Dubbo源码-07-Protocol
作用
- 生产者 将Invoker对象导出
- InjvmProtocol 没有真正的干活逻辑 仅仅是一些属性赋值
- DubboProtol 启动Netty服务
- RegistryProtol
- 通过DubboProtocol启动netty服务端
- 注册远程配置中心
- 消费者 创建Invoker对象
- RegistryProtocol
- 通过Dubboprotocol启动netty客户端
- RegistryProtocol
一 扩展接口
@SPI("dubbo")
public interface Protocol {
/**
* Get default port when user doesn't config the port.
*
* @return default port
*/
int getDefaultPort();
/**
* Export service for remote invocation: <br>
* 1. Protocol should record request source address after receive a request:
* RpcContext.getContext().setRemoteAddress();<br>
* 2. export() must be idempotent, that is, there's no difference between invoking once and invoking twice when
* export the same URL<br>
* 3. Invoker instance is passed in by the framework, protocol needs not to care <br>
*
* @param <T> Service type
* @param invoker Service invoker
* @return exporter reference for exported service, useful for unexport the service later
* @throws RpcException thrown when error occurs during export the service, for example: port is occupied
*/
/**
* 生产者将Invoker对象进行导出
* - 本地
* - 远程
*/
@Adaptive
<T> Exporter<T> export(Invoker<T> invoker) throws RpcException;
/**
* Refer a remote service: <br>
* 1. When user calls `invoke()` method of `Invoker` object which's returned from `refer()` call, the protocol
* needs to correspondingly execute `invoke()` method of `Invoker` object <br>
* 2. It's protocol's responsibility to implement `Invoker` which's returned from `refer()`. Generally speaking,
* protocol sends remote request in the `Invoker` implementation. <br>
* 3. When there's check=false set in URL, the implementation must not throw exception but try to recover when
* connection fails.
*
* @param <T> Service type
* @param type Service class
* @param url URL address for the remote service
* @return invoker service's local proxy
* @throws RpcException when there's any error while connecting to the service provider
*/
@Adaptive
<T> Invoker<T> refer(Class<T> type, URL url) throws RpcException;
/**
* Destroy protocol: <br>
* 1. Cancel all services this protocol exports and refers <br>
* 2. Release all occupied resources, for example: connection, port, etc. <br>
* 3. Protocol can continue to export and refer new service even after it's destroyed.
*/
void destroy();
}
默认实现是dubbo
二 配置文件
dubbo=com.alibaba.dubbo.rpc.protocol.dubbo.DubboProtocol
injvm=com.alibaba.dubbo.rpc.protocol.injvm.InjvmProtocol
实现类上没有@Adaptive注解标识
三 通过生成code方式创建自适应扩展实现类对象
package com.alibaba.dubbo.rpc;
import com.alibaba.dubbo.common.extension.ExtensionLoader;
public class Protocol$Adaptive 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.Exporter export(com.alibaba.dubbo.rpc.Invoker arg0) throws com.alibaba.dubbo.rpc.RpcException {
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);
}
public com.alibaba.dubbo.rpc.Invoker refer(java.lang.Class arg0, com.alibaba.dubbo.common.URL arg1) throws com.alibaba.dubbo.rpc.RpcException {
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);
}
}
四 实现
- 默认dubbo
- URL中协议protocol指定
1 InjvmProtocol
1.1 服务导出
// InjvmProtocol
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
/**
* invoker
* - 要暴露的对象的代理
* - javassist编码创建代理对象
* - Java反射
* serviceKey
* - invoker中注入了URL配置
* - 目标服务的全限定名
*/
return new InjvmExporter<T>(invoker, invoker.getUrl().getServiceKey(), exporterMap);
}
// InjvmExporter.java
InjvmExporter(Invoker<T> invoker, String key, Map<String, Exporter<?>> exporterMap) { // 做一些属性赋值
super(invoker);
this.key = key;
this.exporterMap = exporterMap;
exporterMap.put(key, this);
}
1.2 服务引用
2 RegistryProtocol
2.1 服务导出
/**
* 生产者将目标服务创建Invoker对象导出到远程
* - 启动服务
* - 通过Protocol的DubboProtocol实现
* - 服务注册
* - 通过RegistryFactory的ZookeeperRegistryFactory注册到远程注册中心
*/
@Override
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
//export invoker
/**
* 真正的导出服务
* - 实现在DubboProtocol中
* - 启动目标服务
*/
final ExporterChangeableWrapper<T> exporter = this.doLocalExport(originInvoker);
/**
* 注册中心的地址
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-provider&dubbo=2.0.2&export=dubbo%3A%2F%2F10.10.132.185%3A20880%2Fcom.alibaba.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Dnative-provider%26bind.ip%3D10.10.132.185%26bind.port%3D20880%26dubbo%3D2.0.2%26generic%3Dfalse%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D95551%26qos.port%3D22222%26side%3Dprovider%26timestamp%3D1669363479100&pid=95551&qos.port=22222×tamp=1669363479082
*/
URL registryUrl = getRegistryUrl(originInvoker);
//registry provider
