org.perfcake.common

Class TimeSlidingWindow<E>

java.lang.Object

org.perfcake.common.TimeSlidingWindow<E>

public class TimeSlidingWindow<E>
extends Object

A structure to keep record of elements for a certain period of time. It supports concurrent access and has amortized time complexity to add and remove element of O(1) (each removal is prepaid while the element is added).

The window keeps time order of the elements and although it offers the possibility of providing artificial time, it still needs that the objects are added in a correct time order (older objects first).

The time window is closed on both ends. For example, a sliding window all length 500 at the current time 600 will have both objects for time 100 and 600.

Author:

Martin Večeřa

Constructor Summary

Constructors

Constructor and Description
TimeSlidingWindow(long windowLength) Creates a new time sliding window of the given length in milliseconds.

Method Summary

Modifier and Type	Method and Description
void	add(E object) Adds an object to the sliding window.
void	add(E object, long time) Adds an object to the sliding window with an information about artificial time.
void	clear() Removes all elements from the sliding window.
void	forEach(Consumer<E> action) Performs the given action for each element of the sliding window until all elements have been processed or the action throws an exception.
void	forEach(long currentTime, Consumer<E> action) Performs the given action for each element of the sliding window until all elements have been processed or the action throws an exception.
void	gc() Performs a garbage collection of elements that are out of the time window.
void	gc(long time) Performs a garbage collection based on the provided time information.
long	getLength() Gets the length of the sliding window in milliseconds.
long	size()

Methods inherited from class java.lang.Object

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

Constructor Detail

TimeSlidingWindow

public TimeSlidingWindow(long windowLength)

Creates a new time sliding window of the given length in milliseconds.

Parameters:

windowLength - The length of the sliding window in milliseconds.

Method Detail

getLength

public long getLength()

Gets the length of the sliding window in milliseconds.

Returns:

The length of the sliding window in milliseconds.

add

public void add(E object)

Adds an object to the sliding window. It stays in the window for the time specified by the sliding window length.

Parameters:

object - Object to be added.

add

public void add(E object,
                long time)

Adds an object to the sliding window with an information about artificial time. The object cannot be older than the one added previously (the structure needs to keep time order of elements).

Parameters:

object - The object to be added.

time - Artificial time when the object was added to the window.

clear

public void clear()

Removes all elements from the sliding window.

size

public long size()

forEach

public void forEach(Consumer<E> action)

Performs the given action for each element of the sliding window until all elements have been processed or the action throws an exception.

Only the elements in the valid time window are processed. All older elements are garbage collected.

Parameters:

action - The action to be performed for each element.

forEach

public void forEach(long currentTime,
                    Consumer<E> action)

Performs the given action for each element of the sliding window until all elements have been processed or the action throws an exception.

Only the elements in the valid time window are processed. All older elements are garbage collected.

This action might not return all elements when 1) it was already called with a higher (later) current time, 2) forEach(Consumer) was already called which actually propagated a higher (later) time to this method.

Parameters:

currentTime - Artificial time to control the position of the sliding window.

action - The action to be performed for each element.

gc

public void gc()

Performs a garbage collection of elements that are out of the time window. It is not necessary to call this method manually, however, it might be useful to cut the memory costs when forEach(java.util.function.Consumer<E>) was not called for a long time.

gc

public void gc(long time)

Performs a garbage collection based on the provided time information. This might be useful when controlling the time artificially.

Parameters:

time - Current artificial time.