Add the WeightedLeastActiveLoadBalance algorithm (apache#14406)

dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/loadbalance/WeightedLeastActiveLoadBalance.java

@@ -0,0 +1,104 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcStatus;
+import org.apache.dubbo.rpc.support.RpcUtils;
+
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * WeightedLeastActiveLoadBalance
+ * <p>
+ * Filter the invokers with the least number of active calls based on weight. If there is only one invoker, use the
+ * invoker directly; if there are multiple invokers and the leastActive value is 0, then random according to the total
+ * weight; if there are multiple invokers and have the same weighted active value, then randomly called.
+ */
+public class WeightedLeastActiveLoadBalance extends AbstractLoadBalance {
+
+    public static final String NAME = "weightedleastactive";
+
+    @Override
+    protected <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) {
+        // Number of invokers
+        int length = invokers.size();
+        // The least active value of all invokers
+        int leastActive = -1;
+        // The number of invokers having the same least active value (leastActive)
+        int leastCount = 0;
+        // The index of invokers having the same least active value (leastActive)
+        int[] leastIndexes = new int[length];
+        // the weight of every invokers
+        int[] weights = new int[length];
+        // The sum of the warmup weights of all the least active invokers
+        int totalWeight = 0;
+
+        // Filter out all the least active invokers
+        for (int i = 0; i < length; i++) {
+            Invoker<T> invoker = invokers.get(i);
+            // Get the weight of the invoker's configuration. The default value is 100.
+            int afterWarmup = getWeight(invoker, invocation);
+            // save for later use
+            weights[i] = afterWarmup;
+            // Get the weighted active number of the invoker
+            int weightedActive = afterWarmup
+                    * RpcStatus.getStatus(invoker.getUrl(), RpcUtils.getMethodName(invocation))
+                            .getActive();
+            // If it is the first invoker or the weightedActive number of the invoker is less than the current least
+            // active number
+            if (leastActive == -1 || weightedActive < leastActive) {
+                // Reset the weightedActive number of the current invoker to the least active number
+                leastActive = weightedActive;
+                // Reset the number of least active invokers
+                leastCount = 1;
+                // Put the first least active invoker first in leastIndexes
+                leastIndexes[0] = i;
+                // Reset totalWeight
+                totalWeight = afterWarmup;
+
+                // If current invoker's weightedActive value equals with leaseActive, then accumulating.
+            } else if (weightedActive == leastActive) {
+                // Record the index of the least active invoker in leastIndexes order
+                leastIndexes[leastCount++] = i;
+                // Reset totalWeight
+                totalWeight += afterWarmup;
+            }
+        }
+        // Choose an invoker from all the least active invokers
+        if (leastCount == 1) {
+            // If we got exactly one invoker having the least active value, return this invoker directly.
+            return invokers.get(leastIndexes[0]);
+        }
+        // If there are more than one invoker and the leastActive value is 0, pick an invoker by weighted random.
+        if (leastActive == 0) {
+            int offsetWeight = ThreadLocalRandom.current().nextInt(totalWeight);
+            for (int i = 0; i < leastCount; i++) {
+                int leastIndex = leastIndexes[i];
+                offsetWeight -= weights[leastIndex];
+                if (offsetWeight < 0) {
+                    return invokers.get(leastIndex);
+                }
+            }
+        }
+        // return evenly.
+        return invokers.get(leastIndexes[ThreadLocalRandom.current().nextInt(leastCount)]);
+    }
+}

dubbo-cluster/src/main/resources/META-INF/dubbo/internal/org.apache.dubbo.rpc.cluster.LoadBalance

@@ -1,6 +1,7 @@
 random=org.apache.dubbo.rpc.cluster.loadbalance.RandomLoadBalance
 roundrobin=org.apache.dubbo.rpc.cluster.loadbalance.RoundRobinLoadBalance
 leastactive=org.apache.dubbo.rpc.cluster.loadbalance.LeastActiveLoadBalance
+weightedleastactive=org.apache.dubbo.rpc.cluster.loadbalance.WeightedLeastActiveLoadBalance
 consistenthash=org.apache.dubbo.rpc.cluster.loadbalance.ConsistentHashLoadBalance
 shortestresponse=org.apache.dubbo.rpc.cluster.loadbalance.ShortestResponseLoadBalance
 adaptive=org.apache.dubbo.rpc.cluster.loadbalance.AdaptiveLoadBalance

dubbo-cluster/src/test/java/org/apache/dubbo/rpc/cluster/loadbalance/WeightedLeastActiveBalanceTest.java

