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SocketHubAppender Class Reference

Sends LoggingEvent objects to a set of remote log servers, usually a SocketNode. More...

Inheritance diagram for SocketHubAppender:
AppenderSkeleton Appender ObjectImpl OptionHandler Object Object

Public Member Functions

 SocketHubAppender ()
 
 ~SocketHubAppender ()
 
 SocketHubAppender (int port)
 Connects to remote server at address and port. More...
 
virtual void activateOptions (log4cxx::helpers::Pool &p)
 Set up the socket server on the specified port. More...
 
virtual void setOption (const LogString &option, const LogString &value)
 Set options. More...
 
virtual void close ()
 Release any resources allocated within the appender such as file handles, network connections, etc. More...
 
virtual void append (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &p)
 Append an event to all of current connections. More...
 
virtual bool requiresLayout () const
 The SocketHubAppender does not use a layout. More...
 
void setPort (int port1)
 The Port option takes a positive integer representing the port where the server is waiting for connections. More...
 
int getPort () const
 Returns value of the Port option. More...
 
void setLocationInfo (bool locationInfo1)
 The LocationInfo option takes a boolean value. More...
 
bool getLocationInfo () const
 Returns value of the LocationInfo option. More...
 
- Public Member Functions inherited from AppenderSkeleton
 AppenderSkeleton ()
 
 AppenderSkeleton (const LayoutPtr &layout)
 
void addRef () const
 
void releaseRef () const
 
void finalize ()
 Finalize this appender by calling the derived class' close method. More...
 
void addFilter (const spi::FilterPtr &newFilter)
 Add a filter to end of the filter list. More...
 
void clearFilters ()
 Clear the filters chain. More...
 
const spi::ErrorHandlerPtrgetErrorHandler () const
 Return the currently set spi::ErrorHandler for this Appender. More...
 
spi::FilterPtr getFilter () const
 Returns the head Filter. More...
 
const spi::FilterPtrgetFirstFilter () const
 Return the first filter in the filter chain for this Appender. More...
 
LayoutPtr getLayout () const
 Returns the layout of this appender. More...
 
LogString getName () const
 Returns the name of this Appender. More...
 
const LevelPtrgetThreshold ()
 Returns this appenders threshold level. More...
 
bool isAsSevereAsThreshold (const LevelPtr &level) const
 Check whether the message level is below the appender's threshold. More...
 
void doAppend (const spi::LoggingEventPtr &event, log4cxx::helpers::Pool &pool)
 This method performs threshold checks and invokes filters before delegating actual logging to the subclasses specific AppenderSkeleton::append method. More...
 
void setErrorHandler (const spi::ErrorHandlerPtr &eh)
 Set the ErrorHandler for this Appender. More...
 
void setLayout (const LayoutPtr &layout1)
 Set the layout for this appender. More...
 
void setName (const LogString &name1)
 Set the name of this Appender. More...
 
void setThreshold (const LevelPtr &threshold)
 Set the threshold level. More...
 
- Public Member Functions inherited from Appender
virtual ~Appender ()
 
- Public Member Functions inherited from OptionHandler
virtual ~OptionHandler ()
 
- Public Member Functions inherited from Object
virtual const helpers::ClassgetClass () const
 
virtual ~Object ()
 
virtual bool instanceof (const Class &clazz) const =0
 
virtual const void * cast (const Class &clazz) const =0
 
- Public Member Functions inherited from ObjectImpl
 ObjectImpl ()
 
virtual ~ObjectImpl ()
 
void addRef () const
 
void releaseRef () const
 

Additional Inherited Members

- Static Public Member Functions inherited from Object
static const helpers::ClassgetStaticClass ()
 
static const
log4cxx::helpers::ClassRegistration
registerClass ()
 
- Protected Attributes inherited from AppenderSkeleton
LayoutPtr layout
 The layout variable does not need to be set if the appender implementation has its own layout. More...
 
