「Consistent Hashingをためす」の編集履歴（バックアップ）一覧に戻る
public class Main {
private static String search( NavigableMap<BigInteger, String> circle, BigInteger rec ){
// circleをNavigableMapを使用し、ceilingKeyによりもっとも近いkeyを取得
BigInteger key = circle.ceilingKey(rec);
if( key == null ){
// 指定されたレコードがkeyの最大値を越える場合は最小ノードに入れる
return (String)circle.get(circle.firstKey());
}else{
// ノードの最大値を越える場合は最小ノードに入れる
return (String)circle.get(key);
}
}
private static BigInteger getHash( String value ) throws NoSuchAlgorithmException{
int ret = 0;
MessageDigest digest = MessageDigest.getInstance( "md5" );
byte[] byteHash = digest.digest(value.getBytes());
return new BigInteger(byteHash);
}
public static void main(String[] args) throws NoSuchAlgorithmException {
int numOfReplicants = 0;
NavigableMap<BigInteger, String> circle = new TreeMap<BigInteger, String>();
SortedMap<String, List> nodesmap = new TreeMap<String, List>();
List<String> alphalist = Arrays.asList(
"A","B","C","D","E","F","G","H","I","J","K","L","M",
"N","O","P","Q","R","S","T","U","V","W","X","Y","Z");
for( int i = 0; i < args.length; i++ ){
nodesmap.put( args[i], new LinkedList<String>());
}
for( String node : nodesmap.keySet() ){
circle.put( getHash(node), node );
}
for( String str : alphalist ){
String node = search(circle, getHash(str));
if( !nodesmap.containsKey(node)){
List<String> asciiList = new LinkedList<String>();
asciiList.add(str);
nodesmap.put(node, asciiList);
}else{
nodesmap.get(node).add(str);
}
}
for( String node : nodesmap.keySet()){
System.out.print(node + " ");
List<String> asciiList = nodesmap.get(node);
for( String strascii : asciiList ){
System.out.print(strascii + " ");
}
System.out.print("\n");
}
}
}
$ java Main n1 n2 n3 n4 <-- 引数はノード名です。 n1 H T n2 A B F K M N P S U V W Y n3 C D E J O Q X Z n4 G I L R
$ java Main n1 n2 n3 n1 H T n2 A B F K M N P S U V W Y n3 C D E G I J L O Q R X Z
public class Main_Vnode {
private static String search( NavigableMap<BigInteger, String> circle, BigInteger rec ){
// circleをNavigableMapに変更し、ceilingKeyにより、もっとも近いkeyを取得
BigInteger key = circle.ceilingKey(rec);
if( key == null ){
// 指定されたレコードがkeyの最大値を越える場合は最小ノードに入れる
return (String)circle.get(circle.firstKey());
}else{
// ノードの最大値を越える場合は最小ノードに入れる
return (String)circle.get(key);
}
}
private static BigInteger getHash( String value ) throws NoSuchAlgorithmException{
int ret = 0;
MessageDigest digest = MessageDigest.getInstance( "md5" );
byte[] byteHash = digest.digest(value.getBytes());
return new BigInteger(byteHash);
}
public static void main(String[] args) throws NoSuchAlgorithmException {
int numOfReplicants = 0;
NavigableMap<BigInteger, String> circle = new TreeMap<BigInteger, String>();
SortedMap<String, List> nodesmap = new TreeMap<String, List>();
List<String> alphalist = Arrays.asList(
"A","B","C","D","E","F","G","H","I","J","K","L","M",
"N","O","P","Q","R","S","T","U","V","W","X","Y","Z");
for( int i = 0; i < args.length; i++ ){
if( i == 0){
numOfReplicants = Integer.valueOf(args[0]);
} else {
nodesmap.put( args[i], new LinkedList<String>());
}
}
for( String node : nodesmap.keySet() ){
circle.put( getHash(node), node );
for(int i=1; i <= numOfReplicants; i++){
circle.put( getHash(node + '_' + i), node );
}
}
for( String str : alphalist ){
String node = search(circle, getHash(str));
if( !nodesmap.containsKey(node)){
List<String> asciiList = new LinkedList<String>();
asciiList.add(str);
nodesmap.put(node, asciiList);
}else{
nodesmap.get(node).add(str);
}
}
for( String node : nodesmap.keySet()){
System.out.print(node + " ");
List<String> asciiList = nodesmap.get(node);
for( String strascii : asciiList ){
System.out.print(strascii + " ");
}
System.out.print("\n");
}
}
}
$ java Main_Vnode 100 n1 n2 n3 n4 <---第一引数が１ノードあたりの仮想ノード数で、その後ろの引数はノード名です。 n1 A E F O P Q U V n2 B H S T Y n3 C K L M N Z n4 D G I J R W X
$ java Main_Vnode 100 n1 n2 n3 n1 A D E F O P Q U V n2 B H I S T W Y n3 C G J K L M N R X Z