@@ -0,0 +1,194 @@
+/*
+ * 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.dubbo.rpc.cluster.loadbalance;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcInvocation;
+import org.apache.dubbo.rpc.RpcStatus;
+
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicLong;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+class WeightedLeastActiveBalanceTest extends LoadBalanceBaseTest {
+
+    @BeforeEach
+    public void before() throws Exception {
+        weightInvoker1 = mock(Invoker.class, Mockito.withSettings().stubOnly());
+        weightInvoker2 = mock(Invoker.class, Mockito.withSettings().stubOnly());
+        weightInvoker3 = mock(Invoker.class, Mockito.withSettings().stubOnly());
+
+        weightTestInvocation = new RpcInvocation();
+        weightTestInvocation.setMethodName("test");
+
+        URL url1 = URL.valueOf("test1://127.0.0.1:11/DemoService?weight=3&active=1");
+        URL url2 = URL.valueOf("test2://127.0.0.1:12/DemoService?weight=9&active=1");
+        URL url3 = URL.valueOf("test3://127.0.0.1:13/DemoService?weight=6&active=1");
+
+        given(weightInvoker1.isAvailable()).willReturn(true);
+        given(weightInvoker1.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker1.getUrl()).willReturn(url1);
+
+        given(weightInvoker2.isAvailable()).willReturn(true);
+        given(weightInvoker2.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker2.getUrl()).willReturn(url2);
+
+        given(weightInvoker3.isAvailable()).willReturn(true);
+        given(weightInvoker3.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker3.getUrl()).willReturn(url3);
+
+        weightInvokers.add(weightInvoker1);
+        weightInvokers.add(weightInvoker2);
+        weightInvokers.add(weightInvoker3);
+
+        RpcStatus.beginCount(weightInvoker1.getUrl(), weightTestInvocation.getMethodName());
+        RpcStatus.beginCount(weightInvoker2.getUrl(), weightTestInvocation.getMethodName());
+        RpcStatus.beginCount(weightInvoker3.getUrl(), weightTestInvocation.getMethodName());
+    }
+
+    @Disabled
+    @Test
+    void testWeightedLeastActiveLoadBalance_select() {
+        int runs = 10000;
+        Map<Invoker, AtomicLong> counter = getInvokeCounter(runs, WeightedLeastActiveLoadBalance.NAME);
+        for (Map.Entry<Invoker, AtomicLong> entry : counter.entrySet()) {
+            Long count = entry.getValue().get();
+            //            System.out.println(count);
+            Assertions.assertTrue(
+                    Math.abs(count - runs / (0f + invokers.size())) < runs / (0f + invokers.size()),
+                    "abs diff should < avg");
+        }
+    }
+
+    @Test
+    void testSelectDirectly() {
+
+        int sumInvoker1 = 0;
+        int loop = 10000;
+
+        WeightedLeastActiveLoadBalance lb = new WeightedLeastActiveLoadBalance();
+        for (int i = 0; i < loop; i++) {
+            Invoker selected = lb.select(weightInvokers, null, weightTestInvocation);
+
+            if (selected.getUrl().getProtocol().equals("test1")) {
+                sumInvoker1++;
+            }
+
+            Assertions.assertTrue(
+                    !selected.getUrl().getProtocol().equals("test2"), "select is not the least active one");
+            Assertions.assertTrue(
+                    !selected.getUrl().getProtocol().equals("test3"), "select is not the least active one");
+        }
+
+        Assertions.assertEquals(sumInvoker1, loop, "select failed!");
+    }
+
+    @Test
+    void testSelectByRandom() {
+        Invoker<LoadBalanceBaseTest> weightInvoker4 =
+                mock(Invoker.class, Mockito.withSettings().stubOnly());
