Class EpollEventLoop

java.lang.Object

java.util.concurrent.AbstractExecutorService

io.netty.util.concurrent.AbstractEventExecutor

io.netty.util.concurrent.AbstractScheduledEventExecutor

io.netty.util.concurrent.SingleThreadEventExecutor

io.netty.channel.SingleThreadEventLoop

io.netty.channel.epoll.EpollEventLoop

All Implemented Interfaces:

EventLoop, EventLoopGroup, EventExecutor, EventExecutorGroup, OrderedEventExecutor, Iterable<EventExecutor>, Executor, ExecutorService, ScheduledExecutorService

public class EpollEventLoop
extends SingleThreadEventLoop

EventLoop which uses epoll under the covers. Only works on Linux!

Nested Class Summary

Nested classes/interfaces inherited from class SingleThreadEventLoop

SingleThreadEventLoop.ChannelsReadOnlyIterator<T>

Nested classes/interfaces inherited from class SingleThreadEventExecutor

SingleThreadEventExecutor.NonWakeupRunnable

Nested classes/interfaces inherited from class AbstractEventExecutor

AbstractEventExecutor.LazyRunnable

Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	allowGrowing
private static final long	AWAKE
private final IntObjectMap<AbstractEpollChannel>	channels
private NativeDatagramPacketArray	datagramPacketArray
private static final long	EPOLL_WAIT_MILLIS_THRESHOLD
private FileDescriptor	epollFd
private FileDescriptor	eventFd
private final EpollEventArray	events
private int	ioRatio
private IovArray	iovArray
private static final InternalLogger	logger
private static final long	MAX_SCHEDULED_TIMERFD_NS
private final AtomicLong	nextWakeupNanos
private static final long	NONE
private boolean	pendingWakeup
private final IntSupplier	selectNowSupplier
private final SelectStrategy	selectStrategy
private FileDescriptor	timerFd

Fields inherited from class SingleThreadEventLoop

DEFAULT_MAX_PENDING_TASKS

Constructor Summary

Constructors

Constructor	Description
EpollEventLoop(EventLoopGroup parent, Executor executor, int maxEvents, SelectStrategy strategy, RejectedExecutionHandler rejectedExecutionHandler, EventLoopTaskQueueFactory taskQueueFactory, EventLoopTaskQueueFactory tailTaskQueueFactory)

Method Summary

Modifier and Type	Method	Description
(package private) void	add(AbstractEpollChannel ch)	Register the given epoll with this EventLoop.
protected boolean	afterScheduledTaskSubmitted(long deadlineNanos)	See AbstractScheduledEventExecutor.beforeScheduledTaskSubmitted(long).
protected boolean	beforeScheduledTaskSubmitted(long deadlineNanos)	Called from arbitrary non-EventExecutor threads prior to scheduled task submission.
(package private) NativeDatagramPacketArray	cleanDatagramPacketArray()	Return a cleared NativeDatagramPacketArray that can be used for writes in this EventLoop.
(package private) IovArray	cleanIovArray()	Return a cleared IovArray that can be used for writes in this EventLoop.
protected void	cleanup()	Do nothing, sub-classes may override
private void	closeAll()
private static void	closeFileDescriptor(FileDescriptor fd)
void	closeFileDescriptors()	This method is intended for use by process checkpoint/restore integration, such as OpenJDK CRaC.
private int	epollBusyWait()
private long	epollWait(long deadlineNanos)
private int	epollWaitNoTimerChange()
private int	epollWaitNow()
private int	epollWaitTimeboxed()
int	getIoRatio()	Returns the percentage of the desired amount of time spent for I/O in the event loop.
(package private) void	handleLoopException(Throwable t)	Visible only for testing!
(package private) void	modify(AbstractEpollChannel ch)	The flags of the given epoll was modified so update the registration
protected Queue<Runnable>	newTaskQueue(int maxPendingTasks)	Create a new Queue which will holds the tasks to execute.
private static Queue<Runnable>	newTaskQueue(EventLoopTaskQueueFactory queueFactory)
private static Queue<Runnable>	newTaskQueue0(int maxPendingTasks)
void	openFileDescriptors()	This method is intended for use by a process checkpoint/restore integration, such as OpenJDK CRaC.
private boolean	processReady(EpollEventArray events, int ready)
int	registeredChannels()	Returns the number of Channels registered with this EventLoop or -1 if operation is not supported.
Iterator<Channel>	registeredChannelsIterator()
(package private) void	remove(AbstractEpollChannel ch)	Deregister the given epoll from this EventLoop.
protected void	run()	Run the tasks in the SingleThreadEventExecutor.taskQueue
void	setIoRatio(int ioRatio)	Sets the percentage of the desired amount of time spent for I/O in the event loop.
protected void	wakeup(boolean inEventLoop)

