com.faunos.skwish.sys.mgr
Class PrecedenceComparator

java.lang.Object
  com.faunos.skwish.sys.mgr.PrecedenceComparator

All Implemented Interfaces:

Comparator<Segment>

public class PrecedenceComparator
extends Object
implements Comparator<Segment>

A comparator used by the collector to prune overridden (and therefore dead) segments. The aim is to order dead and live segments as in the diagram below.

                     XXXX
                   ~X
                  ~XX
               XXXXXX
            ~XX
        ~XXXX
     ~0
      XXXXXXXXX
 

The horizontal axis represents entry IDs, and each block of X's represents a segment spanning a range of IDs. Dead segments ignored by the collector are marked with a leading '~' above (understood not to contribute to the segment's range). An empty segment is represented as an '0'.

Under the operational invariants maintained by the collector, then, this ordering has the following property: a segment may only be covered by a preceding segment.

Author:

Babak Farhang

See Also:

UnitDir.Seg.covers(com.faunos.skwish.sys.mgr.UnitDir.Seg)

Field Summary

static Comparator<Segment>

INSTANCE

Constructor Summary

PrecedenceComparator()

Method Summary

int	compare(Segment s1, Segment s2) Compares the two given segments, firstly by their base IDs, secondly by which has more entries.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Field Detail

INSTANCE

public static final Comparator<Segment> INSTANCE

Constructor Detail

PrecedenceComparator

public PrecedenceComparator()

Method Detail

compare

public int compare(Segment s1,
                   Segment s2)

Compares the two given segments, firstly by their base IDs, secondly by which has more entries.

Specified by:

compare in interface Comparator<Segment>