還是先從整體架構入手，先看下Dubbo官方的架構設計圖，調用方從集羣中選擇一個提供者時，首先得調用Directory獲取Invoker列表，再根據配置的路由規則過濾掉不符合的提供者
整個Directory體系UML圖如下
使用了模板模式(注：在Dubbo體系中使用了大量的模板模式)，Node是最頂層的接口，Directory繼承了該接口，AbstractDirectory抽象類封裝了通用的實現邏輯，RegistryDirectory、StaticDirectory子類實現了具體的doList()方法
Node接口
public interface Node {
URL getUrl();
boolean isAvailable();
void destroy();
}
Directory接口
public interface Directory<T> extends Node {
/**
* get service type.
*
* @return service type.
*/
Class<T> getInterface();
/**
* list invokers.
*
* @return invokers
*/
List<Invoker<T>> list(Invocation invocation) throws RpcException;
List<Invoker<T>> getAllInvokers();
URL getConsumerUrl();
}
AbstractDirectory 抽象類
public abstract class AbstractDirectory<T> implements Directory<T> {
private final URL url;
private volatile boolean destroyed = false;
private volatile URL consumerUrl;
protected RouterChain<T> routerChain;
//構造方法
public AbstractDirectory(URL url) {
this(url, null);
}
//構造方法
public AbstractDirectory(URL url, RouterChain<T> routerChain) {
if (url == null) {
throw new IllegalArgumentException("url == null");
}
this.url = url.removeParameter(REFER_KEY).removeParameter(MONITOR_KEY);
this.consumerUrl = url.addParameters(StringUtils.parseQueryString(url.getParameterAndDecoded(REFER_KEY)))
.removeParameter(MONITOR_KEY);
setRouterChain(routerChain);
}
@Override
public List<Invoker<T>> list(Invocation invocation) throws RpcException {
if (destroyed) {
throw new RpcException("Directory already destroyed .url: " + getUrl());
}
return doList(invocation);
}
......省略所有屬性的setter和getter
protected void addRouters(List<Router> routers) {
routers = routers == null ? Collections.emptyList() : routers;
routerChain.addRouters(routers);
}
//留給子類需要實現的根據Invocation獲取所有Invoker列表的具體實現
protected abstract List<Invoker<T>> doList(Invocation invocation) throws RpcException;
}
AbstractDirectory有RegistryDirectory、StaticDirectory兩種實現
- RegistryDirectory實現了NotifyListener接口，而NotifyListener接口的notify回調方法會在註冊中心中提供者發生變化時被調用，從而達到通知RegistryDirectory更新Invoker列表的效果，它是能根據註冊中心動態變化的核心所在。
- StaticDirectory沒有實現NotifyListener接口，它是Directory的靜態列表實現，即將傳入的Invoker列表封裝成靜態的Directory對象，裏面的列表不會改變。StaticDirectory的邏輯非常簡單，在構造方法中需要傳入Invoker列表，doList方法則直接返回初始化時傳入的列表。
RegistryDirectory
因爲RegistryDirectory會動態更新Invoker列表，因此在RegistryDirectory有兩條比較重要的邏輯線
- 框架與註冊中心的訂閱，並動態更新本地Invoker列表、路由列表、配置信息
- 子類實現父類的doList方法
public class RegistryDirectory<T> extends AbstractDirectory<T> implements NotifyListener {
private static final Cluster CLUSTER = ExtensionLoader.getExtensionLoader(Cluster.class).getAdaptiveExtension();
private static final RouterFactory ROUTER_FACTORY = ExtensionLoader.getExtensionLoader(RouterFactory.class)
.getAdaptiveExtension();
private final String serviceKey;
private final Class<T> serviceType;
private final Map<String, String> queryMap;
private final URL directoryUrl;
private final boolean multiGroup;
private Protocol protocol;
private Registry registry;
private volatile boolean forbidden = false;
private boolean shouldRegister;
private boolean shouldSimplified;
private volatile URL overrideDirectoryUrl;
private volatile URL registeredConsumerUrl;
private volatile List<Configurator> configurators;
// Map<url, Invoker> cache service url to invoker mapping.
private volatile Map<String, Invoker<T>> urlInvokerMap;
private volatile List<Invoker<T>> invokers;
// Set<invokerUrls> cache invokeUrls to invokers mapping.
