The AsyncAppender decouples logging event creation from output by processing log events asynchronously. More...

#include <asyncappender.h>

Inheritance diagram for log4cxx::AsyncAppender:

Public Member Functions
	AsyncAppender ()
	Create new instance.

virtual	~AsyncAppender ()
	Destructor.

void	addAppender (const AppenderPtr newAppender) override
	Add appender.

void	doAppend (const spi::LoggingEventPtr &event, helpers::Pool &pool1) override
	This method performs threshold checks and invokes filters before delegating actual logging to the subclasses specific AppenderSkeleton::append method.

void	append (const spi::LoggingEventPtr &event, helpers::Pool &p) override
	Subclasses of `AppenderSkeleton` should implement this method to perform actual logging.

void	close () override
	Close this `AsyncAppender` by interrupting the dispatcher thread which will process all pending events before exiting.

AppenderList	getAllAppenders () const override
	Get iterator over attached appenders.

AppenderPtr	getAppender (const LogString &name) const override
	Get appender by name.

bool	getLocationInfo () const
	Gets whether the location of the logging request call should be captured.

bool	isAttached (const AppenderPtr appender) const override
	Determines if specified appender is attached.

bool	requiresLayout () const override
	Configurators call this method to determine if the appender requires a layout.

void	removeAllAppenders () override
	Removes and closes all attached appenders.

void	removeAppender (const AppenderPtr appender) override
	Removes an appender.

void	removeAppender (const LogString &name) override
	Remove appender by name.

void	setLocationInfo (bool flag)
	The LocationInfo attribute is provided for compatibility with log4j and has no effect on the log output.

void	setBufferSize (int size)
	The BufferSize option takes a non-negative integer value.

int	getBufferSize () const
	Gets the current buffer size.

void	setBlocking (bool value)
	Sets whether appender should wait if there is no space available in the event buffer or immediately return.

bool	getBlocking () const
	Gets whether appender should block calling thread when buffer is full.

void	setOption (const LogString &option, const LogString &value) override
	Set `option` to `value`.

Public Member Functions inherited from log4cxx::spi::AppenderAttachable
virtual void	addAppender (const AppenderPtr newAppender)=0
	Add an appender.

virtual AppenderList	getAllAppenders () const =0
	Get all previously added appenders as an AppenderList.

virtual AppenderPtr	getAppender (const LogString &name) const =0
	Get an appender by name.

virtual bool	isAttached (const AppenderPtr appender) const =0
	Returns `true` if the specified appender is in list of attached appenders, `false` otherwise.

virtual void	removeAllAppenders ()=0
	Remove all previously added appenders.

virtual void	removeAppender (const AppenderPtr appender)=0
	Remove the appender passed as parameter from the list of appenders.

virtual void	removeAppender (const LogString &name)=0
	Remove the appender with the name passed as parameter from the list of appenders.

virtual	~AppenderAttachable ()

Public Member Functions inherited from log4cxx::helpers::Object
virtual	~Object ()

virtual const helpers::Class &	getClass () const =0

virtual bool	instanceof (const Class &clazz) const =0

virtual const void *	cast (const Class &clazz) const =0

Public Member Functions inherited from log4cxx::AppenderSkeleton
	AppenderSkeleton ()

	AppenderSkeleton (const LayoutPtr &layout)

virtual	~AppenderSkeleton ()

void	finalize ()
	Finalize this appender by calling the derived class' `close` method.

void	activateOptions (helpers::Pool &) override
	Activate the options that were previously set with calls to option setters.

void	setOption (const LogString &option, const LogString &value) override
	Set `option` to `value`.

void	addFilter (const spi::FilterPtr newFilter) override
	Add a filter to end of the filter list.

void	clearFilters () override
	Clear the filters chain.

const spi::ErrorHandlerPtr	getErrorHandler () const
	Return the currently set spi::ErrorHandler for this Appender.

spi::FilterPtr	getFilter () const override
	Returns the head Filter.

const spi::FilterPtr	getFirstFilter () const
	Return the first filter in the filter chain for this Appender.

LayoutPtr	getLayout () const override
	Returns the layout of this appender.

