Package io.netty.util.concurrent

Class SingleThreadEventExecutor

java.lang.Object

java.util.concurrent.AbstractExecutorService

io.netty.util.concurrent.AbstractEventExecutor

io.netty.util.concurrent.AbstractScheduledEventExecutor

io.netty.util.concurrent.SingleThreadEventExecutor

All Implemented Interfaces:

EventExecutor, EventExecutorGroup, OrderedEventExecutor, AutoCloseable, Iterable<EventExecutor>, Executor, ExecutorService, ScheduledExecutorService

Direct Known Subclasses:

DefaultEventExecutor, SingleThreadEventLoop

public abstract class SingleThreadEventExecutor
extends AbstractScheduledEventExecutor
implements OrderedEventExecutor

Abstract base class for OrderedEventExecutor's that execute all its submitted tasks in a single thread.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	SingleThreadEventExecutor.DefaultThreadProperties
protected static interface	SingleThreadEventExecutor.NonWakeupRunnable	Deprecated. override wakesUpForTask(java.lang.Runnable) to re-create this behaviour

Nested classes/interfaces inherited from class io.netty.util.concurrent.AbstractEventExecutor

AbstractEventExecutor.LazyRunnable

Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	addTaskWakesUp
(package private) static final int	DEFAULT_MAX_PENDING_EXECUTOR_TASKS
private final Executor	executor
private long	gracefulShutdownQuietPeriod
private long	gracefulShutdownStartTime
private long	gracefulShutdownTimeout
private boolean	interrupted
private long	lastExecutionTime
private static final InternalLogger	logger
private final int	maxPendingTasks
private static final Runnable	NOOP_TASK
private static final AtomicReferenceFieldUpdater<SingleThreadEventExecutor,ThreadProperties>	PROPERTIES_UPDATER
private final RejectedExecutionHandler	rejectedExecutionHandler
private static final long	SCHEDULE_PURGE_INTERVAL
private final Set<Runnable>	shutdownHooks
private static final int	ST_NOT_STARTED
private static final int	ST_SHUTDOWN
private static final int	ST_SHUTTING_DOWN
private static final int	ST_STARTED
private static final int	ST_TERMINATED
private int	state
private static final AtomicIntegerFieldUpdater<SingleThreadEventExecutor>	STATE_UPDATER
private final Queue<Runnable>	taskQueue
private final Promise<?>	terminationFuture
private Thread	thread
private final CountDownLatch	threadLock
private ThreadProperties	threadProperties

Fields inherited from class io.netty.util.concurrent.AbstractScheduledEventExecutor

nextTaskId, scheduledTaskQueue, WAKEUP_TASK

Fields inherited from class io.netty.util.concurrent.AbstractEventExecutor

DEFAULT_SHUTDOWN_QUIET_PERIOD, DEFAULT_SHUTDOWN_TIMEOUT

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor, boolean addTaskWakesUp)	Create a new instance
protected	SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor, boolean addTaskWakesUp, int maxPendingTasks, RejectedExecutionHandler rejectedHandler)	Create a new instance
protected	SingleThreadEventExecutor(EventExecutorGroup parent, Executor executor, boolean addTaskWakesUp, Queue<Runnable> taskQueue, RejectedExecutionHandler rejectedHandler)
protected	SingleThreadEventExecutor(EventExecutorGroup parent, ThreadFactory threadFactory, boolean addTaskWakesUp)	Create a new instance
protected	SingleThreadEventExecutor(EventExecutorGroup parent, ThreadFactory threadFactory, boolean addTaskWakesUp, int maxPendingTasks, RejectedExecutionHandler rejectedHandler)	Create a new instance

