121 lines
3.8 KiB
Java
121 lines
3.8 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.catalina.tribes.group;
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import java.io.Serializable;
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import java.util.Arrays;
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import java.util.Comparator;
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import java.util.List;
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import org.apache.catalina.tribes.Member;
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/**
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* <p>Title: Membership - Absolute Order</p>
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*
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* <p>Description: A simple, yet agreeable and efficient way of ordering members</p>
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* <p>
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* Ordering members can serve as a basis for electing a leader or coordinating efforts.<br>
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* This is stinky simple, it works on the basis of the <code>Member</code> interface
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* and orders members in the following format:
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* </p>
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* <ol>
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* <li>IP comparison - byte by byte, lower byte higher rank</li>
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* <li>IPv4 addresses rank higher than IPv6, ie the lesser number of bytes, the higher rank</li>
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* <li>Port comparison - lower port, higher rank</li>
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* <li>UniqueId comparison- byte by byte, lower byte higher rank</li>
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* </ol>
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*
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*
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* @version 1.0
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* @see org.apache.catalina.tribes.Member
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*/
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public class AbsoluteOrder {
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public static final AbsoluteComparator comp = new AbsoluteComparator();
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protected AbsoluteOrder() {
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super();
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}
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public static void absoluteOrder(Member[] members) {
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if ( members == null || members.length <= 1 ) return;
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Arrays.sort(members,comp);
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}
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public static void absoluteOrder(List<Member> members) {
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if ( members == null || members.size() <= 1 ) return;
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java.util.Collections.sort(members, comp);
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}
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public static class AbsoluteComparator implements Comparator<Member>,
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Serializable {
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private static final long serialVersionUID = 1L;
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@Override
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public int compare(Member m1, Member m2) {
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int result = compareIps(m1,m2);
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if ( result == 0 ) result = comparePorts(m1,m2);
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if ( result == 0 ) result = compareIds(m1,m2);
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return result;
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}
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public int compareIps(Member m1, Member m2) {
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return compareBytes(m1.getHost(),m2.getHost());
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}
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public int comparePorts(Member m1, Member m2) {
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return compareInts(m1.getPort(),m2.getPort());
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}
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public int compareIds(Member m1, Member m2) {
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return compareBytes(m1.getUniqueId(),m2.getUniqueId());
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}
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protected int compareBytes(byte[] d1, byte[] d2) {
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int result = 0;
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if ( d1.length == d2.length ) {
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for (int i=0; (result==0) && (i<d1.length); i++) {
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result = compareBytes(d1[i],d2[i]);
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}
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} else if ( d1.length < d2.length) {
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result = -1;
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} else {
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result = 1;
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}
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return result;
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}
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protected int compareBytes(byte b1, byte b2) {
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return compareInts(b1,b2);
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}
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protected int compareInts(int b1, int b2) {
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int result = 0;
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if ( b1 == b2 ) {
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} else if ( b1 < b2) {
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result = -1;
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} else {
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result = 1;
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}
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return result;
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}
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}
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}
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