LogString name
 Appenders are named. More...
 
LevelPtr threshold
 There is no level threshold filtering by default. More...
 
spi::ErrorHandlerPtr errorHandler
 It is assumed and enforced that errorHandler is never null. More...
 
spi::FilterPtr headFilter
 The first filter in the filter chain. More...
 
spi::FilterPtr tailFilter
 The last filter in the filter chain. More...
 
bool closed
 Is this appender closed? More...
 
log4cxx::helpers::Pool pool
 
log4cxx::helpers::Mutex mutex
 
- Protected Attributes inherited from ObjectImpl
unsigned int volatile ref
 

Detailed Description

Sends LoggingEvent objects to a set of remote log servers, usually a SocketNode.

Acts just like SocketAppender except that instead of connecting to a given remote log server, SocketHubAppender accepts connections from the remote log servers as clients. It can accept more than one connection. When a log event is received, the event is sent to the set of currently connected remote log servers. Implemented this way it does not require any update to the configuration file to send data to another remote log server. The remote log server simply connects to the host and port the SocketHubAppender is running on.

The SocketHubAppender does not store events such that the remote side will events that arrived after the establishment of its connection. Once connected, events arrive in order as guaranteed by the TCP protocol.

This implementation borrows heavily from the SocketAppender.

The SocketHubAppender has the following characteristics:

  • If sent to a SocketNode, logging is non-intrusive as far as the log event is concerned. In other words, the event will be logged with the same time stamp, NDC, location info as if it were logged locally.
  • SocketHubAppender does not use a layout. It ships a serialized spi::LoggingEvent object to the remote side.
  • SocketHubAppender relies on the TCP protocol. Consequently, if the remote side is reachable, then log events will eventually arrive at remote client.
  • If no remote clients are attached, the logging requests are simply dropped.
  • Logging events are automatically buffered by the native TCP implementation. This means that if the link to remote client is slow but still faster than the rate of (log) event production, the application will not be affected by the slow network connection. However, if the network connection is slower then the rate of event production, then the local application can only progress at the network rate. In particular, if the network link to the the remote client is down, the application will be blocked.

    On the other hand, if the network link is up, but the remote client is down, the client will not be blocked when making log requests but the log events will be lost due to client unavailability.

    The single remote client case extends to multiple clients connections. The rate of logging will be determined by the slowest link.
  • If the application hosting the SocketHubAppender exits before the SocketHubAppender is closed either explicitly or subsequent to garbage collection, then there might be untransmitted data in the pipe which might be lost. This is a common problem on Windows based systems.

    To avoid lost data, it is usually sufficient to close the SocketHubAppender either explicitly or by calling the LogManager::shutdown method before exiting the application.

Constructor & Destructor Documentation

SocketHubAppender ( int  port)

Connects to remote server at address and port.

Member Function Documentation

virtual void activateOptions ( log4cxx::helpers::Pool p)
virtual

Set up the socket server on the specified port.

Reimplemented from AppenderSkeleton.

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

Append an event to all of current connections.

Implements AppenderSkeleton.

virtual void close ( )
virtual

Release any resources allocated within the appender such as file handles, network connections, etc.

It is a programming error to append to a closed appender.

Implements Appender.

bool getLocationInfo ( ) const
inline

Returns value of the LocationInfo option.

int getPort ( ) const
inline

Returns value of the Port option.

virtual bool requiresLayout ( ) const
inlinevirtual

The SocketHubAppender does not use a layout.

Hence, this method returns false.

Implements Appender.

void setLocationInfo ( bool  locationInfo1)
inline

The LocationInfo option takes a boolean value.

If true, the information sent to the remote host will include location information. By default no location information is sent to the server.

virtual void setOption ( const LogString option,
const LogString value 
)
virtual

Set options.

Reimplemented from AppenderSkeleton.

void setPort ( int  port1)
inline

The Port option takes a positive integer representing the port where the server is waiting for connections.


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