private volatile Set<URL> cachedInvokerUrls;
private static final ConsumerConfigurationListener CONSUMER_CONFIGURATION_LISTENER = new ConsumerConfigurationListener();
private ReferenceConfigurationListener serviceConfigurationListener;
public RegistryDirectory(Class<T> serviceType, URL url) {
super(url);
if (serviceType == null) {
throw new IllegalArgumentException("service type is null.");
}
shouldRegister = !ANY_VALUE.equals(url.getServiceInterface()) && url.getParameter(REGISTER_KEY, true);
shouldSimplified = !url.getParameter(SIMPLIFIED_KEY, false);
if (url.getServiceKey() == null || url.getServiceKey().length() == 0) {
throw new IllegalArgumentException("registry serviceKey is null.");
}
this.serviceType = serviceType;
this.serviceKey = url.getServiceKey();
this.queryMap = StringUtils.parseQueryString(url.getParameterAndDecoded(REFER_KEY));
this.overrideDirectoryUrl = this.directoryUrl = turnRegistryUrlToConsumerUrl(url);
String group = directoryUrl.getParameter(GROUP_KEY, "");
this.multiGroup = group != null && (ANY_VALUE.equals(group) || group.contains(","));
}
//訂閱某個URL的更新信息
public void subscribe(URL url) {
setConsumerUrl(url);
CONSUMER_CONFIGURATION_LISTENER.addNotifyListener(this);
serviceConfigurationListener = new ReferenceConfigurationListener(this, url);
registry.subscribe(url, this);
}
//取消訂閱某個URL的更新信息
public void unSubscribe(URL url) {
setConsumerUrl(null);
CONSUMER_CONFIGURATION_LISTENER.removeNotifyListener(this);
serviceConfigurationListener.stop();
registry.unsubscribe(url, this);
}
@Override
public void destroy() {
if (isDestroyed()) {
return;
}
// unregister.
try {
if (getRegisteredConsumerUrl() != null && registry != null && registry.isAvailable()) {
registry.unregister(getRegisteredConsumerUrl());
}
} catch (Throwable t) {
logger.warn("unexpected error when unregister service " + serviceKey + "from registry" + registry.getUrl(), t);
}
// unsubscribe.
try {
if (getConsumerUrl() != null && registry != null && registry.isAvailable()) {
registry.unsubscribe(getConsumerUrl(), this);
}
ExtensionLoader.getExtensionLoader(GovernanceRuleRepository.class).getDefaultExtension()
.removeListener(ApplicationModel.getApplication(), CONSUMER_CONFIGURATION_LISTENER);
} catch (Throwable t) {
logger.warn("unexpected error when unsubscribe service " + serviceKey + "from registry" + registry.getUrl(), t);
}
super.destroy(); // must be executed after unsubscribing
try {
destroyAllInvokers();
} catch (Throwable t) {
logger.warn("Failed to destroy service " + serviceKey, t);
}
}
//監聽到配置中心對應的URL的變化，就用調用該方法更新本地的配置數據
@Override
public synchronized void notify(List<URL> urls) {
Map<String, List<URL>> categoryUrls = urls.stream()
.filter(Objects::nonNull)
.filter(this::isValidCategory)
.filter(this::isNotCompatibleFor26x)
.collect(Collectors.groupingBy(this::judgeCategory));
//如果是configurator類型的List，則解析、合併、更新本地配置
List<URL> configuratorURLs = categoryUrls.getOrDefault(CONFIGURATORS_CATEGORY, Collections.emptyList());
this.configurators = Configurator.toConfigurators(configuratorURLs).orElse(this.configurators);
//如果是router類型的List，則解析、更新本地路由
List<URL> routerURLs = categoryUrls.getOrDefault(ROUTERS_CATEGORY, Collections.emptyList());
toRouters(routerURLs).ifPresent(this::addRouters);
// providers
List<URL> providerURLs = categoryUrls.getOrDefault(PROVIDERS_CATEGORY, Collections.emptyList());
/**
* 3.x added for extend URL address
*/
ExtensionLoader<AddressListener> addressListenerExtensionLoader = ExtensionLoader.getExtensionLoader(AddressListener.class);
List<AddressListener> supportedListeners = addressListenerExtensionLoader.getActivateExtension(getUrl(), (String[]) null);
if (supportedListeners != null && !supportedListeners.isEmpty()) {
for (AddressListener addressListener : supportedListeners) {
providerURLs = addressListener.notify(providerURLs, getConsumerUrl(),this);
}
}
//創建新的Invoker，銷燬舊Invoker
refreshOverrideAndInvoker(providerURLs);
}
