show me the code - 一致性hash
介绍
libketama在memcached客户端一致性hash算法中的运用。
代码
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| import java.util.Collection;
import java.util.SortedMap;
import java.util.TreeMap;
public class ConsistentHash<T> {
private final HashFunction hashFunction;
private final int numberOfReplicas;
private final SortedMap<Integer, T> circle = new TreeMap<Integer, T>();
public ConsistentHash(HashFunction hashFunction,
int numberOfReplicas, Collection<T> nodes) {
this.hashFunction = hashFunction;
this.numberOfReplicas = numberOfReplicas;
for (T node : nodes) {
add(node);
}
}
public void add(T node) {
for (int i = 0; i < numberOfReplicas; i++) {
circle.put(hashFunction.hash(node.toString() +":" + i),
node);
}
}
public void remove(T node) {
for (int i = 0; i < numberOfReplicas; i++) {
circle.remove(hashFunction.hash(node.toString() + ":" + i));
}
}
public T get(Object key) {
if (circle.isEmpty()) {
return null;
}
int hash = hashFunction.hash(key);
SortedMap<Integer, T> tailMap =
circle.tailMap(hash);
hash = tailMap.isEmpty() ?
circle.firstKey() : tailMap.firstKey();
return circle.get(hash);
}
}
|
参考
libketama
