Dubbo 服務引用的時機有兩個：
第一個是在 Spring 容器調用 ReferenceBean 的 afterPropertiesSet 方法時引用服務
第二個是在 ReferenceBean 對應的服務被注入到其他類中時引用。
這兩個引用服務的時機區別在於，第一個是餓漢式的，第二個是懶漢式的。默認情況下，Dubbo 使用懶漢式引用服務。
如果需要使用餓漢式，可通過配置 <dubbo:reference> 的 init 屬性開啓。下面我們按照 Dubbo 默認配置進行分析，整個分析過程從 ReferenceBean 的 getObject 方法開始。
方法調用流程圖：
Dubbo消費端入口：
<dubbo:reference id="GpHelloService" interface="com.itheima.dubbo.IGPHello" version="1.0.0"/>
ReferenceBean類(afterPropertiesSet 方法)
Boolean b = isInit();
if (b == null && getConsumer() != null) {
b = getConsumer().isInit();
}
if (b != null && b.booleanValue()) {
getObject();
}
getObject()方法
@Override
public Object getObject() throws Exception {
return get();
}
public synchronized T get() {
if (destroyed) {
throw new IllegalStateException("Already destroyed!");
}
if (ref == null) {
//init方法主要用於處理配置，以及調用createProxy生成代理類
init();
}
return ref;
}
ReferenceConfig類中的init方法
private void init() {
//避免重複初始化
if (initialized) {
return;
}
initialized = true;
//檢查接口的合法性
if (interfaceName == null || interfaceName.length() == 0) {
throw new IllegalStateException("<dubbo:reference interface=\"\" /> interface not allow null!");
}
//檢測consumer變量是否爲空，爲空則創建
checkDefault();
//this = <dubbo:reference singleton="true" uniqueServiceName="com.itheima.dubbo.IGPHello:1.0.0"
//interface="com.itheima.dubbo.IGPHello" generic="false" version="1.0.0" init="true" cluster="failover" id="GpHelloService" />
appendProperties(this);
if (getGeneric() == null && getConsumer() != null) {
setGeneric(getConsumer().getGeneric());
}
if (ProtocolUtils.isGeneric(getGeneric())) {
interfaceClass = GenericService.class;
} else {
try {
//interfaceClass=com.itheima.dubbo.IGPHello
interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
.getContextClassLoader());
} catch (ClassNotFoundException e) {
throw new IllegalStateException(e.getMessage(), e);
}
checkInterfaceAndMethods(interfaceClass, methods);
}
//從系統變量中獲取與接口名對應的屬性值
String resolve = System.getProperty(interfaceName);
String resolveFile = null;
if (resolve == null || resolve.length() == 0) {
//從系統屬性中獲取解析文件路徑
resolveFile = System.getProperty("dubbo.resolve.file");
if (resolveFile == null || resolveFile.length() == 0) {
//從指定位置加載配置文件
File userResolveFile = new File(new File(System.getProperty("user.home")), "dubbo-resolve.properties");
if (userResolveFile.exists()) {
//獲取文件絕對路徑
resolveFile = userResolveFile.getAbsolutePath();
}
}
if (resolveFile != null && resolveFile.length() > 0) {
Properties properties = new Properties();
FileInputStream fis = null;
try {
fis = new FileInputStream(new File(resolveFile));
//從文件中加載配置
properties.load(fis);
} catch (IOException e) {
throw new IllegalStateException("Unload " + resolveFile + ", cause: " + e.getMessage(), e);
} finally {
try {
if (null != fis) fis.close();
} catch (IOException e) {
logger.warn(e.getMessage(), e);
}
}
//獲取與接口名對應的配置
resolve = properties.getProperty(interfaceName);
}
}
if (resolve != null && resolve.length() > 0) {
url = resolve;
if (logger.isWarnEnabled()) {
if (resolveFile != null) {
logger.warn("Using default dubbo resolve file " + resolveFile + " replace " + interfaceName + "" + resolve + " to p2p invoke remote service.");
} else {
logger.warn("Using -D" + interfaceName + "=" + resolve + " to p2p invoke remote service.");
}
}
}
if (consumer != null) {
