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Java example source code file (SingleThreadEventExecutor.java)

This example Java source code file (SingleThreadEventExecutor.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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Java - Java tags/keywords

interruptedexception, nullpointerexception, override, runnable, singlethreadeventexecutor, st_not_started, st_shutdown, st_shutting_down, st_started, st_terminated, suppresswarnings, threading, threadproperties, threads, throwable, util, wakeup_task

The SingleThreadEventExecutor.java Java example source code

/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.util.concurrent;

import io.netty.util.internal.ObjectUtil;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.SystemPropertyUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;

import java.lang.Thread.State;
import java.util.ArrayList;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.Semaphore;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;

/**
 * Abstract base class for {@link EventExecutor}'s that execute all its submitted tasks in a single thread.
 *
 */
public abstract class SingleThreadEventExecutor extends AbstractScheduledEventExecutor {

    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_STARTED = 2;
    private static final int ST_SHUTTING_DOWN = 3;
    private static final int ST_SHUTDOWN = 4;
    private static final int ST_TERMINATED = 5;

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

    private static final AtomicIntegerFieldUpdater<SingleThreadEventExecutor> STATE_UPDATER;
    private static final AtomicReferenceFieldUpdater<SingleThreadEventExecutor, ThreadProperties> PROPERTIES_UPDATER;

    static {
        AtomicIntegerFieldUpdater<SingleThreadEventExecutor> updater =
                PlatformDependent.newAtomicIntegerFieldUpdater(SingleThreadEventExecutor.class, "state");
        if (updater == null) {
            updater = AtomicIntegerFieldUpdater.newUpdater(SingleThreadEventExecutor.class, "state");
        }
        STATE_UPDATER = updater;

        AtomicReferenceFieldUpdater<SingleThreadEventExecutor, ThreadProperties> propertiesUpdater =
                PlatformDependent.newAtomicReferenceFieldUpdater(SingleThreadEventExecutor.class, "threadProperties");
        if (propertiesUpdater == null) {
            propertiesUpdater = AtomicReferenceFieldUpdater.newUpdater(SingleThreadEventExecutor.class,
                                                                   ThreadProperties.class, "threadProperties");
        }
        PROPERTIES_UPDATER = propertiesUpdater;
    }

    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 Semaphore threadLock = new Semaphore(0);
    private final Set<Runnable> shutdownHooks = new LinkedHashSet();
    private final boolean addTaskWakesUp;
    private final int maxPendingTasks;
    private final RejectedExecutionHandler rejectedExecutionHandler;

    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(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}
     * @param addTaskWakesUp    {@code true} if and only if invocation of {@link #addTask(Runnable)} will wake up the
     *                          executor thread
     */
    protected SingleThreadEventExecutor(
            EventExecutorGroup parent, ThreadFactory threadFactory, boolean addTaskWakesUp) {
        this(parent, new ThreadPerTaskExecutor(threadFactory), addTaskWakesUp);
    }

    /**
     * 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}
     * @param addTaskWakesUp    {@code true} if and only if invocation of {@link #addTask(Runnable)} will wake up the
     *                          executor thread
     * @param maxPendingTasks   the maximum number of pending tasks before new tasks will be rejected.
     * @param rejectedHandler   the {@link RejectedExecutionHandler} to use.
     */
    protected SingleThreadEventExecutor(
            EventExecutorGroup parent, ThreadFactory threadFactory,
            boolean addTaskWakesUp, int maxPendingTasks, RejectedExecutionHandler rejectedHandler) {
        this(parent, new ThreadPerTaskExecutor(threadFactory), addTaskWakesUp, maxPendingTasks, rejectedHandler);
    }

    /**
     * Create a new instance
     *
     * @param parent            the {@link EventExecutorGroup} which is the parent of this instance and belongs to it
     * @param executor          the {@link Executor} which will be used for executing
     * @param addTaskWakesUp    {@code true} if and only if invocation of {@link #addTask(Runnable)} will wake up the
     *                          executor thread
     */
    protected SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor, boolean addTaskWakesUp) {
        this(parent, executor, addTaskWakesUp, DEFAULT_MAX_PENDING_EXECUTOR_TASKS, RejectedExecutionHandlers.reject());
    }

