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 class EpollIoHandler.DefaultEpollIoRegistration

private static class EpollIoHandler.RegistrationState

Field Summary

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

Constructor Summary

Constructors
Constructor Description

EpollIoHandler(ThreadAwareExecutor executor, int maxEvents, SelectStrategy strategy)

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
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 io.netty.channel.IoHandler
initialize

- Field Detail
  - 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 Detail
  - EpollIoHandler
```
EpollIoHandler(ThreadAwareExecutor executor,
               int maxEvents,
               SelectStrategy strategy)
```
- Method Detail
  - 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.

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

Class EpollIoHandler

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface io.netty.channel.IoHandler

Field Detail

logger

EPOLL_WAIT_MILLIS_THRESHOLD

prevDeadlineNanos

epollFd

eventFd

timerFd

registrations

allowGrowing

events

nativeArrays

selectStrategy

selectNowSupplier

executor

AWAKE

NONE

nextWakeupNanos

pendingWakeup

numChannels

MAX_SCHEDULED_TIMERFD_NS

Constructor Detail

EpollIoHandler

Method Detail

newFactory

newFactory

cast

cast

openFileDescriptors

closeFileDescriptor

wakeup

prepareToDestroy

destroy

register

isCompatible

numRegisteredChannels

registeredChannelsList

epollWait

epollWaitNoTimerChange

epollWaitNow

epollBusyWait

epollWaitTimeboxed

run

handleLoopException

processReady

closeFileDescriptors