io.netty.util.concurrent.SingleThreadEventExecutor Maven / Gradle / Ivy
Go to download
This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* 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:
*
* https://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.ThreadExecutorMap;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import org.jetbrains.annotations.Async.Schedule;
import java.lang.Thread.State;
import java.util.ArrayList;
import java.util.Collection;
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.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
/**
* Abstract base class for {@link OrderedEventExecutor}'s that execute all its submitted tasks in a single thread.
*
*/
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_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 NOOP_TASK = new Runnable() {
@Override
public void run() {
// Do nothing.
}
};
private static final AtomicIntegerFieldUpdater STATE_UPDATER =
AtomicIntegerFieldUpdater.newUpdater(SingleThreadEventExecutor.class, "state");
private static final AtomicReferenceFieldUpdater PROPERTIES_UPDATER =
AtomicReferenceFieldUpdater.newUpdater(
SingleThreadEventExecutor.class, ThreadProperties.class, "threadProperties");
private final Queue taskQueue;
private volatile Thread thread;
@SuppressWarnings("unused")
private volatile ThreadProperties threadProperties;
private final Executor executor;
private volatile boolean interrupted;
private final CountDownLatch threadLock = new CountDownLatch(1);
private final Set 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 = ThreadExecutorMap.apply(executor, this);
taskQueue = newTaskQueue(this.maxPendingTasks);
rejectedExecutionHandler = ObjectUtil.checkNotNull(rejectedHandler, "rejectedHandler");
}
protected SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor,
boolean addTaskWakesUp, Queue taskQueue,
RejectedExecutionHandler rejectedHandler) {
super(parent);
this.addTaskWakesUp = addTaskWakesUp;
this.maxPendingTasks = DEFAULT_MAX_PENDING_EXECUTOR_TASKS;
this.executor = ThreadExecutorMap.apply(executor, this);
this.taskQueue = ObjectUtil.checkNotNull(taskQueue, "taskQueue");
this.rejectedExecutionHandler = ObjectUtil.checkNotNull(rejectedHandler, "rejectedHandler");
}
/**
* @deprecated Please use and override {@link #newTaskQueue(int)}.
*/
@Deprecated
protected Queue 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 newTaskQueue(int maxPendingTasks) {
return new LinkedBlockingQueue(maxPendingTasks);
}
/**
* Interrupt the current running {@link Thread}.
*/
protected void interruptThread() {
Thread currentThread = thread;
if (currentThread == null) {
interrupted = true;
} else {
currentThread.interrupt();
}
}
/**
* @see Queue#poll()
*/
protected Runnable pollTask() {
assert inEventLoop();
return pollTaskFrom(taskQueue);
}
protected static Runnable pollTaskFrom(Queue taskQueue) {
for (;;) {
Runnable task = taskQueue.poll();
if (task != WAKEUP_TASK) {
return task;
}
}
}
/**
* Take the next {@link Runnable} from the task queue and so will block if no task is currently present.
*
* 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}.
*
*
* @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 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 (scheduledTaskQueue == null || scheduledTaskQueue.isEmpty()) {
return true;
}
long nanoTime = getCurrentTimeNanos();
for (;;) {
Runnable scheduledTask = pollScheduledTask(nanoTime);
if (scheduledTask == null) {
return true;
}
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 {@code true} if at least one scheduled task was executed.
*/
private boolean executeExpiredScheduledTasks() {
if (scheduledTaskQueue == null || scheduledTaskQueue.isEmpty()) {
return false;
}
long nanoTime = getCurrentTimeNanos();
Runnable scheduledTask = pollScheduledTask(nanoTime);
if (scheduledTask == null) {
return false;
}
do {
safeExecute(scheduledTask);
} while ((scheduledTask = pollScheduledTask(nanoTime)) != null);
return true;
}
/**
* @see Queue#peek()
*/
protected Runnable peekTask() {
assert inEventLoop();
return taskQueue.peek();
}
/**
* @see Queue#isEmpty()
*/
protected boolean hasTasks() {
assert inEventLoop();
return !taskQueue.isEmpty();
}
/**
* Return the number of tasks that are pending for processing.
