Logger::LoggerAppender Class Reference

Implements passing LoggerEvent to target destination. More...

#include <Logger.qm.dox.h>

Inheritance diagram for Logger::LoggerAppender:

Public Member Methods
	addFilter (LoggerFilter filter, bool top=False)
	Adds a filter to the chain. More...
	close ()
	Releases any resources allocated by the appender and closes it.
	constructor (*string name)
	Creates the object. More...
list< LoggerFilter >	getFilters ()
	Returns the filter chain as a list. More...
string	getName ()
	Returns the appender name.
*LoggerAppenderQueue	getQueue ()
	Returns async queue or NOTHING when events are processed synchronously.
bool	isOpen ()
	Returns True if the appender is open and therefore active.
	open ()
	Opens logging resources. More...
bool	post (LoggerEvent event)
	Posts the given event to the output queue. More...
	processEvent (int type, auto params)
	Processes an event to the physical target. More...
abstract	processEventImpl (int type, auto params)
	Processes the event to the physical target. More...
	removeAllFilters ()
	Clears the filter chain by removing all filters.
	removeFilter (LoggerFilter filter)
	Removes the given filter from the filter chain. More...
	setQueue (*LoggerAppenderQueue queue)
	Sets the appender queue. More...

Public Attributes
const	EVENT_CLOSE = 3
	close event
const	EVENT_LOG = 2
	logging event
const	EVENT_OPEN = 1
	open event

Private Member Methods
*object	ensureAtomicOperations (int type)
	Returns an object that can be used to ensure atomic operations for appender operations.
RWLock	lock ()
	The lock to ensure proper serialization with concurrent access.
bool	pushEvent (int type, auto params)
	Pushes the given event on the queue or calls processEvent() in case of synchronous processing. More...
abstract auto	serializeImpl (LoggerEvent event)
	Serializes the given event to put in the queue or write to the target device. More...

Private:Internal Attributes
bool	active = False
	An inactive appender won't accept any logging request.
list< LoggerFilter >	filters
	filter chain
string	name
	Appender name.
*LoggerAppenderQueue	queue
	async queue

Detailed Description

Implements passing LoggerEvent to target destination.

subclasses will implement e.g. logging to file, to stderr, to database etc. LoggerAppender supports sync and async logging.

The ability to selectively enable or disable logging requests based on level in Logger is extended in the appender via LoggerFilter, which implements filtering on any criteria.

The appender instance should be closed via close() method explicitely to stop accepting logging events which might arrive later than destructing process has started. This process cannot start by design before all events has been processed as the LoggerEvent instance holds refeence to this appender instance.

Member Function Documentation

addFilter()

Logger::LoggerAppender::addFilter	(	LoggerFilter	filter,
		bool	top = False
	)

Adds a filter to the chain.

Parameters

filter	the new filter to add
top	if True then the filter is added at the start of the filter chain, if False (the default), the filter is added at the end of the chain

Exceptions

LOGGER-ERROR

thrown if the filter is already in the list

constructor()

Logger::LoggerAppender::constructor

(

*string

name

)

Creates the object.

Parameters

name	the appender name

getFilters()

list< LoggerFilter > Logger::LoggerAppender::getFilters

(

)

Returns the filter chain as a list.

Note that appender filter chain may be modified as internal lock is released when copy of list is returned

open()

Logger::LoggerAppender::open

(

)

Opens logging resources.

The appender must be opened to accept any logging events

post()

bool Logger::LoggerAppender::post

(

LoggerEvent

event

)

Posts the given event to the output queue.

Invokes filters; when the event is accepted then it is posted to the queue in case of asynchronous processing, or it is immediately logged by the processEvent() method in case of synchronous processing.

See also

processEvent()

Parameters

event

the event to post

Returns

True if the event has been posted, False if not (filtered out, appender inactive, event not accepted on queue, etc)

processEvent()

Logger::LoggerAppender::processEvent	(	int	type,
		auto	params
	)

Processes an event to the physical target.

See also

serializeImpl()

Parameters

type	see "EVENT_xxx" constants
params	processing parameters

processEventImpl()

abstract Logger::LoggerAppender::processEventImpl ( int  type, auto  params  )

pure virtual

Processes the event to the physical target.

Must be implemented by non-abstract subclasses

See also

serializeImpl()

Parameters

type	see "EVENT_xxx" constants
params	processing parameters

Implemented in Logger::LoggerAppenderNull, Logger::LoggerAppenderStream, Logger::LoggerAppenderFile, Logger::LoggerAppenderStdOut, Logger::LoggerAppenderStdErr, Logger::LoggerAppenderFileRotate, Logger::LoggerAppenderFileRing, Logger::LoggerAppenderFileArchive, and Logger::StdoutAppender.

pushEvent()

bool Logger::LoggerAppender::pushEvent ( int  type, auto  params  )

private

Pushes the given event on the queue or calls processEvent() in case of synchronous processing.

Parameters

type	the event type
params	parameters for the event according to the event type

Returns

True if the event was accepted/processed, False if not

See also

processEvent()

removeFilter()

Logger::LoggerAppender::removeFilter

(

LoggerFilter

filter

)

Removes the given filter from the filter chain.

Parameters

filter

the filter to remove

serializeImpl()

abstract auto Logger::LoggerAppender::serializeImpl ( LoggerEvent  event )

privatepure virtual

Serializes the given event to put in the queue or write to the target device.

The appender implementaion can define any format for serialization. The data are passed to processEvent() method in the params argument when type is EVENT_LOG.

Returns

the serialized event

Implemented in Logger::LoggerAppenderNull, and Logger::LoggerAppenderWithLayout.

setQueue()

Logger::LoggerAppender::setQueue

(

*LoggerAppenderQueue

queue

)

Sets the appender queue.

Data are passed to target device synchronously unless queue is assigned. In this case data are queued and dedicated process will process it asynchronously

Parameters

queue

Exceptions

LOGGER-ERROR

thrown if appender is opened