//判斷監聽到變化的URL類型
private String judgeCategory(URL url) {
if (UrlUtils.isConfigurator(url)) {
return CONFIGURATORS_CATEGORY;
} else if (UrlUtils.isRoute(url)) {
return ROUTERS_CATEGORY;
} else if (UrlUtils.isProvider(url)) {
return PROVIDERS_CATEGORY;
}
return "";
}
private void refreshOverrideAndInvoker(List<URL> urls) {
// mock zookeeper://xxx?mock=return null
overrideDirectoryUrl();
refreshInvoker(urls);
}
//更新Invoker列表
private void refreshInvoker(List<URL> invokerUrls) {
//如果url的大小爲1 && 無可用的提供者 && URL中協議Protocol爲空 ，則銷燬invoker列表
if (invokerUrls.size() == 1
&& invokerUrls.get(0) != null
&& EMPTY_PROTOCOL.equals(invokerUrls.get(0).getProtocol())) {
this.forbidden = true; // Forbid to access
this.invokers = Collections.emptyList();
routerChain.setInvokers(this.invokers);
destroyAllInvokers(); // Close all invokers
} else {
//設置服務爲可用狀態
this.forbidden = false; // Allow to access
Map<String, Invoker<T>> oldUrlInvokerMap = this.urlInvokerMap;
if (invokerUrls == Collections.<URL>emptyList()) {
invokerUrls = new ArrayList<>();
}
if (invokerUrls.isEmpty() && this.cachedInvokerUrls != null) {
invokerUrls.addAll(this.cachedInvokerUrls);
} else {
///緩存invokerUrls列表，便於交叉對比
this.cachedInvokerUrls = new HashSet<>();
this.cachedInvokerUrls.addAll(invokerUrls);
}
if (invokerUrls.isEmpty()) {
return;
}
Map<String, Invoker<T>> newUrlInvokerMap = toInvokers(invokerUrls);
/**
* If the calculation is wrong, it is not processed.
*
* 1. The protocol configured by the client is inconsistent with the protocol of the server.
* eg: consumer protocol = dubbo, provider only has other protocol services(rest).
* 2. The registration center is not robust and pushes illegal specification data.
*
*/
if (CollectionUtils.isEmptyMap(newUrlInvokerMap)) {
logger.error(new IllegalStateException("urls to invokers error .invokerUrls.size :" + invokerUrls.size() + ", invoker.size :0. urls :" + invokerUrls
.toString()));
return;
}
List<Invoker<T>> newInvokers = Collections.unmodifiableList(new ArrayList<>(newUrlInvokerMap.values()));
routerChain.setInvokers(newInvokers);
this.invokers = multiGroup ? toMergeInvokerList(newInvokers) : newInvokers;
this.urlInvokerMap = newUrlInvokerMap;
try {
destroyUnusedInvokers(oldUrlInvokerMap, newUrlInvokerMap); // Close the unused Invoker
} catch (Exception e) {
logger.warn("destroyUnusedInvokers error. ", e);
}
}
}
private List<Invoker<T>> toMergeInvokerList(List<Invoker<T>> invokers) {
List<Invoker<T>> mergedInvokers = new ArrayList<>();
Map<String, List<Invoker<T>>> groupMap = new HashMap<>();
for (Invoker<T> invoker : invokers) {
String group = invoker.getUrl().getParameter(GROUP_KEY, "");
groupMap.computeIfAbsent(group, k -> new ArrayList<>());
groupMap.get(group).add(invoker);
}
if (groupMap.size() == 1) {
mergedInvokers.addAll(groupMap.values().iterator().next());
} else if (groupMap.size() > 1) {
for (List<Invoker<T>> groupList : groupMap.values()) {
StaticDirectory<T> staticDirectory = new StaticDirectory<>(groupList);
staticDirectory.buildRouterChain();
mergedInvokers.add(CLUSTER.join(staticDirectory));
}
} else {
mergedInvokers = invokers;
}
return mergedInvokers;
}
/**
* @param urls
* @return null : no routers ,do nothing
* else :routers list
*/
private Optional<List<Router>> toRouters(List<URL> urls) {
if (urls == null || urls.isEmpty()) {
return Optional.empty();
}
List<Router> routers = new ArrayList<>();
for (URL url : urls) {
if (EMPTY_PROTOCOL.equals(url.getProtocol())) {
continue;
}
String routerType = url.getParameter(ROUTER_KEY);
if (routerType != null && routerType.length() > 0) {
url = url.setProtocol(routerType);
}
try {
Router router = ROUTER_FACTORY.getRouter(url);
if (!routers.contains(router)) {
routers.add(router);
}
} catch (Throwable t) {
logger.error("convert router url to router error, url: " + url, t);
}
}
return Optional.of(routers);
}
/**
* Turn urls into invokers, and if url has been refer, will not re-reference.
