link EventExecutorGroup} which is the parent of this instance and belongs to it
     * @param threadFactory     the {@link ThreadFactory} which will be used for the used {@link Thread}