org.apache.log4j
Class AsyncAppender

java.lang.Object
  org.apache.log4j.AppenderSkeleton
      org.apache.log4j.AsyncAppender

All Implemented Interfaces:

Appender, AppenderAttachable, OptionHandler

public class AsyncAppender
extends AppenderSkeleton
implements AppenderAttachable

The AsyncAppender lets users log events asynchronously. It uses a bounded buffer to store logging events.

The AsyncAppender will collect the events sent to it and then dispatch them to all the appenders that are attached to it. You can attach multiple appenders to an AsyncAppender.

The AsyncAppender uses a separate thread to serve the events in its bounded buffer.

Refer to the results in org.apache.log4j.performance.Logging for the impact of using this appender.

Important note: The AsyncAppender can only be script configured using the DOMConfigurator.

Since:

0.9.1

Author:

Ceki Gülcü

Field Summary

static int

DEFAULT_BUFFER_SIZE The default buffer size is set to 128 events.

Fields inherited from class org.apache.log4j.AppenderSkeleton

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

Constructor Summary

AsyncAppender()

Method Summary

void	addAppender(Appender newAppender) Add an appender.
void	append(LoggingEvent event) Subclasses of AppenderSkeleton should implement this method to perform actual logging.
void	close() Close this AsyncAppender by interrupting the dispatcher thread which will process all pending events before exiting.
Enumeration	getAllAppenders() Get all previously added appenders as an Enumeration.
Appender	getAppender(String name) Get an appender by name.
int	getBufferSize() Returns the current value of the BufferSize option.
boolean	getLocationInfo() Returns the current value of the LocationInfo option.
boolean	isAttached(Appender appender) Is the appender passed as parameter attached to this category?
void	removeAllAppenders() Remove all previously added appenders.
void	removeAppender(Appender appender) Remove the appender passed as parameter from the list of appenders.
void	removeAppender(String name) Remove the appender with the name passed as parameter from the list of appenders.
boolean	requiresLayout() The AsyncAppender does not require a layout.
void	setBufferSize(int size) The BufferSize option takes a non-negative integer value.
void	setLocationInfo(boolean flag) The LocationInfo option takes a boolean value.

Methods inherited from class org.apache.log4j.AppenderSkeleton

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

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_BUFFER_SIZE

public static final int DEFAULT_BUFFER_SIZE

The default buffer size is set to 128 events.

See Also:

Constant Field Values

Constructor Detail

AsyncAppender

public AsyncAppender()

Method Detail

addAppender

public void addAppender(Appender newAppender)

Description copied from interface: AppenderAttachable

Add an appender.

Specified by:

addAppender in interface AppenderAttachable

append

public void append(LoggingEvent event)

Description copied from class: AppenderSkeleton

Subclasses of AppenderSkeleton should implement this method to perform actual logging. See also AppenderSkeleton.doAppend method.

Specified by:

append in class AppenderSkeleton

close

public void close()

Close this AsyncAppender by interrupting the dispatcher thread which will process all pending events before exiting.

Specified by:

close in interface Appender

getAllAppenders

public Enumeration getAllAppenders()

Description copied from interface: AppenderAttachable

Get all previously added appenders as an Enumeration.

Specified by:

getAllAppenders in interface AppenderAttachable

getAppender

public Appender getAppender(String name)

Description copied from interface: AppenderAttachable

Get an appender by name.

Specified by:

getAppender in interface AppenderAttachable

getLocationInfo

public boolean getLocationInfo()

Returns the current value of the LocationInfo option.

isAttached

public boolean isAttached(Appender appender)

Is the appender passed as parameter attached to this category?

Specified by:

isAttached in interface AppenderAttachable

requiresLayout

public boolean requiresLayout()

The AsyncAppender does not require a layout. Hence, this method always returns false.

Specified by:

requiresLayout in interface Appender

removeAllAppenders

public void removeAllAppenders()

Description copied from interface: AppenderAttachable

Remove all previously added appenders.

Specified by:

removeAllAppenders in interface AppenderAttachable

removeAppender

public void removeAppender(Appender appender)

Description copied from interface: AppenderAttachable

Remove the appender passed as parameter from the list of appenders.

Specified by:

removeAppender in interface AppenderAttachable

removeAppender

public void removeAppender(String name)

Description copied from interface: AppenderAttachable

Remove the appender with the name passed as parameter from the list of appenders.

Specified by:

removeAppender in interface AppenderAttachable

setLocationInfo

public void setLocationInfo(boolean flag)

The LocationInfo option takes a boolean value. By default, it is set to false which means there will be no effort to extract the location information related to the event. As a result, the event that will be ultimately logged will likely to contain the wrong location information (if present in the log format).

Location information extraction is comparatively very slow and should be avoided unless performance is not a concern.

setBufferSize

public void setBufferSize(int size)

The BufferSize option takes a non-negative integer value. This integer value determines the maximum size of the bounded buffer. Increasing the size of the buffer is always safe. However, if an existing buffer holds unwritten elements, then decreasing the buffer size will result in event loss. Nevertheless, while script configuring the AsyncAppender, it is safe to set a buffer size smaller than the default buffer size because configurators guarantee that an appender cannot be used before being completely configured.

getBufferSize

public int getBufferSize()

Returns the current value of the BufferSize option.