Merge pull request #97 from complone/master

Provide an example for Dubbo load balancing

dubbo-sample-gateway/README.md

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+# Dubbo-Uniformity HashSelector
+
+Design and implementation of Dubbo adaptive load balancing with priority random load
+
+
+
+
+## Sample introduction
+
+
+
+> Dubbo-based stochastic load balancing
+
+
+
+
+- The random strategy will first determine whether all Invokers have the same weight.
+
+- If they are the same, then the process is relatively simple. Using random. nexInt (length) you can randomly generate an Invoker serial number
+
+- Select the corresponding Invoker according to the serial number. If no weight is set on the service provider, then all Invoker weights are the same, default is 100.
+
+- If the weights are different, then we need to combine the weights to set the random probability.
+
+
+
+> Random Load Balancing after Modification
+
+- Get the address of a service from the locally currently registered provider service, and if it is the same as the IP of the current machine, get the provider first.
+
+- If different, re-load the random load and retrieve a provider service

dubbo-sample-gateway/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <groupId>org.apache.dubbo</groupId>
+    <version>1.0-SNAPSHOT</version>
+
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>dubbo-samples-gateway</artifactId>
+
+    <properties>
+        <source.level>1.8</source.level>
+        <target.level>1.8</target.level>
+        <dubbo.version>2.7.1</dubbo.version>
+        <junit.version>4.12</junit.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo</artifactId>
+            <version>${dubbo.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo-dependencies-zookeeper</artifactId>
+            <version>${dubbo.version}</version>
+            <type>pom</type>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.dubbo</groupId>
+            <artifactId>dubbo-samples-callback</artifactId>
+             <version>1.0-SNAPSHOT</version>
+            <scope>compile</scope>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

dubbo-sample-gateway/src/main/java/org/apache/dubbo/samples/CallbackListenerImpl.java

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+package org.apache.dubbo.samples;
+
+
+import org.apache.dubbo.samples.callback.api.CallbackListener;
+
+
+public class CallbackListenerImpl implements CallbackListener {
+
+    @Override
+    public void changed(String msg) {
+        System.out.println("receive msg from server :" + msg);
+    }
+
+}

dubbo-sample-gateway/src/main/java/org/apache/dubbo/samples/TestClientFilter.java

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+package org.apache.dubbo.samples;
+
+import org.apache.dubbo.common.Constants;
+import org.apache.dubbo.common.extension.Activate;
+import org.apache.dubbo.rpc.Filter;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.Result;
+import org.apache.dubbo.rpc.RpcException;
+
+
+@Activate(group = Constants.CONSUMER)
+public class TestClientFilter implements Filter {
+    @Override
+    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
+        try{
+            Result result = invoker.invoke(invocation);
+            return result;
+        }catch (Exception e){
+            throw e;
+        }
+    }
+
+    @Override
+    public Result onResponse(Result result, Invoker<?> invoker, Invocation invocation) {
+        return result;
+    }
+}

dubbo-sample-gateway/src/main/java/org/apache/dubbo/samples/UserLoadBalance.java

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+package org.apache.dubbo.samples;
+
+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcException;
+import org.apache.dubbo.rpc.cluster.LoadBalance;
+import org.apache.dubbo.rpc.cluster.loadbalance.RandomLoadBalance;
+
+import java.net.InetAddress;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+
+public class UserLoadBalance extends RandomLoadBalance {
+
+    @Override
+    public <T> Invoker<T> doSelect(List<Invoker<T>> invokers, URL url, Invocation invocation) throws RpcException {
+        // 循环当前注册的多个invoker 优先选择与自己IP相同的服务
+        for (Invoker t : invokers) {
+            try {
+                InetAddress addr = InetAddress.getLocalHost();
+                String ip=addr.getHostAddress().toString(); //获取本机ip
+                URL u = t.getUrl();
+                if (u.getIp().equals(ip)) {
+                    return  t;
+                }
+            } catch (Exception e) {
+            }
+        }
+        return super.doSelect(invokers, url, invocation);
+    }
+}

dubbo-sample-gateway/src/main/resources/META-INF/services/org.apache.dubbo.rpc.Filter

