[GitHub] [incubator-eventmesh] horoc commented on a change in pull request #526: add weighted random load balacne selector

[GitBox <gi...@apache.org>]

horoc commented on a change in pull request #526:
URL: https://github.com/apache/incubator-eventmesh/pull/526#discussion_r711465289



##########
File path: eventmesh-common/src/main/java/org/apache/eventmesh/common/loadbalance/WeightRandomLoadBalanceSelector.java
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@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.eventmesh.common.loadbalance;
+
+import org.apache.commons.lang3.RandomUtils;
+
+import java.util.List;
+
+/**
+ * This selector use the weighted random strategy to select from list.
+ * If all the weights are same, it will randomly select one from list.
+ * If the weights are different, it will select one by using RandomUtils.nextInt(0, w0 + w1 ... + wn)
+ *
+ * @param <T> Target type
+ */
+public class WeightRandomLoadBalanceSelector<T> implements LoadBalanceSelector<T> {
+
+    private final List<Weight<T>> clusterGroup;
+
+    private final int totalWeight;
+
+    private boolean sameWeightGroup = true;
+
+    public WeightRandomLoadBalanceSelector(List<Weight<T>> clusterGroup) {

Review comment:
       > We need to throw an Exception if the clusterGroup is empty?
   > And in your code, it seems the `totalWeight` cannot <= 0?
   
   I add a not empty check in the constructor.
   totalWeight equals 0 is acceptable, it will make the sameWeightGroup true.
   totalWeight less than 0 maybe not possiable in the context, the IP_PORT_WEIGHT_PATTERN can not match a negative weight.




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