*/
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) {
ObjectUtil.checkNotNull(task, "task");
if (!offerTask(task)) {
reject(task);
}
}
final boolean offerTask(Runnable task) {
if (isShutdown()) {
reject();
}
return taskQueue.offer(task);
}
/**
* @see Queue#remove(Object)
*/
protected boolean removeTask(Runnable task) {
return taskQueue.remove(ObjectUtil.checkNotNull(task, "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() {
assert inEventLoop();
boolean fetchedAll;
boolean ranAtLeastOne = false;
do {
fetchedAll = fetchFromScheduledTaskQueue();
if (runAllTasksFrom(taskQueue)) {
ranAtLeastOne = true;
}
} while (!fetchedAll); // keep on processing until we fetched all scheduled tasks.
if (ranAtLeastOne) {
lastExecutionTime = getCurrentTimeNanos();
}
afterRunningAllTasks();
return ranAtLeastOne;
}
/**
* Execute all expired scheduled tasks and all current tasks in the executor queue until both queues are empty,
* or {@code maxDrainAttempts} has been exceeded.
* @param maxDrainAttempts The maximum amount of times this method attempts to drain from queues. This is to prevent
* continuous task execution and scheduling from preventing the EventExecutor thread to
* make progress and return to the selector mechanism to process inbound I/O events.
* @return {@code true} if at least one task was run.
*/
protected final boolean runScheduledAndExecutorTasks(final int maxDrainAttempts) {
assert inEventLoop();
boolean ranAtLeastOneTask;
int drainAttempt = 0;
do {
// We must run the taskQueue tasks first, because the scheduled tasks from outside the EventLoop are queued
// here because the taskQueue is thread safe and the scheduledTaskQueue is not thread safe.
ranAtLeastOneTask = runExistingTasksFrom(taskQueue) | executeExpiredScheduledTasks();
} while (ranAtLeastOneTask && ++drainAttempt < maxDrainAttempts);
if (drainAttempt > 0) {
lastExecutionTime = getCurrentTimeNanos();
}
afterRunningAllTasks();
return drainAttempt > 0;
}
/**
* Runs all tasks from the passed {@code taskQueue}.
*
* @param taskQueue To poll and execute all tasks.
*
* @return {@code true} if at least one task was executed.
*/
protected final boolean runAllTasksFrom(Queue taskQueue) {
Runnable task = pollTaskFrom(taskQueue);
if (task == null) {
return false;
}
for (;;) {
safeExecute(task);
task = pollTaskFrom(taskQueue);
if (task == null) {
return true;
}
}
}
/**
* What ever tasks are present in {@code taskQueue} when this method is invoked will be {@link Runnable#run()}.
* @param taskQueue the task queue to drain.
* @return {@code true} if at least {@link Runnable#run()} was called.
*/
private boolean runExistingTasksFrom(Queue taskQueue) {
Runnable task = pollTaskFrom(taskQueue);
if (task == null) {
return false;
}
int remaining = Math.min(maxPendingTasks, taskQueue.size());
safeExecute(task);
// Use taskQueue.poll() directly rather than pollTaskFrom() since the latter may
// silently consume more than one item from the queue (skips over WAKEUP_TASK instances)
while (remaining-- > 0 && (task = taskQueue.poll()) != null) {
safeExecute(task);
}
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) {
afterRunningAllTasks();
return false;
}
final long deadline = timeoutNanos > 0 ? getCurrentTimeNanos() + timeoutNanos : 0;
long runTasks = 0;
long lastExecutionTime;
for (;;) {
safeExecute(task);
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 = getCurrentTimeNanos();
if (lastExecutionTime >= deadline) {
break;
}
}
task = pollTask();
if (task == null) {
lastExecutionTime = getCurrentTimeNanos();
break;
}
}
afterRunningAllTasks();
this.lastExecutionTime = lastExecutionTime;
return true;
}
/**
* Invoked before returning from {@link #runAllTasks()} and {@link #runAllTasks(long)}.
*/
protected void afterRunningAllTasks() { }
/**
* Returns the amount of time left until the scheduled task with the closest dead line is executed.
*/
protected long delayNanos(long currentTimeNanos) {
currentTimeNanos -= initialNanoTime();
ScheduledFutureTask scheduledTask = peekScheduledTask();
if (scheduledTask == null) {
return SCHEDULE_PURGE_INTERVAL;
}
return scheduledTask.delayNanos(currentTimeNanos);
}
/**
* Returns the absolute point in time (relative to {@link #getCurrentTimeNanos()}) at which the next
* closest scheduled task should run.
