大纲
1.Dubbo 2.7和3.x版本的区别
2.Dubbo服务的基本流程和启动入口
3.Dubbo服务发布的主流程
4.服务发布时执行相关组件的初始化
5.服务发布时执行的服务实例刷新操作
6.服务发布时执行的服务实例初始化操作
7.服务发布时执行的服务实例发布操作
8.执行服务实例发布操作时的主流程
9.服务发布过程中ProxyFactory生成Invoker
10.服务发布过程中Protocol组件发布Invoker
11.服务发布过程中NettyServer的构造流程
12.服务发布过程中RegistryProtocol的服务注册
13.Dubbo服务发布的完整流程总结
1.Dubbo 2.7和3.x版本的区别
区别一:后者引入了ModuleDeployer组件专门做服务启动时的初始化工作。将原来的注册中心拆分为三大中心:注册中心、配置中心、元数据中心。
区别二:后者很多地方使用了Double Check来代替前者对方法加Synchronized锁,大量采用了Double Check + Volatile + Static来实现单例模式。
区别三:后者引入了MigrationRuleListener、MigrationRuleHandler、MigrationInvoker,引入DynamicDirectory代替RegistryDirectory。
2.Dubbo服务的基本流程和启动入口
(1)Dubbo服务的基本流程
(2)Provider启动入口
(3)Consumer启动入口
(1)Dubbo服务的基本流程
(2)Provider启动入口
csharp
public class Application {
public static void main(String[] args) throws Exception {
//Service和ServiceConfig是什么
//Service是一个服务,每个服务可能会包含多个接口
//ServiceConfig便是针对这个服务的一些配置
//下面传入的泛型DemoServiceImpl便是服务接口的实现
ServiceConfig<DemoServiceImpl> service = new ServiceConfig<>();
//设置服务暴露出去的接口
service.setInterface(DemoService.class);
//设置暴露出去的接口的实现类
service.setRef(new DemoServiceImpl());
//服务名称,可以在服务框架里进行定位
service.setApplication(new ApplicationConfig("dubbo-demo-api-provider"));
//所有的RPC框架,必须要和注册中心配合使用,服务启动后必须向注册中心进行注册
//注册中心可以知道每个服务有几个实例,每个实例在哪台服务器上
//进行服务调用时,要先找注册中心咨询要调用的服务有几个实例,分别都在什么机器上
//下面便是设置ZooKeeper作为注册中心的地址
service.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
//设置元数据上报的地方
//Dubbo服务实例启动后,会有自己的元数据,需要上报到一个地方进行管理,比如zookeeper
service.setMetadataReportConfig(new MetadataReportConfig("zookeeper://127.0.0.1:2181"));
//配置完毕后,调用ServiceConfig的export()方法启动网络监听程序
//当接收到调用请求时,该网络监听程序会建立网络连接进行通信
//接收按照协议封装的请求数据,该网络监听程序会执行RPC调用
//此外,ServiceConfig的export()方法还会把自己作为一个服务实例注册到zk里
service.export();
System.out.println("dubbo service started");
new CountDownLatch(1).await();
}
}
(3)Consumer启动入口
arduino
public class Application {
public static void main(String[] args) throws Exception {
//Reference和ReferenceConfig是什么
//Reference是一个引用,是对Provider端的一个服务实例的引用
//ReferenceConfig这个服务实例的引用的一些配置
//通过泛型传递了这个服务实例对外暴露的接口
ReferenceConfig<DemoService> reference = new ReferenceConfig<>();
//设置应用名称
reference.setApplication(new ApplicationConfig("dubbo-demo-api-consumer"));
//设置注册中心的地址,默认是ZooKeeper
reference.setRegistry(new RegistryConfig("zookeeper://127.0.0.1:2181"));
//设置元数据上报地址
reference.setMetadataReportConfig(new MetadataReportConfig("zookeeper://127.0.0.1:2181"));
//设置要调用的服务的接口
reference.setInterface(DemoService.class);
//直接通过ReferenceConfig的get()方法来拿到一个DemoService接口
//它是一个动态代理接口,只要被调用,便会通过底层调用Provider服务实例的对应接口
DemoService service = reference.get();
String message = service.sayHello("dubbo");
System.out.println(message);
Thread.sleep(10000000L);
}
}
3.Dubbo服务发布的主流程
ServiceConfig的export()方法在进行服务发布时,首先会初始化相关组件,然后刷新服务实例,接着初始化服务实例,最后发布服务实例。
kotlin
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
@Override
public void export() {
if (this.exported) {
return;
}
//prepare for export
//对比Dubbo 2.6.x和2.7.x源码,Dubbo 3.0的变动还是有点大的,比如这里使用了ModuleDeployer组件
//Dubbo服务实例内部会有很多的代码组件,通过ModuleDeployer便可以避免零零散散的去调用和初始化
//1.执行相关组件的初始化
//通过获取到的ModuleDeployer来对相关组件进行初始化
//比如会对MetadataReport元数据上报组件进行构建和初始化,以及启动(建立跟zk的连接)
getScopeModel().getDeployer().start();
synchronized (this) {
if (this.exported) {
return;
}
//2.执行服务实例的刷新操作
//也就是刷新ProviderConfig->MethodConfig->ArgumentConfig
if (!this.isRefreshed()) {
this.refresh();
}
if (this.shouldExport()) {
//3.执行服务实例的初始化
//也就是会把Metadata元数据给准备好,后续可以进行元数据上报
this.init();
//这是Dubbo服务实例的延迟发布的特性
//如果设置了Dubbo服务实例是延迟发布的,当调用了export()方法后,就会进入这里
//在延迟指定的时间后,再去进行服务的发布
if (shouldDelay()) {
//延迟发布
doDelayExport();
} else {
//立即发布
//4.执行服务实例的发布
//这里可以作为服务发布的直接入口
doExport();
}
}
}
}
...
}
4.服务发布时执行相关组件的初始化
scala
public class DefaultModuleDeployer extends AbstractDeployer<ModuleModel> implements ModuleDeployer {
//已经完成发布的服务实例集合
private List<ServiceConfigBase<?>> exportedServices = new ArrayList<>();
//下面这些组件,本身都是跟model组件体系强关联的
private ModuleModel moduleModel;
//父级ApplicationDeployer组件
private ApplicationDeployer applicationDeployer;
...
@Override
public Future start() throws IllegalStateException {
//initialize,maybe deadlock applicationDeployer lock & moduleDeployer lock
//调用DefaultApplicationDeployer的initialize()方法
applicationDeployer.initialize();
return startSync();
}
@Override
public void prepare() {
//module这个层级是application层级的下层
//application层级是framework层级的下层
applicationDeployer.initialize();
this.initialize();
}
...
}
public class DefaultApplicationDeployer extends AbstractDeployer<ApplicationModel> implements ApplicationDeployer {
private final DubboShutdownHook dubboShutdownHook;
...
@Override
public void initialize() {
if (initialized) {
return;
}
//ApplicationDeployer组件,可能会被多线程并发访问
//Ensure that the initialization is completed when concurrent calls
synchronized (startLock) {
if (initialized) {
return;
}
//注册退出时需要进行资源销毁的ShutdownHook
//register shutdown hook
registerShutdownHook();
//启动配置中心ConfigCenter
//动配置中心是专门存放配置信息的
startConfigCenter();
//加载应用配置
loadApplicationConfigs();
//初始化ModuleDeployer
initModuleDeployers();
//启动元数据中心MetadataCenter
//元数据中心是专门存放发布d的服务实例信息的
startMetadataCenter();
initialized = true;
if (logger.isInfoEnabled()) {
logger.info(getIdentifier() + " has been initialized!");
}
}
//老的Dubbo版本只有注册中心的概念
//后来随着版本的迭代和演进,出现了配置中心、元数据中心等这些用于解耦的概念
//虽然Dubbo的服务实例信息、配置信息、元数据信息,都可以放在zk里
//但如果把一个服务实例的各种数据和信息都存储在zk里,那么这些数据和信息会严重耦合在一起
//下面从扩展性和可用性两个层面来分析,如果把各种数据都耦合放在一个zk里可能会出现的问题
//(1)扩展性
//在一个大规模的微服务系统里,服务本身可能都有上百个,服务实例可能有几百上千个,所以服务实例数据可能就很多
//但每个服务实例关联的配置数据,可能不是太多,尤其是元数据可能也不是太多
//而这里的扩展性不是指功能上的扩展,而是指数据上的扩展
//随着服务实例数据在膨胀,配置数据和元数据虽然可能也在增加,但是增加的速度可能比不上服务实例数据
//此时就需要对注册中心进行扩容或者更换一个系统去存储
//而在这个过程之中,由于所有数据耦合在一起了,牵一发而动全身,不好扩展了
//这就是多种不同类型的数据耦合在一起时会出现的痛点,也就是数据耦合导致数据扩展性差的问题
//(2)可用性
//由于注册数据、配置数据、元数据都放在一个地方比如zk
//那么一旦zk出现了故障,这三种数据就一起没了,这就是可用性问题
//因此,Dubbo3的架构设计会对不同类型的数据进行分离,形成了三种数据:注册数据、元数据、配置数据
//于是就有了三大中心:注册中心、配置中心、元数据中心,这样就可以把三种不同类型的数据,放到不同的地方去
//在扩展性方面,当服务实例数据太多时要进行扩容或者切换存储技术,此时对另外两种数据是没有直接影响的
//在可用性方面,一旦作为注册中心的zk突然挂了,此时配置中心可能是Nacos,对它来说也没有直接影响的
}
private void registerShutdownHook() {
dubboShutdownHook.register();
}
...
}
scala
public class DefaultApplicationDeployer extends AbstractDeployer<ApplicationModel> implements ApplicationDeployer {
...