Method Summary

Modifier and Type	Method	Description
void	addShutdownHook(Runnable task)	Add a Runnable which will be executed on shutdown of this instance
protected void	addTask(Runnable task)	Add a task to the task queue, or throws a RejectedExecutionException if this instance was shutdown before.
protected void	afterRunningAllTasks()	Invoked before returning from runAllTasks() and runAllTasks(long).
boolean	awaitTermination(long timeout, TimeUnit unit)
protected void	cleanup()	Do nothing, sub-classes may override
protected boolean	confirmShutdown()	Confirm that the shutdown if the instance should be done now!
protected long	deadlineNanos()	Returns the absolute point in time (relative to AbstractScheduledEventExecutor.getCurrentTimeNanos()) at which the next closest scheduled task should run.
protected long	delayNanos(long currentTimeNanos)	Returns the amount of time left until the scheduled task with the closest dead line is executed.
private void	doStartThread()
(package private) final int	drainTasks()
private boolean	ensureThreadStarted(int oldState)
void	execute(Runnable task)
private void	execute(Runnable task, boolean immediate)
private void	execute0(Runnable task)
private boolean	executeExpiredScheduledTasks()
private boolean	fetchFromScheduledTaskQueue()
protected boolean	hasTasks()
boolean	inEventLoop(Thread thread)	Return true if the given Thread is executed in the event loop, false otherwise.
protected void	interruptThread()	Interrupt the current running Thread.
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks)
<T> List<Future<T>>	invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
<T> T	invokeAny(Collection<? extends Callable<T>> tasks)
<T> T	invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
boolean	isShutdown()
boolean	isShuttingDown()	Returns true if and only if all EventExecutors managed by this EventExecutorGroup are being shut down gracefully or was shut down.
boolean	isTerminated()
void	lazyExecute(Runnable task)	Like Executor.execute(Runnable) but does not guarantee the task will be run until either a non-lazy task is executed or the executor is shut down.
private void	lazyExecute0(Runnable task)
protected Queue<Runnable>	newTaskQueue()	Deprecated. Please use and override newTaskQueue(int).
protected Queue<Runnable>	newTaskQueue(int maxPendingTasks)	Create a new Queue which will holds the tasks to execute.
(package private) final boolean	offerTask(Runnable task)
protected Runnable	peekTask()
int	pendingTasks()	Return the number of tasks that are pending for processing.
protected Runnable	pollTask()
protected static Runnable	pollTaskFrom(Queue<Runnable> taskQueue)
protected static void	reject()
protected final void	reject(Runnable task)	Offers the task to the associated RejectedExecutionHandler.
void	removeShutdownHook(Runnable task)	Remove a previous added Runnable as a shutdown hook
protected boolean	removeTask(Runnable task)
protected abstract void	run()	Run the tasks in the taskQueue
protected boolean	runAllTasks()	Poll all tasks from the task queue and run them via Runnable.run() method.
protected boolean	runAllTasks(long timeoutNanos)	Poll all tasks from the task queue and run them via Runnable.run() method.
protected final boolean	runAllTasksFrom(Queue<Runnable> taskQueue)	Runs all tasks from the passed taskQueue.
private boolean	runExistingTasksFrom(Queue<Runnable> taskQueue)	What ever tasks are present in taskQueue when this method is invoked will be Runnable.run().
protected final boolean	runScheduledAndExecutorTasks(int maxDrainAttempts)	Execute all expired scheduled tasks and all current tasks in the executor queue until both queues are empty, or maxDrainAttempts has been exceeded.
private boolean	runShutdownHooks()
void	shutdown()	Deprecated.
Future<?>	shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit)	Signals this executor that the caller wants the executor to be shut down.
private void	startThread()
protected Runnable	takeTask()	Take the next Runnable from the task queue and so will block if no task is currently present.
Future<?>	terminationFuture()	Returns the Future which is notified when all EventExecutors managed by this EventExecutorGroup have been terminated.
final ThreadProperties	threadProperties()	Returns the ThreadProperties of the Thread that powers the SingleThreadEventExecutor.
private void	throwIfInEventLoop(String method)
protected void	updateLastExecutionTime()	Updates the internal timestamp that tells when a submitted task was executed most recently.
protected boolean	wakesUpForTask(Runnable task)	Can be overridden to control which tasks require waking the EventExecutor thread if it is waiting so that they can be run immediately.
protected void	wakeup(boolean inEventLoop)

Methods inherited from class io.netty.util.concurrent.AbstractScheduledEventExecutor

afterScheduledTaskSubmitted, beforeScheduledTaskSubmitted, cancelScheduledTasks, deadlineNanos, deadlineToDelayNanos, defaultCurrentTimeNanos, getCurrentTimeNanos, hasScheduledTasks, initialNanoTime, nanoTime, nextScheduledTaskDeadlineNanos, nextScheduledTaskNano, peekScheduledTask, pollScheduledTask, pollScheduledTask, removeScheduled, schedule, schedule, scheduleAtFixedRate, scheduledTaskQueue, scheduleFromEventLoop, scheduleWithFixedDelay, validateScheduled

Methods inherited from class io.netty.util.concurrent.AbstractEventExecutor

inEventLoop, iterator, newFailedFuture, newProgressivePromise, newPromise, newSucceededFuture, newTaskFor, newTaskFor, next, parent, runTask, safeExecute, shutdownGracefully, shutdownNow, submit, submit, submit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.util.concurrent.EventExecutor

inEventLoop, newFailedFuture, newProgressivePromise, newPromise, newSucceededFuture, next, parent

