优化和修复随机权重的算法

discovery-plugin-framework/src/main/java/com/nepxion/discovery/plugin/framework/decorator/PredicateBasedRuleDecorator.java

@@ -18,7 +18,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import com.nepxion.discovery.common.entity.WeightFilterEntity;
 import com.nepxion.discovery.plugin.framework.adapter.PluginAdapter;
 import com.nepxion.discovery.plugin.framework.loadbalance.IWeightRandomLoadBalance;
-import com.nepxion.discovery.plugin.framework.loadbalance.weight.ArrayWeightRandomLoadBalance;
+import com.nepxion.discovery.plugin.framework.loadbalance.weight.MapWeightRandomLoadBalance;
 import com.netflix.loadbalancer.PredicateBasedRule;
 import com.netflix.loadbalancer.Server;
 
@@ -30,7 +30,7 @@ public abstract class PredicateBasedRuleDecorator extends PredicateBasedRule {
 
     @PostConstruct
     private void initialize() {
-        weightRandomLoadBalance = new ArrayWeightRandomLoadBalance();
+        weightRandomLoadBalance = new MapWeightRandomLoadBalance();
         weightRandomLoadBalance.setPluginAdapter(pluginAdapter);
     }
 

discovery-plugin-framework/src/main/java/com/nepxion/discovery/plugin/framework/decorator/ZoneAvoidanceRuleDecorator.java

@@ -18,7 +18,7 @@ import org.springframework.beans.factory.annotation.Autowired;
 import com.nepxion.discovery.common.entity.WeightFilterEntity;
 import com.nepxion.discovery.plugin.framework.adapter.PluginAdapter;
 import com.nepxion.discovery.plugin.framework.loadbalance.weight.AbstractWeightRandomLoadBalance;
-import com.nepxion.discovery.plugin.framework.loadbalance.weight.ArrayWeightRandomLoadBalance;
+import com.nepxion.discovery.plugin.framework.loadbalance.weight.MapWeightRandomLoadBalance;
 import com.netflix.loadbalancer.Server;
 import com.netflix.loadbalancer.ZoneAvoidanceRule;
 
@@ -30,7 +30,7 @@ public class ZoneAvoidanceRuleDecorator extends ZoneAvoidanceRule {
 
     @PostConstruct
     private void initialize() {
-        weightRandomLoadBalance = new ArrayWeightRandomLoadBalance();
+        weightRandomLoadBalance = new MapWeightRandomLoadBalance();
         weightRandomLoadBalance.setPluginAdapter(pluginAdapter);
     }
 

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

@@ -27,10 +27,7 @@ public class ArrayWeightRandomLoadBalance extends AbstractWeightRandomLoadBalanc
         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;
-            }
+            weights[i] = getWeight(server, weightFilterEntity);
         }
 
         int index = getIndex(weights);