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+org.apache.dubbo.samples.TestClientFilter

dubbo-sample-gateway/src/main/resources/META-INF/services/org.apache.dubbo.rpc.cluster.LoadBalance

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+org.apache.dubbo.samples.UserLoadBalance

dubbo-sample-gateway/src/main/resources/META-INF/services/org.apache.dubbo.rpc.listener.CallbackListener

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+org.apache.dubbo.samples.CallbackListenerImpl

dubbo-sample-gateway/src/test/java/UserLoadBalanceTest.java

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+import org.apache.dubbo.common.URL;
+import org.apache.dubbo.common.extension.ExtensionLoader;
+import org.apache.dubbo.rpc.Invocation;
+import org.apache.dubbo.rpc.Invoker;
+import org.apache.dubbo.rpc.RpcStatus;
+import org.apache.dubbo.rpc.cluster.LoadBalance;
+import org.apache.dubbo.rpc.cluster.loadbalance.AbstractLoadBalance;
+import org.apache.dubbo.rpc.cluster.loadbalance.LeastActiveLoadBalance;
+import org.apache.dubbo.rpc.cluster.loadbalance.RandomLoadBalance;
+import org.apache.dubbo.samples.UserLoadBalance;
+import org.junit.Assert;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.junit.Assert.*;
+
+
+public class UserLoadBalanceTest {
+
+    Invocation invocation;
+
+    Invoker<UserLoadBalanceTest> invoker1;
+    Invoker<UserLoadBalanceTest> invoker2;
+    Invoker<UserLoadBalanceTest> invoker3;
+    Invoker<UserLoadBalanceTest> invoker4;
+    Invoker<UserLoadBalanceTest> invoker5;
+
+    List<Invoker<UserLoadBalanceTest>> invokers = new ArrayList<Invoker<UserLoadBalanceTest>>();
+    @org.junit.Test
+    public void doSelect() {
+
+        int runs = 1000;
+        Map<Invoker, AtomicLong> counter = getInvokeCounter(runs, RandomLoadBalance.NAME);
+        for (Map.Entry<Invoker, AtomicLong> entry : counter.entrySet()) {
+            Long count = entry.getValue().get();
+            Assert.assertTrue("abs diff should < avg",Math.abs(count - runs / (0f + invokers.size())) < runs / (0f + invokers.size()));
+        }
+
+        for (int i = 0; i < 5; i++) {
+            for (int j = 0; j <= i; j++) {
+                RpcStatus.beginCount(invokers.get(i).getUrl(), invocation.getMethodName());
+            }
+        }
+        counter = getInvokeCounter(runs, LeastActiveLoadBalance.NAME);
+        for (Map.Entry<Invoker, AtomicLong> entry : counter.entrySet()) {
+            Long count = entry.getValue().get();
+        }
+        Assert.assertEquals(runs, counter.get(invoker1).intValue());
+        Assert.assertEquals(0, counter.get(invoker2).intValue());
+        Assert.assertEquals(0, counter.get(invoker3).intValue());
+        Assert.assertEquals(0, counter.get(invoker4).intValue());
+        Assert.assertEquals(0, counter.get(invoker5).intValue());
+    }
+
+
+    public Map<Invoker, AtomicLong> getInvokeCounter(int runs, String loadbalanceName) {
+        Map<Invoker, AtomicLong> counter = new ConcurrentHashMap<Invoker, AtomicLong>();
+        LoadBalance lb = getLoadBalance(loadbalanceName);
+        for (Invoker invoker : invokers) {
+            counter.put(invoker, new AtomicLong(0));
+        }
+        URL url = invokers.get(0).getUrl();
+        for (int i = 0; i < runs; i++) {
+            Invoker sinvoker = lb.select(invokers, url, invocation);
+            counter.get(sinvoker).incrementAndGet();
+        }
+        return counter;
+    }
+
+    protected AbstractLoadBalance getLoadBalance(String loadbalanceName) {
+        return (AbstractLoadBalance) ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(loadbalanceName);
+    }
+
+}