Dubbo解析(一)
服务发布
Dubbo扩展了spring Schema实现了解析类(DubboNameSpaceHandler),通过DubboBeanDefinitionParse进行解析，将对应xml解析为bean(XML id)对象。
ServiceBean实现了spring套件的一系列接口,较为关键的InitializingBean,ApplicationListener
首先看afterPropertiesSet()：
经过DubboBeanDefinitionParse解析成bean后，检验和装填配置(如果没配置则会默认)
Map<String, ProviderConfig> providerConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProviderConfig.class, false, false);
if (providerConfigMap != null && providerConfigMap.size() > 0) {
Map<String, ProtocolConfig> protocolConfigMap = applicationContext == null ? null : BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, ProtocolConfig.class, false, false);
if (CollectionUtils.isEmptyMap(protocolConfigMap)
&& providerConfigMap.size() > 1) { // backward compatibility
List<ProviderConfig> providerConfigs = new ArrayList<ProviderConfig>();
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() != null && config.isDefault()) {
providerConfigs.add(config);
}
}
if (!providerConfigs.isEmpty()) {
setProviders(providerConfigs);
}
} else {
ProviderConfig providerConfig = null;
for (ProviderConfig config : providerConfigMap.values()) {
if (config.isDefault() == null || config.isDefault()) {
if (providerConfig != null) {
throw new IllegalStateException("Duplicate provider configs: " + providerConfig + " and " + config);
}
providerConfig = config;
}
}
if (providerConfig != null) {
setProvider(providerConfig);
}
}
}
实现了ApplicationListener当容器初始化之后，就开始进行服务的暴露:
public void onApplicationEvent(ContextRefreshedEvent event) {
if (!isExported() && !isUnexported()) {
if (logger.isInfoEnabled()) {
logger.info("The service ready on spring started. service: " + getInterface());
}
export();
}
}
服务暴露的具体方法由ServiceBean父类ServiceConfig实现，暴露方法会对参数做些检查，并且可以配为延迟：
public synchronized void export() {
checkAndUpdateSubConfigs();
if (provider != null) {
if (export == null) {
export = provider.getExport();
}
if (delay == null) {
delay = provider.getDelay();
}
}
if (export != null && !export) {
return;
}
if (delay != null && delay > 0) {
delayExportExecutor.schedule(this::doExport, delay, TimeUnit.MILLISECONDS);
} else {
doExport();
}
}
接下来执行doExport()方法，将ServiceConfig几个主要参数生成ProviderModel放到Map里
protected synchronized void doExport() {
if (unexported) {
throw new IllegalStateException("The service " + interfaceClass.getName() + " has already unexported!");
}
if (exported) {
return;
}
exported = true;
if (StringUtils.isEmpty(path)) {
path = interfaceName;
}
String uniqueServiceName = getUniqueServiceName();
ProviderModel providerModel = new ProviderModel(uniqueServiceName, ref, interfaceClass);
//此处Map uniqueServiceName为全名(如org.apache.dubbo.demo.DemoService)
ApplicationModel.initProviderModel(uniqueServiceName, providerModel);
doExportUrls();
}
针对不同协议拼接url，并进行暴露:主要过程是先将配置对象的信息加到Map中（因为dubbo:method 和dubbo：argument 标签有层级关系，判断起来逻辑多),然后获取主机名和端口号。生成url（url：dubbo://10.16.20.12:20880/org.apache.dubbo.demo.DemoService?anyhost=true&application=dubbo-demo-annotation-provider&bean.name=ServiceBean:org.apache.dubbo.demo.DemoService&bind.ip=10.16.20.12&bind.port=20880&default.deprecated=false&default.dynamic=false&default.export=true&default.register=true&deprecated=false&dubbo=2.0.2&dynamic=false&export=true&generic=false&interface=org.apache.dubbo.demo.DemoService&methods=sayHello&pid=5448®ister=true&release=&side=provider×tamp=1552372020001）
url比较关键的信息：协议 IP地址 端口号 要暴露的接口路径 辅助参数(dubbo版本、时间戳、方法名)
将一些配置对象的信息添加到Map中
String name = protocolConfig.getName();
if (StringUtils.isEmpty(name)) {
name = Constants.DUBBO;
}
Map<String, String> map = new HashMap<String, String>();