//启动元数据中心
private void startMetadataCenter() {
//先分析元数据中心是否需要用注册中心来做元数据中心
useRegistryAsMetadataCenterIfNecessary();
ApplicationConfig applicationConfig = getApplication();
//获取元数据类型metadataType
String metadataType = applicationConfig.getMetadataType();
//进行元数据的配置,里面包含了MetadataReport的配置
Collection<MetadataReportConfig> metadataReportConfigs = configManager.getMetadataConfigs();
if (CollectionUtils.isEmpty(metadataReportConfigs)) {
return;
}
//从applicationModel中获取一个BeanFactory
//再根据BeanFactory获取一个元数据上报组件的实例MetadataReportInstance
MetadataReportInstance metadataReportInstance = applicationModel.getBeanFactory().getBean(MetadataReportInstance.class);
List<MetadataReportConfig> validMetadataReportConfigs = new ArrayList<>(metadataReportConfigs.size());
for (MetadataReportConfig metadataReportConfig : metadataReportConfigs) {
ConfigValidationUtils.validateMetadataConfig(metadataReportConfig);
validMetadataReportConfigs.add(metadataReportConfig);
}
//对于唯一的一个MetadataReport,会在这里进行初始化
//把配置的metadataReport地址和config传递进init()方法进行初始化
metadataReportInstance.init(validMetadataReportConfigs);
if (!metadataReportInstance.inited()) {
throw new IllegalStateException(String.format("%s MetadataConfigs found, but none of them is valid.", metadataReportConfigs.size()));
}
//所以MetadataReport的启动
//其实就是根据配置去获取对应的BeanFactory,然后通过BeanFactory创建出对应的MetadataReport实例
//最后根据配置对元数据上报组件的实例MetadataReportInstance进行初始化
}
...
}
public class MetadataReportInstance implements Disposable {
...
public void init(List<MetadataReportConfig> metadataReportConfigs) {
if (!init.compareAndSet(false, true)) {
return;
}
this.metadataType = applicationModel.getApplicationConfigManager().getApplicationOrElseThrow().getMetadataType();
if (metadataType == null) {
this.metadataType = DEFAULT_METADATA_STORAGE_TYPE;
}
//在这里会通过SPI机制的adaptive自适应,生成一个代理类
//底层会通过自适应的机制,根据url里的参数去拿到对应的实现类,来调用它的方法
//如果使用zk作为元数据中心,那么拿到的应该是一个ZooKeeperMetadataReportFactory
MetadataReportFactory metadataReportFactory = applicationModel.getExtensionLoader(MetadataReportFactory.class).getAdaptiveExtension();
for (MetadataReportConfig metadataReportConfig : metadataReportConfigs) {
init(metadataReportConfig, metadataReportFactory);
}
}
private void init(MetadataReportConfig config, MetadataReportFactory metadataReportFactory) {
...
//这种url一般来说是针对zk的url地址
MetadataReport metadataReport = metadataReportFactory.getMetadataReport(url);
if (metadataReport != null) {
metadataReports.put(relatedRegistryId, metadataReport);
}
}
...
}
public abstract class AbstractMetadataReportFactory implements MetadataReportFactory {
...
@Override
public MetadataReport getMetadataReport(URL url) {
...
metadataReport = createMetadataReport(url);
...
}
protected abstract MetadataReport createMetadataReport(URL url);
...
}
public class ZookeeperMetadataReportFactory extends AbstractMetadataReportFactory {
...
@Override
public MetadataReport createMetadataReport(URL url) {
return new ZookeeperMetadataReport(url, zookeeperTransporter);
}
...
}
public class ZookeeperMetadataReport extends AbstractMetadataReport {
private final String root;
ZookeeperClient zkClient;
...
public ZookeeperMetadataReport(URL url, ZookeeperTransporter zookeeperTransporter) {
super(url);
...
zkClient = zookeeperTransporter.connect(url);
}
...
}
5.服务发布时执行的服务实例刷新操作
完成相关组件的初始化后,便会调用ServiceConfig的refresh()方法执行服务实例的刷新操作。
scss
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
@Override
public void export() {
...
//1.执行相关组件的初始化
//通过获取到的ModuleDeployer来对相关组件进行初始化
//比如会对MetadataReport元数据上报组件进行构建和初始化,以及启动(建立跟zk的连接)
getScopeModel().getDeployer().start();
synchronized (this) {
if (this.exported) {
return;
}
//2.执行服务实例的刷新操作
//也就是刷新ProviderConfig->MethodConfig->ArgumentConfig
if (!this.isRefreshed()) {
//执行AbstractConfig的refresh()方法
this.refresh();
}
...
}
}
...
}
public abstract class AbstractConfig implements Serializable {
...
public void refresh() {
//check and init before do refresh
//调用AbstractConfig的子类ServiceConfigBase的preProcessRefresh()方法
//初始化一个ProviderConfig,也就是Provider服务实例
preProcessRefresh();
//Model组件体系对Dubbo的运行很关键,可以认为它是SPI机制使用的入口
//而ScopeModel是Model组件体系的一个基础,ScopeModel类型是可以转换为ModuleModel、ApplicationModel
//比如像ModuleServiceRepository、ModelEnvironment、BeanFactory等很多通用的组件都可以通过ScopeModel去获取
Environment environment = getScopeModel().getModelEnvironment();//获取Environment对象
List<Map<String, String>> configurationMaps = environment.getConfigurationMaps();
//Search props starts with PREFIX in order
//接下来要获取和拼接preferredPrefix
String preferredPrefix = null;
List<String> prefixes = getPrefixes();
for (String prefix : prefixes) {
if (ConfigurationUtils.hasSubProperties(configurationMaps, prefix)) {
preferredPrefix = prefix;
break;
}
}
if (preferredPrefix == null) {
preferredPrefix = prefixes.get(0);
}
...
//使用反射注入需要的方法
assignProperties(this, environment, subProperties, subPropsConfiguration);
//process extra refresh of subclass, e.g. refresh method configs
//调用AbstractInterfaceConfig的processExtraRefresh()方法
//该方法中preferredPrefix是关键,它的值可能是:dubbo.service.org.apache.dubbo.demo.DemoService
//其中dubbo.service代表dubbo服务名称的一个固定前缀,属于固定拼接的
//而中间的org.apache.dubbo.demo,则是从服务接口所在包名里截取出来的,并且最后会加上服务接口的接口名
//所以preferredPrefix会作为当前dubbo服务的全限定的名字
//而这段refresh的代码的作用,就是处理这个preferredPrefix以及其他相关的配置信息
processExtraRefresh(preferredPrefix, subPropsConfiguration);
postProcessRefresh();
refreshed.set(true);
}
protected void preProcessRefresh() {
// pre-process refresh
}
protected void processExtraRefresh(String preferredPrefix, InmemoryConfiguration subPropsConfiguration) {
// process extra refresh
}
protected void postProcessRefresh() {
// post-process refresh
checkDefault();
}
...
}
public abstract class AbstractInterfaceConfig extends AbstractMethodConfig {
private List<MethodConfig> methods;
...
//该方法会通过反射技术,对需要发布的服务的接口方法和参数封装成MethodConfig、ArgumentConfig
@Override
protected void processExtraRefresh(String preferredPrefix, InmemoryConfiguration subPropsConfiguration) {
if (StringUtils.hasText(interfaceName)) {
//通过反射技术获取需要发布的服务的接口
Class<?> interfaceClass;
interfaceClass = ClassUtils.forName(interfaceName);
...
//Auto create MethodConfig/ArgumentConfig according to config props
Map<String, String> configProperties = subPropsConfiguration.getProperties();
//获取需要发布的服务的接口的所有方法
Method[] methods;
methods = interfaceClass.getMethods();
//接下来对需要发布的服务的接口方法进行处理
//整理出MethodConfig对象及其对应的ArgumentConfig对象
//接口里的每个方法都要创建一个MethodConfig
//方法里的每一个参数都要创建一个ArgumentConfig
for (Method method : methods) {
//因为服务端每次处理客户端调用时,不可能都通过反射来获取method和args的情况
//所以在刚开始启动时就需要对接口进行解析,将所有的method和args整理到methods属性中
if (ConfigurationUtils.hasSubProperties(configProperties, method.getName())) {
MethodConfig methodConfig = getMethodByName(method.getName());
//Add method config if not found
if (methodConfig == null) {
//需要发布的的服务的每个方法,都创建一个MethodConfig对象
methodConfig = new MethodConfig();
methodConfig.setName(method.getName());
//将MethodConfig对象添加到methods属性中
this.addMethod(methodConfig);
}
//Add argument config
//dubbo.service.{interfaceName}.{methodName}.{arg-index}.xxx=xxx
java.lang.reflect.Parameter[] arguments = method.getParameters();
for (int i = 0; i < arguments.length; i++) {
if (getArgumentByIndex(methodConfig, i) == null && hasArgumentConfigProps(configProperties, methodConfig.getName(), i)) {
//方法里的每个args参数,都创建一个ArgumentConfig对象
ArgumentConfig argumentConfig = new ArgumentConfig();
argumentConfig.setIndex(i);
//将ArgumentConfig对象添加到MethodConfig对象中
methodConfig.addArgument(argumentConfig);
}
}
}
}
//refresh MethodConfigs,刷新刚才解析出来的MethodConfig对象
List<MethodConfig> methodConfigs = this.getMethods();
if (methodConfigs != null && methodConfigs.size() > 0) {
//whether ignore invalid method config
Object ignoreInvalidMethodConfigVal = getEnvironment().getConfiguration()
.getProperty(ConfigKeys.DUBBO_CONFIG_IGNORE_INVALID_METHOD_CONFIG, "false");
boolean ignoreInvalidMethodConfig = Boolean.parseBoolean(ignoreInvalidMethodConfigVal.toString());
Class<?> finalInterfaceClass = interfaceClass;
List<MethodConfig> validMethodConfigs = methodConfigs.stream().filter(methodConfig -> {
methodConfig.setParentPrefix(preferredPrefix);
//关联Model组件
methodConfig.setScopeModel(getScopeModel());
methodConfig.refresh();
//verify method config
return verifyMethodConfig(methodConfig, finalInterfaceClass, ignoreInvalidMethodConfig);
}).collect(Collectors.toList());
this.setMethods(validMethodConfigs);
}
}
}
public void addMethod(MethodConfig methodConfig) {
if (this.methods == null) {
this.methods = new ArrayList<>();
}
this.methods.add(methodConfig);
}
...
}
6.服务发布时执行的服务实例初始化操作
kotlin
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
@Override
public void export() {
...
synchronized (this) {
...
if (this.shouldExport()) {
//3.执行服务实例的初始化
//也就是会把Metadata元数据给准备好,后续可以进行元数据上报
this.init();
...