LogString	getName () const override
	Returns the name of this Appender.

const LevelPtr	getThreshold () const
	Returns this appenders threshold level.

bool	isAsSevereAsThreshold (const LevelPtr &level) const
	Check whether the message level is below the appender's threshold.

void	doAppend (const spi::LoggingEventPtr &event, helpers::Pool &pool) override
	This method performs threshold checks and invokes filters before delegating actual logging to the subclasses specific AppenderSkeleton::append method.

void	setErrorHandler (const spi::ErrorHandlerPtr eh)
	Set the `ErrorHandler` for this Appender.

void	setLayout (const LayoutPtr layout1) override
	Set the layout for this appender.

void	setName (const LogString &name1) override
	Set the name of this Appender.

void	setThreshold (const LevelPtr &threshold)
	Set the threshold level.

Public Member Functions inherited from log4cxx::Appender
virtual	~Appender ()

virtual void	addFilter (const spi::FilterPtr newFilter)=0
	Add a filter to the end of the filter list.

virtual spi::FilterPtr	getFilter () const =0
	Returns the head Filter.

virtual void	clearFilters ()=0
	Clear the list of filters by removing all the filters in it.

virtual void	close ()=0
	Release any resources allocated within the appender such as file handles, network connections, etc.

virtual void	doAppend (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &pool)=0
	Log in `Appender` specific way.

virtual LogString	getName () const =0
	Get the name of this appender.

virtual void	setLayout (const LayoutPtr layout)=0
	Set the Layout for this appender.

virtual LayoutPtr	getLayout () const =0
	Returns this appenders layout.

virtual void	setName (const LogString &name)=0
	Set the name of this appender.

virtual bool	requiresLayout () const =0
	Configurators call this method to determine if the appender requires a layout.

Public Member Functions inherited from log4cxx::spi::OptionHandler
virtual	~OptionHandler ()

virtual void	activateOptions (helpers::Pool &p)=0
	Activate the options that were previously set with calls to option setters.

virtual void	setOption (const LogString &option, const LogString &value)=0
	Set `option` to `value`.

Additional Inherited Members
Protected Member Functions inherited from log4cxx::AppenderSkeleton
	AppenderSkeleton (LOG4CXX_PRIVATE_PTR(AppenderSkeletonPrivate) priv)

virtual void	append (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &p)=0
	Subclasses of `AppenderSkeleton` should implement this method to perform actual logging.

void	doAppendImpl (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &pool)

Detailed Description

The AsyncAppender decouples logging event creation from output by processing log events asynchronously.

The AsyncAppender stores the logging event in a bounded buffer and then returns control to the application. A separate thread forwards events to the attached appender(s). You can attach multiple appenders to an AsyncAppender.

The AsyncAppender is useful when outputting to a slow event sink, for example, a remote SMTP server or a database. Attaching a FileAppender to AsyncAppender is not recommended as the inter-thread communication overhead can exceed the time to write directly to a file.

When the application produces logging events faster than the background thread is able to process, the bounded buffer can become full. In this situation AsyncAppender will either block until the bounded buffer has a free slot or discard the event. The Blocking property controls which behaviour is used. When events are discarded, the logged output will indicate this with a log message prefixed with Discarded. The output may contain one Discarded message per logger name, the logging event of the highest level for each logger whose events have been discarded.

To determine whether the application produces logging events faster than the background thread is able to process, enable Log4cxx internal debugging. The AsyncAppender will output a histogram of queue length frequencies when closed.

Important note: The AsyncAppender can only be script configured using the DOMConfigurator.

Constructor & Destructor Documentation

◆ AsyncAppender()

log4cxx::AsyncAppender::AsyncAppender ( )

Create new instance.

◆ ~AsyncAppender()

virtual log4cxx::AsyncAppender::~AsyncAppender ( )

virtual

Destructor.

Member Function Documentation

◆ addAppender()

void log4cxx::AsyncAppender::addAppender ( const AppenderPtr newAppender )

overridevirtual

Add appender.

Parameters

newAppender appender to add, may not be null.

Implements log4cxx::spi::AppenderAttachable.

◆ append()

void log4cxx::AsyncAppender::append	(	const spi::LoggingEventPtr &	event,
		helpers::Pool &	p
	)

overridevirtual

Subclasses of AppenderSkeleton should implement this method to perform actual logging.

See also AppenderSkeleton::doAppend method.

Implements log4cxx::AppenderSkeleton.

◆ close()

void log4cxx::AsyncAppender::close ( )

overridevirtual

Close this AsyncAppender by interrupting the dispatcher thread which will process all pending events before exiting.

Implements log4cxx::Appender.

◆ doAppend()

void log4cxx::AsyncAppender::doAppend	(	const spi::LoggingEventPtr &	event,
		helpers::Pool &	pool
	)

overridevirtual

This method performs threshold checks and invokes filters before delegating actual logging to the subclasses specific AppenderSkeleton::append method.