final Registry registry = getRegistry(originInvoker);
final URL registeredProviderUrl = getRegisteredProviderUrl(originInvoker);
//to judge to delay publish whether or not
boolean register = registeredProviderUrl.getParameter("register", true);
ProviderConsumerRegTable.registerProvider(originInvoker, registryUrl, registeredProviderUrl);
if (register) {
/**
* 注册到远程注册中心
* - registryUrl
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-provider&dubbo=2.0.2&export=dubbo%3A%2F%2F10.10.132.185%3A20880%2Fcom.alibaba.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Dnative-provider%26bind.ip%3D10.10.132.185%26bind.port%3D20880%26dubbo%3D2.0.2%26generic%3Dfalse%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D95899%26qos.port%3D22222%26side%3Dprovider%26timestamp%3D1669364001492&pid=95899&qos.port=22222×tamp=1669364001477
* - registeredProviderUrl
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=95899&side=provider×tamp=1669364001492
*/
this.register(registryUrl, registeredProviderUrl);
ProviderConsumerRegTable.getProviderWrapper(originInvoker).setReg(true);
}
// 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(registeredProviderUrl);
final OverrideListener overrideSubscribeListener = new OverrideListener(overrideSubscribeUrl, originInvoker);
overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
//Ensure that a new exporter instance is returned every time export
return new DestroyableExporter<T>(exporter, originInvoker, overrideSubscribeUrl, registeredProviderUrl);
}
实现两个功能
- 目标服务的启动
- 注册远程配置中心
2.1.1 服务启动
// RegistryProtocol.java
private <T> ExporterChangeableWrapper<T> doLocalExport(final Invoker<T> originInvoker) {
String key = getCacheKey(originInvoker);
ExporterChangeableWrapper<T> exporter = (ExporterChangeableWrapper<T>) bounds.get(key);
if (exporter == null) {
synchronized (bounds) {
exporter = (ExporterChangeableWrapper<T>) bounds.get(key);
if (exporter == null) {
final Invoker<?> invokerDelegete = new InvokerDelegete<T>(originInvoker, getProviderUrl(originInvoker));
/**
* invokerDelegate是真正运行的目标对象的代理
* - invoker的协议已经被篡改了
* - 本地的话是InjvmProtocol 协议是injvm
* - 远程的话是RegistryProtocol 协议是registry
* - 因此现在要真正启动服务需要再用当时的运行协议
* - 这个地方是dubbo协议 使用的实现是DubboRegistry
*/
exporter = new ExporterChangeableWrapper<T>((Exporter<T>) protocol.export(invokerDelegete), originInvoker);
bounds.put(key, exporter);
}
}
}
return exporter;
}
服务启动实现在DubboProtocol中
2.1.2 注册远程配置中心
if (register) {
/**
* 注册到远程注册中心
* - registryUrl
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-provider&dubbo=2.0.2&export=dubbo%3A%2F%2F10.10.132.185%3A20880%2Fcom.alibaba.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Dnative-provider%26bind.ip%3D10.10.132.185%26bind.port%3D20880%26dubbo%3D2.0.2%26generic%3Dfalse%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D95899%26qos.port%3D22222%26side%3Dprovider%26timestamp%3D1669364001492&pid=95899&qos.port=22222×tamp=1669364001477
* - registeredProviderUrl
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=95899&side=provider×tamp=1669364001492
*/
this.register(registryUrl, registeredProviderUrl);
ProviderConsumerRegTable.getProviderWrapper(originInvoker).setReg(true);
}
public void register(URL registryUrl, URL registedProviderUrl) {
/**
* registryUrl
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-provider&dubbo=2.0.2&export=dubbo%3A%2F%2F10.10.132.185%3A20880%2Fcom.alibaba.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Dnative-provider%26bind.ip%3D10.10.132.185%26bind.port%3D20880%26dubbo%3D2.0.2%26generic%3Dfalse%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D95948%26qos.port%3D22222%26side%3Dprovider%26timestamp%3D1669364071921&pid=95948&qos.port=22222×tamp=1669364071907
* registedProviderUrl
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=95948&side=provider×tamp=1669364071921
*
* RegistryFactory实现扩展
* - 默认dubbo
* - URL协议指定
* - 这个地方使用ZookeeperRegistryFactory实现
*
* 拿到zkClient 准备进行读写
*/
Registry registry = registryFactory.getRegistry(registryUrl);
/**
* 不同注册中心实现关注各自的读写
* - ZookeeperRegistry负责zk的读写
*/
registry.register(registedProviderUrl);
}
// FailbackRegistry.java
@Override
public void register(URL url) {
super.register(url);
failedRegistered.remove(url);
failedUnregistered.remove(url);
try {
// Sending a registration request to the server side
/**
* 远程注册中心由各自实现关注读写
* - ZookeeperRegistry关注zk读写
*/
this.doRegister(url);
} catch (Exception e) {
Throwable t = e;
// If the startup detection is opened, the Exception is thrown directly.