if (application == null) {
//從consumer中獲取Application 實例，對應配置文件中<dubbo:application>
application = consumer.getApplication();
}
if (module == null) {
//從consumer中獲取Module實例，對應配置文件中<dubbo:module>
module = consumer.getModule();
}
if (registries == null) {
//從consumer中獲取Module實例，對應配置文件中<dubbo:registry>
registries = consumer.getRegistries();
}
if (monitor == null) {
//從consumer中獲取Module實例，對應配置文件中<dubbo:monitor>
monitor = consumer.getMonitor();
}
}
if (module != null) {
if (registries == null) {
registries = module.getRegistries();
}
if (monitor == null) {
monitor = module.getMonitor();
}
}
if (application != null) {
if (registries == null) {
registries = application.getRegistries();
}
if (monitor == null) {
monitor = application.getMonitor();
}
}
//檢測Application合法性
checkApplication();
//
checkStub(interfaceClass);
checkMock(interfaceClass);
//添加side、協議版本信息、時間戳和進程號等信息到map中
Map<String, String> map = new HashMap<String, String>();
Map<Object, Object> attributes = new HashMap<Object, Object>();
map.put(Constants.SIDE_KEY, Constants.CONSUMER_SIDE);
map.put(Constants.DUBBO_VERSION_KEY, Version.getProtocolVersion());
map.put(Constants.TIMESTAMP_KEY, String.valueOf(System.currentTimeMillis()));
if (ConfigUtils.getPid() > 0) {
map.put(Constants.PID_KEY, String.valueOf(ConfigUtils.getPid()));
}
//非泛化服務
if (!isGeneric()) {
//獲取版本號
String revision = Version.getVersion(interfaceClass, version);
if (revision != null && revision.length() > 0) {
map.put("revision", revision);
}
//根據interfaceClass獲取methods列表，加入到map中
String[] methods = Wrapper.getWrapper(interfaceClass).getMethodNames();
if (methods.length == 0) {
logger.warn("NO method found in service interface " + interfaceClass.getName());
map.put("methods", Constants.ANY_VALUE);
} else {
map.put("methods", StringUtils.join(new HashSet<String>(Arrays.asList(methods)), ","));
}
}
map.put(Constants.INTERFACE_KEY, interfaceName);
//將ApplicationConfig、ConsumerConfig、ReferenceConfig等對象的字段信息添加到map中
appendParameters(map, application);
appendParameters(map, module);
appendParameters(map, consumer, Constants.DEFAULT_KEY);
appendParameters(map, this);
//從map中獲取前綴prefix=com.itheima.dubbo.IGPHello:1.0.0
String prefix = StringUtils.getServiceKey(map);
if (methods != null && !methods.isEmpty()) {
//遍歷MethodConfig列表
for (MethodConfig method : methods) {
appendParameters(map, method, method.getName());
//retryKey=methodName.retry
String retryKey = method.getName() + ".retry";
if (map.containsKey(retryKey)) {
String retryValue = map.remove(retryKey);
if ("false".equals(retryValue)) {
//添加重試次數配置methodName.retries
map.put(method.getName() + ".retries", "0");
}
}
appendAttributes(attributes, method, prefix + "." + method.getName());
checkAndConvertImplicitConfig(method, map, attributes);
}
}
//獲取服務消費者ip地址
String hostToRegistry = ConfigUtils.getSystemProperty(Constants.DUBBO_IP_TO_REGISTRY);
if (hostToRegistry == null || hostToRegistry.length() == 0) {
//獲取本地地址
hostToRegistry = NetUtils.getLocalHost();
} else if (isInvalidLocalHost(hostToRegistry)) {
throw new IllegalArgumentException("Specified invalid registry ip from property:" + Constants.DUBBO_IP_TO_REGISTRY + ", value:" + hostToRegistry);
}
map.put(Constants.REGISTER_IP_KEY, hostToRegistry);
//attributes are stored by system context.
