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dubbo工作原理

本文轉載自   查看原文   2016-05-26 15:16   4051    dubbo

part -- 外掛
1.dubbo借助spring的schema啟動和初始化
1.1 spring掃描所有jar下META-INF的spring.handlers和spring.schemas。
1.2 運行spring.handlers下定義的DubboNamespaceHandler的init方法。
1.3 spring加載xml，執行DubboBeanDefinitionParser的parse方法，通過RootBeanDefinition將serviceBean暴露給spring。（實際調用AutowireCapableBeanFactory.registerBeanDefinition）
1.4 serviceBean實現了BeanNameAware接口，自動注入spring中的單例name。

part -- 服務暴露（生產者）
2.dubbo服務暴露
2.1 serviceBean實現了ApplicationListener，在bean初始化時觸發onApplicationEvent方法，調用serviceConfig的export方法。
2.2 serviceConfig初始化，先初始化靜態變量protocol和proxyFactory。
getExtensionLoader.getExtensionLoader ->getAdaptiveExtension->createAdaptiveExtension->getAdaptiveExtensionClass->getExtensionClasses->loadExtensionClasses
->loadFile->createAdaptiveExtensionClassCode
loadFile采用的是java spi的思想，分別讀取META-INF/services/，META-INF/dubbo/，META-INF/dubbo/internal/下文件進行解析。
以protocol為例，其中ProtocolFilterWrapper和ProtocolListenerWrapper是有參數為protocol構造函數的，被放到Set<Class<?>> cachedWrapperClasses（后面會用到）中。
沒有protocol構造函數，但是有@Adaptive注解的，被放到Holder<Object> cachedAdaptiveInstance中。
以上都不滿足的放到cachedClasses中。
createAdaptiveExtensionClassCode通過javassist字節碼技術生成代理類Protocol$Adpative，ProxyFactory$Adpative。
附上兩個動態類的源碼。可以看到protocol默認的是dubbo，proxy默認的是javassist。
2.3 export判斷是否需要延遲暴露，執行暴露方法doExport()。
2.4 doExport檢查通過，調用doExportUrls
2.5 doExportUrls根據不同的協議將服務以URL（dubbo）形式暴露。
2.6 如果服務未配置成remote,則本地暴露（exportLocal），如果未配置成local，則注冊服務（registryProtocol）
2.7 exportLocal：生成本地protocol（Constants.LOCAL_PROTOCOL = injvm），
proxyFactory.getInvoker StubProxyFactoryWrapper->JavassistProxyFactory.getInvoker。Wrapper.getWrappery獲取服務的封裝代理類（javassist動態字節碼）,詳細參照ClassGenerator.toClass。
protocol.export ExtensionLoader.getExtension(injvm)->createExtension -> getExtensionClasses(返回cachedClasses對應的值)
接着循環cachedWrapperClasses,層層裝飾（裝飾模式）,InjvmProtocol,ProtocolFilterWrapper，ProtocolListenerWrapper增強服務。
ProtocolFilterWrapper buildInvokerChain建立了filter鏈，方便開發者根據業務進行擴展。
registryProtocol export ->ProtocolFilterWrapper export-> ProtocolListenerWrapper export->dubboProtocol export。

3.netty啟動
3.1 openServer netty server打開偵聽服務，並緩存服務。
dubbo -> export() -> openServer() -> createServer() -> Exchangers.bind()(HeaderExchanger) -> NettyTransporter -> NettyServer.open()(編碼解碼采用exchange)
netty ChannelFactory(boss worker) ChannelPipeline(責任鏈模式) ChannelHandler(處理器) --- 反應器模式

part -- 服務引用(消費者)
4.dubbo服務引用
4.1 referenceBean實現了InitializingBean接口，在afterPropertiesSet后執行getObject()方法，調用referenceConfig的init方法。
4.2 StaticContext.getSystemContext()是dubbo全局的線程安全上下文，存放方法調用的相關信息。
4.2 createProxy，設置invoker，這里的invoker有協議默認的dubbo invoker，cluster invoker（重連機制，默認Failover，重試兩次，一共三次）
返回InvokerInvocationHandler(javassist動態字節碼改造后的代理，執行方法時，實際執行的是invoker的doinvoke方法)
cluster invoker的doinvoke方法會調用select()，負載均衡，默認RandomLoadBalance
4.3 獲取dubbo invoker時，調用dubbo的refer，調用getClients獲取ExchangeClient，默認的ExchangeClient是共享的getSharedClient。initClient默認是非延遲的，調用Exchangers.connect，最終調用HeaderExchanger.connect,調用
Transporters.connect，同生產者一樣，默認的Transporters是netty。因此最終的ExchangeClient是NettyClient。
4.3 dubbo invoker doinvoke方法，ExchangeClient.request方法，結果通過future的get方法返回，get方法通過lock+while+超時控制。
4.4 ExchageClient.request最終調用的是nettyChannel
1.NettyHandler.messageReceived(ChannelHandlerContext ctx, MessageEvent e)
2.AbstractPeer.received(Channel ch, Object msg)
3.MultiMessageHandler.received(Channel channel, Object message)
4.AllChannelHandler.received(Channel channel, Object message)
5.DecodeHandler.received(Channel channel, Object message)
6.HeaderExchangeHandler.received(Channel channel, Object message)
7.DefaultFuture.received(Channel channel, Response response) //注意是static方法
DefaultFuture future = FUTURES.remove(response.getId());
if (future != null) {
future.doReceived(response);
}