discovery-plugin-framework/src/main/java/com/nepxion/discovery/plugin/framework/loadbalance/weight/MapWeightRandomLoadBalance.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.ArrayList;
+import java.util.List;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+import org.apache.commons.collections4.CollectionUtils;
+import org.apache.commons.collections4.MapUtils;
+import org.apache.commons.lang3.tuple.ImmutablePair;
+import org.apache.commons.lang3.tuple.Pair;
+
+import com.nepxion.discovery.common.entity.WeightFilterEntity;
+import com.nepxion.discovery.common.exception.DiscoveryException;
+import com.netflix.loadbalancer.Server;
+
+public class MapWeightRandomLoadBalance extends AbstractWeightRandomLoadBalance {
+    @Override
+    public Server choose(List<Server> serverList, WeightFilterEntity weightFilterEntity) {
+        if (CollectionUtils.isEmpty(serverList)) {
+            return null;
+        }
+
+        List<Pair<Server, Integer>> weightPairList = new ArrayList<Pair<Server, Integer>>();
+        for (Server server : serverList) {
+            int weight = getWeight(server, weightFilterEntity);
+            weightPairList.add(new ImmutablePair<Server, Integer>(server, weight));
+        }
+
+        MapWeightRandom<Server, Integer> weightRandom = new MapWeightRandom<Server, Integer>(weightPairList);
+
+        return weightRandom.random();
+    }
+
+    public class MapWeightRandom<K, V extends Number> {
+        private TreeMap<Double, K> weightMap = new TreeMap<Double, K>();
+
+        public MapWeightRandom(List<Pair<K, V>> pairlist) {
+            for (Pair<K, V> pair : pairlist) {
+                double value = pair.getValue().doubleValue();
+                if (value <= 0) {
+                    continue;
+                }
+
+                double lastWeight = weightMap.size() == 0 ? 0 : weightMap.lastKey().doubleValue();
+                weightMap.put(value + lastWeight, pair.getKey());
+            }
+        }
+
+        public K random() {
+            if (MapUtils.isEmpty(weightMap)) {
+                throw new DiscoveryException("No weight value is configed");
+            }
+
+            double randomWeight = weightMap.lastKey() * Math.random();
+            SortedMap<Double, K> tailMap = weightMap.tailMap(randomWeight, false);
+
+            return weightMap.get(tailMap.firstKey());
+        }
+    }
+}
\ No newline at end of file

discovery-plugin-framework/src/test/java/com/nepxion/discovery/plugin/framework/loadbalance/ArrayWeightRandomLoadBalanceTest.java

+package com.nepxion.discovery.plugin.framework.loadbalance;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ThreadLocalRandom;
+
+import org.apache.commons.collections4.CollectionUtils;
+
+public class ArrayWeightRandomLoadBalanceTest {
+    public static void main(String[] args) {
+        long t = System.currentTimeMillis();
+
+        List<String> serverList = new ArrayList<String>();
+        serverList.add("1.0");
+        serverList.add("2.0");
+        serverList.add("3.0");
+        serverList.add("1.0");
+        serverList.add("2.0");
+        serverList.add("3.0");
+        serverList.add("4.0");
+        serverList.add("4.0");
+        serverList.add("5.0");
+        serverList.add("5.0");
+
+        Map<String, Integer> weightMap = new HashMap<String, Integer>();
+        weightMap.put("1.0", 0);
+        weightMap.put("2.0", 90);
+        weightMap.put("3.0", 10);
+        weightMap.put("4.0", 0);
+        weightMap.put("5.0", 0);
+
+        int v1Count = 0;
+        int v2Count = 0;
+        int v3Count = 0;
+        int v4Count = 0;
+        int v5Count = 0;
+        for (int i = 0; i < 1000000; i++) {
+            String server = choose(serverList, weightMap);
+            if (server.startsWith("1.0")) {
+                v1Count++;
+            }
+            if (server.startsWith("2.0")) {
+                v2Count++;
+            }
+            if (server.startsWith("3.0")) {
+                v3Count++;
+            }
+            if (server.startsWith("4.0")) {
+                v4Count++;
+            }
+            if (server.startsWith("5.0")) {
+                v5Count++;
+            }
+        }
+
+        System.out.println("1.0版本服务随机权重=" + v1Count);
+        System.out.println("2.0版本服务随机权重=" + v2Count);
+        System.out.println("3.0版本服务随机权重=" + v3Count);
+        System.out.println("4.0版本服务随机权重=" + v4Count);
+        System.out.println("5.0版本服务随机权重=" + v5Count);
+        System.out.println("耗时时间：" + (System.currentTimeMillis() - t));
+    }
+
+    public static String choose(List<String> serverList, Map<String, Integer> weightMap) {
+        if (CollectionUtils.isEmpty(serverList)) {
+            return null;
+        }
+
+        int[] weights = new int[serverList.size()];
+        for (int i = 0; i < serverList.size(); i++) {
+            String server = serverList.get(i);
+            weights[i] = weightMap.get(server);
+        }
+
+        int index = getIndex(weights);
+
+        return serverList.get(index);
+    }
+
+    private static 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];
+    }
+}
\ No newline at end of file

discovery-plugin-framework/src/test/java/com/nepxion/discovery/plugin/framework/loadbalance/MapWeightRandomLoadBalanceTest.java