boolean check = getUrl().getParameter(Constants.CHECK_KEY, true)
&& url.getParameter(Constants.CHECK_KEY, true)
&& !Constants.CONSUMER_PROTOCOL.equals(url.getProtocol());
boolean skipFailback = t instanceof SkipFailbackWrapperException;
if (check || skipFailback) {
if (skipFailback) {
t = t.getCause();
}
throw new IllegalStateException("Failed to register " + url + " to registry " + getUrl().getAddress() + ", cause: " + t.getMessage(), t);
} else {
logger.error("Failed to register " + url + ", waiting for retry, cause: " + t.getMessage(), t);
}
// Record a failed registration request to a failed list, retry regularly
failedRegistered.add(url);
}
}
// ZookeeperRegistry.java
@Override
protected void doRegister(URL url) {
try {
/**
* zk读写操作
* - 创建节点
* - path
* - /dubbo/com.alibaba.dubbo.demo.DemoService/providers/dubbo%3A%2F%2F192.168.0.11%3A20880%2Fcom.alibaba.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Dnative-provider%26dubbo%3D2.0.2%26generic%3Dfalse%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D41099%26side%3Dprovider%26timestamp%3D1669562090672
* - 永久/临时
* - 默认临时节点
*/
this.zkClient.create(toUrlPath(url), url.getParameter(Constants.DYNAMIC_KEY, true));
} catch (Throwable e) {
throw new RpcException("Failed to register " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
}
}
// AbstractZookeeperClient.java
@Override
public void create(String path, boolean ephemeral) {
if (!ephemeral) {
if(persistentExistNodePath.contains(path)){
return;
}
if (checkExists(path)) {
persistentExistNodePath.add(path);
return;
}
}
int i = path.lastIndexOf('/');
if (i > 0) {
create(path.substring(0, i), false); // 递归创建上一级
}
if (ephemeral) {
createEphemeral(path); // 创建临时节点
} else {
createPersistent(path); // 创建永久节点
persistentExistNodePath.add(path);
}
}
// CuratorZookeeperClient.java
@Override
public void createEphemeral(String path) {
try {
client.create().withMode(CreateMode.EPHEMERAL).forPath(path);
} catch (NodeExistsException e) {
} catch (Exception e) {
throw new IllegalStateException(e.getMessage(), e);
}
}
2.2 服务引用
// RegistryProtocol
// type 目标对象的接口
@Override
@SuppressWarnings("unchecked")
public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
/**
* url
* - registry://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-consumer&dubbo=2.0.2&pid=60408&qos.port=33333&refer=application%3Dnative-consumer%26dubbo%3D2.0.2%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D60408%26qos.port%3D33333%26register.ip%3D10.10.132.185%26side%3Dconsumer%26timestamp%3D1669944562056®istry=zookeeper×tamp=1669944567721
* 根据registry配置替换协议
* url
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-consumer&dubbo=2.0.2&pid=60408&qos.port=33333&refer=application%3Dnative-consumer%26dubbo%3D2.0.2%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D60408%26qos.port%3D33333%26register.ip%3D10.10.132.185%26side%3Dconsumer%26timestamp%3D1669944562056×tamp=1669944567721
*/
url = url.setProtocol(url.getParameter(Constants.REGISTRY_KEY, Constants.DEFAULT_REGISTRY)).removeParameter(Constants.REGISTRY_KEY);
Registry registry = registryFactory.getRegistry(url); // ZookeeperRegistry
if (RegistryService.class.equals(type)) {
return proxyFactory.getInvoker((T) registry, type, url);
}
// group="a,b" or group="*"
Map<String, String> qs = StringUtils.parseQueryString(url.getParameterAndDecoded(Constants.REFER_KEY));
String group = qs.get(Constants.GROUP_KEY);
if (group != null && group.length() > 0) {
if ((Constants.COMMA_SPLIT_PATTERN.split(group)).length > 1
|| "*".equals(group)) {
return doRefer(getMergeableCluster(), registry, type, url);
}
}
/**
* url
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-consumer&dubbo=2.0.2&pid=83684&qos.port=33333&refer=application%3Dnative-consumer%26dubbo%3D2.0.2%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D83684%26qos.port%3D33333%26register.ip%3D198.18.0.1%26side%3Dconsumer%26timestamp%3D1669711051058×tamp=1669711051113
* cluster是扩展接口 运行时决定实现
* - 默认failover
* - URL中cluster配置
*/
return this.doRefer(cluster, registry, type, url);
}
// RegistryProtocol.java
private <T> Invoker<T> doRefer(Cluster cluster, Registry registry, Class<T> type, URL url) {
/**
* url
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?application=native-consumer&dubbo=2.0.2&pid=86868&qos.port=33333&refer=application%3Dnative-consumer%26dubbo%3D2.0.2%26interface%3Dcom.alibaba.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D86868%26qos.port%3D33333%26register.ip%3D10.10.132.185%26side%3Dconsumer%26timestamp%3D1669771749570×tamp=1669771749634
*/
RegistryDirectory<T> directory = new RegistryDirectory<T>(type, url);
directory.setRegistry(registry);
directory.setProtocol(protocol);
// all attributes of REFER_KEY
/**
* URL中携带的配置
* - side=consumer
* - application=native-consumer
* - register.ip=10.10.132.185
* - methods=sayHello
* - qos.port=33333
* - dubbo=2.0.2
* - pid=86934
* - interface=com.alibaba.dubbo.demo.DemoService
* - timestamp=1669771845357
*/
Map<String, String> parameters = new HashMap<String, String>(directory.getUrl().getParameters());
URL subscribeUrl = new URL(Constants.CONSUMER_PROTOCOL, parameters.remove(Constants.REGISTER_IP_KEY), 0, type.getName(), parameters);
if (!Constants.ANY_VALUE.equals(url.getServiceInterface())
&& url.getParameter(Constants.REGISTER_KEY, true)) {
