Class EpollIoHandler

java.lang.Object

io.netty.channel.epoll.EpollIoHandler

All Implemented Interfaces:

IoHandler

public class EpollIoHandler
extends java.lang.Object
implements IoHandler

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

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private final class	EpollIoHandler.DefaultEpollIoRegistration
private static enum	EpollIoHandler.RegistrationState

Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	allowGrowing
private static final long	AWAKE
private static final long	EPOLL_WAIT_MILLIS_THRESHOLD
private FileDescriptor	epollFd
private FileDescriptor	eventFd
private final EpollEventArray	events
private final ThreadAwareExecutor	executor
private static final InternalLogger	logger
private static final long	MAX_SCHEDULED_TIMERFD_NS
private final NativeArrays	nativeArrays
private final java.util.concurrent.atomic.AtomicLong	nextWakeupNanos
private static final long	NONE
private int	numChannels
private boolean	pendingWakeup
private long	prevDeadlineNanos
private final IntObjectMap<EpollIoHandler.DefaultEpollIoRegistration>	registrations
private final IntSupplier	selectNowSupplier
private final SelectStrategy	selectStrategy
private FileDescriptor	timerFd

Constructor Summary

Constructors

Constructor	Description
EpollIoHandler(ThreadAwareExecutor executor, int maxEvents, SelectStrategy strategy)

Method Summary

Modifier and Type	Method	Description
private static EpollIoHandle	cast(IoHandle handle)
private static EpollIoOps	cast(IoOps ops)
private static void	closeFileDescriptor(FileDescriptor fd)
void	closeFileDescriptors()	This method is intended for use by process checkpoint/restore integration, such as OpenJDK CRaC.
void	destroy()	Destroy the IoHandler and free all its resources.
private int	epollBusyWait()
private long	epollWait(IoHandlerContext context, long deadlineNanos)
private int	epollWaitNoTimerChange()
private int	epollWaitNow()
private int	epollWaitTimeboxed()
(package private) void	handleLoopException(java.lang.Throwable t)	Visible only for testing!
boolean	isCompatible(java.lang.Class<? extends IoHandle> handleType)	Returns true if the given type is compatible with this IoHandler and so can be registered, false otherwise.
static IoHandlerFactory	newFactory()	Returns a new IoHandlerFactory that creates EpollIoHandler instances.
static IoHandlerFactory	newFactory(int maxEvents, SelectStrategyFactory selectStrategyFactory)	Returns a new IoHandlerFactory that creates EpollIoHandler instances.
(package private) int	numRegisteredChannels()
void	openFileDescriptors()	This method is intended for use by a process checkpoint/restore integration, such as OpenJDK CRaC.
void	prepareToDestroy()	Prepare to destroy this IoHandler.
private int	processReady(EpollEventArray events, int ready)
IoRegistration	register(IoHandle handle)	Register a IoHandle for IO.
(package private) java.util.List<Channel>	registeredChannelsList()
int	run(IoHandlerContext context)	Run the IO handled by this IoHandler.
void	wakeup()	Wakeup the IoHandler, which means if any operation blocks it should be unblocked and return as soon as possible.

Methods inherited from class java.lang.Object

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

Methods inherited from interface IoHandler

initialize

Field Details

logger

private static final InternalLogger logger

EPOLL_WAIT_MILLIS_THRESHOLD

private static final long EPOLL_WAIT_MILLIS_THRESHOLD

prevDeadlineNanos

private long prevDeadlineNanos

epollFd

private FileDescriptor epollFd

eventFd

private FileDescriptor eventFd

timerFd

private FileDescriptor timerFd

registrations

private final IntObjectMap<EpollIoHandler.DefaultEpollIoRegistration> registrations

allowGrowing

private final boolean allowGrowing

events

private final EpollEventArray events

nativeArrays

private final NativeArrays nativeArrays

selectStrategy

private final SelectStrategy selectStrategy

selectNowSupplier

private final IntSupplier selectNowSupplier

executor

private final ThreadAwareExecutor executor

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 java.util.concurrent.atomic.AtomicLong nextWakeupNanos

pendingWakeup

private boolean pendingWakeup

numChannels

private int numChannels

MAX_SCHEDULED_TIMERFD_NS

private static final long MAX_SCHEDULED_TIMERFD_NS

See Also:

