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. | |
| virtual Decision | decide (const LoggingEvent &event) |
| Decide whether to accept or deny a LoggingEvent. | |
| Filter () | |
| Default Constructor for Filter. | |
| virtual Filter * | getChainedFilter () |
| Get the next Filter in the Filter chain. | |
| virtual Filter * | getEndOfChain () |
| Get the last Filter in the Filter chain. | |
| virtual void | setChainedFilter (Filter *filter) |
| Set the next Filter in the Filter chain. | |
| virtual | ~Filter () |
| Destructor for Filter. | |
Protected Member Functions | |
| virtual Decision | _decide (const LoggingEvent &event)=0 |
| Decide whether this Filter accepts or denies the given LoggingEvent. | |
Private Attributes | |
| Filter * | _chainedFilter |
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.
| enum Filter::Decision |
| Filter::Filter | ( | ) |
Default Constructor for Filter.
| virtual Filter::~Filter | ( | ) | [virtual] |
Destructor for Filter.
| virtual Decision Filter::_decide | ( | const LoggingEvent & | event | ) | [protected, pure virtual] |
Decide whether this Filter accepts or denies the given LoggingEvent.
Actual implementation of Filter should override this method and not decide(LoggingEvent&).
| event | The LoggingEvent to decide on. |
| virtual void Filter::appendChainedFilter | ( | Filter * | filter | ) | [virtual] |
Add a Filter to the end of the Filter chain.
Convience method for getEndOfChain()->setChainedFilter(filter).
| 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.
| event | The LoggingEvent to decide on. |
| virtual Filter* Filter::getChainedFilter | ( | ) | [virtual] |
| virtual Filter* Filter::getEndOfChain | ( | ) | [virtual] |
| virtual void Filter::setChainedFilter | ( | Filter * | filter | ) | [virtual] |
Filter* Filter::_chainedFilter [private] |