    /**
     * Create a new instance
     *
     * @param parent            the {@link EventExecutorGroup} which is the parent of this instance and belongs to it
     * @param executor          the {@link Executor} which will be used for executing
     * @param addTaskWakesUp    {@code true} if and only if invocation of {@link #addTask(Runnable)} will wake up the
     *                          executor thread
     * @param maxPendingTasks   the maximum number of pending tasks before new tasks will be rejected.
     * @param rejectedHandler   the {@link RejectedExecutionHandler} to use.
     */
    protected SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor,
                                        boolean addTaskWakesUp, int maxPendingTasks,
                                        RejectedExecutionHandler rejectedHandler) {
        super(parent);
        this.addTaskWakesUp = addTaskWakesUp;
        this.maxPendingTasks = Math.max(16, maxPendingTasks);
        this.executor = ObjectUtil.checkNotNull(executor, "executor");
        taskQueue = newTaskQueue();
        rejectedExecutionHandler = ObjectUtil.checkNotNull(rejectedHandler, "rejectedHandler");
    }

    /**
     * @deprecated Please use and override {@link #newTaskQueue(int)}.
     */
    @Deprecated
    protected Queue<Runnable> newTaskQueue() {
        return newTaskQueue(maxPendingTasks);
    }

    /**
     * Create a new {@link Queue} which will holds the tasks to execute. This default implementation will return a
     * {@link LinkedBlockingQueue} but if your sub-class of {@link SingleThreadEventExecutor} will not do any blocking
     * calls on the this {@link Queue} it may make sense to {@code @Override} this and return some more performant
     * implementation that does not support blocking operations at all.
     */
    protected Queue<Runnable> newTaskQueue(int maxPendingTasks) {
        return new LinkedBlockingQueue<Runnable>(maxPendingTasks);
    }

    /**
     * Interrupt the current running {@link Thread}.
     */
    protected void interruptThread() {
        Thread currentThread = thread;
        if (currentThread == null) {
            interrupted = true;
        } else {
            currentThread.interrupt();
        }
    }

    /**
     * @see {@link Queue#poll()}
     */
    protected Runnable pollTask() {
        assert inEventLoop();
        for (;;) {
            Runnable task = taskQueue.poll();
            if (task == WAKEUP_TASK) {
                continue;
            }
            return task;
        }
    }

    /**
     * Take the next {@link Runnable} from the task queue and so will block if no task is currently present.
     * <p>
     * Be aware that this method will throw an {@link UnsupportedOperationException} if the task queue, which was
     * created via {@link #newTaskQueue()}, does not implement {@link BlockingQueue}.
     * </p>
     *
     * @return {@code null} if the executor thread has been interrupted or waken up.
     */
    protected Runnable takeTask() {
        assert inEventLoop();
        if (!(taskQueue instanceof BlockingQueue)) {
            throw new UnsupportedOperationException();
        }

        BlockingQueue<Runnable> taskQueue = (BlockingQueue) this.taskQueue;
        for (;;) {
            ScheduledFutureTask<?> scheduledTask = peekScheduledTask();
            if (scheduledTask == null) {
                Runnable task = null;
                try {
                    task = taskQueue.take();
                    if (task == WAKEUP_TASK) {
                        task = null;
                    }
                } catch (InterruptedException e) {
                    // Ignore
                }
                return task;
            } else {
                long delayNanos = scheduledTask.delayNanos();
                Runnable task = null;
                if (delayNanos > 0) {
                    try {
                        task = taskQueue.poll(delayNanos, TimeUnit.NANOSECONDS);
                    } catch (InterruptedException e) {
                        // Waken up.
                        return null;
                    }
                }
                if (task == null) {
                    // We need to fetch the scheduled tasks now as otherwise there may be a chance that
                    // scheduled tasks are never executed if there is always one task in the taskQueue.
                    // This is for example true for the read task of OIO Transport
                    // See https://github.com/netty/netty/issues/1614
                    fetchFromScheduledTaskQueue();
                    task = taskQueue.poll();
                }

