Package com.ericsson.ssa.sip.dns

Source Code of com.ericsson.ssa.sip.dns.SrvComparator

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package com.ericsson.ssa.sip.dns;

import org.xbill.DNS.SRVRecord;

import java.util.Comparator;


public class SrvComparator implements Comparator {
    private static final int compBEFORE = -1;
    private static final int compEQUAL = 0;
    private static final int compAFTER = 1;

    public SrvComparator() {
    }

    public int compare(Object o1, Object o2) {
        SRVRecord rec1 = (SRVRecord) o1;
        SRVRecord rec2 = (SRVRecord) o2;
        int comparison = comparePriority(rec1, rec2);

        if (comparison != compEQUAL) {
            return comparison;
        }

        comparison = compareWeight(rec1, rec2);

        if (comparison != compEQUAL) {
            return comparison;
        }

        // for records which has the same priority&weight
        // compare hashcode so the sortorder is allways the same
        // otherwise the random distributions of srv records is fucked up
        // due to that the caching is decided to be performed in dnsjava
        return compareHashCode(rec1, rec2);
    }

    public int comparePriority(SRVRecord rec1, SRVRecord rec2) {
        return ((rec1.getPriority() < rec2.getPriority()) ? compBEFORE
                                                          : ((rec1.getPriority() == rec2.getPriority())
        ? compEQUAL : compAFTER));
    }

    public int compareWeight(SRVRecord rec1, SRVRecord rec2) {
        return ((rec1.getWeight() < rec2.getWeight()) ? compBEFORE
                                                      : ((rec1.getWeight() == rec2.getWeight())
        ? compEQUAL : compAFTER));
    }

    public int compareHashCode(SRVRecord rec1, SRVRecord rec2) {
        return ((rec1.hashCode() < rec2.hashCode()) ? compBEFORE
                                                    : ((rec1.hashCode() == rec2.hashCode())
        ? compEQUAL : compAFTER));
    }

    public boolean equals(Object obj) {
        return equals(obj);
    }
}
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