*/
protected long deadlineNanos() {
ScheduledFutureTask scheduledTask = peekScheduledTask();
if (scheduledTask == null) {
return getCurrentTimeNanos() + SCHEDULE_PURGE_INTERVAL;
}
return scheduledTask.deadlineNanos();
}
/**
* 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 = getCurrentTimeNanos();
}
/**
* Run the tasks in the {@link #taskQueue}
*/
protected abstract void run();
/**
* Do nothing, sub-classes may override
*/
protected void cleanup() {
// NOOP
}
protected void wakeup(boolean inEventLoop) {
if (!inEventLoop) {
// 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 copy = new ArrayList(shutdownHooks);
shutdownHooks.clear();
for (Runnable task: copy) {
try {
runTask(task);
} catch (Throwable t) {
logger.warn("Shutdown hook raised an exception.", t);
} finally {
ran = true;
}
}
}
if (ran) {
lastExecutionTime = getCurrentTimeNanos();
}
return ran;
}
@Override
public Future shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit) {
ObjectUtil.checkPositiveOrZero(quietPeriod, "quietPeriod");
if (timeout < quietPeriod) {
throw new IllegalArgumentException(
"timeout: " + timeout + " (expected >= quietPeriod (" + quietPeriod + "))");
}
ObjectUtil.checkNotNull(unit, "unit");
if (isShuttingDown()) {
return terminationFuture();
}
boolean inEventLoop = inEventLoop();
boolean wakeup;
int oldState;
for (;;) {
if (isShuttingDown()) {
return terminationFuture();
}
int newState;
wakeup = true;
oldState = state;
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 (ensureThreadStarted(oldState)) {
return terminationFuture;
}
if (wakeup) {
taskQueue.offer(WAKEUP_TASK);
if (!addTaskWakesUp) {
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;
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 (ensureThreadStarted(oldState)) {
return;
}
if (wakeup) {
taskQueue.offer(WAKEUP_TASK);
if (!addTaskWakesUp) {
wakeup(inEventLoop);
}
}
}
@Override
public boolean isShuttingDown() {
return state >= ST_SHUTTING_DOWN;
}
@Override
public boolean isShutdown() {
return state >= ST_SHUTDOWN;
}
@Override
public boolean isTerminated() {
return state == 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 = getCurrentTimeNanos();
}
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 or
// terminate if the quiet period is 0.
// See https://github.com/netty/netty/issues/4241
if (gracefulShutdownQuietPeriod == 0) {
return true;
}
taskQueue.offer(WAKEUP_TASK);
return false;
}
final long nanoTime = getCurrentTimeNanos();
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.
taskQueue.offer(WAKEUP_TASK);
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 {
ObjectUtil.checkNotNull(unit, "unit");
if (inEventLoop()) {
throw new IllegalStateException("cannot await termination of the current thread");
}
threadLock.await(timeout, unit);
return isTerminated();
}
@Override
public void execute(Runnable task) {
execute0(task);
}
@Override
public void lazyExecute(Runnable task) {
lazyExecute0(task);
}
private void execute0(@Schedule Runnable task) {
ObjectUtil.checkNotNull(task, "task");
execute(task, wakesUpForTask(task));
}
private void lazyExecute0(@Schedule Runnable task) {
execute(ObjectUtil.checkNotNull(task, "task"), false);
}
private void execute(Runnable task, boolean immediate) {
boolean inEventLoop = inEventLoop();
addTask(task);
if (!inEventLoop) {
startThread();
if (isShutdown()) {
boolean reject = false;
try {
if (removeTask(task)) {
reject = true;
}
} catch (UnsupportedOperationException e) {
// The task queue does not support removal so the best thing we can do is to just move on and
// hope we will be able to pick-up the task before its completely terminated.
// In worst case we will log on termination.
