com.cloudhopper.commons.util

Class RoundRobinLoadBalancedList<E>

java.lang.Object

com.cloudhopper.commons.util.RoundRobinLoadBalancedList<E>

All Implemented Interfaces:

LoadBalancedList<E>

public class RoundRobinLoadBalancedList<E>
extends Object
implements LoadBalancedList<E>

Implementation of a load balanced list that returns items using a weighted, round-robin algorithm. If "A" is added with weight 2 and "B" is added with weight 1, then getNext() will return the items in this order: A, B, A, A, B, A, A, B, A, .... NOTE: This class does not synchronize access. Any concurrent access to this object MUST be externally synchronized. NOTE: This class only works for small lists. You need to assume every call to get the next selection is O(n).

Author:

joelauer (twitter: @jjlauer or http://twitter.com/jjlauer)

Nested Class Summary

Nested classes/interfaces inherited from interface com.cloudhopper.commons.util.LoadBalancedList

LoadBalancedList.Node<E>

Constructor Summary

Constructors

Constructor and Description
RoundRobinLoadBalancedList()

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clears all entries from the list.
boolean	contains(E item) Checks if the item is already contained in this list.
E	getNext() Gets the next item to use from the list.
int	getRemainingSize()
int	getSize() Gets the total number of items (size) of the list.
List<LoadBalancedList.Node<E>>	getValues() Gets a list of all nodes.
protected void	rebuildRemainingItems()
void	remove(E item) Removes an item from the list.
protected void	resetCountsAndRebuildRemainingItems()
void	set(E item, int weight) Adds the item to the list if it doesn't yet exist.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

RoundRobinLoadBalancedList

public RoundRobinLoadBalancedList()

Method Detail

getValues

public List<LoadBalancedList.Node<E>> getValues()

Description copied from interface: LoadBalancedList

Gets a list of all nodes.

Specified by:

getValues in interface LoadBalancedList<E>

Returns:

A list of all nodes.

clear

public void clear()

Description copied from interface: LoadBalancedList

Clears all entries from the list.

Specified by:

clear in interface LoadBalancedList<E>

contains

public boolean contains(E item)

Description copied from interface: LoadBalancedList

Checks if the item is already contained in this list.

Specified by:

contains in interface LoadBalancedList<E>

Parameters:

item - The item to check for in list

Returns:

True if in list, or false if its not found.

set

public void set(E item,
       int weight)

Description copied from interface: LoadBalancedList

Adds the item to the list if it doesn't yet exist. If the item is already in the list, then this method will update the weight of the item.

Specified by:

set in interface LoadBalancedList<E>

Parameters:

item - The item to add or set

weight - The new weight of the item

remove

public void remove(E item)

Description copied from interface: LoadBalancedList

Removes an item from the list. If the item doesn't exist, this method will do nothing.

Specified by:

remove in interface LoadBalancedList<E>

Parameters:

item - The item to remove.

rebuildRemainingItems

protected void rebuildRemainingItems()

resetCountsAndRebuildRemainingItems

protected void resetCountsAndRebuildRemainingItems()

getSize

public int getSize()

Description copied from interface: LoadBalancedList

Gets the total number of items (size) of the list.

Specified by:

getSize in interface LoadBalancedList<E>

Returns:

The size of the list (number of items)

getRemainingSize

public int getRemainingSize()

getNext

public E getNext()

Description copied from interface: LoadBalancedList

Gets the next item to use from the list.

Specified by:

getNext in interface LoadBalancedList<E>

Returns:

The next item to use or null if no items were available.

toString

public String toString()

Overrides:

toString in class Object