net.fortytwo.stream.caching

Class SolutionGroup<T>

java.lang.Object

net.fortytwo.stream.caching.SolutionGroup<T>

public class SolutionGroup<T>
extends Object

A group of solutions with identical bindings but potentially different sets of matched tuple patterns. The group takes advantage of containment relationships to eliminate redundant or weak solutions, saving work. There is only one solution group per unique set of bindings per solution index.

Author:

Joshua Shinavier (http://fortytwo.net)

Constructor Summary

Constructors

Constructor and Description
SolutionGroup(Bindings<T> bindings) Creates a new solution group for a set of bindings

Method Summary

Modifier and Type	Method and Description
boolean	add(Solution<T> sol, long now) Adds a solution, logically, to this group.
boolean	equals(Object other)
Bindings<T>	getBindings() Gets the bindings of this solution group
LList<SolutionPattern>	getSolutions() Gets the solutions contained in this group
int	hashCode()
int	removeExpired(long now) Removes all expired solutions from this group.

Methods inherited from class java.lang.Object

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

Constructor Detail

SolutionGroup

public SolutionGroup(Bindings<T> bindings)

Creates a new solution group for a set of bindings

Parameters:

bindings - a set of bindings. A solution group is uniquely identified by its bindings, in combination with the query variables from which they are drawn.

Method Detail

getBindings

public Bindings<T> getBindings()

Gets the bindings of this solution group

Returns:

a set of bindings

getSolutions

public LList<SolutionPattern> getSolutions()

Gets the solutions contained in this group

Returns:

a linked list of solution pattern contained in this group. Logically, a solution is a solution pattern combined with a set of bindings, which are provided here by getBindings().

add

public boolean add(Solution<T> sol,
                   long now)

Adds a solution, logically, to this group. The provided solution may simply be appended to the list of solution patterns or, if it is equal to, contains or is contained in another pattern in the group, will replace another pattern or simply be ignored if the expiration times of the solutions in question make this possible.

Parameters:

sol - a new solution for potential addition to this group. The bindings of the added solution must be identical to those of this group.

now - the current time in milliseconds since the Unix epoch. The solution group is updated with respect to this time stamp in that an expired solution will be rejected and expired solutions still present in the group and encountered in the process of insertion will be removed.

Returns:

whether the provided solution has been inserted. If an existing solution makes it redundant, it may not be.

removeExpired

public int removeExpired(long now)

Removes all expired solutions from this group. Note that this operation may cause the group to become empty.

Parameters:

now - the current time, in milliseconds since the Unix epoch

Returns:

the number of solutions removed from this group

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object other)

Overrides:

equals in class Object