*
* @param urls
* @return invokers
*/
private Map<String, Invoker<T>> toInvokers(List<URL> urls) {
Map<String, Invoker<T>> newUrlInvokerMap = new HashMap<>();
if (urls == null || urls.isEmpty()) {
return newUrlInvokerMap;
}
Set<String> keys = new HashSet<>();
String queryProtocols = this.queryMap.get(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 (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(DISABLED_KEY)) {
enabled = !url.getParameter(DISABLED_KEY, false);
} else {
enabled = url.getParameter(ENABLED_KEY, true);
}
if (enabled) {
invoker = new InvokerDelegate<>(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;
}
/**
* Merge url parameters. the order is: override > -D >Consumer > Provider
*
* @param providerUrl
* @return
*/
private URL mergeUrl(URL providerUrl) {
providerUrl = ClusterUtils.mergeUrl(providerUrl, queryMap); // Merge the consumer side parameters
providerUrl = overrideWithConfigurator(providerUrl);
providerUrl = providerUrl.addParameter(Constants.CHECK_KEY, String.valueOf(false)); // Do not check whether the connection is successful or not, always create Invoker!
// The combination of directoryUrl and override is at the end of notify, which can't be handled here
this.overrideDirectoryUrl = this.overrideDirectoryUrl.addParametersIfAbsent(providerUrl.getParameters()); // Merge the provider side parameters
if ((providerUrl.getPath() == null || providerUrl.getPath()
.length() == 0) && DUBBO_PROTOCOL.equals(providerUrl.getProtocol())) { // Compatible version 1.0
//fix by tony.chenl DUBBO-44
String path = directoryUrl.getParameter(INTERFACE_KEY);
if (path != null) {
int i = path.indexOf('/');
if (i >= 0) {
path = path.substring(i + 1);
}
i = path.lastIndexOf(':');
if (i >= 0) {
path = path.substring(0, i);
}
providerUrl = providerUrl.setPath(path);
}
}
return providerUrl;
}
private URL overrideWithConfigurator(URL providerUrl) {
// override url with configurator from "override://" URL for dubbo 2.6 and before
providerUrl = overrideWithConfigurators(this.configurators, providerUrl);
// override url with configurator from configurator from "app-name.configurators"
providerUrl = overrideWithConfigurators(CONSUMER_CONFIGURATION_LISTENER.getConfigurators(), providerUrl);
// override url with configurator from configurators from "service-name.configurators"
if (serviceConfigurationListener != null) {
providerUrl = overrideWithConfigurators(serviceConfigurationListener.getConfigurators(), providerUrl);
}
return providerUrl;
}
private URL overrideWithConfigurators(List<Configurator> configurators, URL url) {
if (CollectionUtils.isNotEmpty(configurators)) {
for (Configurator configurator : configurators) {
url = configurator.configure(url);
}
}
return url;
}
/**
* Close all invokers
*/
private void destroyAllInvokers() {
Map<String, Invoker<T>> localUrlInvokerMap = this.urlInvokerMap; // local reference
if (localUrlInvokerMap != null) {
for (Invoker<T> invoker : new ArrayList<>(localUrlInvokerMap.values())) {
try {
invoker.destroy();
} catch (Throwable t) {
logger.warn("Failed to destroy service " + serviceKey + " to provider " + invoker.getUrl(), t);
}
}
localUrlInvokerMap.clear();
}
invokers = null;
}
/**
* Check whether the invoker in the cache needs to be destroyed
* If set attribute of url: refer.autodestroy=false, the invokers will only increase without decreasing,there may be a refer leak
*
* @param oldUrlInvokerMap
* @param newUrlInvokerMap
*/
private void destroyUnusedInvokers(Map<String, Invoker<T>> oldUrlInvokerMap, Map<String, Invoker<T>> newUrlInvokerMap) {
if (newUrlInvokerMap == null || newUrlInvokerMap.size() == 0) {
destroyAllInvokers();
return;
}
