一致性hash负载均衡实现

Author: KevinClair

src/main/java/org/hegemol/ymir/core/balance/ConsistentHashLoadBalance.java

@@ -0,0 +1,34 @@
+package org.hegemol.ymir.core.balance;
+
+import java.util.List;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+import org.hegemol.ymir.common.entity.ServiceBean;
+
+/**
+ * 一致性hash
+ *
+ * @author KevinClair
+ **/
+public class ConsistentHashLoadBalance extends AbstractLoadBalance{
+
+    private static final String INSTANCE = "-INSTANCE-";
+
+    @Override
+    protected ServiceBean loadMethod(final List<ServiceBean> services, final String address) {
+        TreeMap<Long, ServiceBean> treeMap = new TreeMap<>();
+        services.forEach(each -> {
+            for (int i = 0; i < each.getFictitiousInstance()-1; i++) {
+                Long hashKey = hash(each.getAddress() + INSTANCE + i);
+                treeMap.put(hashKey, each);
+            }
+        });
+        long clientHash = hash(address);
+        SortedMap<Long, ServiceBean> sortedMap = treeMap.tailMap(clientHash);
+        if (!sortedMap.isEmpty()) {
+            return sortedMap.get(sortedMap.firstKey());
+        }
+        return treeMap.firstEntry().getValue();
+    }
+}