+package com.nepxion.discovery.plugin.framework.loadbalance;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+import org.apache.commons.collections4.MapUtils;
+import org.apache.commons.lang3.tuple.ImmutablePair;
+import org.apache.commons.lang3.tuple.Pair;
+
+import com.nepxion.discovery.common.exception.DiscoveryException;
+
+public class MapWeightRandomLoadBalanceTest {
+    public static class MapWeightRandom<K, V extends Number> {
+        private TreeMap<Double, K> weightMap = new TreeMap<Double, K>();
+
+        public MapWeightRandom(List<Pair<K, V>> pairlist) {
+            for (Pair<K, V> pair : pairlist) {
+                double value = pair.getValue().doubleValue();
+                if (value <= 0) {
+                    continue;
+                }
+
+                double lastWeight = weightMap.size() == 0 ? 0 : weightMap.lastKey().doubleValue();
+                weightMap.put(value + lastWeight, pair.getKey());
+            }
+        }
+
+        public K random() {
+            if (MapUtils.isEmpty(weightMap)) {
+                throw new DiscoveryException("No weight value is configed");
+            }
+
+            double randomWeight = weightMap.lastKey() * Math.random();
+            SortedMap<Double, K> tailMap = weightMap.tailMap(randomWeight, false);
+
+            return weightMap.get(tailMap.firstKey());
+        }
+    }
+
+    public static void main(String[] args) {
+        long t = System.currentTimeMillis();
+
+        List<Pair<String, Double>> list = new ArrayList<Pair<String, Double>>();
+        list.add(new ImmutablePair<String, Double>("1.0", 0D));
+        list.add(new ImmutablePair<String, Double>("2.0", 90D));
+        list.add(new ImmutablePair<String, Double>("3.0", 10D));
+        list.add(new ImmutablePair<String, Double>("1.0", 0D));
+        list.add(new ImmutablePair<String, Double>("2.0", 90D));
+        list.add(new ImmutablePair<String, Double>("3.0", 10D));
+        list.add(new ImmutablePair<String, Double>("4.0", 0D));
+        list.add(new ImmutablePair<String, Double>("4.0", 0D));
+        list.add(new ImmutablePair<String, Double>("5.0", 0D));
+        list.add(new ImmutablePair<String, Double>("5.0", 0D));
+
+        int v1Count = 0;
+        int v2Count = 0;
+        int v3Count = 0;
+        int v4Count = 0;
+        int v5Count = 0;
+        for (int i = 0; i < 1000000; i++) {
+            MapWeightRandom<String, Double> weightRandom = new MapWeightRandom<String, Double>(list);
+            String server = weightRandom.random();
+            if (server.startsWith("1.0")) {
+                v1Count++;
+            }
+            if (server.startsWith("2.0")) {
+                v2Count++;
+            }
+            if (server.startsWith("3.0")) {
+                v3Count++;
+            }
+            if (server.startsWith("4.0")) {
+                v4Count++;
+            }
+            if (server.startsWith("5.0")) {
+                v5Count++;
+            }
+        }
+
+        System.out.println("1.0版本服务随机权重=" + v1Count);
+        System.out.println("2.0版本服务随机权重=" + v2Count);
+        System.out.println("3.0版本服务随机权重=" + v3Count);
+        System.out.println("4.0版本服务随机权重=" + v4Count);
+        System.out.println("5.0版本服务随机权重=" + v5Count);
+        System.out.println("耗时时间：" + (System.currentTimeMillis() - t));
+    }
+}
\ No newline at end of file