}
}
}
public void init() {
//通过SPI机制获取ServiceListener扩展点的所有实现类实例
//然后添加到ServiceConfig的serviceListeners字段里
if (this.initialized.compareAndSet(false, true)) {
//load ServiceListeners from extension
ExtensionLoader<ServiceListener> extensionLoader = this.getExtensionLoader(ServiceListener.class);
this.serviceListeners.addAll(extensionLoader.getSupportedExtensionInstances());
}
//初始化ServiceMetadata,也就是服务元数据
//这需要与前面设置的MetadataCenter元数据中心配合起来看
//ServiceMetadata作为服务实例的元数据,会对服务实例做一些描述,比如版本号、实现类等
initServiceMetadata(provider);
serviceMetadata.setServiceType(getInterfaceClass());
serviceMetadata.setTarget(getRef());
serviceMetadata.generateServiceKey();
}
...
}
7.服务发布时执行的服务实例发布操作
首先调用ServiceConfig的doExportUrls()方法发布服务,然后再调用其exported()方法进行服务发布后的处理,比如打印日志和回调监听器。
scala
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
@Override
public void export() {
...
//4.执行服务实例的发布
//进行debug时,可以通过控制台打印的日志去分析运行流程
//比如通过log日志可以发现服务发布的流程可能涉及:
//一.export Dubbo Service,发布dubbo服务实例
//二.register Dubbo Service,往zk进行注册
//三.启动NettyServer,监听端口和请求处理
//四.服务发现注册
//五.MetadataReport:服务实例上报
//六.关闭JVM时的逆向处理过程
//这里可以作为一个服务发布的直接入口
doExport();
}
protected synchronized void doExport() {
...
//发布服务
doExportUrls();
//服务发布完成后的处理,比如打印日志和回调监听器
exported();
}
...
}
8.执行服务实例发布操作时的主流程
首先通过ScopeModel组件体系获取服务数据存储组件,然后将要发布的服务注册到服务数据存储组件里,接着把相关信息封装成一个服务提供者,并将该服务提供者也注册到服务数据存储组件中,然后生成注册的URL,最后根据协议和生成的注册的URL来发布服务。
scala
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
@SuppressWarnings({"unchecked", "rawtypes"})
private void doExportUrls() {
//所谓的ScopeModel,真实的类型是ModuleModel
//下面这行代码会通过AbstractMethodConfig的getScopeModel()方法获取ScopeModel
//接着会通过ModuleModel的getServiceRepository()方法去获取ServiceRepository
//事实上,Dubbo会把它的各个组件都集中在ScopeModel(ModuleModel)里,而ScopeModel就类似于设计模式里的门面模式
//ScopeModel、ModuleModel、ApplicationModel、FrameworkModel等多个Model会组成一个Model组件体系
//1.通过ScopeModel组件体系获取服务数据存储组件ModuleServiceRepository
ModuleServiceRepository repository = getScopeModel().getServiceRepository();
//ServiceRepository是Dubbo服务的数据存储组件
//一个系统可以发布多个Dubbo服务
//每个Dubbo服务的核心就是一个接口和一个实现类
//2.把当前要发布的服务注册到Dubbo的服务数据存储组件中
ServiceDescriptor serviceDescriptor;
final boolean serverService = ref instanceof ServerService;
if (serverService) {
serviceDescriptor = ((ServerService) ref).getServiceDescriptor();
repository.registerService(serviceDescriptor);
} else {
serviceDescriptor = repository.registerService(getInterfaceClass());
}
//ProviderModel也就是服务提供者,由于这里是暴露服务出去的,所以属于Provider
//3.把所有相关的信息封装成一个服务提供者ProviderModel
providerModel = new ProviderModel(
serviceMetadata.getServiceKey(),
ref,//ref代表的是实际实现的类,通过泛型传入
serviceDescriptor,//表示服务实例相关的信息
getScopeModel(),
serviceMetadata,
interfaceClassLoader
);
providerModel.setConfig(this);
providerModel.setDestroyRunner(getDestroyRunner());
//3.将服务提供者ProviderModel注册到服务数据存储组件中
repository.registerProvider(providerModel);
//4.生成注册的URL:包含2181的端口号、注册到zk中
//service-discovery-registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103 //registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103
List<URL> registryURLs = ConfigValidationUtils.loadRegistries(this, true);
for (ProtocolConfig protocolConfig : protocols) {
String pathKey = URL.buildKey(
getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path),
group,
version
);
//stub service will use generated service name
if (!serverService) {
//In case user specified path, register service one more time to map it to path.
//将接口注册到服务数据存储组件中
repository.registerService(pathKey, interfaceClass);
}
//5.调用doExportUrlsFor1Protocol()方法,根据协议和注册的URL来发布服务
doExportUrlsFor1Protocol(protocolConfig, registryURLs);
}
providerModel.setServiceUrls(urls);
}
private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
Map<String, String> map = buildAttributes(protocolConfig);
//remove null key and null value
map.keySet().removeIf(key -> StringUtils.isEmpty(key) || StringUtils.isEmpty(map.get(key)));
//init serviceMetadata attachments
//将map数据放入serviceMetadata中,这与元数据相关
serviceMetadata.getAttachments().putAll(map);
//根据ProtocolConfig构建URL
URL url = buildUrl(protocolConfig, map);
//发布服务
exportUrl(url, registryURLs);
}
...
}
//ScopeModel、ModuleModel、ApplicationModel、FrameworkModel等多个Model会组成一个Model组件体系
public class ModuleModel extends ScopeModel {
public static final String NAME = "ModuleModel";
//ApplicationModel内部封装了其他很多组件,在这里是一个引用关系,通过构造方法传入进来
private final ApplicationModel applicationModel;
//包含了ServiceModule环境相关的数据,里面封装的都是各种各样的配置信息
private ModuleEnvironment moduleEnvironment;
//serviceRepository是一个服务仓储组件,存储了一些服务相关的数据
private ModuleServiceRepository serviceRepository;
//这是module配置管理器,用于存放一些服务相关的配置数据
private ModuleConfigManager moduleConfigManager;
//这是ModuleDeployer组件,用于管理其他的一些组件和模块的生命周期
private ModuleDeployer deployer;
...
}
public class ApplicationModel extends ScopeModel {
...
//包含了多个ModuleModel
private final List<ModuleModel> moduleModels = new CopyOnWriteArrayList<>();
private final List<ModuleModel> pubModuleModels = new CopyOnWriteArrayList<>();
//环境变量、配置信息
private Environment environment;
//服务配置相关的一些信息
private ConfigManager configManager;
//服务数据相关的一些存储
private ServiceRepository serviceRepository;
//属于application层级的一些组件的生命周期管理
private ApplicationDeployer deployer;
//父级组件
private final FrameworkModel frameworkModel;
//内部的一个ModuleModel组件
private ModuleModel internalModule;
//默认的一个ModuleModel组件
private volatile ModuleModel defaultModule;
//internal module index is 0, default module index is 1
private AtomicInteger moduleIndex = new AtomicInteger(0);
//是一个锁
private Object moduleLock = new Object();
...
}
public class FrameworkModel extends ScopeModel {
...
//它没有父层级了,所以只能通过static静态变量,类级别去引用自己的FrameworkModel集合
private static List<FrameworkModel> allInstances = new CopyOnWriteArrayList<>();
//包含了多个ApplicationModel
private List<ApplicationModel> applicationModels = new CopyOnWriteArrayList<>();
//通过Framework、Application、Module各个层级都可以获取到service相关的配置和数据
private FrameworkServiceRepository serviceRepository;
...
}
public class ModuleServiceRepository {
private final ModuleModel moduleModel;
//services,代表服务相关的数据,StubServiceDescriptor
private final ConcurrentMap<String, List<ServiceDescriptor>> services = new ConcurrentHashMap<>();
//consumers(key - group/interface:version, value - consumerModel list)
//代表服务的调用方(consumer即消费方/调用方)
private final ConcurrentMap<String, List<ConsumerModel>> consumers = new ConcurrentHashMap<>();
//providers,代表服务提供方
private final ConcurrentMap<String, ProviderModel> providers = new ConcurrentHashMap<>();
//FrameworkServiceRepository存储的也是一些服务相关的数据
private final FrameworkServiceRepository frameworkServiceRepository;
...
}
public class ModuleServiceRepository {
//services,代表服务相关的数据,StubServiceDescriptor
private final ConcurrentMap<String, List<ServiceDescriptor>> services = new ConcurrentHashMap<>();
...
public ServiceDescriptor registerService(ServiceDescriptor serviceDescriptor) {
return registerService(serviceDescriptor.getServiceInterfaceClass(), serviceDescriptor);
}
public ServiceDescriptor registerService(Class<?> interfaceClazz) {
ServiceDescriptor serviceDescriptor = new ReflectionServiceDescriptor(interfaceClazz);
return registerService(interfaceClazz, serviceDescriptor);
}
public ServiceDescriptor registerService(Class<?> interfaceClazz, ServiceDescriptor serviceDescriptor) {
List<ServiceDescriptor> serviceDescriptors = services.computeIfAbsent(interfaceClazz.getName(), k -> new CopyOnWriteArrayList<>());
synchronized (serviceDescriptors) {
Optional<ServiceDescriptor> previous = serviceDescriptors.stream()
.filter(s -> s.getServiceInterfaceClass().equals(interfaceClazz)).findFirst();
if (previous.isPresent()) {
return previous.get();
} else {
serviceDescriptors.add(serviceDescriptor);
return serviceDescriptor;
}
}
}
...