Methods inherited from class SingleThreadEventLoop

afterRunningAllTasks, executeAfterEventLoopIteration, hasTasks, next, parent, pendingTasks, register, register, register

Methods inherited from class SingleThreadEventExecutor

addShutdownHook, addTask, awaitTermination, confirmShutdown, deadlineNanos, delayNanos, execute, inEventLoop, interruptThread, invokeAll, invokeAll, invokeAny, invokeAny, isShutdown, isShuttingDown, isTerminated, lazyExecute, newTaskQueue, peekTask, pollTask, pollTaskFrom, reject, reject, removeShutdownHook, removeTask, runAllTasks, runAllTasks, runAllTasksFrom, runScheduledAndExecutorTasks, shutdown, shutdownGracefully, takeTask, terminationFuture, threadProperties, updateLastExecutionTime, wakesUpForTask

Methods inherited from class AbstractScheduledEventExecutor

cancelScheduledTasks, deadlineToDelayNanos, getCurrentTimeNanos, hasScheduledTasks, initialNanoTime, nanoTime, nextScheduledTaskDeadlineNanos, nextScheduledTaskNano, pollScheduledTask, pollScheduledTask, schedule, schedule, scheduleAtFixedRate, scheduleWithFixedDelay, validateScheduled

Methods inherited from class AbstractEventExecutor

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

Methods inherited from class Object

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

Methods inherited from interface EventExecutor

inEventLoop, inEventLoop, newFailedFuture, newProgressivePromise, newPromise, newSucceededFuture

Methods inherited from interface EventExecutorGroup

isShuttingDown, iterator, schedule, schedule, scheduleAtFixedRate, scheduleWithFixedDelay, shutdown, shutdownGracefully, shutdownGracefully, shutdownNow, submit, submit, submit, terminationFuture

Methods inherited from interface Executor

execute

Methods inherited from interface ExecutorService

awaitTermination, invokeAll, invokeAll, invokeAny, invokeAny, isShutdown, isTerminated

Methods inherited from interface Iterable

forEach, spliterator

Field Details

logger

private static final InternalLogger logger

EPOLL_WAIT_MILLIS_THRESHOLD

private static final long EPOLL_WAIT_MILLIS_THRESHOLD

epollFd

private FileDescriptor epollFd

eventFd

private FileDescriptor eventFd

timerFd

private FileDescriptor timerFd

channels

private final IntObjectMap<AbstractEpollChannel> channels

allowGrowing

private final boolean allowGrowing

events

private final EpollEventArray events

iovArray

private IovArray iovArray

datagramPacketArray

private NativeDatagramPacketArray datagramPacketArray

selectStrategy

private final SelectStrategy selectStrategy

selectNowSupplier

private final IntSupplier selectNowSupplier

AWAKE

private static final long AWAKE

See Also:

• Constant Field Values

NONE

private static final long NONE

See Also:

• Constant Field Values

nextWakeupNanos

private final AtomicLong nextWakeupNanos

pendingWakeup

private boolean pendingWakeup

ioRatio

private volatile int ioRatio

MAX_SCHEDULED_TIMERFD_NS

private static final long MAX_SCHEDULED_TIMERFD_NS

See Also:

• Constant Field Values

Constructor Details

EpollEventLoop

EpollEventLoop(EventLoopGroup parent,
 Executor executor,
 int maxEvents,
 SelectStrategy strategy,
 RejectedExecutionHandler rejectedExecutionHandler,
 EventLoopTaskQueueFactory taskQueueFactory,
 EventLoopTaskQueueFactory tailTaskQueueFactory)

Method Details

openFileDescriptors

@UnstableApi
public void openFileDescriptors()

This method is intended for use by a process checkpoint/restore integration, such as OpenJDK CRaC.

closeFileDescriptor

private static void closeFileDescriptor(FileDescriptor fd)

newTaskQueue

private static Queue<Runnable> newTaskQueue(EventLoopTaskQueueFactory queueFactory)

cleanIovArray

IovArray cleanIovArray()

Return a cleared IovArray that can be used for writes in this EventLoop.

cleanDatagramPacketArray

NativeDatagramPacketArray cleanDatagramPacketArray()

Return a cleared NativeDatagramPacketArray that can be used for writes in this EventLoop.

wakeup

protected void wakeup(boolean inEventLoop)

Overrides:

wakeup in class SingleThreadEventExecutor

beforeScheduledTaskSubmitted

protected boolean beforeScheduledTaskSubmitted(long deadlineNanos)

Description copied from class: AbstractScheduledEventExecutor

Called from arbitrary non-EventExecutor threads prior to scheduled task submission. Returns true if the EventExecutor thread should be woken immediately to process the scheduled task (if not already awake).

