ref[move]: move hash to net package

net/src/main/java/com/zfoo/net/consumer/balancer/ConsistentHashConsumerLoadBalancer.java

@@ -22,7 +22,7 @@ import com.zfoo.protocol.collection.CollectionUtils;
 import com.zfoo.protocol.exception.RunException;
 import com.zfoo.protocol.model.Pair;
 import com.zfoo.protocol.registration.ProtocolModule;
-import com.zfoo.util.math.ConsistentHash;
+import com.zfoo.net.util.ConsistentHash;
 import org.springframework.lang.Nullable;
 
 import java.util.TreeMap;

net/src/main/java/com/zfoo/net/util/ConsistentHash.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and limitations under the License.
+ */
+
+package com.zfoo.net.util;
+
+import com.zfoo.protocol.model.Pair;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.TreeMap;
+
+/**
+ * 带虚拟节点的一致性Hash算法，参考：http://www.zsythink.net/archives/1182
+ *
+ * @author godotg
+ * @version 3.0
+ */
+
+public class ConsistentHash<K, V> {
+
+    // 真实结点列表,考虑到服务器上线、下线的场景，即添加、删除的场景会比较频繁，这里使用LinkedList会更好
+    private List<Pair<K, V>> realNodes = new ArrayList<>();
+
+    // 虚拟节点，key表示虚拟节点的hash值，value表示虚拟节点的名称
+    private TreeMap<Integer, Pair<K, V>> virtualNodeTreeMap = new TreeMap<>();
+
+    // 虚拟节点的数目，数量越大约均匀
+    private int virtualNodes = 0;
+
+    public ConsistentHash(List<Pair<K, V>> realNodes, int virtualNodes) {
+        // 先把原始的服务器添加到真实结点列表中
+        this.realNodes.addAll(realNodes);
+        this.virtualNodes = virtualNodes;
+
+        // 初始化
+        // 再添加虚拟节点，遍历LinkedList使用foreach循环效率会比较高
+        for (var realNode : realNodes) {
+            addNode(realNode);
+        }
+    }
+
+    public void addNode(Pair<K, V> realNode) {
+        for (var i = 0; i < this.virtualNodes; i++) {
+            var virtualNode = realNode.getKey().toString() + "&&VN" + i;
+            var hash = HashUtils.fnvHash(virtualNode);
+            virtualNodeTreeMap.put(hash, realNode);
+        }
+    }
+
+
+    // 得到应当路由到的结点
+    public Pair<K, V> getRealNode(Object key) {
+        // 得到该key的hash值
+        var hash = HashUtils.fnvHash(key);
+        // 第一个Key就是顺时针过去离node最近的那个结点
+        var entry = virtualNodeTreeMap.ceilingEntry(hash);
+        if (Objects.isNull(entry)) {
+            // 如果没有比该key的hash值大的，则从第一个node开始
+            return virtualNodeTreeMap.firstEntry().getValue();
+        }
+        return entry.getValue();
+    }
+
+    public TreeMap<Integer, Pair<K, V>> getVirtualNodeTreeMap() {
+        return virtualNodeTreeMap;
+    }
+}

net/src/main/java/com/zfoo/net/util/HashUtils.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2020 The zfoo Authors
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and limitations under the License.
+ */
+
+package com.zfoo.net.util;
+
+/**
+ * 改进的hash算法虽然发布比较均匀，但是没有Java自带的hash算法速度快，所以需要知道自己需要什么
+ *
+ * @author godotg
+ * @version 3.0
+ */
+public abstract class HashUtils {
+
+
+    private static final int P = 16777619;
+    private static final int INIT_HASH = (int) 2166136261L;
+
+    /**
+     * 改进的32位FNV算法1
+     *
+     * @param data 数组
+     * @return hash结果
+     */
+    public static int fnvHash(byte[] data) {
+        var hash = INIT_HASH;
+        for (byte b : data) {
+            hash = (hash ^ b) * P;
+        }
+        hash += hash << 13;
+        hash ^= hash >> 7;
+        hash += hash << 3;
+        hash ^= hash >> 17;
+        hash += hash << 5;
+        return Math.abs(hash);
+    }
+
+    /**
+     * 改进的32位FNV算法1
+     *
+     * @param object 计算hash的对象，会调用toString方法
+     * @return hash结果
+     */
+    public static int fnvHash(Object object) {
+        var hash = object.toString().chars().reduce(INIT_HASH, (left, right) -> (left ^ right) * P);
+        hash += hash << 13;
+        hash ^= hash >> 7;
+        hash += hash << 3;
+        hash ^= hash >> 17;
+        hash += hash << 5;
+        return Math.abs(hash);
+    }
+
+}