+        Invoker<LoadBalanceBaseTest> weightInvoker5 =
+                mock(Invoker.class, Mockito.withSettings().stubOnly());
+        URL url4 = URL.valueOf("test4://127.0.0.1:14/DemoService?weight=2&active=1");
+        URL url5 = URL.valueOf("test5://127.0.0.1:15/DemoService?weight=1&active=2");
+        given(weightInvoker4.isAvailable()).willReturn(true);
+        given(weightInvoker4.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker4.getUrl()).willReturn(url4);
+        RpcStatus.beginCount(weightInvoker4.getUrl(), weightTestInvocation.getMethodName());
+
+        given(weightInvoker5.isAvailable()).willReturn(true);
+        given(weightInvoker5.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker5.getUrl()).willReturn(url5);
+        RpcStatus.beginCount(weightInvoker5.getUrl(), weightTestInvocation.getMethodName());
+        RpcStatus.beginCount(weightInvoker5.getUrl(), weightTestInvocation.getMethodName());
+
+        weightInvokers.add(weightInvoker4);
+        weightInvokers.add(weightInvoker5);
+
+        int sumInvoker4 = 0;
+        int sumInvoker5 = 0;
+        int loop = 10000;
+
+        WeightedLeastActiveLoadBalance lb = new WeightedLeastActiveLoadBalance();
+        for (int i = 0; i < loop; i++) {
+            Invoker selected = lb.select(weightInvokers, null, weightTestInvocation);
+
+            if (selected.getUrl().getProtocol().equals("test4")) {
+                sumInvoker4++;
+            }
+            if (selected.getUrl().getProtocol().equals("test5")) {
+                sumInvoker5++;
+            }
+        }
+
+        // the sumInvoker1 : sumInvoker2 approximately equal to 1: 1
+        System.out.println(sumInvoker4);
+        System.out.println(sumInvoker5);
+
+        Assertions.assertEquals(sumInvoker4 + sumInvoker5, loop, "select failed!");
+    }
+
+    @Test
+    void testSelectByWeight() {
+        Invoker<LoadBalanceBaseTest> weightInvoker6 =
+                mock(Invoker.class, Mockito.withSettings().stubOnly());
+        Invoker<LoadBalanceBaseTest> weightInvoker7 =
+                mock(Invoker.class, Mockito.withSettings().stubOnly());
+        URL url6 = URL.valueOf("test6://127.0.0.1:14/DemoService?weight=2&active=0");
+        URL url7 = URL.valueOf("test7://127.0.0.1:14/DemoService?weight=8&active=0");
+        given(weightInvoker6.isAvailable()).willReturn(true);
+        given(weightInvoker6.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker6.getUrl()).willReturn(url6);
+
+        given(weightInvoker7.isAvailable()).willReturn(true);
+        given(weightInvoker7.getInterface()).willReturn(LoadBalanceBaseTest.class);
+        given(weightInvoker7.getUrl()).willReturn(url7);
+        weightInvokers.add(weightInvoker6);
+        weightInvokers.add(weightInvoker7);
+
+        int sumInvoker4 = 0;
+        int sumInvoker5 = 0;
+        int loop = 10000;
+
+        WeightedLeastActiveLoadBalance lb = new WeightedLeastActiveLoadBalance();
+        for (int i = 0; i < loop; i++) {
+            Invoker selected = lb.select(weightInvokers, null, weightTestInvocation);
+
+            if (selected.getUrl().getProtocol().equals("test6")) {
+                sumInvoker4++;
+            }
+            if (selected.getUrl().getProtocol().equals("test7")) {
+                sumInvoker5++;
+            }
+        }
+
+        // the sumInvoker1 : sumInvoker2 approximately equal to 1: 4
+        System.out.println(sumInvoker4);
+        System.out.println(sumInvoker5);
+
+        Assertions.assertEquals(sumInvoker4 + sumInvoker5, loop, "select failed!");
+    }
+}