}
9.服务发布过程中ProxyFactory生成Invoker
typescript
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
private void doExportUrlsFor1Protocol(ProtocolConfig protocolConfig, List<URL> registryURLs) {
Map<String, String> map = buildAttributes(protocolConfig);
//remove null key and null value
map.keySet().removeIf(key -> StringUtils.isEmpty(key) || StringUtils.isEmpty(map.get(key)));
//init serviceMetadata attachments
//将map数据放入serviceMetadata中,这与元数据相关
serviceMetadata.getAttachments().putAll(map);
//根据ProtocolConfig构建URL
URL url = buildUrl(protocolConfig, map);
//发布服务
exportUrl(url, registryURLs);
}
private URL buildUrl(ProtocolConfig protocolConfig, Map<String, String> params) {
//获取协议名称
String name = protocolConfig.getName();
if (StringUtils.isEmpty(name)) {
//默认使用Dubbo协议
name = DUBBO;
}
//获取host值
String host = findConfiguredHosts(protocolConfig, provider, params);
//获取port值
Integer port = findConfiguredPort(protocolConfig, provider, this.getExtensionLoader(Protocol.class), name, params);
//根据上面获取的host、port以及前文获取的map集合组装URL
URL url = new ServiceConfigURL(name, null, null, host, port, getContextPath(protocolConfig).map(p -> p + "/" + path).orElse(path), params);
//通过Configurator覆盖或添加新的参数
if (this.getExtensionLoader(ConfiguratorFactory.class).hasExtension(url.getProtocol())) {
url = this.getExtensionLoader(ConfiguratorFactory.class).getExtension(url.getProtocol()).getConfigurator(url).configure(url);
}
url = url.setScopeModel(getScopeModel());
url = url.setServiceModel(providerModel);
return url;
}
private void exportUrl(URL url, List<URL> registryURLs) {
//从URL中获取scope参数,其中可选值有none、remote、local三个,分别代表不发布、发布到本地以及发布到远端
String scope = url.getParameter(SCOPE_KEY);
//scope不为none,才进行发布
if (!SCOPE_NONE.equalsIgnoreCase(scope)) {
//scope为local,只发布到本地
if (!SCOPE_REMOTE.equalsIgnoreCase(scope)) {
exportLocal(url);
}
//export to remote if the config is not local (export to local only when config is local)
//scope为remote,发布到远端的注册中心
if (!SCOPE_LOCAL.equalsIgnoreCase(scope)) {
//进行远程发布
url = exportRemote(url, registryURLs);
if (!isGeneric(generic) && !getScopeModel().isInternal()) {
//通过MetadataUtils推送这个服务实例的元数据到元数据中心
//元数据中心是一个动态的配置中心,可以从里面获取参数,也可以添加监听器监听配置项的变更
MetadataUtils.publishServiceDefinition(url, providerModel.getServiceModel(), getApplicationModel());
}
}
}
this.urls.add(url);
}
private void exportLocal(URL url) {
//创建新URL
URL local = URLBuilder.from(url)
.setProtocol(LOCAL_PROTOCOL)
.setHost(LOCALHOST_VALUE)
.setPort(0)
.build();
local = local.setScopeModel(getScopeModel()).setServiceModel(providerModel);
//本地发布
doExportUrl(local, false);
//exportLocal,指的是发布到本地
//具体就是在jvm内部完成了组件之间的一些交互关系和发布
logger.info("Export dubbo service " + interfaceClass.getName() + " to local registry url : " + local);
}
private URL exportRemote(URL url, List<URL> registryURLs) {
//如果当前配置了至少一个注册中心
if (CollectionUtils.isNotEmpty(registryURLs)) {
//URL里有很多的信息,比如协议、各种参数等
//URL可以在后续代码运行过程中提供配置和信息
//接下来会向每个注册中心发布服务
for (URL registryURL : registryURLs) {
//registryURL.getProtocol()会获取协议
if (SERVICE_REGISTRY_PROTOCOL.equals(registryURL.getProtocol())) {
url = url.addParameterIfAbsent(SERVICE_NAME_MAPPING_KEY, "true");
}
//injvm协议只在exportLocal()中有用,不会将服务发布到注册中心,所以这里忽略injvm协议
if (LOCAL_PROTOCOL.equalsIgnoreCase(url.getProtocol())) {
continue;
}
//设置服务URL的dynamic参数
url = url.addParameterIfAbsent(DYNAMIC_KEY, registryURL.getParameter(DYNAMIC_KEY));
//创建monitorUrl,并作为monitor参数添加到服务URL中
URL monitorUrl = ConfigValidationUtils.loadMonitor(this, registryURL);
if (monitorUrl != null) {
url = url.putAttribute(MONITOR_KEY, monitorUrl);
}
//For providers, this is used to enable custom proxy to generate invoker
//设置服务URL的proxy参数,即生成动态代理方式(jdk或是javassist),作为参数添加到RegistryURL中
String proxy = url.getParameter(PROXY_KEY);
if (StringUtils.isNotEmpty(proxy)) {
registryURL = registryURL.addParameter(PROXY_KEY, proxy);
}
doExportUrl(registryURL.putAttribute(EXPORT_KEY, url), true);
}
} else {
//不存在注册中心,仅发布服务,不会将服务信息发布到注册中心
doExportUrl(url, true);
}
return url;
}
private void doExportUrl(URL url, boolean withMetaData) {
//动态代理技术有很多种,比如cglib,jdk
//而动态代理就是:面向一个接口,动态生成该接口的一个实现类,然后根据这个实现类再动态生成对应的对象
//这个对象就是动态代理的对象,所以该对象会代理自己背后的一个实现类
//当这个对象被调用时,背后的实现类也会被调用
//ProxyFactory,Proxy就是动态代理
//下面传入的ref指的是实现类
//下面传入的interfaceClass指的是接口
//下面传入的url就是服务实例对外暴露出去的一些核心信息
//proxyFactory.getInvoker()获取到的是Invoker调用组件
//当Dubbo的NettyServer监听到网络连接进行请求处理时,需要有一个调用组件去根据请求进行调用
//Invoker调用组件可以认为是ProxyFactory基于DemoService接口生成的动态代理
//当需要根据请求调用接口时,底层就会回调自己写的实现类DemoServiceImpl
//proxyFactory.getInvoker()会封装一个AbstractProxyInvoker,对本地实现类进行代理
//默认情况下,会通过Javassist技术生成Wrapper,该Wrapper会将本地实现类包装进去
//调用AbstractProxyInvoker的invoke方法时,最终就会基于Javassist动态生成的Wrapper进行调用
//下面这一行代码是为服务实现类的对象创建相应的Invoker
//其中传入的服务url会作为export参数添加到RegistryURL中
//这里的proxyFactory就是ProxyFactory接口的适配器,会通过SPI机制进行初始化
//比如下面就会调用JavassistProxyFactory.getInvoker()方法
//proxyFactory.getInvoker()会获取到Invoker调用组件(生成Invoker动态代理)
//所以下面这一行代码会为本地实现类的对象创建相应的Invoker(封装着AbstractProxyInvoker)
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);
if (withMetaData) {
//DelegateProviderMetaDataInvoker是个装饰类
//它会将当前ServiceConfig和Invoker关联起来
invoker = new DelegateProviderMetaDataInvoker(invoker, this);
}
//调用Protocol的实现进行发布,protocolSPI是Protocol接口的适配器
//进行本地发布时,使用的是InjvmProtocol + InjvmExporter
//进行远程发布时,使用的是RegistryProtocol,它会对DubboProtocol进行包装和装饰
//RegistryProtocol会先执行来处理服务注册的一些事情
//DubboProtocol会后执行来启动NettyServer网络服务器
Exporter<?> exporter = protocolSPI.export(invoker);
exporters.add(exporter);
}
...
}
public class JavassistProxyFactory extends AbstractProxyFactory {
...
@Override
public <T> Invoker<T> getInvoker(T proxy, Class<T> type, URL url) throws RpcException {
//下面会通过Wrapper创建一个包装类对象
//该对象是动态构建出来的,它属于Wrapper的一个子类,里面会拼接一个关键的方法invokeMethod(),拼接代码由javassist动态生成
final Wrapper wrapper = Wrapper.getWrapper(proxy.getClass().getName().indexOf('$') < 0 ? proxy.getClass() : type);
//下面会创建一个实现了AbstractProxyInvoker的匿名内部类
//其doInvoker()方法会直接委托给Wrapper对象的invokeMethod()方法
return new AbstractProxyInvoker<T>(proxy, type, url) {
@Override
protected Object doInvoke(T proxy, String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Throwable {
//当AbstractProxyInvoker.invoke()方法被调用时,便会执行到这里
//这里会通过类似于JDK反射的技术,调用本地实现类如DemoServiceImpl.sayHello()
//这个wrapper对象是由javassist技术动态生成的,已经对本地实现类进行包装
//这个动态生成的wrapper对象会通过javassist技术自己特有的方法
//在invokerMethod()方法被调用时执行本地实现类的目标方法
return wrapper.invokeMethod(proxy, methodName, parameterTypes, arguments);
}
};
}
...
}
public abstract class AbstractProxyInvoker<T> implements Invoker<T> {
...
//当Netty Server接受到了请求后,经过解析就会知道是要调用什么
//然后会把解析出来的数据放入Invocation中,通过AbstractProxyInvoker的invoke()方法来进行调用
@Override
public Result invoke(Invocation invocation) throws RpcException {
...
//执行doInvoke()方法,调用业务实现
Object value = doInvoke(proxy, invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments());
...
//将value值封装成CompletableFuture对象
CompletableFuture<Object> future = wrapWithFuture(value, invocation);
//再次转换,转换为CompletableFuture<AppResponse>类型
CompletableFuture<AppResponse> appResponseFuture = future.handle((obj, t) -> {
AppResponse result = new AppResponse(invocation);
...
//将CompletableFuture封装成AsyncRpcResult返回
return new AsyncRpcResult(appResponseFuture, invocation);
}
protected abstract Object doInvoke(T proxy, String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Throwable;
...