Methods inherited from interface io.netty.util.concurrent.EventExecutorGroup

iterator, schedule, schedule, scheduleAtFixedRate, scheduleWithFixedDelay, shutdownGracefully, shutdownNow, submit, submit, submit

Methods inherited from interface java.util.concurrent.ExecutorService

close

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Details

DEFAULT_MAX_PENDING_EXECUTOR_TASKS

static final int DEFAULT_MAX_PENDING_EXECUTOR_TASKS

logger

private static final InternalLogger logger

ST_NOT_STARTED

private static final int ST_NOT_STARTED

See Also:

• Constant Field Values

ST_STARTED

private static final int ST_STARTED

See Also:

• Constant Field Values

ST_SHUTTING_DOWN

private static final int ST_SHUTTING_DOWN

See Also:

• Constant Field Values

ST_SHUTDOWN

private static final int ST_SHUTDOWN

See Also:

• Constant Field Values

ST_TERMINATED

private static final int ST_TERMINATED

See Also:

• Constant Field Values

NOOP_TASK

private static final Runnable NOOP_TASK

STATE_UPDATER

private static final AtomicIntegerFieldUpdater<SingleThreadEventExecutor> STATE_UPDATER

PROPERTIES_UPDATER

private static final AtomicReferenceFieldUpdater<SingleThreadEventExecutor,ThreadProperties> PROPERTIES_UPDATER

taskQueue

private final Queue<Runnable> taskQueue

thread

private volatile Thread thread

threadProperties

private volatile ThreadProperties threadProperties

executor

private final Executor executor

interrupted

private volatile boolean interrupted

threadLock

private final CountDownLatch threadLock

shutdownHooks

private final Set<Runnable> shutdownHooks

addTaskWakesUp

private final boolean addTaskWakesUp

maxPendingTasks

private final int maxPendingTasks

rejectedExecutionHandler

private final RejectedExecutionHandler rejectedExecutionHandler

lastExecutionTime

private long lastExecutionTime

state

private volatile int state

gracefulShutdownQuietPeriod

private volatile long gracefulShutdownQuietPeriod

gracefulShutdownTimeout

private volatile long gracefulShutdownTimeout

gracefulShutdownStartTime

private long gracefulShutdownStartTime

terminationFuture

private final Promise<?> terminationFuture

SCHEDULE_PURGE_INTERVAL

private static final long SCHEDULE_PURGE_INTERVAL

Constructor Details

SingleThreadEventExecutor

protected SingleThreadEventExecutor(EventExecutorGroup parent,
 ThreadFactory threadFactory,
 boolean addTaskWakesUp)

Create a new instance

Parameters:

parent - the EventExecutorGroup which is the parent of this instance and belongs to it

threadFactory - the ThreadFactory which will be used for the used Thread

addTaskWakesUp - true if and only if invocation of addTask(Runnable) will wake up the executor thread

SingleThreadEventExecutor

protected SingleThreadEventExecutor(EventExecutorGroup parent,
 ThreadFactory threadFactory,
 boolean addTaskWakesUp,
 int maxPendingTasks,
 RejectedExecutionHandler rejectedHandler)

Create a new instance

Parameters:

parent - the EventExecutorGroup which is the parent of this instance and belongs to it

threadFactory - the ThreadFactory which will be used for the used Thread

addTaskWakesUp - true if and only if invocation of addTask(Runnable) will wake up the executor thread

maxPendingTasks - the maximum number of pending tasks before new tasks will be rejected.

rejectedHandler - the RejectedExecutionHandler to use.

SingleThreadEventExecutor

protected SingleThreadEventExecutor(EventExecutorGroup parent,
 Executor executor,
 boolean addTaskWakesUp)

Create a new instance

Parameters:

parent - the EventExecutorGroup which is the parent of this instance and belongs to it

executor - the Executor which will be used for executing

addTaskWakesUp - true if and only if invocation of addTask(Runnable) will wake up the executor thread

SingleThreadEventExecutor

protected SingleThreadEventExecutor(EventExecutorGroup parent,
 Executor executor,
 boolean addTaskWakesUp,
 int maxPendingTasks,
 RejectedExecutionHandler rejectedHandler)

Create a new instance

Parameters:

parent - the EventExecutorGroup which is the parent of this instance and belongs to it

executor - the Executor which will be used for executing

addTaskWakesUp - true if and only if invocation of addTask(Runnable) will wake up the executor thread

maxPendingTasks - the maximum number of pending tasks before new tasks will be rejected.

rejectedHandler - the RejectedExecutionHandler to use.