// consumer://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=consumers&check=false&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=87054&qos.port=33333&side=consumer×tamp=1669772040508
URL registeredConsumerUrl = getRegisteredConsumerUrl(subscribeUrl, url);
registry.register(registeredConsumerUrl);
directory.setRegisteredConsumerUrl(registeredConsumerUrl);
}
/**
* subscribeUrl
* - consumer://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=61016&qos.port=33333&side=consumer×tamp=1669945422405
* 添加个配置项
* - category
* - providers,configurators,routers
* zk远程注册中心的实现下
* - 给providers configurators routers这3个指定的节点添加监听器
* - 自然获取了指定节点下的所有子节点
* - providers就包含了当时生产者注册的目标服务信息
*/
directory.subscribe(subscribeUrl.addParameter(Constants.CATEGORY_KEY,
Constants.PROVIDERS_CATEGORY
+ "," + Constants.CONFIGURATORS_CATEGORY
+ "," + Constants.ROUTERS_CATEGORY));
/**
* directory中包含的URL
* - zookeeper://localhost:2181/com.alibaba.dubbo.registry.RegistryService?anyhost=true&application=native-consumer&check=false&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=87857&qos.port=33333®ister.ip=10.10.132.185&remote.timestamp=1669771379640&side=consumer×tamp=1669773134257
* url的cluster配置
*/
Invoker invoker = cluster.join(directory);
ProviderConsumerRegTable.registerConsumer(invoker, url, subscribeUrl, directory);
return invoker;
}
2.2.1 创建Invoker对象
// RegistryDirectory.java
public void subscribe(URL url) {
setConsumerUrl(url);
/**
* registry
* - ZookeeperRegistry
* url
* - consumer://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=providers,configurators,routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62081&qos.port=33333&side=consumer×tamp=1669946946551
*/
this.registry.subscribe(url, this);
}
// FailbackRegistry.java
@Override
public void subscribe(URL url, NotifyListener listener) {
super.subscribe(url, listener);
removeFailedSubscribed(url, listener);
try {
// Sending a subscription request to the server side
/**
* 父类抽象方法 延迟到子类实现
* - ZookeeperRegistry
*/
this.doSubscribe(url, listener);
} catch (Exception e) {
Throwable t = e;
List<URL> urls = getCacheUrls(url);
if (urls != null && !urls.isEmpty()) {
notify(url, listener, urls);
logger.error("Failed to subscribe " + url + ", Using cached list: " + urls + " from cache file: " + getUrl().getParameter(Constants.FILE_KEY, System.getProperty("user.home") + "/dubbo-registry-" + url.getHost() + ".cache") + ", cause: " + t.getMessage(), t);
} else {
// If the startup detection is opened, the Exception is thrown directly.
boolean check = getUrl().getParameter(Constants.CHECK_KEY, true)
&& url.getParameter(Constants.CHECK_KEY, true);
boolean skipFailback = t instanceof SkipFailbackWrapperException;
if (check || skipFailback) {
if (skipFailback) {
t = t.getCause();
}
throw new IllegalStateException("Failed to subscribe " + url + ", cause: " + t.getMessage(), t);
} else {
logger.error("Failed to subscribe " + url + ", waiting for retry, cause: " + t.getMessage(), t);
}
}
// Record a failed registration request to a failed list, retry regularly
addFailedSubscribed(url, listener);
}
}
// ZookeeperRegistry.java
@Override
protected void doSubscribe(final URL url, final NotifyListener listener) {
/**
* url
* - consumer://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=providers,configurators,routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62162&qos.port=33333&side=consumer×tamp=1669947064021
* listener
* - RegistryDirectory
*/
try {
if (Constants.ANY_VALUE.equals(url.getServiceInterface())) {
String root = toRootPath();
ConcurrentMap<NotifyListener, ChildListener> listeners = zkListeners.get(url);
if (listeners == null) {
zkListeners.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, ChildListener>());
listeners = zkListeners.get(url);
}
ChildListener zkListener = listeners.get(listener);
if (zkListener == null) {
listeners.putIfAbsent(listener, new ChildListener() {
@Override
public void childChanged(String parentPath, List<String> currentChilds) {
for (String child : currentChilds) {
child = URL.decode(child);
if (!anyServices.contains(child)) {
anyServices.add(child);
subscribe(url.setPath(child).addParameters(Constants.INTERFACE_KEY, child,
Constants.CHECK_KEY, String.valueOf(false)), listener);
}
}
}
});
zkListener = listeners.get(listener);
}
zkClient.create(root, false);
List<String> services = zkClient.addChildListener(root, zkListener);
if (services != null && !services.isEmpty()) {
for (String service : services) {
service = URL.decode(service);
anyServices.add(service);
subscribe(url.setPath(service).addParameters(Constants.INTERFACE_KEY, service,
Constants.CHECK_KEY, String.valueOf(false)), listener);
}
}
} else {
List<URL> urls = new ArrayList<URL>();
/**
* url
* - consumer://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=providers,configurators,routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62443&qos.port=33333&side=consumer×tamp=1669947468801
* category
* - /dubbo/com.alibaba.dubbo.demo.DemoService/providers
* - /dubbp/com.alibaba.dubbo.demo.DemoService/configurators
* - /dubbo/com.alibaba.dubbo.demo.DemoService/routers
*/
for (String path : toCategoriesPath(url)) {
ConcurrentMap<NotifyListener, ChildListener> listeners = zkListeners.get(url);
if (listeners == null) {
