优化和修复随机权重的算法

discovery-plugin-framework/src/main/java/com/nepxion/discovery/plugin/framework/loadbalance/IWeightRandomLoadBalance.java

+package com.nepxion.discovery.plugin.framework.loadbalance;
+
+/**
+ * <p>Title: Nepxion Discovery</p>
+ * <p>Description: Nepxion Discovery</p>
+ * <p>Copyright: Copyright (c) 2017-2050</p>
+ * <p>Company: Nepxion</p>
+ * @author Haojun Ren
+ * @version 1.0
+ */
+
+import java.util.List;
+
+import com.nepxion.discovery.common.entity.WeightFilterEntity;
+import com.nepxion.discovery.plugin.framework.adapter.PluginAdapter;
+import com.netflix.loadbalancer.Server;
+
+public interface IWeightRandomLoadBalance {
+    void setPluginAdapter(PluginAdapter pluginAdapter);
+
+    WeightFilterEntity getWeightFilterEntity();
+
+    Server choose(List<Server> serverList, WeightFilterEntity weightFilterEntity);
+}
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discovery-plugin-framework/src/main/java/com/nepxion/discovery/plugin/framework/loadbalance/weight/ArrayWeightRandomLoadBalance.java

+package com.nepxion.discovery.plugin.framework.loadbalance.weight;
+
+/**
+ * <p>Title: Nepxion Discovery</p>
+ * <p>Description: Nepxion Discovery</p>
+ * <p>Copyright: Copyright (c) 2017-2050</p>
+ * <p>Company: Nepxion</p>
+ * @author Haojun Ren
+ * @version 1.0
+ */
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+
+import org.apache.commons.collections4.CollectionUtils;
+
+import com.nepxion.discovery.common.entity.WeightFilterEntity;
+import com.netflix.loadbalancer.Server;
+
+public class ArrayWeightRandomLoadBalance extends AbstractWeightRandomLoadBalance {
+    @Override
+    public Server choose(List<Server> serverList, WeightFilterEntity weightFilterEntity) {
+        if (CollectionUtils.isEmpty(serverList)) {
+            return null;
+        }
+
+        int[] weights = new int[serverList.size()];
+        for (int i = 0; i < serverList.size(); i++) {
+            Server server = serverList.get(i);
+            int weight = getWeight(server, weightFilterEntity);
+            if (weight > 0) {
+                weights[i] = weight;
+            }
+        }
+
+        int index = getIndex(weights);
+
+        return serverList.get(index);
+    }
+
+    private int getIndex(int[] weights) {
+        // 次序号/权重区间值
+        int[][] weightHolder = new int[weights.length][2];
+        // 总权重
+        int totalWeight = 0;
+        // 赋值次序号和区间值累加的数组值，从小到大排列
+        // 例如，对于权重分别为20，40， 60的三个服务，将形成[0, 20)，[20, 60)，[60, 120]三个区间
+        for (int i = 0; i < weights.length; i++) {
+            if (weights[i] <= 0) {
+                continue;
+            }
+
+            totalWeight += weights[i];
+            weightHolder[i][0] = i;
+            weightHolder[i][1] = totalWeight;
+        }
+
+        // 获取介于0(含)和n(不含)伪随机，均匀分布的int值
+        int hitWeight = ThreadLocalRandom.current().nextInt(totalWeight) + 1; // [1, totalWeight)
+        for (int i = 0; i < weightHolder.length; i++) {
+            if (hitWeight <= weightHolder[i][1]) {
+                return weightHolder[i][0];
+            }
+        }
+
+        return weightHolder[0][0];
+    }
+}
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