}
if (reject) {
reject();
}
}
}
if (!addTaskWakesUp && immediate) {
wakeup(inEventLoop);
}
}
@Override
public T invokeAny(Collection> tasks) throws InterruptedException, ExecutionException {
throwIfInEventLoop("invokeAny");
return super.invokeAny(tasks);
}
@Override
public T invokeAny(Collection> tasks, long timeout, TimeUnit unit)
throws InterruptedException, ExecutionException, TimeoutException {
throwIfInEventLoop("invokeAny");
return super.invokeAny(tasks, timeout, unit);
}
@Override
public List> invokeAll(Collection> tasks)
throws InterruptedException {
throwIfInEventLoop("invokeAll");
return super.invokeAll(tasks);
}
@Override
public List> invokeAll(
Collection> tasks, long timeout, TimeUnit unit) throws InterruptedException {
throwIfInEventLoop("invokeAll");
return super.invokeAll(tasks, timeout, unit);
}
private void throwIfInEventLoop(String method) {
if (inEventLoop()) {
throw new RejectedExecutionException("Calling " + method + " from within the EventLoop is not allowed");
}
}
/**
* 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
* 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;
}
/**
* @deprecated override {@link SingleThreadEventExecutor#wakesUpForTask} to re-create this behaviour
*/
@Deprecated
protected interface NonWakeupRunnable extends LazyRunnable { }
/**
* Can be overridden to control which tasks require waking the {@link EventExecutor} thread
* if it is waiting so that they can be run immediately.
*/
protected boolean wakesUpForTask(Runnable task) {
return true;
}
protected static void reject() {
throw new RejectedExecutionException("event executor terminated");
}
/**
* Offers the task to the associated {@link RejectedExecutionHandler}.
*
* @param task to reject.
*/
protected final void reject(Runnable task) {
rejectedExecutionHandler.rejected(task, this);
}
// ScheduledExecutorService implementation
private static final long SCHEDULE_PURGE_INTERVAL = TimeUnit.SECONDS.toNanos(1);
private void startThread() {
if (state == ST_NOT_STARTED) {
if (STATE_UPDATER.compareAndSet(this, ST_NOT_STARTED, ST_STARTED)) {
boolean success = false;
try {
doStartThread();
success = true;
} finally {
if (!success) {
STATE_UPDATER.compareAndSet(this, ST_STARTED, ST_NOT_STARTED);
}
}
}
}
}
private boolean ensureThreadStarted(int oldState) {
if (oldState == ST_NOT_STARTED) {
try {
doStartThread();
} catch (Throwable cause) {
STATE_UPDATER.set(this, ST_TERMINATED);
terminationFuture.tryFailure(cause);
if (!(cause instanceof Exception)) {
// Also rethrow as it may be an OOME for example
PlatformDependent.throwException(cause);
}
return true;
}
}
return false;
}
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;
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) {
if (logger.isErrorEnabled()) {
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. At this point the event loop
// is in ST_SHUTTING_DOWN state still accepting tasks which is needed for
// graceful shutdown with quietPeriod.
for (;;) {
if (confirmShutdown()) {
break;
}
}
// Now we want to make sure no more tasks can be added from this point. This is
// achieved by switching the state. Any new tasks beyond this point will be rejected.
for (;;) {
int oldState = state;
if (oldState >= ST_SHUTDOWN || STATE_UPDATER.compareAndSet(
SingleThreadEventExecutor.this, oldState, ST_SHUTDOWN)) {
break;
}
}
// We have the final set of tasks in the queue now, no more can be added, run all remaining.
// No need to loop here, this is the final pass.
confirmShutdown();
} finally {
try {
cleanup();
} finally {
// Lets remove all FastThreadLocals for the Thread as we are about to terminate and notify
// the future. The user may block on the future and once it unblocks the JVM may terminate
// and start unloading classes.
// See https://github.com/netty/netty/issues/6596.
FastThreadLocal.removeAll();
STATE_UPDATER.set(SingleThreadEventExecutor.this, ST_TERMINATED);
threadLock.countDown();
int numUserTasks = drainTasks();
if (numUserTasks > 0 && logger.isWarnEnabled()) {
logger.warn("An event executor terminated with " +
"non-empty task queue (" + numUserTasks + ')');
}
terminationFuture.setSuccess(null);
}
}
}
}
});
}
final int drainTasks() {
int numTasks = 0;
for (;;) {
Runnable runnable = taskQueue.poll();
if (runnable == null) {
break;
}
// WAKEUP_TASK should be just discarded as these are added internally.
// The important bit is that we not have any user tasks left.
if (WAKEUP_TASK != runnable) {
numTasks++;
}
}
return numTasks;
}
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();
}
}
}