http://blog.csdn.net/a19881029/article/details/51058428

spring
1. 入口ContextLoaderListener監聽器，調用contextInitialized方法，ContextLoder的initWebApplicationContext，createWebApplicationContext默認創建ContextLoader.properties里的XmlWebApplicationContext,強制轉換成configureAndRefreshWebApplicationContext
最終調用AbstractApplicationContext的refresh方法（前面調用了ApplicationContextInitializer的initialize，這里可以做一些spring默認規則的修改，比如id重復bean處理，spring默認覆蓋）
2.

 

 動態生成的Protocol$Adpative.class

package com.alibaba.dubbo.rpc;

import com.alibaba.dubbo.common.extension.ExtensionLoader;

public class Protocol$Adpative implements com.alibaba.dubbo.rpc.Protocol {
    public void destroy() {
        throw new UnsupportedOperationException(
                "method public abstract void com.alibaba.dubbo.rpc.Protocol.destroy() of interface com.alibaba.dubbo.rpc.Protocol is not adaptive method!");
    }

    public int getDefaultPort() {
        throw new UnsupportedOperationException(
                "method public abstract int com.alibaba.dubbo.rpc.Protocol.getDefaultPort() of interface com.alibaba.dubbo.rpc.Protocol is not adaptive method!");
    }

    public com.alibaba.dubbo.rpc.Invoker refer(java.lang.Class arg0, com.alibaba.dubbo.common.URL arg1)
            throws java.lang.Class {
        if (arg1 == null)
            throw new IllegalArgumentException("url == null");
        com.alibaba.dubbo.common.URL url = arg1;
        String extName = (url.getProtocol() == null ? "dubbo" : url.getProtocol());
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url("
                    + url.toString() + ") use keys([protocol])");
        com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol) ExtensionLoader
                .getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class).getExtension(extName);
        return extension.refer(arg0, arg1);
    }

    public com.alibaba.dubbo.rpc.Exporter export(com.alibaba.dubbo.rpc.Invoker arg0)
            throws com.alibaba.dubbo.rpc.Invoker {
        if (arg0 == null)
            throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument == null");
        if (arg0.getUrl() == null)
            throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument getUrl() == null");
        com.alibaba.dubbo.common.URL url = arg0.getUrl();
        String extName = (url.getProtocol() == null ? "dubbo" : url.getProtocol());
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url("
                    + url.toString() + ") use keys([protocol])");
        com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol) ExtensionLoader
                .getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class).getExtension(extName);
        return extension.export(arg0);
    }
}
View Code

 

動態生成的ProxyFactory$Adpative.class

package com.alibaba.dubbo.rpc;

import com.alibaba.dubbo.common.extension.ExtensionLoader;

public class ProxyFactory$Adpative implements com.alibaba.dubbo.rpc.ProxyFactory {
    public java.lang.Object getProxy(com.alibaba.dubbo.rpc.Invoker arg0) throws com.alibaba.dubbo.rpc.Invoker {
        if (arg0 == null)
            throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument == null");
        if (arg0.getUrl() == null)
            throw new IllegalArgumentException("com.alibaba.dubbo.rpc.Invoker argument getUrl() == null");
        com.alibaba.dubbo.common.URL url = arg0.getUrl();
        String extName = url.getParameter("proxy", "javassist");
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.ProxyFactory) name from url("
                    + url.toString() + ") use keys([proxy])");
        com.alibaba.dubbo.rpc.ProxyFactory extension = (com.alibaba.dubbo.rpc.ProxyFactory) ExtensionLoader
                .getExtensionLoader(com.alibaba.dubbo.rpc.ProxyFactory.class).getExtension(extName);
        return extension.getProxy(arg0);
    }

    public com.alibaba.dubbo.rpc.Invoker getInvoker(java.lang.Object arg0, java.lang.Class arg1,
            com.alibaba.dubbo.common.URL arg2) throws java.lang.Object {
        if (arg2 == null)
            throw new IllegalArgumentException("url == null");
        com.alibaba.dubbo.common.URL url = arg2;
        String extName = url.getParameter("proxy", "javassist");
        if (extName == null)
            throw new IllegalStateException("Fail to get extension(com.alibaba.dubbo.rpc.ProxyFactory) name from url("
                    + url.toString() + ") use keys([proxy])");
        com.alibaba.dubbo.rpc.ProxyFactory extension = (com.alibaba.dubbo.rpc.ProxyFactory) ExtensionLoader
                .getExtensionLoader(com.alibaba.dubbo.rpc.ProxyFactory.class).getExtension(extName);
        return extension.getInvoker(arg0, arg1, arg2);
    }
}