zkListeners.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, ChildListener>());
listeners = zkListeners.get(url);
}
ChildListener zkListener = listeners.get(listener);
if (zkListener == null) {
listeners.putIfAbsent(listener, new ChildListener() {
@Override
public void childChanged(String parentPath, List<String> currentChilds) {
ZookeeperRegistry.this.notify(url, listener, toUrlsWithEmpty(url, parentPath, currentChilds));
}
});
zkListener = listeners.get(listener);
}
zkClient.create(path, false); // zk写节点
List<String> children = zkClient.addChildListener(path, zkListener);
if (children != null) {
urls.addAll(toUrlsWithEmpty(url, path, children));
}
}
super.notify(url, listener, urls);
}
} catch (Throwable e) {
throw new RpcException("Failed to subscribe " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
}
}
// FailbackRegistry.java
/**
* url
* - consumer://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=providers,configurators,routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62655&qos.port=33333&side=consumer×tamp=1669947773381
* listener
* - RegistryDirectory
* urls
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=60396&side=provider×tamp=1669944550279
* - empty://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=configurators&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62655&qos.port=33333&side=consumer×tamp=1669947773381
* - empty://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62655&qos.port=33333&side=consumer×tamp=1669947773381
*/
@Override
protected void notify(URL url, NotifyListener listener, List<URL> urls) {
if (url == null) {
throw new IllegalArgumentException("notify url == null");
}
if (listener == null) {
throw new IllegalArgumentException("notify listener == null");
}
try {
this.doNotify(url, listener, urls);
} catch (Exception t) {
// Record a failed registration request to a failed list, retry regularly
Map<NotifyListener, List<URL>> listeners = failedNotified.get(url);
if (listeners == null) {
failedNotified.putIfAbsent(url, new ConcurrentHashMap<NotifyListener, List<URL>>());
listeners = failedNotified.get(url);
}
listeners.put(listener, urls);
logger.error("Failed to notify for subscribe " + url + ", waiting for retry, cause: " + t.getMessage(), t);
}
}
// FailbackRegistry.java
protected void doNotify(URL url, NotifyListener listener, List<URL> urls) {
super.notify(url, listener, urls);
}
// AbstractRegistry.java
protected void notify(URL url, NotifyListener listener, List<URL> urls) {
if (url == null) {
throw new IllegalArgumentException("notify url == null");
}
if (listener == null) {
throw new IllegalArgumentException("notify listener == null");
}
if ((urls == null || urls.isEmpty())
&& !Constants.ANY_VALUE.equals(url.getServiceInterface())) {
logger.warn("Ignore empty notify urls for subscribe url " + url);
return;
}
if (logger.isInfoEnabled()) {
logger.info("Notify urls for subscribe url " + url + ", urls: " + urls);
}
Map<String, List<URL>> result = new HashMap<String, List<URL>>();
for (URL u : urls) {
if (UrlUtils.isMatch(url, u)) {
String category = u.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);
List<URL> categoryList = result.get(category);
if (categoryList == null) {
categoryList = new ArrayList<URL>();
result.put(category, categoryList);
}
categoryList.add(u);
}
}
if (result.size() == 0) {
return;
}
Map<String, List<URL>> categoryNotified = notified.get(url);
if (categoryNotified == null) {
notified.putIfAbsent(url, new ConcurrentHashMap<String, List<URL>>());
categoryNotified = notified.get(url);
}
/**
* hash表
* -
* - configurators
* - empty://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=configurators&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62889&qos.port=33333&side=consumer×tamp=1669948138707
* -
* - routers
* - empty://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62889&qos.port=33333&side=consumer×tamp=1669948138707
* -
* - providers
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=60396&side=provider×tamp=1669944550279
*/
for (Map.Entry<String, List<URL>> entry : result.entrySet()) {
String category = entry.getKey();
List<URL> categoryList = entry.getValue();
categoryNotified.put(category, categoryList);
saveProperties(url);
/**
* 此时已经持有了生产者写在注册中心中的信息
* providers侧的信息
* 再将执行权回到RegistryDirectory中 使用DubboProtocol创建Netty客户端
*/
listener.notify(categoryList);
}
}
// RegistryDirectory.java
/**
* urls
* - configurators
* - empty://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=configurators&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62889&qos.port=33333&side=consumer×tamp=1669948138707
* - routers
* - empty://10.10.132.185/com.alibaba.dubbo.demo.DemoService?application=native-consumer&category=routers&dubbo=2.0.2&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=62889&qos.port=33333&side=consumer×tamp=1669948138707
* - providers
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=60396&side=provider×tamp=1669944550279
*/
@Override
public synchronized void notify(List<URL> urls) {
List<URL> invokerUrls = new ArrayList<URL>(); // 关注的是providers路径
List<URL> routerUrls = new ArrayList<URL>(); // 关注的是routers路径
List<URL> configuratorUrls = new ArrayList<URL>(); // 关注的是configurators路径
for (URL url : urls) { // 将urls分门别类到上面3个缓存中
String protocol = url.getProtocol();