                if (task != null) {
                    return task;
                }
            }
        }
    }

    private boolean fetchFromScheduledTaskQueue() {
        if (hasScheduledTasks()) {
            long nanoTime = AbstractScheduledEventExecutor.nanoTime();
            for (;;) {
                Runnable scheduledTask = pollScheduledTask(nanoTime);
                if (scheduledTask == null) {
                    break;
                }
                if (!taskQueue.offer(scheduledTask)) {
                    // No space left in the task queue add it back to the scheduledTaskQueue so we pick it up again.
                    scheduledTaskQueue().add((ScheduledFutureTask<?>) scheduledTask);
                    return false;
                }
            }
        }
        return true;
    }

    /**
     * @see {@link Queue#peek()}
     */
    protected Runnable peekTask() {
        assert inEventLoop();
        return taskQueue.peek();
    }

    /**
     * @see {@link Queue#isEmpty()}
     */
    protected boolean hasTasks() {
        assert inEventLoop();
        return !taskQueue.isEmpty();
    }

    /**
     * Return the number of tasks that are pending for processing.
     *
     * <strong>Be aware that this operation may be expensive as it depends on the internal implementation of the
     * SingleThreadEventExecutor. So use it was care!</strong>
     */
    public int pendingTasks() {
        return taskQueue.size();
    }

    /**
     * Add a task to the task queue, or throws a {@link RejectedExecutionException} if this instance was shutdown
     * before.
     */
    protected void addTask(Runnable task) {
        if (task == null) {
            throw new NullPointerException("task");
        }
        if (!offerTask(task)) {
            rejectedExecutionHandler.rejected(task, this);
        }
    }

    final boolean offerTask(Runnable task) {
        if (isShutdown()) {
            reject();
        }
        return taskQueue.offer(task);
    }

    /**
     * @see {@link Queue#remove(Object)}
     */
    protected boolean removeTask(Runnable task) {
        if (task == null) {
            throw new NullPointerException("task");
        }
        return taskQueue.remove(task);
    }

    /**
     * Poll all tasks from the task queue and run them via {@link Runnable#run()} method.
     *
     * @return {@code true} if and only if at least one task was run
     */
    protected boolean runAllTasks() {
        boolean fetchedAll;
        do {
            fetchedAll = fetchFromScheduledTaskQueue();
            Runnable task = pollTask();
            if (task == null) {
                return false;
            }

            for (;;) {
                try {
                    task.run();
                } catch (Throwable t) {
                    logger.warn("A task raised an exception.", t);
                }

                task = pollTask();
                if (task == null) {
                    break;
                }
            }
        } while (!fetchedAll); // keep on processing until we fetched all scheduled tasks.

        lastExecutionTime = ScheduledFutureTask.nanoTime();
        return true;
    }

    /**
     * Poll all tasks from the task queue and run them via {@link Runnable#run()} method.  This method stops running
     * the tasks in the task queue and returns if it ran longer than {@code timeoutNanos}.
     */
    protected boolean runAllTasks(long timeoutNanos) {
        fetchFromScheduledTaskQueue();
        Runnable task = pollTask();
        if (task == null) {
            return false;
        }

        final long deadline = ScheduledFutureTask.nanoTime() + timeoutNanos;
        long runTasks = 0;
        long lastExecutionTime;
        for (;;) {
            try {
                task.run();
            } catch (Throwable t) {
                logger.warn("A task raised an exception.", t);
            }

            runTasks ++;