{class com.alibaba.dubbo.config.spring.extension.SpringExtensionFactory=com.alibaba.dubbo.config.spring.extension.SpringExtensionFactory@5d1275be, class com.alibaba.dubbo.common.compiler.support.JavassistCompiler=com.alibaba.dubbo.common.compiler.support.JavassistCompiler@66f03cae, class com.alibaba.dubbo.common.extension.factory.SpiExtensionFactory=com.alibaba.dubbo.common.extension.factory.SpiExtensionFactory@261ff84e}

injvm://127.0.0.1/com.ihome.tf.order.service.IBenefitFoundService?anyhost=true&application=tf-order&default.retries=0&default.timeout=10000&dubbo=2.5.3&interface=com.ihome.tf.order.service.IBenefitFoundService&methods=update,clear,qryBenefitFndOrderList,qryCheckPassedBenefitList,qryBenefitFoundOrderSumInf,verify,qryBenefitFound&owner=tf&pid=1492&revision=0.0.1-SNAPSHOT&side=provider&timestamp=1457518110700
View Code

 

動態生成的Wrapper1.class

package com.alibaba.dubbo.common.bytecode;

import com.prepay.dto.ShareRulesReq;
import com.prepay.service.IOutShareService;
import java.lang.reflect.InvocationTargetException;
import java.util.Map;

public class Wrapper1 extends Wrapper
  implements ClassGenerator.DC
{
  public static String[] pns;
  public static Map pts;
  public static String[] mns;
  public static String[] dmns;
  public static Class[] mts0;
  public static Class[] mts1;
  public static Class[] mts2;

  public String[] getPropertyNames()
  {
    return pns;
  }

  public boolean hasProperty(String paramString)
  {
    return jdField_pts_of_type_JavaUtilMap.containsKey(paramString);
  }

  public Class getPropertyType(String paramString)
  {
    return (Class)jdField_pts_of_type_JavaUtilMap.get(paramString);
  }

  public String[] getMethodNames()
  {
    return mns;
  }

  public String[] getDeclaredMethodNames()
  {
    return dmns;
  }

  public void setPropertyValue(Object paramObject1, String paramString, Object paramObject2)
  {
    try
    {
      IOutShareService localIOutShareService = (IOutShareService)paramObject1;
    }
    catch (Throwable localThrowable)
    {
      throw new IllegalArgumentException(localThrowable);
    }
    throw new NoSuchPropertyException("Not found property \"" + paramString + "\" filed or setter method in class com.ihome.prepay.service.IOutShareService.");
  }

  public Object getPropertyValue(Object paramObject, String paramString)
  {
    try
    {
      IOutShareService localIOutShareService = (IOutShareService)paramObject;
    }
    catch (Throwable localThrowable)
    {
      throw new IllegalArgumentException(localThrowable);
    }
    throw new NoSuchPropertyException("Not found property \"" + paramString + "\" filed or setter method in class com.ihome.prepay.service.IOutShareService.");
  }

  public Object invokeMethod(Object paramObject, String paramString, Class[] paramArrayOfClass, Object[] paramArrayOfObject)
    throws InvocationTargetException
  {
    IOutShareService localIOutShareService;
    try
    {
      localIOutShareService = (IOutShareService)paramObject;
    }
    catch (Throwable localThrowable1)
    {
      throw new IllegalArgumentException(localThrowable1);
    }
    try
    {
      if ((!"queryShareRuleDetail".equals(paramString)) || (paramArrayOfClass.length == 1))
        return localIOutShareService.queryShareRuleDetail((String)paramArrayOfObject[0]);
      if ((!"queryShareRuleList".equals(paramString)) || (paramArrayOfClass.length == 1))
        return localIOutShareService.queryShareRuleList((ShareRulesReq)paramArrayOfObject[0]);
      if ((!"querySharePullDownList".equals(paramString)) || (paramArrayOfClass.length == 0))
        return localIOutShareService.querySharePullDownList();
    }
    catch (Throwable localThrowable2)
    {
      throw new InvocationTargetException(localThrowable2);
    }
    throw new NoSuchMethodException("Not found method \"" + paramString + "\" in class com.ihome.prepay.service.IOutShareService.");
  }
}
View Code

 

 

<以上內容由同事提供>

  

 

如果想了解更多Dubbo源碼的知識，請移步 Dubbo源碼解讀——通向高手之路 的視頻講解： http://edu.51cto.com/sd/2e565

 


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