map.put(Constants.SIDE_KEY, Constants.PROVIDER_SIDE);
appendRuntimeParameters(map);
appendParameters(map, application);
appendParameters(map, module);
appendParameters(map, provider, Constants.DEFAULT_KEY);
appendParameters(map, protocolConfig);
appendParameters(map, this);
//methods为methodCofig集合 ，MethodConfig中存储了<dubbo:method>标签的配置信息
//arguments为ArgumentConfig列表: 它的目的是将<dubbo:argument>标签方法参数配置也加载到map中
if (CollectionUtils.isNotEmpty(methods)) {
for (MethodConfig method : methods) {
appendParameters(map, method, method.getName());
String retryKey = method.getName() + ".retry";
if (map.containsKey(retryKey)) {
String retryValue = map.remove(retryKey);
if ("false".equals(retryValue)) {
map.put(method.getName() + ".retries", "0");
}
}
List<ArgumentConfig> arguments = method.getArguments();
if (CollectionUtils.isNotEmpty(arguments)) {
for (ArgumentConfig argument : arguments) {
// convert argument type
if (argument.getType() != null && argument.getType().length() > 0) {
Method[] methods = interfaceClass.getMethods();
// visit all methods
if (methods != null && methods.length > 0) {
for (int i = 0; i < methods.length; i++) {
String methodName = methods[i].getName();
// target the method, and get its signature
if (methodName.equals(method.getName())) {
Class<?>[] argtypes = methods[i].getParameterTypes();
// one callback in the method
if (argument.getIndex() != -1) {
if (argtypes[argument.getIndex()].getName().equals(argument.getType())) {
appendParameters(map, argument, method.getName() + "." + argument.getIndex());
} else {
throw new IllegalArgumentException("Argument config error : the index attribute and type attribute not match :index :" + argument.getIndex() + ", type:" + argument.getType());
}
} else {
// multiple callbacks in the method
for (int j = 0; j < argtypes.length; j++) {
Class<?> argclazz = argtypes[j];
if (argclazz.getName().equals(argument.getType())) {
appendParameters(map, argument, method.getName() + "." + j);
if (argument.getIndex() != -1 && argument.getIndex() != j) {
throw new IllegalArgumentException("Argument config error : the index attribute and type attribute not match :index :" + argument.getIndex() + ", type:" + argument.getType());
}
}
}
}
}
}
}
} else if (argument.getIndex() != -1) {
appendParameters(map, argument, method.getName() + "." + argument.getIndex());
} else {
throw new IllegalArgumentException("Argument config must set index or type attribute.eg: <dubbo:argument index='0' .../> or <dubbo:argument type=xxx .../>");
}
}
}
} // end of methods for
}
if (ProtocolUtils.isGeneric(generic)) {
map.put(Constants.GENERIC_KEY, generic);
map.put(Constants.METHODS_KEY, Constants.ANY_VALUE);
} else {
String revision = Version.getVersion(interfaceClass, version);
if (revision != null && revision.length() > 0) {
map.put("revision", revision);
}
String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames();
if (methods.length == 0) {
logger.warn("No method found in service interface " + interfaceClass.getName());
map.put(Constants.METHODS_KEY, Constants.ANY_VALUE);
} else {
map.put(Constants.METHODS_KEY, StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));
}
}
if (!ConfigUtils.isEmpty(token)) {
if (ConfigUtils.isDefault(token)) {
map.put(Constants.TOKEN_KEY, UUID.randomUUID().toString());
} else {
map.put(Constants.TOKEN_KEY, token);
}
}
// export service
String contextPath = protocolConfig.getContextpath();
if (StringUtils.isEmpty(contextPath) && provider != null) {
contextPath = provider.getContextpath();
}
//获取主机地址