SingleThreadEventExecutor

protected SingleThreadEventExecutor(EventExecutorGroup parent,
 Executor executor,
 boolean addTaskWakesUp,
 Queue<Runnable> taskQueue,
 RejectedExecutionHandler rejectedHandler)

Method Details

newTaskQueue

@Deprecated
protected Queue<Runnable> newTaskQueue()

Deprecated.

Please use and override newTaskQueue(int).

newTaskQueue

protected Queue<Runnable> newTaskQueue(int maxPendingTasks)

Create a new Queue which will holds the tasks to execute. This default implementation will return a LinkedBlockingQueue but if your sub-class of SingleThreadEventExecutor will not do any blocking calls on the this Queue it may make sense to @Override this and return some more performant implementation that does not support blocking operations at all.

interruptThread

protected void interruptThread()

Interrupt the current running Thread.

pollTask

protected Runnable pollTask()

See Also:

• Queue.poll()

pollTaskFrom

protected static Runnable pollTaskFrom(Queue<Runnable> taskQueue)

takeTask

protected Runnable takeTask()

Take the next Runnable from the task queue and so will block if no task is currently present.

Be aware that this method will throw an UnsupportedOperationException if the task queue, which was created via newTaskQueue(), does not implement BlockingQueue.

Returns:

null if the executor thread has been interrupted or waken up.

fetchFromScheduledTaskQueue

private boolean fetchFromScheduledTaskQueue()

executeExpiredScheduledTasks

private boolean executeExpiredScheduledTasks()

Returns:

true if at least one scheduled task was executed.

peekTask

protected Runnable peekTask()

See Also:

• Queue.peek()

hasTasks

protected boolean hasTasks()

See Also:

• Collection.isEmpty()

pendingTasks

public int pendingTasks()

Return the number of tasks that are pending for processing.

addTask

protected void addTask(Runnable task)

Add a task to the task queue, or throws a RejectedExecutionException if this instance was shutdown before.

offerTask

final boolean offerTask(Runnable task)

removeTask

protected boolean removeTask(Runnable task)

See Also:

• Collection.remove(Object)

runAllTasks

protected boolean runAllTasks()

Poll all tasks from the task queue and run them via Runnable.run() method.

Returns:

true if and only if at least one task was run

runScheduledAndExecutorTasks

protected final boolean runScheduledAndExecutorTasks(int maxDrainAttempts)

Execute all expired scheduled tasks and all current tasks in the executor queue until both queues are empty, or maxDrainAttempts has been exceeded.

Parameters:

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.

Returns:

true if at least one task was run.

runAllTasksFrom

protected final boolean runAllTasksFrom(Queue<Runnable> taskQueue)

Runs all tasks from the passed taskQueue.

Parameters:

taskQueue - To poll and execute all tasks.

Returns:

true if at least one task was executed.

runExistingTasksFrom

private boolean runExistingTasksFrom(Queue<Runnable> taskQueue)

What ever tasks are present in taskQueue when this method is invoked will be Runnable.run().

Parameters:

taskQueue - the task queue to drain.

Returns:

true if at least Runnable.run() was called.

runAllTasks

protected boolean runAllTasks(long timeoutNanos)

Poll all tasks from the task queue and run them via Runnable.run() method. This method stops running the tasks in the task queue and returns if it ran longer than timeoutNanos.

afterRunningAllTasks

protected void afterRunningAllTasks()

Invoked before returning from runAllTasks() and runAllTasks(long).

delayNanos

protected long delayNanos(long currentTimeNanos)

Returns the amount of time left until the scheduled task with the closest dead line is executed.

deadlineNanos

protected long deadlineNanos()

Returns the absolute point in time (relative to AbstractScheduledEventExecutor.getCurrentTimeNanos()) at which the next closest scheduled task should run.

updateLastExecutionTime

protected void updateLastExecutionTime()

Updates the internal timestamp that tells when a submitted task was executed most recently. runAllTasks() and 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 takeTask() or pollTask(), you have to call this method at the end of task execution loop for accurate quiet period checks.

run

protected abstract void run()

Run the tasks in the taskQueue

cleanup

protected void cleanup()

Do nothing, sub-classes may override

wakeup

protected void wakeup(boolean inEventLoop)

inEventLoop

public boolean inEventLoop(Thread thread)

Description copied from interface: EventExecutor

Return true if the given Thread is executed in the event loop, false otherwise.

