Filter Class Reference

Users should extend this class to implement customized logging event filtering. More...

#include <Filter.hh>

Public Types
enum	Decision { DENY = -1, NEUTRAL = 0, ACCEPT = 1 }

Public Member Functions
virtual void	appendChainedFilter (Filter *filter)
	Add a Filter to the end of the Filter chain. More...
virtual Decision	decide (const LoggingEvent &event)
	Decide whether to accept or deny a LoggingEvent. More...
	Filter ()
	Default Constructor for Filter. More...
virtual Filter *	getChainedFilter ()
	Get the next Filter in the Filter chain. More...
virtual Filter *	getEndOfChain ()
	Get the last Filter in the Filter chain. More...
virtual void	setChainedFilter (Filter *filter)
	Set the next Filter in the Filter chain. More...
virtual	~Filter ()
	Destructor for Filter. More...

Protected Member Functions
virtual Decision	_decide (const LoggingEvent &event)=0
	Decide whether this Filter accepts or denies the given LoggingEvent. More...

Private Attributes
Filter *	_chainedFilter

Detailed Description

Users should extend this class to implement customized logging event filtering.

Note that log4cpp::Category and lof4cpp::Appender have built-in filtering rules. It is suggested that you first use and understand the built-in rules before rushing to write your own custom filters.

This abstract class assumes and also imposes that filters be organized in a linear chain. The decide(LoggingEvent) method of each filter is called sequentially, in the order of their addition to the chain.

The decide(LoggingEvent) method must return a Decision value, either DENY, NEUTRAL or ACCCEPT.

If the value DENY is returned, then the log event is dropped immediately without consulting with the remaining filters.

If the value NEUTRAL is returned, then the next filter in the chain is consulted. If there are no more filters in the chain, then the log event is logged. Thus, in the presence of no filters, the default behaviour is to log all logging events.

If the value ACCEPT is returned, then the log event is logged without consulting the remaining filters.

The philosophy of log4cpp filters is largely inspired from the Linux ipchains.

Definition at line 49 of file Filter.hh.

Member Enumeration Documentation

enum Filter::Decision

Enumerator
DENY
NEUTRAL
ACCEPT

Definition at line 52 of file Filter.hh.

Constructor & Destructor Documentation

Filter::Filter

(

)

Default Constructor for Filter.

virtual Filter::~Filter ( )

virtual

Destructor for Filter.

Member Function Documentation

virtual Decision Filter::_decide ( const LoggingEvent &  event )

protectedpure virtual

Decide whether this Filter accepts or denies the given LoggingEvent.

Actual implementation of Filter should override this method and not decide(LoggingEvent&).

Parameters

event

The LoggingEvent to decide on.

Returns

The Decision

virtual void Filter::appendChainedFilter ( Filter *  filter )

virtual

Add a Filter to the end of the Filter chain.

Convience method for getEndOfChain()->setChainedFilter(filter).

Parameters

filter

The filter to add to the end of the chain.

virtual Decision Filter::decide ( const LoggingEvent &  event )

virtual

Decide whether to accept or deny a LoggingEvent.

This method will walk the entire chain until a non neutral decision has been made or the end of the chain has been reached.

Parameters

event

The LoggingEvent to decide on.

Returns

The Decision

virtual Filter* Filter::getChainedFilter ( )

virtual

Get the next Filter in the Filter chain.

Returns

The next Filter or NULL if the current filter is the last in the chain

virtual Filter* Filter::getEndOfChain ( )

virtual

Get the last Filter in the Filter chain.

Returns

The last Filter in the Filter chain

virtual void Filter::setChainedFilter ( Filter *  filter )

virtual

Set the next Filter in the Filter chain.

Parameters

filter

The filter to chain

Member Data Documentation

Filter* Filter::_chainedFilter

private

Definition at line 114 of file Filter.hh.

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

• Filter.hh