String category = url.getParameter(Constants.CATEGORY_KEY, Constants.DEFAULT_CATEGORY);
if (Constants.ROUTERS_CATEGORY.equals(category)
|| Constants.ROUTE_PROTOCOL.equals(protocol)) {
routerUrls.add(url);
} else if (Constants.CONFIGURATORS_CATEGORY.equals(category)
|| Constants.OVERRIDE_PROTOCOL.equals(protocol)) {
configuratorUrls.add(url);
} else if (Constants.PROVIDERS_CATEGORY.equals(category)) {
invokerUrls.add(url);
} else {
logger.warn("Unsupported category " + category + " in notified url: " + url + " from registry " + getUrl().getAddress() + " to consumer " + NetUtils.getLocalHost());
}
}
// configurators
if (configuratorUrls != null && !configuratorUrls.isEmpty()) {
this.configurators = toConfigurators(configuratorUrls);
}
// routers
if (routerUrls != null && !routerUrls.isEmpty()) {
List<Router> routers = toRouters(routerUrls);
if (routers != null) { // null - do nothing
setRouters(routers);
}
}
List<Configurator> localConfigurators = this.configurators; // local reference
// merge override parameters
this.overrideDirectoryUrl = directoryUrl;
if (localConfigurators != null && !localConfigurators.isEmpty()) {
for (Configurator configurator : localConfigurators) {
this.overrideDirectoryUrl = configurator.configure(overrideDirectoryUrl);
}
}
// providers
/**
* 关注的是providers
* dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=60396&side=provider×tamp=1669944550279
* 从zk中providers节点下拿到了所有子节点 也就是生产者写在注册中心中的信息
*/
this.refreshInvoker(invokerUrls);
}
// RegistryDirectory.java
private void refreshInvoker(List<URL> invokerUrls) {
// dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=60396&side=provider×tamp=1669944550279
if (invokerUrls != null && invokerUrls.size() == 1 && invokerUrls.get(0) != null
&& Constants.EMPTY_PROTOCOL.equals(invokerUrls.get(0).getProtocol())) {
this.forbidden = true; // Forbid to access
this.methodInvokerMap = null; // Set the method invoker map to null
destroyAllInvokers(); // Close all invokers
} else {
this.forbidden = false; // Allow to access
Map<String, Invoker<T>> oldUrlInvokerMap = this.urlInvokerMap; // local reference
if (invokerUrls.isEmpty() && this.cachedInvokerUrls != null) {
invokerUrls.addAll(this.cachedInvokerUrls);
} else {
this.cachedInvokerUrls = new HashSet<URL>();
this.cachedInvokerUrls.addAll(invokerUrls);//Cached invoker urls, convenient for comparison
}
if (invokerUrls.isEmpty()) {
return;
}
// 创建Invoker对象
Map<String, Invoker<T>> newUrlInvokerMap = this.toInvokers(invokerUrls);// Translate url list to Invoker map
Map<String, List<Invoker<T>>> newMethodInvokerMap = toMethodInvokers(newUrlInvokerMap); // Change method name to map Invoker Map
// state change
// If the calculation is wrong, it is not processed.
if (newUrlInvokerMap == null || newUrlInvokerMap.size() == 0) {
logger.error(new IllegalStateException("urls to invokers error .invokerUrls.size :" + invokerUrls.size() + ", invoker.size :0. urls :" + invokerUrls.toString()));
return;
}
this.methodInvokerMap = multiGroup ? toMergeMethodInvokerMap(newMethodInvokerMap) : newMethodInvokerMap;
this.urlInvokerMap = newUrlInvokerMap;
try {
destroyUnusedInvokers(oldUrlInvokerMap, newUrlInvokerMap); // Close the unused Invoker
} catch (Exception e) {
logger.warn("destroyUnusedInvokers error. ", e);
}
}
}
// RegistryDirectory.java
private Map<String, Invoker<T>> toInvokers(List<URL> urls) {
Map<String, Invoker<T>> newUrlInvokerMap = new HashMap<String, Invoker<T>>();
if (urls == null || urls.isEmpty()) {
return newUrlInvokerMap;
}
Set<String> keys = new HashSet<String>();
String queryProtocols = this.queryMap.get(Constants.PROTOCOL_KEY);
for (URL providerUrl : urls) {
// If protocol is configured at the reference side, only the matching protocol is selected
if (queryProtocols != null && queryProtocols.length() > 0) {
boolean accept = false;
String[] acceptProtocols = queryProtocols.split(",");
for (String acceptProtocol : acceptProtocols) {
if (providerUrl.getProtocol().equals(acceptProtocol)) {
accept = true;
break;
}
}
if (!accept) {
continue;
}
}
if (Constants.EMPTY_PROTOCOL.equals(providerUrl.getProtocol())) {
continue;
}
if (!ExtensionLoader.getExtensionLoader(Protocol.class).hasExtension(providerUrl.getProtocol())) {
logger.error(new IllegalStateException("Unsupported protocol " + providerUrl.getProtocol() + " in notified url: " + providerUrl + " from registry " + getUrl().getAddress() + " to consumer " + NetUtils.getLocalHost()
+ ", supported protocol: " + ExtensionLoader.getExtensionLoader(Protocol.class).getSupportedExtensions()));
continue;
}
URL url = mergeUrl(providerUrl);
String key = url.toFullString(); // The parameter urls are sorted
if (keys.contains(key)) { // Repeated url
continue;
}
keys.add(key);
// Cache key is url that does not merge with consumer side parameters, regardless of how the consumer combines parameters, if the server url changes, then refer again
Map<String, Invoker<T>> localUrlInvokerMap = this.urlInvokerMap; // local reference
Invoker<T> invoker = localUrlInvokerMap == null ? null : localUrlInvokerMap.get(key);
if (invoker == null) { // Not in the cache, refer again
try {
boolean enabled = true;
if (url.hasParameter(Constants.DISABLED_KEY)) {
enabled = !url.getParameter(Constants.DISABLED_KEY, false);
} else {
enabled = url.getParameter(Constants.ENABLED_KEY, true);
}
if (enabled) {
/**
* url