// check deleted invoker
List<String> deleted = null;
if (oldUrlInvokerMap != null) {
Collection<Invoker<T>> newInvokers = newUrlInvokerMap.values();
for (Map.Entry<String, Invoker<T>> entry : oldUrlInvokerMap.entrySet()) {
if (!newInvokers.contains(entry.getValue())) {
if (deleted == null) {
deleted = new ArrayList<>();
}
deleted.add(entry.getKey());
}
}
}
if (deleted != null) {
for (String url : deleted) {
if (url != null) {
Invoker<T> invoker = oldUrlInvokerMap.remove(url);
if (invoker != null) {
try {
invoker.destroy();
if (logger.isDebugEnabled()) {
logger.debug("destroy invoker[" + invoker.getUrl() + "] success. ");
}
} catch (Exception e) {
logger.warn("destroy invoker[" + invoker.getUrl() + "] failed. " + e.getMessage(), e);
}
}
}
}
}
}
@Override
public List<Invoker<T>> doList(Invocation invocation) {
//檢查服務是否被禁用，如果沒有提供者，或者提供者被禁用了，則拋出異常
if (forbidden) {
// 1. No service provider 2. Service providers are disabled
throw new RpcException(RpcException.FORBIDDEN_EXCEPTION, "No provider available from registry " +
getUrl().getAddress() + " for service " + getConsumerUrl().getServiceKey() + " on consumer " +
NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion() +
", please check status of providers(disabled, not registered or in blacklist).");
}
if (multiGroup) {
return this.invokers == null ? Collections.emptyList() : this.invokers;
}
List<Invoker<T>> invokers = null;
try {
// 使用routerChain來過濾掉不符合規則的invoker
invokers = routerChain.route(getConsumerUrl(), invocation);
} catch (Throwable t) {
logger.error("Failed to execute router: " + getUrl() + ", cause: " + t.getMessage(), t);
}
return invokers == null ? Collections.emptyList() : invokers;
}
private void overrideDirectoryUrl() {
// merge override parameters
this.overrideDirectoryUrl = directoryUrl;
List<Configurator> localConfigurators = this.configurators; // local reference
doOverrideUrl(localConfigurators);
List<Configurator> localAppDynamicConfigurators = CONSUMER_CONFIGURATION_LISTENER.getConfigurators(); // local reference
doOverrideUrl(localAppDynamicConfigurators);
if (serviceConfigurationListener != null) {
List<Configurator> localDynamicConfigurators = serviceConfigurationListener.getConfigurators(); // local reference
doOverrideUrl(localDynamicConfigurators);
}
}
private void doOverrideUrl(List<Configurator> configurators) {
if (CollectionUtils.isNotEmpty(configurators)) {
for (Configurator configurator : configurators) {
this.overrideDirectoryUrl = configurator.configure(overrideDirectoryUrl);
}
}
}
private static class ReferenceConfigurationListener extends AbstractConfiguratorListener {
private RegistryDirectory directory;
private URL url;
ReferenceConfigurationListener(RegistryDirectory directory, URL url) {
this.directory = directory;
this.url = url;
this.initWith(DynamicConfiguration.getRuleKey(url) + CONFIGURATORS_SUFFIX);
}
void stop() {
this.stopListen(DynamicConfiguration.getRuleKey(url) + CONFIGURATORS_SUFFIX);
}
@Override
protected void notifyOverrides() {
// to notify configurator/router changes
directory.refreshInvoker(Collections.emptyList());
}
}
private static class ConsumerConfigurationListener extends AbstractConfiguratorListener {
List<RegistryDirectory> listeners = new ArrayList<>();
ConsumerConfigurationListener() {
this.initWith(ApplicationModel.getApplication() + CONFIGURATORS_SUFFIX);
}
void addNotifyListener(RegistryDirectory listener) {
this.listeners.add(listener);
}
void removeNotifyListener(RegistryDirectory listener) {
this.listeners.remove(listener);
}
@Override
protected void notifyOverrides() {
listeners.forEach(listener -> listener.refreshInvoker(Collections.emptyList()));
}
}
}