            // Check timeout every 64 tasks because nanoTime() is relatively expensive.
            // XXX: Hard-coded value - will make it configurable if it is really a problem.
            if ((runTasks & 0x3F) == 0) {
                lastExecutionTime = ScheduledFutureTask.nanoTime();
                if (lastExecutionTime >= deadline) {
                    break;
                }
            }

            task = pollTask();
            if (task == null) {
                lastExecutionTime = ScheduledFutureTask.nanoTime();
                break;
            }
        }

        this.lastExecutionTime = lastExecutionTime;
        return true;
    }

    /**
     * Returns the amount of time left until the scheduled task with the closest dead line is executed.
     */
    protected long delayNanos(long currentTimeNanos) {
        ScheduledFutureTask<?> scheduledTask = peekScheduledTask();
        if (scheduledTask == null) {
            return SCHEDULE_PURGE_INTERVAL;
        }

        return scheduledTask.delayNanos(currentTimeNanos);
    }

    /**
     * Updates the internal timestamp that tells when a submitted task was executed most recently.
     * {@link #runAllTasks()} and {@link #runAllTasks(long)} updates this timestamp automatically, and thus there's
     * usually no need to call this method.  However, if you take the tasks manually using {@link #takeTask()} or
     * {@link #pollTask()}, you have to call this method at the end of task execution loop for accurate quiet period
     * checks.
     */
    protected void updateLastExecutionTime() {
        lastExecutionTime = ScheduledFutureTask.nanoTime();
    }

    /**
     *
     */
    protected abstract void run();

    /**
     * Do nothing, sub-classes may override
     */
    protected void cleanup() {
        // NOOP
    }

    protected void wakeup(boolean inEventLoop) {
        if (!inEventLoop || STATE_UPDATER.get(this) == ST_SHUTTING_DOWN) {
            // Use offer as we actually only need this to unblock the thread and if offer fails we do not care as there
            // is already something in the queue.
            taskQueue.offer(WAKEUP_TASK);
        }
    }

    @Override
    public boolean inEventLoop(Thread thread) {
        return thread == this.thread;
    }

    /**
     * Add a {@link Runnable} which will be executed on shutdown of this instance
     */
    public void addShutdownHook(final Runnable task) {
        if (inEventLoop()) {
            shutdownHooks.add(task);
        } else {
            execute(new Runnable() {
                @Override
                public void run() {
                    shutdownHooks.add(task);
                }
            });
        }
    }

    /**
     * Remove a previous added {@link Runnable} as a shutdown hook
     */
    public void removeShutdownHook(final Runnable task) {
        if (inEventLoop()) {
            shutdownHooks.remove(task);
        } else {
            execute(new Runnable() {
                @Override
                public void run() {
                    shutdownHooks.remove(task);
                }
            });
        }
    }

    private boolean runShutdownHooks() {
        boolean ran = false;
        // Note shutdown hooks can add / remove shutdown hooks.
        while (!shutdownHooks.isEmpty()) {
            List<Runnable> copy = new ArrayList(shutdownHooks);
            shutdownHooks.clear();
            for (Runnable task: copy) {
                try {
                    task.run();
                } catch (Throwable t) {
                    logger.warn("Shutdown hook raised an exception.", t);
                } finally {
                    ran = true;
                }
            }
        }

        if (ran) {
            lastExecutionTime = ScheduledFutureTask.nanoTime();
        }

        return ran;
    }

    @Override
    public Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
        if (quietPeriod < 0) {
            throw new IllegalArgumentException("quietPeriod: " + quietPeriod + " (expected >= 0)");
        }
        if (timeout < quietPeriod) {
            throw new IllegalArgumentException(
                    "timeout: " + timeout + " (expected >= quietPeriod (" + quietPeriod + "))");
        }
        if (unit == null) {
            throw new NullPointerException("unit");
        }

        if (isShuttingDown()) {
            return terminationFuture();
        }

        boolean inEventLoop = inEventLoop();
        boolean wakeup;
        int oldState;
        for (;;) {
            if (isShuttingDown()) {
                return terminationFuture();
            }
            int newState;
            wakeup = true;
            oldState = STATE_UPDATER.get(this);
            if (inEventLoop) {
                newState = ST_SHUTTING_DOWN;
            } else {
                switch (oldState) {
                    case ST_NOT_STARTED:
                    case ST_STARTED:
                        newState = ST_SHUTTING_DOWN;
                        break;
                    default:
                        newState = oldState;
                        wakeup = false;
                }
            }
            if (STATE_UPDATER.compareAndSet(this, oldState, newState)) {
                break;
            }
        }
        gracefulShutdownQuietPeriod = unit.toNanos(quietPeriod);
        gracefulShutdownTimeout = unit.toNanos(timeout);

        if (oldState == ST_NOT_STARTED) {
            doStartThread();
        }

        if (wakeup) {
            wakeup(inEventLoop);
        }

        return terminationFuture();
    }

    @Override
    public Future<?> terminationFuture() {
        return terminationFuture;
    }