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-consumer&check=false&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=63208&qos.port=33333®ister.ip=10.10.132.185&remote.timestamp=1669944550279&side=consumer×tamp=1669948619250
* providerUrl
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=60396&side=provider×tamp=1669944550279
*
* 这个地方Protocol扩展接口会根据url中的协议dubbo确定实现为DubboProtocol
* 在DubboProtocol中会涉及Netty客户端的建立
*/
invoker = new InvokerDelegate<T>(protocol.refer(serviceType, url), url, providerUrl);
}
} catch (Throwable t) {
logger.error("Failed to refer invoker for interface:" + serviceType + ",url:(" + url + ")" + t.getMessage(), t);
}
if (invoker != null) { // Put new invoker in cache
newUrlInvokerMap.put(key, invoker);
}
} else {
newUrlInvokerMap.put(key, invoker);
}
}
keys.clear();
return newUrlInvokerMap;
}
由此进入到DubboProtocol的refer(...)实现中
2.2.2 合并Invoker对象
3 DubboProtocol
3.1 服务导出
3.1.1 服务启动
// DubboProtocol.java
@Override
public <T> Exporter<T> export(Invoker<T> invoker) throws RpcException {
// dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&bind.ip=10.10.132.185&bind.port=20880&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=94935&qos.port=22222&side=provider×tamp=1669362564480
URL url = invoker.getUrl();
// export service.
/**
* key标识着服务的目标对象
* com.alibaba.dubbo.demo.DemoService:20880
*/
String key = serviceKey(url);
DubboExporter<T> exporter = new DubboExporter<T>(invoker, key, exporterMap);
exporterMap.put(key, exporter);
//export an stub service for dispatching event
Boolean isStubSupportEvent = url.getParameter(Constants.STUB_EVENT_KEY, Constants.DEFAULT_STUB_EVENT);
Boolean isCallbackservice = url.getParameter(Constants.IS_CALLBACK_SERVICE, false);
if (isStubSupportEvent && !isCallbackservice) {
String stubServiceMethods = url.getParameter(Constants.STUB_EVENT_METHODS_KEY);
if (stubServiceMethods == null || stubServiceMethods.length() == 0) {
if (logger.isWarnEnabled()) {
logger.warn(new IllegalStateException("consumer [" + url.getParameter(Constants.INTERFACE_KEY) +
"], has set stubproxy support event ,but no stub methods founded."));
}
} else {
stubServiceMethodsMap.put(url.getServiceKey(), stubServiceMethods);
}
}
// dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&bind.ip=10.10.132.185&bind.port=20880&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=94935&qos.port=22222&side=provider×tamp=1669362564480
this.openServer(url);
optimizeSerialization(url);
return exporter;
}
// DubboProtocol.java
private void openServer(URL url) {
// find server.
String key = url.getAddress(); // 10.10.132.185:20880
//client can export a service which's only for server to invoke
boolean isServer = url.getParameter(Constants.IS_SERVER_KEY, true);
if (isServer) {
ExchangeServer server = serverMap.get(key);
if (server == null) {
serverMap.put(key, this.createServer(url));
} else {
// server supports reset, use together with override
server.reset(url);
}
}
}
// DubboProtocol.java
private ExchangeServer createServer(URL url) {
// send readonly event when server closes, it's enabled by default
url = url.addParameterIfAbsent(Constants.CHANNEL_READONLYEVENT_SENT_KEY, Boolean.TRUE.toString());
// enable heartbeat by default
url = url.addParameterIfAbsent(Constants.HEARTBEAT_KEY, String.valueOf(Constants.DEFAULT_HEARTBEAT));
String str = url.getParameter(Constants.SERVER_KEY, Constants.DEFAULT_REMOTING_SERVER);
if (str != null && str.length() > 0 && !ExtensionLoader.getExtensionLoader(Transporter.class).hasExtension(str))
throw new RpcException("Unsupported server type: " + str + ", url: " + url);
url = url.addParameter(Constants.CODEC_KEY, DubboCodec.NAME);
ExchangeServer server;
try {
server = Exchangers.bind(url, requestHandler);
} catch (RemotingException e) {
throw new RpcException("Fail to start server(url: " + url + ") " + e.getMessage(), e);
}
str = url.getParameter(Constants.CLIENT_KEY);
if (str != null && str.length() > 0) {
Set<String> supportedTypes = ExtensionLoader.getExtensionLoader(Transporter.class).getSupportedExtensions();
if (!supportedTypes.contains(str)) {
throw new RpcException("Unsupported client type: " + str);
}
}
return server;
}
public static ExchangeServer bind(URL url, ExchangeHandler handler) throws RemotingException {
if (url == null) {
throw new IllegalArgumentException("url == null");
}
if (handler == null) {
throw new IllegalArgumentException("handler == null");
}
url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");
/**
* url
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-provider&bind.ip=10.10.132.185&bind.port=20880&channel.readonly.sent=true&codec=dubbo&dubbo=2.0.2&generic=false&heartbeat=60000&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=95076&qos.port=22222&side=provider×tamp=1669362762912
*/
return getExchanger(url).bind(url, handler);
}
public static Exchanger getExchanger(URL url) {
// header
String type = url.getParameter(Constants.EXCHANGER_KEY, Constants.DEFAULT_EXCHANGER);
return getExchanger(type);
}
public static Exchanger getExchanger(String type) {
// header
return ExtensionLoader.getExtensionLoader(Exchanger.class).getExtension(type);
}
3.2 服务引用
// DubboProtocol.java
@Override
public <T> Invoker<T> refer(Class<T> serviceType, URL url) throws RpcException {
optimizeSerialization(url);
// create rpc invoker.