StaticContext.getSystemContext().putAll(attributes);
//關鍵代碼(createProxy)
//創建代理類
ref = createProxy(map);
//根據服務名，ReferenceConfig，代理類構建 ConsumerModel，並將 ConsumerModel 存入到 ApplicationModel 中
ConsumerModel consumerModel = new ConsumerModel(getUniqueServiceName(), this, ref, interfaceClass.getMethods());
ApplicationModel.initConsumerModel(getUniqueServiceName(), consumerModel);
}
ReferenceConfig類中的createProxy方法
private T createProxy(Map<String, String> map) {
//根據map中的參數列表組成tmpUrl
//temp://localhost?application=dubbo-client&cluster=failover&dubbo=2.0.2&init=true&interface=com.itheima.dubbo.IGPHello&
//methods=sayHello&owner=wql&pid=12412®ister.ip=192.168.56.100&revision=1.0-SNAPSHOT&side=consumer×tamp=1577155533925&version=1.0.0
URL tmpUrl = new URL("temp", "localhost", 0, map);
final boolean isJvmRefer;
if (isInjvm() == null) {
if (url != null && url.length() > 0) { // if a url is specified, don't do local reference
isJvmRefer = false;
//根據 url 的協議、scope 以及 injvm 等參數檢測是否需要本地引用
//比如如果用戶顯式配置了 scope=local，此時 isInjvmRefer 返回 true
//如果配置 scope=none，則不會進行服務暴露；如果沒有配置scope或者scope=local，則會進行本地暴露。
} else if (InjvmProtocol.getInjvmProtocol().isInjvmRefer(tmpUrl)) {
// by default, reference local service if there is
isJvmRefer = true;
} else {
isJvmRefer = false;
}
} else {
//獲取 injvm 配置值
isJvmRefer = isInjvm().booleanValue();
}
//isJvmRefer=false
//本地引用
if (isJvmRefer) {
//生成本地引用URL，協議爲injvm
URL url = new URL(Constants.LOCAL_PROTOCOL, NetUtils.LOCALHOST, 0, interfaceClass.getName()).addParameters(map);
//調用refer方法構建InjvmInvoker實例
invoker = refprotocol.refer(interfaceClass, url);
if (logger.isInfoEnabled()) {
logger.info("Using injvm service " + interfaceClass.getName());
}
//遠程調用
} else {
//用戶指定的URL，可以是點對點地址，也可以是註冊中心的地址
if (url != null && url.length() > 0) {
//當需要配置多個url 時，可用分號進行分割，這裏會進行切分
String[] us = Constants.SEMICOLON_SPLIT_PATTERN.split(url);
if (us != null && us.length > 0) {
for (String u : us) {
URL url = URL.valueOf(u);
if (url.getPath() == null || url.getPath().length() == 0) {
url = url.setPath(interfaceName);
}
//檢測url協議是否爲registry，若是，表明用戶想使用指定的註冊中心
if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
//將map轉換爲查詢字符串，並作爲refer參數的值添加到url中
urls.add(url.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map)));
} else {
//合併 url，移除服務提供者的一些配置（這些配置來源於用戶配置的 url 屬性），
//比如線程池相關配置。並保留服務提供者的部分配置，比如版本，group，時間戳等
//最後將合併後的配置設置爲 url 查詢字符串中。
urls.add(ClusterUtils.mergeUrl(url, map));
}
}
}
} else {
//從註冊中心加載URL
//us = registry://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService?application=dubbo-client&dubbo=2.0.2&owner=wql&pid=12412®istry=zookeeper×tamp=1577157985630
List<URL> us = loadRegistries(false);
if (us != null && !us.isEmpty()) {
for (URL u : us) {
URL monitorUrl = loadMonitor(u);
if (monitorUrl != null) {
map.put(Constants.MONITOR_KEY, URL.encode(monitorUrl.toFullString()));
}
//添加refer參數到url中，並將url添加到urls中
urls.add(u.addParameterAndEncoded(Constants.REFER_KEY, StringUtils.toQueryString(map)));
}
}
if (urls.isEmpty()) {
throw new IllegalStateException("No such any registry to reference " + interfaceName + " on the consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion() + ", please config <dubbo:registry address=\"...\" /> to your spring config.");
}
}
//單個註冊中心或服務提供者
if (urls.size() == 1) {
//這個invoker實例是MockClusterInvoker
//invoker :interface com.itheima.dubbo.IGPHello -> zookeeper://192.168.56.102:218137d3d232