}
10.服务发布过程中Protocol组件发布Invoker
(1)Protocol协议接口
(2)Protocol组件发布Invoker
(1)Protocol协议接口
java
@SPI(value = "dubbo", scope = ExtensionScope.FRAMEWORK)
public interface Protocol {
//默认端口
int getDefaultPort();
//Protocol接收到一个请求之后,必须要记录请求的源地址
//对同一个服务实例(url)发布一次和发布多次,是没有任何区别的
//export()方法会将一个Invoker发布出去
//export()方法的实现需要是幂等的,即同一个服务暴露多次和暴露一次的效果是相同的
@Adaptive
<T> Exporter<T> export(Invoker<T> invoker) throws RpcException;
//Protocol必须根据一个url和接口类型,获取到对应的Invoker
//refer()方法会引用一个Invoker
//refer()方法会根据参数返回一个Invoker对象,Consumer端可以通过这个Invoker请求到Provider端的服务
@Adaptive
<T> Invoker<T> refer(Class<T> type, URL url) throws RpcException;
//销毁export()方法以及refer()方法使用到的Invoker对象,释放当前Protocol对象底层占用的资源
void destroy();
//返回当前Protocol底层的全部ProtocolServer
default List<ProtocolServer> getServers() {
return Collections.emptyList();
}
}
(2)Protocol组件发布Invoker
本地发布时使用InjvmProtocol + InjvmExporter,远程发布时使用RegistryProtocol + DestroyableExporter。
RegistryProtocol的export()方法被远程发布调用的时候,会调用到DubboProtocol的export()方法,并最终调用到HeaderExchanger的bind()方法执行NettyTransporter的bind()方法构建Netty服务器。
scala
public class ServiceConfig<T> extends ServiceConfigBase<T> {
...
private void doExportUrl(URL url, boolean withMetaData) {
//动态代理技术有很多种,比如cglib,jdk
//而动态代理就是:面向一个接口,动态生成该接口的一个实现类,然后根据这个实现类再动态生成对应的对象
//这个对象就是动态代理的对象,所以该对象会代理自己背后的一个实现类
//当这个对象被调用时,背后的实现类也会被调用
//ProxyFactory,Proxy就是动态代理
//下面传入的ref指的是实现类
//下面传入的interfaceClass指的是接口
//下面传入的url就是服务实例对外暴露出去的一些核心信息
//proxyFactory.getInvoker()获取到的是Invoker调用组件
//当Dubbo的NettyServer监听到网络连接进行请求处理时,需要有一个调用组件去根据请求进行调用
//Invoker调用组件可以认为是ProxyFactory基于DemoService接口生成的动态代理
//当需要根据请求调用接口时,底层就会回调自己写的实现类DemoServiceImpl
//proxyFactory.getInvoker()会封装一个AbstractProxyInvoker,对本地实现类进行代理
//默认情况下,会通过Javassist技术生成Wrapper,该Wrapper会将本地实现类包装进去
//调用AbstractProxyInvoker的invoke方法时,最终就会基于Javassist动态生成的Wrapper进行调用
//下面这一行代码是为服务实现类的对象创建相应的Invoker
//其中传入的服务url会作为export参数添加到RegistryURL中
//这里的proxyFactory就是ProxyFactory接口的适配器,会通过SPI机制进行初始化
//比如下面就会调用JavassistProxyFactory.getInvoker()方法
//proxyFactory.getInvoker()会获取到Invoker调用组件(生成Invoker动态代理)
//所以下面这一行代码会为本地实现类的对象创建相应的Invoker(封装着AbstractProxyInvoker)
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);
if (withMetaData) {
//DelegateProviderMetaDataInvoker是个装饰类
//它会将当前ServiceConfig和Invoker关联起来
invoker = new DelegateProviderMetaDataInvoker(invoker, this);
}
//调用Protocol的实现进行发布,protocolSPI是Protocol接口的适配器
//进行本地发布时,使用的是InjvmProtocol + InjvmExporter
//进行远程发布时,使用的是RegistryProtocol,它会对DubboProtocol进行包装和装饰
//RegistryProtocol会先执行来处理服务注册的一些事情
//DubboProtocol会后执行来启动NettyServer网络服务器
Exporter<?> exporter = protocolSPI.export(invoker);
exporters.add(exporter);
}
...
}
scala
//-> Protocol$Adaptive.export()
//-> ProtocolSerializationWrapper.export()
//-> ProtocolFilterWrapper.export()
//-> ProtocolListenerWrapper.export()
//-> InjvmProtocol.export()
public class InjvmProtocol extends AbstractProtocol implements Protocol {
...
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
return new InjvmExporter<T>(invoker, invoker.getUrl().getServiceKey(), exporterMap);
}
...
}
public class InjvmExporter<T> extends AbstractExporter<T> {
private final String key;
//这就是在JVM里存放了
private final Map<String, Exporter<?>> exporterMap;
InjvmExporter(Invoker<T> invoker, String key, Map<String, Exporter<?>> exporterMap) {
super(invoker);
this.key = key;
this.exporterMap = exporterMap;
exporterMap.put(key, this);
}
...
}
scss
//-> Protocol$Adaptive.export()
//-> ProtocolSerializationWrapper.export()
//-> ProtocolFilterWrapper.export()
//-> ProtocolListenerWrapper.export()
//-> RegistryProtocol.export()
//-> Protocol$Adaptive.export()
//-> ProtocolSerializationWrapper.export()
//-> ProtocolFilterWrapper.export()
//-> ProtocolListenerWrapper.export()
//-> DubboProtocol.export()
//-> DubboProtocol.openServer()
//-> DubboProtocol.createServer()
//-> Exchangers.bind()
//-> HeaderExchanger.bind()
//-> Transporters.bind()
//-> NettyTransporter.bind()
//-> NettyServer
@Activate
public class ProtocolSerializationWrapper implements Protocol {
private Protocol protocol;
public ProtocolSerializationWrapper(Protocol protocol) {
this.protocol = protocol;
}
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
getFrameworkModel(invoker.getUrl().getScopeModel()).getServiceRepository().registerProviderUrl(invoker.getUrl());
//下面会调用ProtocolFilterWrapper.export()方法
return protocol.export(invoker);
}
...
}
@Activate(order = 100)
public class ProtocolFilterWrapper implements Protocol {
private final Protocol protocol;
public ProtocolFilterWrapper(Protocol protocol) {
if (protocol == null) {
throw new IllegalArgumentException("protocol == null");
}
this.protocol = protocol;
}
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
if (UrlUtils.isRegistry(invoker.getUrl())) {
return protocol.export(invoker);
}
FilterChainBuilder builder = getFilterChainBuilder(invoker.getUrl());
//下面会调用ProtocolListenerWrapper.export()方法
return protocol.export(builder.buildInvokerChain(invoker, SERVICE_FILTER_KEY, CommonConstants.PROVIDER));
}
private <T> FilterChainBuilder getFilterChainBuilder(URL url) {
return ScopeModelUtil.getExtensionLoader(FilterChainBuilder.class, url.getScopeModel()).getDefaultExtension();
}
...
}
@Activate
public class DefaultFilterChainBuilder implements FilterChainBuilder {
//build consumer/provider filter chain
@Override
public <T> Invoker<T> buildInvokerChain(final Invoker<T> originalInvoker, String key, String group) {
Invoker<T> last = originalInvoker;
URL url = originalInvoker.getUrl();
List<ModuleModel> moduleModels = getModuleModelsFromUrl(url);
List<Filter> filters;
//通过SPI机制来获取Filter
if (moduleModels != null && moduleModels.size() == 1) {
filters = ScopeModelUtil.getExtensionLoader(Filter.class, moduleModels.get(0)).getActivateExtension(url, key, group);
} else if (moduleModels != null && moduleModels.size() > 1) {
filters = new ArrayList<>();
List<ExtensionDirector> directors = new ArrayList<>();
for (ModuleModel moduleModel : moduleModels) {
List<Filter> tempFilters = ScopeModelUtil.getExtensionLoader(Filter.class, moduleModel).getActivateExtension(url, key, group);
filters.addAll(tempFilters);
directors.add(moduleModel.getExtensionDirector());
}
filters = sortingAndDeduplication(filters, directors);
} else {
filters = ScopeModelUtil.getExtensionLoader(Filter.class, null).getActivateExtension(url, key, group);
}
//构建Filter链条
if (!CollectionUtils.isEmpty(filters)) {
for (int i = filters.size() - 1; i >= 0; i--) {
final Filter filter = filters.get(i);
final Invoker<T> next = last;
last = new CopyOfFilterChainNode<>(originalInvoker, next, filter);
}
return new CallbackRegistrationInvoker<>(last, filters);
}
return last;
}
...
}
@Activate(order = 200)
public class ProtocolListenerWrapper implements Protocol {
private final Protocol protocol;
public ProtocolListenerWrapper(Protocol protocol) {
if (protocol == null) {
throw new IllegalArgumentException("protocol == null");
}
this.protocol = protocol;
}
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
if (UrlUtils.isRegistry(invoker.getUrl())) {
return protocol.export(invoker);
}
//下面会调用RegistryProtocol.export()
return new ListenerExporterWrapper<T>(protocol.export(invoker),
Collections.unmodifiableList(ScopeModelUtil.getExtensionLoader(ExporterListener.class, invoker.getUrl().getScopeModel())
.getActivateExtension(invoker.getUrl(), EXPORTER_LISTENER_KEY)));
}
...
}
public class RegistryProtocol implements Protocol, ScopeModelAware {
...
@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
...
//export invoker
//下面进行导出服务,底层会通过会执行DubboProtocol.export()方法,启动对应的Server
//也就是会涉及到对另外一个protocol组件的调用,远程发布服务时其实就是执行DubboProtocol的export方法
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
...
}
private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker, URL providerUrl) {
String key = getCacheKey(originInvoker);
return (ExporterChangeableWrapper<T>) bounds.computeIfAbsent(key, s -> {
Invoker<?> invokerDelegate = new InvokerDelegate<>(originInvoker, providerUrl);
//下面会调用DubboProtocol的export()方法
return new ExporterChangeableWrapper<>((Exporter<T>) protocol.export(invokerDelegate), originInvoker);
});
}
...
}
public class DubboProtocol extends AbstractProtocol {
...
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
checkDestroyed();
URL url = invoker.getUrl();
//export service.
//创建ServiceKey
String key = serviceKey(url);
//exporter组件,代表了指定的invoker被发布出去
//下面代码会将上层传入的Invoker对象封装成DubboExporter对象,然后记录到exporterMap集合中
DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);
...
//启动ProtocolServer,这个就是打开对外的网络服务器,可以对外提供网络请求处理
openServer(url);
//序列化的优化处理
optimizeSerialization(url);
return exporter;
}
private void openServer(URL url) {
checkDestroyed();
//find server.
//获取host:port这个地址
String key = url.getAddress();
//client can export a service which only for server to invoke
boolean isServer = url.getParameter(IS_SERVER_KEY, true);
//只有Server端才能启动Server对象
if (isServer) {
ProtocolServer server = serverMap.get(key);
//无ProtocolServer监听该地址
if (server == null) {
//DoubleCheck,防止并发问题
synchronized (this) {
server = serverMap.get(key);
if (server == null) {
//调用createServer()方法创建ProtocolServer对象
serverMap.put(key, createServer(url));
return;
}
}
}
//server supports reset, use together with override
server.reset(url);
}
}
private ProtocolServer createServer(URL url) {
...
