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com.tangosol.net.partition
Class SimpleAssignmentStrategy.AnalysisContext.StrengthComparator

java.lang.Object
com.tangosol.net.partition.SimpleAssignmentStrategy.AnalysisContext.StrengthComparator

All Implemented Interfaces:

java.util.Comparator

Enclosing class:

SimpleAssignmentStrategy.AnalysisContext

public class SimpleAssignmentStrategy.AnalysisContext.StrengthComparator

extends java.lang.Object

implements java.util.Comparator

StrengthComparator is an Comparator that can be used to compare two Member objects based on their "distance" from a given set of members (as represented by an Ownership object). Member distances are expressed with the granularity of "machine", "rack", and "site".

A member is ordered "lower" than another member if it has a larger combined distance from the reference members (ownership) (i.e. it is "stronger"). Members with equivalent distances are ordered arbitrarily.

Note: This comparator does not define an ordering that is "consistent with equals". If used in a context requiring such a natural ordering, it should be chained with comparator that does provide a natural ordering.

Field Summary

protected Ownership

m_owners The ownership.

Constructor Summary

SimpleAssignmentStrategy.AnalysisContext.StrengthComparator(Ownership owners)
Construct a StrengthComparator for the specified reference ownership.

Method Summary

int	compare(java.lang.Object o1, java.lang.Object o2) Compares its two arguments for order.
protected int	getDistance(Member member) Return the "distance" of the specified member from the reference ownership.
protected int	getDistance(Member member1, Member member2) Return the "distance" between the specified members.
Ownership	getOwnership() Return the ownership to use in comparing member strength.

Methods inherited from interface java.util.Comparator

equals

Field Detail

m_owners

protected Ownership m_owners

The ownership.

Constructor Detail

SimpleAssignmentStrategy.AnalysisContext.StrengthComparator

public SimpleAssignmentStrategy.AnalysisContext.StrengthComparator(Ownership owners)

Construct a StrengthComparator for the specified reference ownership.

Parameters:

owners - the ownership, from which to determine member strength

Method Detail

getOwnership

public Ownership getOwnership()

Return the ownership to use in comparing member strength.

Returns:

the ownership

compare

public int compare(java.lang.Object o1,
                   java.lang.Object o2)

Compares its two arguments for order. Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)

The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.

Finally, the implementer must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn(compare(y, z)) for all z.

It is generally the case, but not strictly required that (compare(x, y)==0) == (x.equals(y)). Generally speaking, any comparator that violates this condition should clearly indicate this fact. The recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."

Specified by:

compare in interface java.util.Comparator

Parameters:

o1 - the first object to be compared.

o2 - the second object to be compared.

Returns:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

getDistance

protected int getDistance(Member member)

Return the "distance" of the specified member from the reference ownership. The distance reflects granularities of "machine", "rack" and "site", and in the case of multiple-backups, reflects combined distances to each backup.

Parameters:

member - the member to return the distance for

Returns:

the "distance"

getDistance

protected int getDistance(Member member1,
                          Member member2)

Return the "distance" between the specified members.

Parameters:

member1 - the first member

member2 - the second member

Returns:

the "distance" between the specified members

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