    @Override
    @Deprecated
    public void shutdown() {
        if (isShutdown()) {
            return;
        }

        boolean inEventLoop = inEventLoop();
        boolean wakeup;
        int oldState;
        for (;;) {
            if (isShuttingDown()) {
                return;
            }
            int newState;
            wakeup = true;
            oldState = STATE_UPDATER.get(this);
            if (inEventLoop) {
                newState = ST_SHUTDOWN;
            } else {
                switch (oldState) {
                    case ST_NOT_STARTED:
                    case ST_STARTED:
                    case ST_SHUTTING_DOWN:
                        newState = ST_SHUTDOWN;
                        break;
                    default:
                        newState = oldState;
                        wakeup = false;
                }
            }
            if (STATE_UPDATER.compareAndSet(this, oldState, newState)) {
                break;
            }
        }

        if (oldState == ST_NOT_STARTED) {
            doStartThread();
        }

        if (wakeup) {
            wakeup(inEventLoop);
        }
    }

    @Override
    public boolean isShuttingDown() {
        return STATE_UPDATER.get(this) >= ST_SHUTTING_DOWN;
    }

    @Override
    public boolean isShutdown() {
        return STATE_UPDATER.get(this) >= ST_SHUTDOWN;
    }

    @Override
    public boolean isTerminated() {
        return STATE_UPDATER.get(this) == ST_TERMINATED;
    }

    /**
     * Confirm that the shutdown if the instance should be done now!
     */
    protected boolean confirmShutdown() {
        if (!isShuttingDown()) {
            return false;
        }

        if (!inEventLoop()) {
            throw new IllegalStateException("must be invoked from an event loop");
        }

        cancelScheduledTasks();

        if (gracefulShutdownStartTime == 0) {
            gracefulShutdownStartTime = ScheduledFutureTask.nanoTime();
        }

        if (runAllTasks() || runShutdownHooks()) {
            if (isShutdown()) {
                // Executor shut down - no new tasks anymore.
                return true;
            }

            // There were tasks in the queue. Wait a little bit more until no tasks are queued for the quiet period.
            wakeup(true);
            return false;
        }

        final long nanoTime = ScheduledFutureTask.nanoTime();

        if (isShutdown() || nanoTime - gracefulShutdownStartTime > gracefulShutdownTimeout) {
            return true;
        }

        if (nanoTime - lastExecutionTime <= gracefulShutdownQuietPeriod) {
            // Check if any tasks were added to the queue every 100ms.
            // TODO: Change the behavior of takeTask() so that it returns on timeout.
            wakeup(true);
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                // Ignore
            }

            return false;
        }

        // No tasks were added for last quiet period - hopefully safe to shut down.
        // (Hopefully because we really cannot make a guarantee that there will be no execute() calls by a user.)
        return true;
    }

    @Override
    public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
        if (unit == null) {
            throw new NullPointerException("unit");
        }

        if (inEventLoop()) {
            throw new IllegalStateException("cannot await termination of the current thread");
        }

        if (threadLock.tryAcquire(timeout, unit)) {
            threadLock.release();
        }

        return isTerminated();
    }

    @Override
    public void execute(Runnable task) {
        if (task == null) {
            throw new NullPointerException("task");
        }

        boolean inEventLoop = inEventLoop();
        if (inEventLoop) {
            addTask(task);
        } else {
            startThread();
            addTask(task);
            if (isShutdown() && removeTask(task)) {
                reject();
            }
        }

        if (!addTaskWakesUp && wakesUpForTask(task)) {
            wakeup(inEventLoop);
        }
    }