//調用RegistryProtocol的refer構建Invoker實例
invoker = refprotocol.refer(interfaceClass, urls.get(0));
} else {
//多個註冊中心或多個服務提供者，或者兩者混合
List<Invoker<?>> invokers = new ArrayList<Invoker<?>>();
URL registryURL = null;
//獲取所有的 Invoker
//通過 refprotocol 調用refer構建 Invoker，refprotocol 會在運行時根據url協議頭加載指定的 Protocol 實例，並調用實例的 refer 方法
for (URL url : urls) {
invokers.add(refprotocol.refer(interfaceClass, url));
if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
registryURL = url; // use last registry url
}
}
if (registryURL != null) { // registry url is available
// use AvailableCluster only when register's cluster is available
//如果註冊中心鏈接不爲空，則將使用 AvailableCluster
URL u = registryURL.addParameter(Constants.CLUSTER_KEY, AvailableCluster.NAME);
invoker = cluster.join(new StaticDirectory(u, invokers));
} else { // not a registry url
invoker = cluster.join(new StaticDirectory(invokers));
}
}
}
Boolean c = check;
if (c == null && consumer != null) {
c = consumer.isCheck();
}
if (c == null) {
c = true; // default true
}
//invoker可用性檢查
if (c && !invoker.isAvailable()) {
// make it possible for consumer to retry later if provider is temporarily unavailable
initialized = false;
throw new IllegalStateException("Failed to check the status of the service " + interfaceName + ". No provider available for the service " + (group == null ? "" : group + "/") + interfaceName + (version == null ? "" : ":" + version) + " from the url " + invoker.getUrl() + " to the consumer " + NetUtils.getLocalHost() + " use dubbo version " + Version.getVersion());
}
if (logger.isInfoEnabled()) {
logger.info("Refer dubbo service " + interfaceClass.getName() + " from url " + invoker.getUrl());
//Refer dubbo service com.itheima.dubbo.IGPHello from url zookeeper://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService?
//anyhost=true&application=dubbo-client&check=false&cluster=failover&default.delay=10&delay=10&dubbo=2.0.2&init=true&
//interface=com.itheima.dubbo.IGPHello&methods=sayHello&owner=wql&pid=12412®ister.ip=192.168.56.100&remote.timestamp=15771487932
//97&revision=1.0-SNAPSHOT&side=consumer×tamp=1577155533925&version=1.0.0, dubbo version: 2.6.7, current host: 192.168.56.100
}
// create service proxy
return (T) proxyFactory.getProxy(invoker);
}
從註冊中心加載URL(AbstractInterfaceConfig類中的loadRegustries方法)
protected List<URL> loadRegistries(boolean provider) {
checkRegistry();
List<URL> registryList = new ArrayList<URL>();
if (registries != null && !registries.isEmpty()) {
for (RegistryConfig config : registries) {
String address = config.getAddress();
if (address == null || address.length() == 0) {
address = Constants.ANYHOST_VALUE;
}
String sysaddress = System.getProperty("dubbo.registry.address");
if (sysaddress != null && sysaddress.length() > 0) {
address = sysaddress;
}
if (address.length() > 0 && !RegistryConfig.NO_AVAILABLE.equalsIgnoreCase(address)) {
Map<String, String> map = new HashMap<String, String>();
appendParameters(map, application);
appendParameters(map, config);
map.put("path", RegistryService.class.getName());
map.put("dubbo", Version.getProtocolVersion());
map.put(Constants.TIMESTAMP_KEY, String.valueOf(System.currentTimeMillis()));
if (ConfigUtils.getPid() > 0) {
map.put(Constants.PID_KEY, String.valueOf(ConfigUtils.getPid()));
}
if (!map.containsKey("protocol")) {