ExchangeServer server;
//通过Exchangers门面类,创建ExchangeServer对象
server = Exchangers.bind(url, requestHandler);
...
//将ExchangeServer封装成DubboProtocolServer返回
DubboProtocolServer protocolServer = new DubboProtocolServer(server);
loadServerProperties(protocolServer);
return protocolServer;
}
...
}
public class DubboExporter<T> extends AbstractExporter<T> {
private final String key;
private final Map<String, Exporter<?>> exporterMap;
public DubboExporter(Invoker<T> invoker, String key, Map<String, Exporter<?>> exporterMap) {
super(invoker);
this.key = key;
this.exporterMap = exporterMap;
exporterMap.put(key, this);
}
...
}
public class Exchangers {
...
public static ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");
//先获取到一个Exchanger组件,再用这个Exchanger组件去进行bind,拿到对应的ExchangeServer
//getExchanger()会通过SPI机制,获取到HeaderExchanger,然后将DubboProtocol的requestHandler传入bind()方法中
return getExchanger(url).bind(url, handler);
}
public static Exchanger getExchanger(URL url) {
String type = url.getParameter(Constants.EXCHANGER_KEY, Constants.DEFAULT_EXCHANGER);
//根据SPI机制,通过model组件体系去拿到对应的SPI扩展实现类实例
return url.getOrDefaultFrameworkModel().getExtensionLoader(Exchanger.class).getExtension(type);
}
...
}
public class HeaderExchanger implements Exchanger {
...
@Override
public ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
//Exchanger这一层的代码可以理解为是位于上层的代码,它会把一些RpcInvocation调用转为请求/响应的模型,以及进行同步转异步的处理
//从Exchanger这层开始,便进入网络模型的范围,引入了请求的概念,并最终会通过底层的网络框架把请求发送出去
//因此需要获取到网络框架底层的Server和Client,并将它们封装到Exchanger组件如HeaderExchangeServer/HeaderExchangeClient中
//为什么需要不同的Transporter?
//在Exchanger这一层里其实是可以使用不同的网络技术的,比如Netty、Mina这些网络通信框架
//由于Netty、Mina这些不同的框架,它们的用法和API都是不同的,所以在Exchanger这一层,不能把Netty、Mina的API直接提供过来
//为了把这些不同的网络框架技术进行统一的封装,需要做一层Transporter,由Transporter来实现抽象统一的底层网络框架的使用标准
//所以Exchanger这一层是基于Transporter这一层提供的标准模型来实现请求/响应处理
//下面的Transporters.bind()会返回一个NettyServer
return new HeaderExchangeServer(Transporters.bind(url, new DecodeHandler(new HeaderExchangeHandler(handler))));
}
...
}
public class Transporters {
...
public static RemotingServer bind(URL url, ChannelHandler... handlers) throws RemotingException {
ChannelHandler handler;
if (handlers.length == 1) {
handler = handlers[0];
} else {
handler = new ChannelHandlerDispatcher(handlers);
}
return getTransporter(url).bind(url, handler);
}
public static Transporter getTransporter(URL url) {
//下面使用了getAdaptiveExtension()的自适应机制,针对接口动态生成代码然后创建代理类
//代理类的方法,会根据url的参数动态提取对应的实现类的name名称,以及获取真正的需要使用的实现类
//有了真正的实现类后,就可以去调用实现类的extension实例的方法了
//比如下面会获取到一个NettyTransporter实例
return url.getOrDefaultFrameworkModel().getExtensionLoader(Transporter.class).getAdaptiveExtension();
}
...
}
//不同的框架可以有不同的Transporter
//每个框架对应的Transporter可以创建自己的Server和Client
public class NettyTransporter implements Transporter {
public static final String NAME = "netty";
@Override
public RemotingServer bind(URL url, ChannelHandler handler) throws RemotingException {
return new NettyServer(url, handler);
}
@Override
public Client connect(URL url, ChannelHandler handler) throws RemotingException {
//传入的handler装饰了DubboProtocol的requestHandler,返回一个NettyClient
return new NettyClient(url, handler);
}
}
11.服务发布过程中NettyServer的构造流程
scss
public abstract class AbstractServer extends AbstractEndpoint implements RemotingServer {
...
//业务线程池
private Set<ExecutorService> executors = new ConcurrentHashSet<>();
private InetSocketAddress localAddress;
private InetSocketAddress bindAddress;
private int accepts;
private ExecutorRepository executorRepository;
public AbstractServer(URL url, ChannelHandler handler) throws RemotingException {
//调用父类的构造方法
super(url, handler);
//通过使用SPI机制,从applicationModel组件中根据扩展接口ExecutorRepository去获取ExtensionLoader,然后拿到其默认实现类
this.executorRepository = url.getOrDefaultApplicationModel().getExtensionLoader(ExecutorRepository.class).getDefaultExtension();
//根据传入的URL初始化localAddress和bindAddress
this.localAddress = getUrl().toInetSocketAddress();
String bindIp = getUrl().getParameter(Constants.BIND_IP_KEY, getUrl().getHost());
int bindPort = getUrl().getParameter(Constants.BIND_PORT_KEY, getUrl().getPort());
if (url.getParameter(ANYHOST_KEY, false) || NetUtils.isInvalidLocalHost(bindIp)) {
bindIp = ANYHOST_VALUE;
}
this.bindAddress = new InetSocketAddress(bindIp, bindPort);
//初始化accepts等字段
this.accepts = url.getParameter(ACCEPTS_KEY, DEFAULT_ACCEPTS);
//调用doOpen()这个抽象方法,启动该Server
doOpen();
//获取该Server关联的线程池,通过DefaultExecutorRepository创建一个FixedThreadPool线程池出来
this.executors.add(executorRepository.createExecutorIfAbsent(url));
}
protected abstract void doOpen() throws Throwable;
...
}
public class NettyServer extends AbstractServer {
...
private Map<String, Channel> channels;
private ServerBootstrap bootstrap;
private io.netty.channel.Channel channel;
private EventLoopGroup bossGroup;
private EventLoopGroup workerGroup;
private final int serverShutdownTimeoutMills;
//NettyServer在构建的过程中,会构建和打开真正的网络服务器
//这里是基于netty4技术去实现了网络服务器构建和打开的
//一旦打开后,Netty Server就开始监听指定的端口号
//当发现有请求过来就可以去进行处理,也就是通过ProxyInvoker去调用本地实现类的目标方法
//入参handler其实就是DubboProtocol中的requestHandler
public NettyServer(URL url, ChannelHandler handler) throws RemotingException {
//you can customize name and type of client thread pool by THREAD_NAME_KEY and THREAD_POOL_KEY in CommonConstants.
//the handler will be wrapped: MultiMessageHandler->HeartbeatHandler->handler
super(ExecutorUtil.setThreadName(url, SERVER_THREAD_POOL_NAME), ChannelHandlers.wrap(handler, url));
//read config before destroy
serverShutdownTimeoutMills = ConfigurationUtils.getServerShutdownTimeout(getUrl().getOrDefaultModuleModel());
}
//Init and start netty server
@Override
protected void doOpen() throws Throwable {
//创建ServerBootstrap
bootstrap = new ServerBootstrap();
//EventLoop,也可以理解为网络服务器,它会监听一个本地的端口号
//外部系统针对本地服务器端口号发起连接、通信、网络事件时,监听的端口号就会不停的产生网络事件
//EventLoop网络服务器,还会不停轮询监听到的网络事件
//boss的意思是负责监听端口号是否有外部系统的连接请求,它是一个EventLoopGroup线程池
//如果发现了网络事件,就需要进行请求处理,可以通过workerGroup里的多个线程进行并发处理
//创建boss EventLoopGroup,线程数是1
bossGroup = createBossGroup();
//创建worker EventLoopGroup,线程数是CPU核数+1,但最多不会超过32个线程
workerGroup = createWorkerGroup();
//创建NettyServerHandler
//它是一个Netty中的ChannelHandler实现,不是Dubbo Remoting层的ChannelHandler接口的实现
final NettyServerHandler nettyServerHandler = createNettyServerHandler();
//获取当前NettyServer创建的所有Channel
//channels集合中的Channel不是Netty中的Channel对象,而是Dubbo Remoting层的Channel对象
channels = nettyServerHandler.getChannels();
//初始化ServerBootstrap,指定boss和worker EventLoopGroup
initServerBootstrap(nettyServerHandler);
//绑定指定的地址和端口
ChannelFuture channelFuture = bootstrap.bind(getBindAddress());
//等待bind操作完成
channelFuture.syncUninterruptibly();
channel = channelFuture.channel();
}
protected EventLoopGroup createBossGroup() {
return NettyEventLoopFactory.eventLoopGroup(1, EVENT_LOOP_BOSS_POOL_NAME);
}
protected EventLoopGroup createWorkerGroup() {
return NettyEventLoopFactory.eventLoopGroup(getUrl().getPositiveParameter(IO_THREADS_KEY, Constants.DEFAULT_IO_THREADS), EVENT_LOOP_WORKER_POOL_NAME);
}
protected NettyServerHandler createNettyServerHandler() {
return new NettyServerHandler(getUrl(), this);
}
protected void initServerBootstrap(NettyServerHandler nettyServerHandler) {
boolean keepalive = getUrl().getParameter(KEEP_ALIVE_KEY, Boolean.FALSE);
bootstrap.group(bossGroup, workerGroup)
.channel(NettyEventLoopFactory.serverSocketChannelClass())
.option(ChannelOption.SO_REUSEADDR, Boolean.TRUE)
.childOption(ChannelOption.TCP_NODELAY, Boolean.TRUE)
.childOption(ChannelOption.SO_KEEPALIVE, keepalive)
.childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//连接空闲超时时间
int idleTimeout = UrlUtils.getIdleTimeout(getUrl());
//NettyCodecAdapter中会创建Decoder和Encoder
NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyServer.this);
if (getUrl().getParameter(SSL_ENABLED_KEY, false)) {
ch.pipeline().addLast("negotiation", new SslServerTlsHandler(getUrl()));
}
ch.pipeline()
//注册Decoder和Encoder
.addLast("decoder", adapter.getDecoder())
.addLast("encoder", adapter.getEncoder())
//注册IdleStateHandler
.addLast("server-idle-handler", new IdleStateHandler(0, 0, idleTimeout, MILLISECONDS))
//注册NettyServerHandler
.addLast("handler", nettyServerHandler);
}
});
}
...
