org.apache.log4j.helpers
Class CyclicBuffer

java.lang.Object
  org.apache.log4j.helpers.CyclicBuffer

public class CyclicBuffer
extends Object

CyclicBuffer is used by other appenders to hold LoggingEvents for immediate or differed display.

This buffer gives read access to any element in the buffer not just the first or last element.

Since:

0.9.0

Author:

Ceki Gülcü

Constructor Summary

CyclicBuffer(int maxSize)
Instantiate a new CyclicBuffer of at most maxSize events.

Method Summary

void	add(LoggingEvent event) Add an event as the last event in the buffer.
LoggingEvent	get() Get the oldest (first) element in the buffer.
LoggingEvent	get(int i) Get the ith oldest event currently in the buffer.
int	getMaxSize()
int	length() Get the number of elements in the buffer.
void	resize(int newSize) Resize the cyclic buffer to newSize.

Methods inherited from class java.lang.Object

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

Constructor Detail

CyclicBuffer

public CyclicBuffer(int maxSize)
             throws IllegalArgumentException

Instantiate a new CyclicBuffer of at most maxSize events. The maxSize argument must a positive integer.

Parameters:

maxSize - The maximum number of elements in the buffer.

Throws:

IllegalArgumentException

Method Detail

add

public void add(LoggingEvent event)

Add an event as the last event in the buffer.

get

public LoggingEvent get(int i)

Get the ith oldest event currently in the buffer. If i is outside the range 0 to the number of elements currently in the buffer, then null is returned.

getMaxSize

public int getMaxSize()

get

public LoggingEvent get()

Get the oldest (first) element in the buffer. The oldest element is removed from the buffer.

length

public int length()

Get the number of elements in the buffer. This number is guaranteed to be in the range 0 to maxSize (inclusive).

resize

public void resize(int newSize)

Resize the cyclic buffer to newSize.

Throws:

IllegalArgumentException - if newSize is negative.