if (ExtensionLoader.getExtensionLoader(RegistryFactory.class).hasExtension("remote")) {
map.put("protocol", "remote");
} else {
map.put("protocol", "dubbo");
}
}
List<URL> urls = UrlUtils.parseURLs(address, map);
for (URL url : urls) {
url = url.addParameter(Constants.REGISTRY_KEY, url.getProtocol());
url = url.setProtocol(Constants.REGISTRY_PROTOCOL);
if ((provider && url.getParameter(Constants.REGISTER_KEY, true))
|| (!provider && url.getParameter(Constants.SUBSCRIBE_KEY, true))) {
registryList.add(url);
}
}
}
}
}
return registryList;
}
分析ReferenceConfig類中的代碼片段
interfaceClass = com.itheima.dubbo.IGPHello -> zookeeper://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService
urls = registry://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService51705101
if (urls.size() == 1) {
//interfaceClass = com.itheima.dubbo.IGPHello -> zookeeper://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService
//urls = registry://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService51705101
invoker = refprotocol.refer(interfaceClass, urls.get(0));
} else {
List<Invoker<?>> invokers = new ArrayList<Invoker<?>>();
URL registryURL = null;
for (URL url : urls) {
invokers.add(refprotocol.refer(interfaceClass, url));
if (Constants.REGISTRY_PROTOCOL.equals(url.getProtocol())) {
registryURL = url; // use last registry url
}
}
if (registryURL != null) { // registry url is available
// use AvailableCluster only when register's cluster is available
URL u = registryURL.addParameter(Constants.CLUSTER_KEY, AvailableCluster.NAME);
invoker = cluster.join(new StaticDirectory(u, invokers));
} else { // not a registry url
invoker = cluster.join(new StaticDirectory(invokers));
}
}
代碼中的 refprotocol.refer()表示protocol$Adaptive.refer()，對應protocol$Adaptive類中refer方法
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);
}
com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol)ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class).getExtension(extName);
上面指定名稱的protocol在這裏指的是RegistryProtocol對應下面代碼：
Protocol extension = ExtensionLoader.getExtensionLoader(Protocol.class).getExtension(“registry”);
映射到RegistryProtocol類中的refer方法
public <T> Invoker<T> refer(Class<T> type, URL url) throws RpcException {
//url= zookeeper://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService
url = url.setProtocol(url.getParameter(Constants.REGISTRY_KEY, Constants.DEFAULT_REGISTRY)).removeParameter(Constants.REGISTRY_KEY);
//獲得一個註冊中心,得到一個zookeeperRegistry
Registry registry = registryFactory.getRegistry(url);
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);
}
}
return doRefer(cluster, registry, type, url);
}
RegistryProtocol類中的doRefer方法
Cluster = Cluster$Adaptive(自適應擴展點)
registry = zookeeper://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService
type = interface com.itheima.dubbo.IGPHello
url = zookeeper://192.168.56.102:2181/com.alibaba.dubbo.registry.RegistryService
private <T> Invoker<T> doRefer(Cluster cluster, Registry registry, Class<T> type, URL url) {
RegistryDirectory<T> directory = new RegistryDirectory<T>(type, url);
directory.setRegistry(registry);
//protocol = protoco$Adaptive
directory.setProtocol(protocol);
// all attributes of REFER_KEY
Map<String, String> parameters = new HashMap<String, String>(directory.getUrl().getParameters());