}
12.服务发布过程中RegistryProtocol的服务注册
(1)首先注册service-discovery-registry的URL
(2)然后注册registry的URL
服务发布过程中需要进行注册的URL有两个:
ini
service-discovery-registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103
registry://127.0.0.1:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&pid=989®istry=zookeeper×tamp=1724302222103
(1)首先注册service-discovery-registry的URL
此时,在RegistryProtocol.export()方法中,进行服务注册时使用的Registry其实是一个ListenerRegistryWrapper装饰器,装饰着使用了ZookeeperServiceDiscovery的ServiceDiscoveryRegistry。
ZookeeperServiceDiscovery.doRegister()处理的URL注册其实就是在本地进行注册。
bash
//-> RegistryProtocol.export()
//-> RegistryProtocol.getRegistry()
//-> RegistryFactory$Adaptive.getRegistry()
//-> RegistryFactoryWrapper.getRegistry()
//-> ServiceDiscoveryRegistryFactory.getRegistry()
//-> ServiceDiscoveryRegistryFactory.createRegistry()
//-> new ServiceDiscoveryRegistry()
//-> ServiceDiscoveryRegistry.createServiceDiscovery()
//=> ListenerRegistryWrapper、ServiceDiscoveryRegistry、ZookeeperServiceDiscovery
//-> RegistryProtocol.register()
//-> ListenerRegistryWrapper.register()
//-> ServiceDiscoveryRegistry.register()
//-> AbstractServiceDiscovery.register()
//-> ZookeeperServiceDiscovery.doRegister()
java
public class RegistryProtocol implements Protocol, ScopeModelAware {
...
@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
//将"registry://"协议(Remote URL)转换成"zookeeper://"协议(Registry URL)
URL registryUrl = getRegistryUrl(originInvoker);
//url to export locally
//获取export参数,其中存储了一个"dubbo://"协议的Provider URL
URL providerUrl = getProviderUrl(originInvoker);
//Subscribe the override data
//FIXME When the provider subscribes, it will affect the scene : a certain JVM exposes the service and call the same service.
//Because the subscribed is cached key with the name of the service, it causes the subscription information to cover.
final URL overrideSubscribeUrl = getSubscribedOverrideUrl(providerUrl);
final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
Map<URL, NotifyListener> overrideListeners = getProviderConfigurationListener(providerUrl).getOverrideListeners();
overrideListeners.put(registryUrl, overrideSubscribeListener);
providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);
//1.export invoker
//下面进行导出服务,底层会通过会执行DubboProtocol.export()方法,启动对应的Server
//也就是会涉及到对另外一个Protocol组件的调用,远程发布服务时其实就是执行DubboProtocol的export方法
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
//2.url to registry 完成服务注册的事情
//下面会根据RegistryURL获取对应的注册中心Registry对象,其中会依赖RegistryFactory
//远程发布时,下面的registry其实是一个ListenerRegistryWrapper装饰器,装饰着使用了ZookeeperServiceDiscovery的ServiceDiscoveryRegistry
//在基于注册中心的url地址去构建对应的注册中心组件时,默认是基于zk的
//而构建一个基于zk的注册中心组件,同时跟zk完成连接的建立,则由curator5框架来实现
final Registry registry = getRegistry(registryUrl);
//获取将要发布到注册中心上的Provider URL,其中会删除一些多余的参数信息
final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);
//decide if we need to delay publish (provider itself and registry should both need to register)
//根据register参数值决定是否注册服务
boolean register = providerUrl.getParameter(REGISTER_KEY, true) && registryUrl.getParameter(REGISTER_KEY, true);
if (register) {
//调用Registry.register()方法将registeredProviderUrl发布到注册中心
register(registry, registeredProviderUrl);
}
//register stated url on provider model
//将Provider相关信息记录到的ProviderModel中
registerStatedUrl(registryUrl, registeredProviderUrl, register);
exporter.setRegisterUrl(registeredProviderUrl);
exporter.setSubscribeUrl(overrideSubscribeUrl);
if (!registry.isServiceDiscovery()) {
//Deprecated! Subscribe to override rules in 2.6.x or before.
//向注册中心进行订阅override数据,主要是监听该服务的configurators节点
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
}
//触发RegistryProtocolListener监听器
notifyExport(exporter);
//Ensure that a new exporter instance is returned every time export
return new DestroyableExporter<>(exporter);
}
protected Registry getRegistry(final URL registryUrl) {
//通过SPI自适应机制,去拿到对应的extension实例
//这里的registryFactory为RegistryFactory$Adaptive
RegistryFactory registryFactory = ScopeModelUtil.getExtensionLoader(RegistryFactory.class, registryUrl.getScopeModel()).getAdaptiveExtension();
//调用RegistryFactory$Adaptive的getRegistry()方法
return registryFactory.getRegistry(registryUrl);
}
private void register(Registry registry, URL registeredProviderUrl) {
//下面会调用ListenerRegistryWrapper.register()方法
registry.register(registeredProviderUrl);
}
private void registerStatedUrl(URL registryUrl, URL registeredProviderUrl, boolean registered) {
ProviderModel model = (ProviderModel) registeredProviderUrl.getServiceModel();
model.addStatedUrl(
new ProviderModel.RegisterStatedURL(
registeredProviderUrl,
registryUrl,
registered
)
);
}
...
}
public class RegistryFactory$Adaptive implements org.apache.dubbo.registry.RegistryFactory {
public org.apache.dubbo.registry.Registry getRegistry(org.apache.dubbo.common.URL arg0) {
if (arg0 == null) throw new IllegalArgumentException("url == null");
org.apache.dubbo.common.URL url = arg0;
String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() );
//注册service-discovery-registry的URL时,extName=service-discovery-registry
if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.registry.RegistryFactory) name from url (" + url.toString() + ") use keys([protocol])");
ScopeModel scopeModel = ScopeModelUtil.getOrDefault(url.getScopeModel(), org.apache.dubbo.registry.RegistryFactory.class);
//此时获取到的extension为RegistryFactoryWrapper
//RegistryFactoryWrapper的registryFactory为ServiceDiscoveryRegistryFactory
org.apache.dubbo.registry.RegistryFactory extension = (org.apache.dubbo.registry.RegistryFactory)scopeModel.getExtensionLoader(org.apache.dubbo.registry.RegistryFactory.class).getExtension(extName);
//调用RegistryFactoryWrapper的getRegistry()方法
return extension.getRegistry(arg0);
}
}
public class RegistryFactoryWrapper implements RegistryFactory {
//此时的registryFactory为ServiceDiscoveryRegistryFactory
private RegistryFactory registryFactory;
public RegistryFactoryWrapper(RegistryFactory registryFactory) {
this.registryFactory = registryFactory;
}
@Override
public Registry getRegistry(URL url) {
//调用ServiceDiscoveryRegistryFactory的getRegistry()方法获取一个ServiceDiscoveryRegistry
//所以这里会返回一个封装了ServiceDiscoveryRegistry的ListenerRegistryWrapper
return new ListenerRegistryWrapper(registryFactory.getRegistry(url),
Collections.unmodifiableList(
url.getOrDefaultApplicationModel()
.getExtensionLoader(RegistryServiceListener.class)
.getActivateExtension(url, "registry.listeners")
)
);
}
}
public abstract class AbstractRegistryFactory implements RegistryFactory, ScopeModelAware {
...
@Override
public Registry getRegistry(URL url) {
...
registry = createRegistry(url);
...
return registry;
}
...
}
public class ServiceDiscoveryRegistryFactory extends AbstractRegistryFactory {
@Override
protected Registry createRegistry(URL url) {
if (UrlUtils.hasServiceDiscoveryRegistryProtocol(url)) {
//将"service-discovery-registry://"协议替换为"zookeeper://"
String protocol = url.getParameter(REGISTRY_KEY, DEFAULT_REGISTRY);
url = url.setProtocol(protocol).removeParameter(REGISTRY_KEY);
}
return new ServiceDiscoveryRegistry(url, applicationModel);
}
}
public class ServiceDiscoveryRegistry extends FailbackRegistry {
private final ServiceDiscovery serviceDiscovery;
...
public ServiceDiscoveryRegistry(URL registryURL, ApplicationModel applicationModel) {
super(registryURL);
this.serviceDiscovery = createServiceDiscovery(registryURL);
this.serviceNameMapping = (AbstractServiceNameMapping) ServiceNameMapping.getDefaultExtension(registryURL.getScopeModel());
super.applicationModel = applicationModel;
}
protected ServiceDiscovery createServiceDiscovery(URL registryURL) {
//根据registryURL获取对应的ServiceDiscovery实现
//此时由于url的协议已经由"service-discovery-registry://"变为"zookeeper://"
//所以会获取一个ZookeeperServiceDiscovery进行返回
return getServiceDiscovery(registryURL.addParameter(INTERFACE_KEY, ServiceDiscovery.class.getName())
.removeParameter(REGISTRY_TYPE_KEY));
}
...
}
public class ListenerRegistryWrapper implements Registry {
private final Registry registry;
...
public void register(URL url) {
...
//此时下面会调用ServiceDiscoveryRegistry.register()方法
registry.register(url);
}
}
public class ServiceDiscoveryRegistry extends FailbackRegistry {
//RegistryProtocol.export()方法中获取Registry时,这里会是一个ZookeeperServiceDiscovery
private final ServiceDiscovery serviceDiscovery;
...
public final void register(URL url) {
//检测URL中的side参数是否为provider
if (!shouldRegister(url)) {
return;
}
doRegister(url);
}
public void doRegister(URL url) {
//将元数据发布到MetadataService
url = addRegistryClusterKey(url);
//下面会调用ZookeeperServiceDiscovery.register()方法
//此时只是将url添加到对象的属性中而已
serviceDiscovery.register(url);
}
}
public abstract class AbstractServiceDiscovery implements ServiceDiscovery {
protected volatile ServiceInstance serviceInstance;
protected volatile MetadataInfo metadataInfo;
...
@Override
public void register(URL url) {
//将要注册的url添加到metadataInfo属性
metadataInfo.addService(url);
}
...