• Constant Field Values

Constructor Details

EpollIoHandler

EpollIoHandler(ThreadAwareExecutor executor,
 int maxEvents,
 SelectStrategy strategy)

Method Details

newFactory

public static IoHandlerFactory newFactory()

Returns a new IoHandlerFactory that creates EpollIoHandler instances.

newFactory

public static IoHandlerFactory newFactory(int maxEvents,
 SelectStrategyFactory selectStrategyFactory)

Returns a new IoHandlerFactory that creates EpollIoHandler instances.

cast

private static EpollIoHandle cast(IoHandle handle)

cast

private static EpollIoOps cast(IoOps ops)

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)

wakeup

public void wakeup()

Description copied from interface: IoHandler

Wakeup the IoHandler, which means if any operation blocks it should be unblocked and return as soon as possible.

Specified by:

wakeup in interface IoHandler

prepareToDestroy

public void prepareToDestroy()

Description copied from interface: IoHandler

Prepare to destroy this IoHandler. This method will be called before IoHandler.destroy() and may be called multiple times.

Specified by:

prepareToDestroy in interface IoHandler

destroy

public void destroy()

Description copied from interface: IoHandler

Destroy the IoHandler and free all its resources. Once destroyed using the IoHandler will cause undefined behaviour.

Specified by:

destroy in interface IoHandler

register

public IoRegistration register(IoHandle handle)
                        throws java.lang.Exception

Description copied from interface: IoHandler

Register a IoHandle for IO.

Specified by:

register in interface IoHandler

Parameters:

handle - the IoHandle to register.

Throws:

java.lang.Exception - thrown if an error happens during registration.

isCompatible

public boolean isCompatible(java.lang.Class<? extends IoHandle> handleType)

Description copied from interface: IoHandler

Returns true if the given type is compatible with this IoHandler and so can be registered, false otherwise.

Specified by:

isCompatible in interface IoHandler

Parameters:

handleType - the type of the IoHandle.

Returns:

if compatible of not.

numRegisteredChannels

int numRegisteredChannels()

registeredChannelsList

java.util.List<Channel> registeredChannelsList()

epollWait

private long epollWait(IoHandlerContext context,
 long deadlineNanos)
                throws java.io.IOException

Throws:

java.io.IOException

epollWaitNoTimerChange

private int epollWaitNoTimerChange()
                            throws java.io.IOException

Throws:

java.io.IOException

epollWaitNow

private int epollWaitNow()
                  throws java.io.IOException

Throws:

java.io.IOException

epollBusyWait

private int epollBusyWait()
                   throws java.io.IOException

Throws:

java.io.IOException

epollWaitTimeboxed

private int epollWaitTimeboxed()
                        throws java.io.IOException

Throws:

java.io.IOException

run

public int run(IoHandlerContext context)

Description copied from interface: IoHandler

Run the IO handled by this IoHandler. The IoHandlerContext should be used to ensure we not execute too long and so block the processing of other task that are scheduled on the ThreadAwareExecutor. This is done by taking IoHandlerContext.delayNanos(long) or IoHandlerContext.deadlineNanos() into account.

Specified by:

run in interface IoHandler

Parameters:

context - the IoHandlerContext.

Returns:

the number of IoHandle for which I/O was handled. Internal events such as wakeups and timer expirations must not be included in this count.

handleLoopException

void handleLoopException(java.lang.Throwable t)

Visible only for testing!

processReady

private int processReady(EpollEventArray events,
 int ready)

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.