Reimplemented from log4cxx::AppenderSkeleton.

◆ getAllAppenders()

AppenderList log4cxx::AsyncAppender::getAllAppenders ( ) const

overridevirtual

Get iterator over attached appenders.

Returns: list of all attached appenders.

Implements log4cxx::spi::AppenderAttachable.

◆ getAppender()

AppenderPtr log4cxx::AsyncAppender::getAppender ( const LogString & name ) const

overridevirtual

Get appender by name.

Parameters

name	name, may not be null.

Returns: matching appender or null.

Implements log4cxx::spi::AppenderAttachable.

◆ getBlocking()

bool log4cxx::AsyncAppender::getBlocking ( ) const

Gets whether appender should block calling thread when buffer is full.

If false, messages will be counted by logger and a summary message appended after the contents of the buffer have been appended.

Returns: true if calling thread will be blocked when buffer is full.

◆ getBufferSize()

int log4cxx::AsyncAppender::getBufferSize ( ) const

Gets the current buffer size.

Returns: the current value of the BufferSize option.

◆ getLocationInfo()

bool log4cxx::AsyncAppender::getLocationInfo ( ) const

Gets whether the location of the logging request call should be captured.

Returns: the current value of the LocationInfo option.

◆ isAttached()

bool log4cxx::AsyncAppender::isAttached ( const AppenderPtr appender ) const

overridevirtual

Determines if specified appender is attached.

Parameters

appender appender.

Returns: true if attached.

Implements log4cxx::spi::AppenderAttachable.

◆ removeAllAppenders()

void log4cxx::AsyncAppender::removeAllAppenders ( )

overridevirtual

Removes and closes all attached appenders.

Implements log4cxx::spi::AppenderAttachable.

◆ removeAppender() [1/2]

void log4cxx::AsyncAppender::removeAppender ( const AppenderPtr appender )

overridevirtual

Removes an appender.

Parameters

appender appender to remove.

Implements log4cxx::spi::AppenderAttachable.

◆ removeAppender() [2/2]

void log4cxx::AsyncAppender::removeAppender ( const LogString & name )

overridevirtual

Remove appender by name.

Parameters

name name.

Implements log4cxx::spi::AppenderAttachable.

◆ requiresLayout()

bool log4cxx::AsyncAppender::requiresLayout ( ) const

overridevirtual

Configurators call this method to determine if the appender requires a layout.

If this method returns true, meaning that layout is required, then the configurator will configure an layout using the configuration information at its disposal. If this method returns false, meaning that a layout is not required, then layout configuration will be skipped even if there is available layout configuration information at the disposal of the configurator..

In the rather exceptional case, where the appender implementation admits a layout but can also work without it, then the appender should return true.

Implements log4cxx::Appender.

◆ setBlocking()

void log4cxx::AsyncAppender::setBlocking ( bool value )

Sets whether appender should wait if there is no space available in the event buffer or immediately return.

Parameters

value true if appender should wait until available space in buffer.

◆ setBufferSize()

void log4cxx::AsyncAppender::setBufferSize ( int size )

The BufferSize option takes a non-negative integer value.

This integer value determines the maximum size of the bounded buffer.

◆ setLocationInfo()

void log4cxx::AsyncAppender::setLocationInfo ( bool flag )

The LocationInfo attribute is provided for compatibility with log4j and has no effect on the log output.

Parameters

flag	new value.

◆ setOption()

void log4cxx::AsyncAppender::setOption	(	const LogString &	option,
		const LogString &	value
	)

overridevirtual

Set option to value.

Supported options	Supported values	Default value
LocationInfo	True,False	False
BufferSize	int	128
Blocking	True,False	True

See also: AppenderSkeleton::setOption()

Reimplemented from log4cxx::AppenderSkeleton.

The documentation for this class was generated from the following file:

asyncappender.h

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ AsyncAppender()

◆ ~AsyncAppender()

Member Function Documentation

◆ addAppender()

◆ append()

◆ close()

◆ doAppend()

◆ getAllAppenders()

◆ getAppender()

◆ getBlocking()

◆ getBufferSize()

◆ getLocationInfo()

◆ isAttached()

◆ removeAllAppenders()

◆ removeAppender() [1/2]

◆ removeAppender() [2/2]

◆ requiresLayout()

◆ setBlocking()

◆ setBufferSize()

◆ setLocationInfo()

◆ setOption()