Specified by:

inEventLoop in interface EventExecutor

addShutdownHook

public void addShutdownHook(Runnable task)

Add a Runnable which will be executed on shutdown of this instance

removeShutdownHook

public void removeShutdownHook(Runnable task)

Remove a previous added Runnable as a shutdown hook

runShutdownHooks

private boolean runShutdownHooks()

shutdownGracefully

public Future<?> shutdownGracefully(long quietPeriod,
 long timeout,
 TimeUnit unit)

Description copied from interface: EventExecutorGroup

Signals this executor that the caller wants the executor to be shut down. Once this method is called, EventExecutorGroup.isShuttingDown() starts to return true, and the executor prepares to shut itself down. Unlike EventExecutorGroup.shutdown(), graceful shutdown ensures that no tasks are submitted for 'the quiet period' (usually a couple seconds) before it shuts itself down. If a task is submitted during the quiet period, it is guaranteed to be accepted and the quiet period will start over.

Specified by:

shutdownGracefully in interface EventExecutorGroup

Parameters:

quietPeriod - the quiet period as described in the documentation

timeout - the maximum amount of time to wait until the executor is EventExecutorGroup.shutdown() regardless if a task was submitted during the quiet period

unit - the unit of quietPeriod and timeout

Returns:

the EventExecutorGroup.terminationFuture()

terminationFuture

public Future<?> terminationFuture()

Description copied from interface: EventExecutorGroup

Returns the Future which is notified when all EventExecutors managed by this EventExecutorGroup have been terminated.

Specified by:

terminationFuture in interface EventExecutorGroup

shutdown

@Deprecated
public void shutdown()

Deprecated.

Specified by:

shutdown in interface EventExecutorGroup

Specified by:

shutdown in interface ExecutorService

Specified by:

shutdown in class AbstractEventExecutor

isShuttingDown

public boolean isShuttingDown()

Description copied from interface: EventExecutorGroup

Returns true if and only if all EventExecutors managed by this EventExecutorGroup are being shut down gracefully or was shut down.

Specified by:

isShuttingDown in interface EventExecutorGroup

isShutdown

public boolean isShutdown()

Specified by:

isShutdown in interface ExecutorService

isTerminated

public boolean isTerminated()

Specified by:

isTerminated in interface ExecutorService

confirmShutdown

protected boolean confirmShutdown()

Confirm that the shutdown if the instance should be done now!

awaitTermination

public boolean awaitTermination(long timeout,
 TimeUnit unit)
                         throws InterruptedException

Specified by:

awaitTermination in interface ExecutorService

Throws:

InterruptedException

execute

public void execute(Runnable task)

Specified by:

execute in interface Executor

lazyExecute

public void lazyExecute(Runnable task)

Description copied from class: AbstractEventExecutor

Like Executor.execute(Runnable) but does not guarantee the task will be run until either a non-lazy task is executed or the executor is shut down.

The default implementation just delegates to Executor.execute(Runnable).

Overrides:

lazyExecute in class AbstractEventExecutor

execute0

private void execute0(Runnable task)

lazyExecute0

private void lazyExecute0(Runnable task)

execute

private void execute(Runnable task,
 boolean immediate)

invokeAny

public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
                throws InterruptedException,
ExecutionException

Specified by:

invokeAny in interface ExecutorService

Overrides:

invokeAny in class AbstractExecutorService

Throws:

InterruptedException

ExecutionException

invokeAny

public <T> T invokeAny(Collection<? extends Callable<T>> tasks,
 long timeout,
 TimeUnit unit)
                throws InterruptedException,
ExecutionException,
TimeoutException

Specified by:

invokeAny in interface ExecutorService

Overrides:

invokeAny in class AbstractExecutorService

Throws:

InterruptedException

ExecutionException

TimeoutException

invokeAll

public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
                              throws InterruptedException

Specified by:

invokeAll in interface ExecutorService

Overrides:

invokeAll in class AbstractExecutorService

Throws:

InterruptedException

invokeAll

public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks,
 long timeout,
 TimeUnit unit)
                              throws InterruptedException

Specified by:

invokeAll in interface ExecutorService

Overrides:

invokeAll in class AbstractExecutorService

Throws:

InterruptedException

throwIfInEventLoop

private void throwIfInEventLoop(String method)

threadProperties

public final ThreadProperties threadProperties()

Returns the ThreadProperties of the Thread that powers the SingleThreadEventExecutor. If the SingleThreadEventExecutor is not started yet, this operation will start it and block until it is fully started.

wakesUpForTask

protected boolean wakesUpForTask(Runnable task)

Can be overridden to control which tasks require waking the EventExecutor thread if it is waiting so that they can be run immediately.

reject

protected static void reject()

reject

protected final void reject(Runnable task)

Offers the task to the associated RejectedExecutionHandler.

Parameters:

task - to reject.

startThread

private void startThread()

ensureThreadStarted

private boolean ensureThreadStarted(int oldState)

doStartThread

private void doStartThread()

drainTasks

final int drainTasks()