org.apache.hadoop.hbase.util

Class RegionSplitCalculator<R extends KeyRange>

java.lang.Object

org.apache.hadoop.hbase.util.RegionSplitCalculator<R>

Type Parameters:

R -

@InterfaceAudience.Private
public class RegionSplitCalculator<R extends KeyRange>
extends Object

This is a generic region split calculator. It requires Ranges that provide start, end, and a comparator. It works in two phases -- the first adds ranges and rejects backwards ranges. Then one calls calcRegions to generate the multimap that has a start split key as a key and possibly multiple Ranges as members. To traverse, one normally would get the split set, and iterate through the calcRegions. Normal regions would have only one entry, holes would have zero, and any overlaps would have multiple entries. The interface is a bit cumbersome currently but is exposed this way so that clients can choose how to iterate through the region splits.

Field Summary

Fields

Modifier and Type	Field and Description
static Comparator<byte[]>	BYTES_COMPARATOR

Constructor Summary

Constructors

Constructor and Description
RegionSplitCalculator(Comparator<R> cmp)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	add(R range) Adds an edge to the split calculator
com.google.common.collect.Multimap<byte[],R>	calcCoverage() Generates a coverage multimap from split key to Regions that start with the split key.
static <R extends KeyRange> List<R>	findBigRanges(Collection<R> bigOverlap, int count) Find specified number of top ranges in a big overlap group.
TreeSet<byte[]>	getSplits()
com.google.common.collect.Multimap<byte[],R>	getStarts()

Methods inherited from class java.lang.Object

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

Field Detail

BYTES_COMPARATOR

public static final Comparator<byte[]> BYTES_COMPARATOR

Constructor Detail

RegionSplitCalculator

public RegionSplitCalculator(Comparator<R> cmp)

Method Detail

add

public boolean add(R range)

Adds an edge to the split calculator

Returns:

true if is included, false if backwards/invalid

calcCoverage

public com.google.common.collect.Multimap<byte[],R> calcCoverage()

Generates a coverage multimap from split key to Regions that start with the split key.

Returns:

coverage multimap

getSplits

public TreeSet<byte[]> getSplits()

getStarts

public com.google.common.collect.Multimap<byte[],R> getStarts()

findBigRanges

public static <R extends KeyRange> List<R> findBigRanges(Collection<R> bigOverlap,
                                         int count)

Find specified number of top ranges in a big overlap group. It could return less if there are not that many top ranges. Once these top ranges are excluded, the big overlap group will be broken into ranges with no overlapping, or smaller overlapped groups, and most likely some holes.

Parameters:

bigOverlap - a list of ranges that overlap with each other

count - the max number of ranges to find

Returns:

a list of ranges that overlap with most others