de.fhg.igd.logging.log4j
Class AsynchronousWriterAppender

java.lang.Object
  org.apache.log4j.AppenderSkeleton
      org.apache.log4j.WriterAppender
          de.fhg.igd.logging.log4j.AsynchronousWriterAppender

All Implemented Interfaces:

org.apache.log4j.Appender, Messenger, org.apache.log4j.spi.OptionHandler

public class AsynchronousWriterAppender

extends org.apache.log4j.WriterAppender

implements Messenger

This Appender is intended to be used for logging across slow or instable network connections. Because of the contained AbstractAsynchronousMessageDispatcher implementation append(org.apache.log4j.spi.LoggingEvent) will always return immediately, to make sure the delay of the main thread caused by the logging mechanism is minimized even under unfavorable network conditions.

Version:

"$Id: AsynchronousWriterAppender.java 1913 2007-08-08 02:41:53Z jpeters $"

Author:

Matthias Pressfreund

Nested Class Summary

private static class

AsynchronousWriterAppender.Log4jMessageDispatcher This is the dispatcher implementation for the Log4J logging mechanism.

Field Summary

private boolean	closed_ This flag will be set to true once close() has been called
private AbstractAsynchronousMessageDispatcher	dispatcher_ The Asynchronous Message Dispatcher thread

Fields inherited from class org.apache.log4j.WriterAppender

encoding, immediateFlush, qw

Fields inherited from class org.apache.log4j.AppenderSkeleton

closed, errorHandler, headFilter, layout, name, tailFilter, threshold

Constructor Summary

AsynchronousWriterAppender(org.apache.log4j.Layout layout, OutputStream os, int maxbuf)
Create an AsynchronousWriterAppender.

Method Summary

void	append(org.apache.log4j.spi.LoggingEvent event) Hand over a log event to be posted as soon as possible.
void	close() This method will close underlying streams and free used resources.
void	post(Object event) Actually post a message into the underlying logging system.
String	toString()

Methods inherited from class org.apache.log4j.WriterAppender

activateOptions, checkEntryConditions, closeWriter, createWriter, getEncoding, getImmediateFlush, requiresLayout, reset, setEncoding, setErrorHandler, setImmediateFlush, setWriter, subAppend, writeFooter, writeHeader

Methods inherited from class org.apache.log4j.AppenderSkeleton

addFilter, clearFilters, doAppend, finalize, getErrorHandler, getFilter, getFirstFilter, getLayout, getName, getThreshold, isAsSevereAsThreshold, setLayout, setName, setThreshold

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

dispatcher_

private AbstractAsynchronousMessageDispatcher dispatcher_

The Asynchronous Message Dispatcher thread

closed_

private boolean closed_

This flag will be set to true once close() has been called

Constructor Detail

AsynchronousWriterAppender

public AsynchronousWriterAppender(org.apache.log4j.Layout layout,
                                  OutputStream os,
                                  int maxbuf)

Create an AsynchronousWriterAppender.

Parameters:

layout - The layout to be used for message formatting

os - The underlying output stream

maxbuf - The maximum number of messages that can be stored in the internal buffer (must be at least 1)

Throws:

IllegalArgumentException - if the maximum buffer size is less than 1

Method Detail

append

public void append(org.apache.log4j.spi.LoggingEvent event)

Hand over a log event to be posted as soon as possible.

Parameters:

event - The log event to be appended

post

public void post(Object event)

Description copied from interface: Messenger

Actually post a message into the underlying logging system.

Specified by:

post in interface Messenger

Parameters:

event - The message to post

close

public void close()

This method will close underlying streams and free used resources. When it returns, all events will have been written by the included AbstractAsynchronousMessageDispatcher.

Specified by:

close in interface org.apache.log4j.Appender

toString

public String toString()