String host = this.findConfigedHosts(protocolConfig, registryURLs, map);
//获取端口号
Integer port = this.findConfigedPorts(protocolConfig, name, map);
//拼接Url
URL url = new URL(name, host, port, (StringUtils.isEmpty(contextPath) ? "" : contextPath + "/") + path, map);
if (ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class)
.hasExtension(url.getProtocol())) {
url = ExtensionLoader.getExtensionLoader(ConfiguratorFactory.class)
.getExtension(url.getProtocol()).getConfigurator(url).configure(url);
}
String scope = url.getParameter(Constants.SCOPE_KEY);
// don't export when none is configured
if (!Constants.SCOPE_NONE.equalsIgnoreCase(scope)) {
// export to local if the config is not remote (export to remote only when config is remote)
if (!Constants.SCOPE_REMOTE.equalsIgnoreCase(scope)) {
//通过url进行本地暴露
exportLocal(url);
}
// export to remote if the config is not local (export to local only when config is local)
if (!Constants.SCOPE_LOCAL.equalsIgnoreCase(scope)) {
if (logger.isInfoEnabled()) {
logger.info("Export dubbo service " + interfaceClass.getName() + " to url " + url);
}
if (CollectionUtils.isNotEmpty(registryURLs)) {
for (URL registryURL : registryURLs) {
url = url.addParameterIfAbsent(Constants.DYNAMIC_KEY, registryURL.getParameter(Constants.DYNAMIC_KEY));
//获取监控地址
URL monitorUrl = loadMonitor(registryURL);
if (monitorUrl != null) {
//将监控地址也加入到url当中
url = url.addParameterAndEncoded(Constants.MONITOR_KEY, monitorUrl.toFullString());
}
if (logger.isInfoEnabled()) {
logger.info("Register dubbo service " + interfaceClass.getName() + " url " + url + " to registry " + registryURL);
}
// For providers, this is used to enable custom proxy to generate invoker
String proxy = url.getParameter(Constants.PROXY_KEY);
if (StringUtils.isNotEmpty(proxy)) {
registryURL = registryURL.addParameter(Constants.PROXY_KEY, proxy);
}
//生成Invoker
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, registryURL.addParameterAndEncoded(Constants.EXPORT_KEY, url.toFullString()));
//将Invoker和serviceConfig配置封装成wrapperInvoker
DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);
//对应协议进行远程暴露
Exporter<?> exporter = protocol.export(wrapperInvoker);
exporters.add(exporter);
}
} else {
Invoker<?> invoker = proxyFactory.getInvoker(ref, (Class) interfaceClass, url);
DelegateProviderMetaDataInvoker wrapperInvoker = new DelegateProviderMetaDataInvoker(invoker, this);
Exporter<?> exporter = protocol.export(wrapperInvoker);
exporters.add(exporter);
}
/**
* @since 2.7.0
* ServiceData Store
*/
MetadataReportService metadataReportService = null;
if ((metadataReportService = getMetadataReportService()) != null) {
metadataReportService.publishProvider(url);
}
}
}
this.urls.add(url);
}
本地暴露：获取Invoker（默认是javassist）、根据协议（本地暴露采用的是INJVM伪协议）生成InjvmExporter
private void exportLocal(URL url) {
if (!Constants.LOCAL_PROTOCOL.equalsIgnoreCase(url.getProtocol())) {
URL local = URL.valueOf(url.toFullString())
.setProtocol(Constants.LOCAL_PROTOCOL)
.setHost(LOCALHOST_VALUE)
.setPort(0);
Exporter<?> exporter = protocol.export(
proxyFactory.getInvoker(ref, (Class) interfaceClass, local));
exporters.add(exporter);
logger.info("Export dubbo service " + interfaceClass.getName() + " to local registry");
}
}
class InjvmExporter<T> extends AbstractExporter<T> {
private final String key;
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);
}
@Override
public void unexport() {
super.unexport();
exporterMap.remove(key);
}
}
远程暴露（Dubbo协议），生成DubboExporter，根据url打开netty服务器
public <T> Exporter<T> export(Invoker<T>) throws RpcException {
URL url = invoker.getUrl();
// export service.