DubboInvoker<T> invoker = new DubboInvoker<T>(serviceType, url, getClients(url), invokers);
invokers.add(invoker);
return invoker;
}
// DubboProtocol.java
private ExchangeClient getSharedClient(URL url) {
String key = url.getAddress();
ReferenceCountExchangeClient client = referenceClientMap.get(key);
if (client != null) {
if (!client.isClosed()) {
client.incrementAndGetCount();
return client;
} else {
referenceClientMap.remove(key);
}
}
locks.putIfAbsent(key, new Object());
synchronized (locks.get(key)) {
if (referenceClientMap.containsKey(key)) {
return referenceClientMap.get(key);
}
ExchangeClient exchangeClient = initClient(url);
client = new ReferenceCountExchangeClient(exchangeClient, ghostClientMap);
referenceClientMap.put(key, client);
ghostClientMap.remove(key);
locks.remove(key);
return client;
}
}
// DubboProtocol.java
private ExchangeClient[] getClients(URL url) {
// whether to share connection
boolean service_share_connect = false; // 标识 共享客户端
int connections = url.getParameter(Constants.CONNECTIONS_KEY, 0);
// if not configured, connection is shared, otherwise, one connection for one service
if (connections == 0) {
service_share_connect = true;
connections = 1;
}
ExchangeClient[] clients = new ExchangeClient[connections];
for (int i = 0; i < clients.length; i++) {
if (service_share_connect) {
clients[i] = this.getSharedClient(url);
} else {
clients[i] = this.initClient(url);
}
}
return clients;
}
// DubboProtocol.java
private ExchangeClient initClient(URL url) {
// client type setting.
/**
* url
* - dubbo://10.10.132.185:20880/com.alibaba.dubbo.demo.DemoService?anyhost=true&application=native-consumer&check=false&dubbo=2.0.2&generic=false&interface=com.alibaba.dubbo.demo.DemoService&methods=sayHello&pid=72549&qos.port=33333®ister.ip=10.10.132.185&remote.timestamp=1669962678300&side=consumer×tamp=1669963221353
*/
String str = url.getParameter(Constants.CLIENT_KEY, url.getParameter(Constants.SERVER_KEY, Constants.DEFAULT_REMOTING_CLIENT));
url = url.addParameter(Constants.CODEC_KEY, DubboCodec.NAME);
// enable heartbeat by default
url = url.addParameterIfAbsent(Constants.HEARTBEAT_KEY, String.valueOf(Constants.DEFAULT_HEARTBEAT));
// BIO is not allowed since it has severe performance issue.
if (str != null && str.length() > 0 && !ExtensionLoader.getExtensionLoader(Transporter.class).hasExtension(str)) {
throw new RpcException("Unsupported client type: " + str + "," +
" supported client type is " + StringUtils.join(ExtensionLoader.getExtensionLoader(Transporter.class).getSupportedExtensions(), " "));
}
ExchangeClient client;
try {
// connection should be lazy
if (url.getParameter(Constants.LAZY_CONNECT_KEY, false)) {
client = new LazyConnectExchangeClient(url, requestHandler);
} else {
client = Exchangers.connect(url, requestHandler);
}
} catch (RemotingException e) {
throw new RpcException("Fail to create remoting client for service(" + url + "): " + e.getMessage(), e);
}
return client;
}
// Exchangers.java
public static ExchangeClient connect(URL url, ExchangeHandler handler) throws RemotingException {
if (url == null) {
throw new IllegalArgumentException("url == null");
}
if (handler == null) {
throw new IllegalArgumentException("handler == null");
}
url = url.addParameterIfAbsent(Constants.CODEC_KEY, "exchange");
// HeaderExchanger
/**
* - 获取Exchanger对象
* - Exchanger实现
* - netty
*/
return getExchanger(url).connect(url, handler);
}
下面就是
- 获取Exchanger对象，这个地方和服务导出流程中是一样的
- Exchanger的connect(...)实现
3.2.1 获取Exchanger对象
// Exchangers.java
public static Exchanger getExchanger(URL url) {
// header
String type = url.getParameter(Constants.EXCHANGER_KEY, Constants.DEFAULT_EXCHANGER);
return getExchanger(type);
}
// Exchangers.java
public static Exchanger getExchanger(String type) {
// header
return ExtensionLoader.getExtensionLoader(Exchanger.class).getExtension(type);
}
