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.

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 buffer.

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

Since:

0.9.1

Author:

Ceki Gülcü, Curt Arnold

Field Summary

Fields

Modifier and Type	Field and Description
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

Constructors

Constructor and Description
AsyncAppender() Create new instance.

Method Summary

Modifier and Type	Method and Description
void	addAppender(Appender newAppender) Add 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 iterator over attached appenders.
Appender	getAppender(String name) Get appender by name.
boolean	getBlocking() Gets whether appender should block calling thread when buffer is full.
int	getBufferSize() Gets the current buffer size.
boolean	getLocationInfo() Gets whether the location of the logging request call should be captured.
boolean	isAttached(Appender appender) Determines if specified appender is attached.
void	removeAllAppenders() Removes and closes all attached appenders.
void	removeAppender(Appender appender) Removes an appender.
void	removeAppender(String name) Remove appender by name.
boolean	requiresLayout() Configurators call this method to determine if the appender requires a layout.
void	setBlocking(boolean value) Sets whether appender should wait if there is no space available in the event buffer or immediately return.
void	setBufferSize(int size) Sets the number of messages allowed in the event buffer before the calling thread is blocked (if blocking is true) or until messages are summarized and discarded.
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()

Create new instance.

Method Detail

addAppender

public void addAppender(Appender newAppender)

Add appender.

Specified by:

addAppender in interface AppenderAttachable

Parameters:

newAppender - appender to add, may not be null.

append

public void append(LoggingEvent event)

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()

Get iterator over attached appenders.

Specified by:

getAllAppenders in interface AppenderAttachable

Returns:

iterator or null if no attached appenders.

getAppender

public Appender getAppender(String name)

Get appender by name.

Specified by:

getAppender in interface AppenderAttachable

Parameters:

name - name, may not be null.

Returns:

matching appender or null.

getLocationInfo

public boolean getLocationInfo()

Gets whether the location of the logging request call should be captured.

Returns:

the current value of the LocationInfo option.

isAttached

public boolean isAttached(Appender appender)

Determines if specified appender is attached.

Specified by:

isAttached in interface AppenderAttachable

Parameters:

appender - appender.

Returns:

true if attached.

requiresLayout

public boolean requiresLayout()

Configurators call this method to determine if the appender requires a layout. If this method returns true, meaning that layout is required, then the configurator will configure an layout using the configuration information at its disposal. If this method returns false, meaning that a layout is not required, then layout configuration will be skipped even if there is available layout configuration information at the disposal of the configurator..

In the rather exceptional case, where the appender implementation admits a layout but can also work without it, then the appender should return true.

Specified by:

requiresLayout in interface Appender

removeAllAppenders

public void removeAllAppenders()

Removes and closes all attached appenders.

Specified by:

removeAllAppenders in interface AppenderAttachable

removeAppender

public void removeAppender(Appender appender)

Removes an appender.

Specified by:

removeAppender in interface AppenderAttachable

Parameters:

appender - appender to remove.

removeAppender

public void removeAppender(String name)

Remove appender by name.

Specified by:

removeAppender in interface AppenderAttachable

Parameters:

name - name.

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.

Parameters:

flag - true if location information should be extracted.

setBufferSize

public void setBufferSize(int size)

Sets the number of messages allowed in the event buffer before the calling thread is blocked (if blocking is true) or until messages are summarized and discarded. Changing the size will not affect messages already in the buffer.

Parameters:

size - buffer size, must be positive.

getBufferSize

public int getBufferSize()

Gets the current buffer size.

Returns:

the current value of the BufferSize option.

setBlocking

public void setBlocking(boolean value)

Sets whether appender should wait if there is no space available in the event buffer or immediately return.

Parameters:

value - true if appender should wait until available space in buffer.

Since:

1.2.14

getBlocking

public boolean getBlocking()

Gets whether appender should block calling thread when buffer is full. If false, messages will be counted by logger and a summary message appended after the contents of the buffer have been appended.

Returns:

true if calling thread will be blocked when buffer is full.

Since:

1.2.14