If false is returned, AbstractScheduledEventExecutor.afterScheduledTaskSubmitted(long) will be called with the same value after the scheduled task is enqueued, providing another opportunity to wake the EventExecutor thread if required.

Overrides:

beforeScheduledTaskSubmitted in class AbstractScheduledEventExecutor

Parameters:

deadlineNanos - deadline of the to-be-scheduled task relative to AbstractScheduledEventExecutor.getCurrentTimeNanos()

Returns:

true if the EventExecutor thread should be woken, false otherwise

afterScheduledTaskSubmitted

protected boolean afterScheduledTaskSubmitted(long deadlineNanos)

Description copied from class: AbstractScheduledEventExecutor

See AbstractScheduledEventExecutor.beforeScheduledTaskSubmitted(long). Called only after that method returns false.

Overrides:

afterScheduledTaskSubmitted in class AbstractScheduledEventExecutor

Parameters:

deadlineNanos - relative to AbstractScheduledEventExecutor.getCurrentTimeNanos()

Returns:

true if the EventExecutor thread should be woken, false otherwise

add

void add(AbstractEpollChannel ch)
  throws IOException

Register the given epoll with this EventLoop.

Throws:

IOException

modify

void modify(AbstractEpollChannel ch)
     throws IOException

The flags of the given epoll was modified so update the registration

Throws:

IOException

remove

void remove(AbstractEpollChannel ch)
     throws IOException

Deregister the given epoll from this EventLoop.

Throws:

IOException

newTaskQueue

protected Queue<Runnable> newTaskQueue(int maxPendingTasks)

Description copied from class: SingleThreadEventExecutor

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.

Overrides:

newTaskQueue in class SingleThreadEventExecutor

newTaskQueue0

private static Queue<Runnable> newTaskQueue0(int maxPendingTasks)

getIoRatio

public int getIoRatio()

Returns the percentage of the desired amount of time spent for I/O in the event loop.

setIoRatio

public void setIoRatio(int ioRatio)

Sets the percentage of the desired amount of time spent for I/O in the event loop. The default value is 50, which means the event loop will try to spend the same amount of time for I/O as for non-I/O tasks.

registeredChannels

public int registeredChannels()

Description copied from class: SingleThreadEventLoop

Returns the number of Channels registered with this EventLoop or -1 if operation is not supported. The returned value is not guaranteed to be exact accurate and should be viewed as a best effort.

Overrides:

registeredChannels in class SingleThreadEventLoop

registeredChannelsIterator

public Iterator<Channel> registeredChannelsIterator()

Overrides:

registeredChannelsIterator in class SingleThreadEventLoop

Returns:

read-only iterator of active Channels registered with this EventLoop. The returned value is not guaranteed to be exact accurate and should be viewed as a best effort. This method is expected to be called from within event loop.

epollWait

private long epollWait(long deadlineNanos)
                throws IOException

Throws:

IOException

epollWaitNoTimerChange

private int epollWaitNoTimerChange()
                            throws IOException

Throws:

IOException

epollWaitNow

private int epollWaitNow()
                  throws IOException

Throws:

IOException

epollBusyWait

private int epollBusyWait()
                   throws IOException

Throws:

IOException

epollWaitTimeboxed

private int epollWaitTimeboxed()
                        throws IOException

Throws:

IOException

run

protected void run()

Description copied from class: SingleThreadEventExecutor

Run the tasks in the SingleThreadEventExecutor.taskQueue

Specified by:

run in class SingleThreadEventExecutor

handleLoopException

void handleLoopException(Throwable t)

Visible only for testing!

closeAll

private void closeAll()

processReady

private boolean processReady(EpollEventArray events,
 int ready)

cleanup

protected void cleanup()

Description copied from class: SingleThreadEventExecutor

Do nothing, sub-classes may override

Overrides:

cleanup in class SingleThreadEventExecutor

closeFileDescriptors

@UnstableApi
public void closeFileDescriptors()

This method is intended for use by process checkpoint/restore integration, such as OpenJDK CRaC. It's up to the caller to ensure that there is no concurrent use of the FDs while these are closed, e.g. by blocking the executor.