}
public class ZookeeperServiceDiscovery extends AbstractServiceDiscovery {
...
...
}
public class MetadataInfo implements Serializable {
//key format is '{group}/{interface name}:{version}:{protocol}'
//map里存放了多个服务实例的ServiceInfo
private final Map<String, ServiceInfo> services;
...
public synchronized void addService(URL url) {
if (this.loader == null) {
this.loader = url.getOrDefaultApplicationModel().getExtensionLoader(MetadataParamsFilter.class);
}
List<MetadataParamsFilter> filters = loader.getActivateExtension(url, "params-filter");
//generate service level metadata
ServiceInfo serviceInfo = new ServiceInfo(url, filters);
this.services.put(serviceInfo.getMatchKey(), serviceInfo);
//extract common instance level params
extractInstanceParams(url, filters);
if (exportedServiceURLs == null) {
exportedServiceURLs = new ConcurrentSkipListMap<>();
}
addURL(exportedServiceURLs, url);
updated = true;
}
...
}
(2)然后注册registry的URL
此时,在RegistryProtocol.export()方法中,进行服务注册时使用的Registry其实是一个ListenerRegistryWrapper装饰器,装饰着一个ZooKeeperRegistry。
ZooKeeperRegistry.doRegister()处理的URL注册其实就是往注册中心注册。
bash
//-> RegistryProtocol.export()
//-> RegistryProtocol.getRegistry()
//-> RegistryFactory$Adaptive.getRegistry()
//-> RegistryFactoryWrapper.getRegistry()
//-> ZookeeperRegistryFactory.getRegistry()
//-> ZookeeperRegistryFactory.createRegistry()
//-> new ZookeeperRegistry()
//=> ListenerRegistryWrapper、ZookeeperRegistry
//-> RegistryProtocol.register()
//-> ListenerRegistryWrapper.register()
//-> FailbackRegistry.register()
//-> ZookeeperRegistry.doRegister()
java
public class RegistryProtocol implements Protocol, ScopeModelAware {
...
@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
//将"registry://"协议(Remote URL)转换成"zookeeper://"协议(Registry URL)
URL registryUrl = getRegistryUrl(originInvoker);
//url to export locally
//获取export参数,其中存储了一个"dubbo://"协议的Provider URL
URL providerUrl = getProviderUrl(originInvoker);
//Subscribe the override data
//FIXME When the provider subscribes, it will affect the scene : a certain JVM exposes the service and call the same service.
//Because the subscribed is cached key with the name of the service, it causes the subscription information to cover.
final URL overrideSubscribeUrl = getSubscribedOverrideUrl(providerUrl);
final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
Map<URL, NotifyListener> overrideListeners = getProviderConfigurationListener(providerUrl).getOverrideListeners();
overrideListeners.put(registryUrl, overrideSubscribeListener);
providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);
//1.export invoker
//下面进行导出服务,底层会通过会执行DubboProtocol.export()方法,启动对应的Server
//也就是会涉及到对另外一个Protocol组件的调用,远程发布服务时其实就是执行DubboProtocol的export方法
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
//2.url to registry 完成服务注册的事情
//下面会根据RegistryURL获取对应的注册中心Registry对象,其中会依赖RegistryFactory
//远程发布时,下面的registry其实是一个ListenerRegistryWrapper装饰器,装饰着使用了ZookeeperServiceDiscovery的ServiceDiscoveryRegistry
//在基于注册中心的url地址去构建对应的注册中心组件时,默认是基于zk的
//而构建一个基于zk的注册中心组件,同时跟zk完成连接的建立,则由curator5框架来实现
final Registry registry = getRegistry(registryUrl);
//获取将要发布到注册中心上的Provider URL,其中会删除一些多余的参数信息
final URL registeredProviderUrl = getUrlToRegistry(providerUrl, registryUrl);
//decide if we need to delay publish (provider itself and registry should both need to register)
//根据register参数值决定是否注册服务
boolean register = providerUrl.getParameter(REGISTER_KEY, true) && registryUrl.getParameter(REGISTER_KEY, true);
if (register) {
//调用Registry.register()方法将registeredProviderUrl发布到注册中心
register(registry, registeredProviderUrl);
}
//register stated url on provider model
//将Provider相关信息记录到的ProviderModel中
registerStatedUrl(registryUrl, registeredProviderUrl, register);
exporter.setRegisterUrl(registeredProviderUrl);
exporter.setSubscribeUrl(overrideSubscribeUrl);
if (!registry.isServiceDiscovery()) {
//Deprecated! Subscribe to override rules in 2.6.x or before.
//向注册中心进行订阅override数据,主要是监听该服务的configurators节点
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
}
//触发RegistryProtocolListener监听器
notifyExport(exporter);
//Ensure that a new exporter instance is returned every time export
return new DestroyableExporter<>(exporter);
}
protected Registry getRegistry(final URL registryUrl) {
//通过SPI自适应机制,去拿到对应的extension实例
//这里的registryFactory为RegistryFactory$Adaptive
RegistryFactory registryFactory = ScopeModelUtil.getExtensionLoader(RegistryFactory.class, registryUrl.getScopeModel()).getAdaptiveExtension();
//调用RegistryFactory$Adaptive的getRegistry()方法
return registryFactory.getRegistry(registryUrl);
}
private void register(Registry registry, URL registeredProviderUrl) {
//下面会调用ListenerRegistryWrapper.register()方法
registry.register(registeredProviderUrl);
}
private void registerStatedUrl(URL registryUrl, URL registeredProviderUrl, boolean registered) {
ProviderModel model = (ProviderModel) registeredProviderUrl.getServiceModel();
model.addStatedUrl(new ProviderModel.RegisterStatedURL(
registeredProviderUrl,
registryUrl,
registered));
}
...
}
public class RegistryFactory$Adaptive implements org.apache.dubbo.registry.RegistryFactory {
public org.apache.dubbo.registry.Registry getRegistry(org.apache.dubbo.common.URL arg0) {
if (arg0 == null) throw new IllegalArgumentException("url == null");
org.apache.dubbo.common.URL url = arg0;
String extName = ( url.getProtocol() == null ? "dubbo" : url.getProtocol() );
//注册registry的URL时,由于RegistryProtocol.export()方法会将"registry://"协议替换为"zookeeper://"协议
//所以此时extName=zookeeper
if (extName == null) throw new IllegalStateException("Failed to get extension (org.apache.dubbo.registry.RegistryFactory) name from url (" + url.toString() + ") use keys([protocol])");
ScopeModel scopeModel = ScopeModelUtil.getOrDefault(url.getScopeModel(), org.apache.dubbo.registry.RegistryFactory.class);
//此时获取到的extension为RegistryFactoryWrapper
//RegistryFactoryWrapper的registryFactory为ZookeeperRegistryFactory
org.apache.dubbo.registry.RegistryFactory extension = (org.apache.dubbo.registry.RegistryFactory)scopeModel.getExtensionLoader(org.apache.dubbo.registry.RegistryFactory.class).getExtension(extName);
//调用RegistryFactoryWrapper的getRegistry()方法
return extension.getRegistry(arg0);
}
}
public class RegistryFactoryWrapper implements RegistryFactory {
//此时的registryFactory为ZookeeperRegistryFactory
private RegistryFactory registryFactory;
public RegistryFactoryWrapper(RegistryFactory registryFactory) {
this.registryFactory = registryFactory;
}
@Override
public Registry getRegistry(URL url) {
//调用ZookeeperRegistryFactory的getRegistry()方法获取一个ZookeeperRegistry
//所以这里会返回一个封装了ZookeeperRegistry的ListenerRegistryWrapper
return new ListenerRegistryWrapper(registryFactory.getRegistry(url),
Collections.unmodifiableList(
url.getOrDefaultApplicationModel()
.getExtensionLoader(RegistryServiceListener.class)
.getActivateExtension(url, "registry.listeners")
)
);
}
}
public abstract class AbstractRegistryFactory implements RegistryFactory, ScopeModelAware {
...
@Override
public Registry getRegistry(URL url) {
...
registry = createRegistry(url);
...
return registry;
}
...
}
public class ZookeeperRegistryFactory extends AbstractRegistryFactory {
private ZookeeperTransporter zookeeperTransporter;
public ZookeeperRegistryFactory() {
this(ApplicationModel.defaultModel());
}
public ZookeeperRegistryFactory(ApplicationModel applicationModel) {
this.applicationModel = applicationModel;
this.zookeeperTransporter = ZookeeperTransporter.getExtension(applicationModel);
}
@Override
public Registry createRegistry(URL url) {
return new ZookeeperRegistry(url, zookeeperTransporter);
}
...
}
public class ListenerRegistryWrapper implements Registry {
private final Registry registry;
...
public void register(URL url) {
...
//此时下面会调用ZookeeperRegistry.register()方法
//由于ZookeeperRegistry继承自FailbackRegistry
//所以会调用FailbackRegistry.register()方法
registry.register(url);
}
}
public abstract class FailbackRegistry extends AbstractRegistry {
...
@Override
public void register(URL url) {
super.register(url);
removeFailedRegistered(url);
removeFailedUnregistered(url);
doRegister(url);
}
public abstract void doRegister(URL url);
...
}
public class ZookeeperRegistry extends CacheableFailbackRegistry {
//跟zk建立网络连接的客户端
private ZookeeperClient zkClient;
//刚开始构建这个zookeeper registry,核心的就是去连接zk,与zk建立连接
public ZookeeperRegistry(URL url, ZookeeperTransporter zookeeperTransporter) {
//首先根据传入的url执行父类的构造函数
//该url就是zk的连接地址,比如zookeeper://localhost:2181/
super(url);
...
//基于zk的API去构建与zk之间的连接
this.zkClient = zookeeperTransporter.connect(url);
...
}
@Override
public void doRegister(URL url) {
//一个url代表了一个Provider服务实例的所有信息、配置和属性
//或者说一个url就代表了一个Provider服务实例
//服务注册中的核心注册,即Dubbo往zk进行服务实例注册的方法就在此处
try {
checkDestroyed();
//对于一个应用而言,它的注册其实就是往zk中创建的一个znode节点
zkClient.create(toUrlPath(url), url.getParameter(DYNAMIC_KEY, true));
} catch (Throwable e) {
throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
}
}
...
}
13.Dubbo服务发布的完整流程总结