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);
}
}
//打开netty服务器
openServer(url);
optimizeSerialization(url);
return exporter;
}
但是我们一般采用注册中心的方式将服务发布订阅在注册中心上 这时候会采用RegistryProtocol（伪协议）对原协议进行包装进行暴露: 这个方法 首先拼接注册中心url，获取本地url 根据原协议进行远程暴露,创建要写入注册中心的数据(url),将数据写入注册中心
public <T> Exporter<T> export(final Invoker<T> originInvoker) throws RpcException {
//拼接注册中心地址，比如：
zookeeper://172.17.162.219:2181/org.apache.dubbo.registry.RegistryService?application=dubbo-demo-api-provider&dubbo=2.0.2&export=dubbo%3A%2F%2F10.16.20.12%3A20880%2Forg.apache.dubbo.demo.DemoService%3Fanyhost%3Dtrue%26application%3Ddubbo-demo-api-provider%26bind.ip%3D10.16.20.12%26bind.port%3D20880%26default.deprecated%3Dfalse%26default.dynamic%3Dfalse%26default.export%3Dtrue%26default.register%3Dtrue%26deprecated%3Dfalse%26dubbo%3D2.0.2%26dynamic%3Dfalse%26export%3Dtrue%26generic%3Dfalse%26interface%3Dorg.apache.dubbo.demo.DemoService%26methods%3DsayHello%26pid%3D35028%26register%3Dtrue%26release%3D%26side%3Dprovider%26timestamp%3D1552466005792&pid=35028×tamp=1552465982556
URL registryUrl = getRegistryUrl(originInvoker);
// url to export locally 这里是本地地址
dubbo://10.16.20.12:20880/org.apache.dubbo.demo.DemoService?anyhost=true&application=dubbo-demo-api-provider&bind.ip=10.16.20.12&bind.port=20880&default.deprecated=false&default.dynamic=false&default.export=true&default.register=true&deprecated=false&dubbo=2.0.2&dynamic=false&export=true&generic=false&interface=org.apache.dubbo.demo.DemoService&methods=sayHello&pid=35028®ister=true&release=&side=provider×tamp=1552466005792
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);
overrideListeners.put(overrideSubscribeUrl, overrideSubscribeListener);
providerUrl = overrideUrlWithConfig(providerUrl, overrideSubscribeListener);
//export invoker 根据包装前的协议（如dubbo）进行暴露
final ExporterChangeableWrapper<T> exporter = doLocalExport(originInvoker, providerUrl);
// url to registry
final Registry registry = getRegistry(originInvoker);
//获取将要暴露的url(写入注册中心，例如zk 创建url节点)
final URL registeredProviderUrl = getRegisteredProviderUrl(providerUrl, registryUrl);
ProviderInvokerWrapper<T> providerInvokerWrapper = ProviderConsumerRegTable.registerProvider(originInvoker,
registryUrl, registeredProviderUrl);
//to judge if we need to delay publish
boolean register = registeredProviderUrl.getParameter("register", true);
if (register) {
register(registryUrl, registeredProviderUrl);
providerInvokerWrapper.setReg(true);
}
// Deprecated! Subscribe to override rules in 2.6.x or before.
registry.subscribe(overrideSubscribeUrl, overrideSubscribeListener);
exporter.setRegisterUrl(registeredProviderUrl);
exporter.setSubscribeUrl(overrideSubscribeUrl);
//Ensure that a new exporter instance is returned every time export
return new DestroyableExporter<>(exporter);
} 
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