    /**
     * Returns the {@link ThreadProperties} of the {@link Thread} that powers the {@link SingleThreadEventExecutor}.
     * If the {@link SingleThreadEventExecutor} is not started yet, this operation will start it and block until the
     * it is fully started.
     */
    public final ThreadProperties threadProperties() {
        ThreadProperties threadProperties = this.threadProperties;
        if (threadProperties == null) {
            Thread thread = this.thread;
            if (thread == null) {
                assert !inEventLoop();
                submit(NOOP_TASK).syncUninterruptibly();
                thread = this.thread;
                assert thread != null;
            }

            threadProperties = new DefaultThreadProperties(thread);
            if (!PROPERTIES_UPDATER.compareAndSet(this, null, threadProperties)) {
                threadProperties = this.threadProperties;
            }
        }

        return threadProperties;
    }

    @SuppressWarnings("unused")
    protected boolean wakesUpForTask(Runnable task) {
        return true;
    }

    protected static void reject() {
        throw new RejectedExecutionException("event executor terminated");
    }

    // ScheduledExecutorService implementation

    private static final long SCHEDULE_PURGE_INTERVAL = TimeUnit.SECONDS.toNanos(1);

    private void startThread() {
        if (STATE_UPDATER.get(this) == ST_NOT_STARTED) {
            if (STATE_UPDATER.compareAndSet(this, ST_NOT_STARTED, ST_STARTED)) {
                doStartThread();
            }
        }
    }

    private void doStartThread() {
        assert thread == null;
        executor.execute(new Runnable() {
            @Override
            public void run() {
                thread = Thread.currentThread();
                if (interrupted) {
                    thread.interrupt();
                }

                boolean success = false;
                updateLastExecutionTime();
                try {
                    SingleThreadEventExecutor.this.run();
                    success = true;
                } catch (Throwable t) {
                    logger.warn("Unexpected exception from an event executor: ", t);
                } finally {
                    for (;;) {
                        int oldState = STATE_UPDATER.get(SingleThreadEventExecutor.this);
                        if (oldState >= ST_SHUTTING_DOWN || STATE_UPDATER.compareAndSet(
                                SingleThreadEventExecutor.this, oldState, ST_SHUTTING_DOWN)) {
                            break;
                        }
                    }

                    // Check if confirmShutdown() was called at the end of the loop.
                    if (success && gracefulShutdownStartTime == 0) {
                        logger.error("Buggy " + EventExecutor.class.getSimpleName() + " implementation; " +
                                SingleThreadEventExecutor.class.getSimpleName() + ".confirmShutdown() must be called " +
                                "before run() implementation terminates.");
                    }

                    try {
                        // Run all remaining tasks and shutdown hooks.
                        for (;;) {
                            if (confirmShutdown()) {
                                break;
                            }
                        }
                    } finally {
                        try {
                            cleanup();
                        } finally {
                            STATE_UPDATER.set(SingleThreadEventExecutor.this, ST_TERMINATED);
                            threadLock.release();
                            if (!taskQueue.isEmpty()) {
                                logger.warn(
                                        "An event executor terminated with " +
                                                "non-empty task queue (" + taskQueue.size() + ')');
                            }

                            terminationFuture.setSuccess(null);
                        }
                    }
                }
            }
        });
    }

    private static final class DefaultThreadProperties implements ThreadProperties {
        private final Thread t;

        DefaultThreadProperties(Thread t) {
            this.t = t;
        }

        @Override
        public State state() {
            return t.getState();
        }

        @Override
        public int priority() {
            return t.getPriority();
        }

        @Override
        public boolean isInterrupted() {
            return t.isInterrupted();
        }

        @Override
        public boolean isDaemon() {
            return t.isDaemon();
        }

        @Override
        public String name() {
            return t.getName();
        }

        @Override
        public long id() {
            return t.getId();
        }

        @Override
        public StackTraceElement[] stackTrace() {
            return t.getStackTrace();
        }

        @Override
        public boolean isAlive() {
            return t.isAlive();
        }
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java SingleThreadEventExecutor.java source code file:

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