// subscribeUrl = consumer://192.168.56.100/com.itheima.dubbo.IGPHello?application=dubbo-client&dubbo=2.0.2&interface=com.itheima.dubbo.IGPHello
URL subscribeUrl = new URL(Constants.CONSUMER_PROTOCOL, parameters.remove(Constants.REGISTER_IP_KEY), 0, type.getName(), parameters);
//會把customer地址註冊到註冊中心
if (!Constants.ANY_VALUE.equals(url.getServiceInterface())
&& url.getParameter(Constants.REGISTER_KEY, true)) {
URL registeredConsumerUrl = getRegisteredConsumerUrl(subscribeUrl, url);
registry.register(registeredConsumerUrl);
directory.setRegisteredConsumerUrl(registeredConsumerUrl);
}
//訂閱
directory.subscribe(subscribeUrl.addParameter(Constants.CATEGORY_KEY,
Constants.PROVIDERS_CATEGORY
+ "," + Constants.CONFIGURATORS_CATEGORY
+ "," + Constants.ROUTERS_CATEGORY));
//下面解析
Invoker invoker = cluster.join(directory);
//join方法實現的是MockClusterWrapper類中的join方法
ProviderConsumerRegTable.registerConsumer(invoker, url, subscribeUrl, directory);
return invoker;
}
從zookeeper中訂閱（RegistryProtocol類）
RegistryDirectory<T> directory = new RegistryDirectory<T>(type, url);
....
directory.subscribe(subscribeUrl.addParameter(Constants.CATEGORY_KEY,
Constants.PROVIDERS_CATEGORY
+ "," + Constants.CONFIGURATORS_CATEGORY
+ "," + Constants.ROUTERS_CATEGORY));
RegistryDirectory類中(subscribe方法)
public void subscribe(URL url) {
setConsumerUrl(url);
registry.subscribe(url, this);
}
FailbackRegistry類中的(subscribe方法)
public void subscribe(URL url, NotifyListener listener) {
//先調用父類(AbstractRegistry)的中的subscribe
//url=consumer://192.168.56.100/com.itheima.dubbo.IGPHello?application=dubbo-client&category=providers,configurators,routers&cluster=failover&dubbo=2.0.2&init=true&interface=com.itheima.dubbo.IGPHello&methods=sayHello&owner=wql&pid=8800&revision=1.0-SNAPSHOT&side=consumer×tamp=1577324210064&version=1.0.0
super.subscribe(url, listener);
removeFailedSubscribed(url, listener);
try {
//向服務器端發送訂閱請求(子類ZookeeperRegistry)
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);
}
}
private void addFailedSubscribed(URL url, NotifyListener listener) {
Set<NotifyListener> listeners = failedSubscribed.get(url);
if (listeners == null) {
failedSubscribed.putIfAbsent(url, new ConcurrentHashSet<NotifyListener>());
listeners = failedSubscribed.get(url);
}
listeners.add(listener);
}
ZookeeperRegistry類中doSubscribe方法
protected void doSubscribe(final URL url, final NotifyListener listener) {
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>();
//path=/dubbo/com.itheima.dubbo.IGPHello/providers
//path=/dubbo/com.itheima.dubbo.IGPHello/configurators
//path=/dubbo/com.itheima.dubbo.IGPHello/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);
}
//zookeeper創建監聽目錄
//1:/dubbo/com.itheima.dubbo.IGPHello/providers
//2:/dubbo/com.itheima.dubbo.IGPHello/configurators
//3:/dubbo/com.itheima.dubbo.IGPHello/routers
zkClient.create(path, false);
List<String> children = zkClient.addChildListener(path, zkListener);
if (children != null) {
urls.addAll(toUrlsWithEmpty(url, path, children));
}
}
//通知
notify(url, listener, urls);
}
} catch (Throwable e) {
throw new RpcException("Failed to subscribe " + url + " to zookeeper " + getUrl() + ", cause: " + e.getMessage(), e);
}
}
FailbackRegistry類中的notify方法
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 {
//具體的通知
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類中的doNotify方法
protected void doNotify(URL url, NotifyListener listener, List<URL> urls) {
super.notify(url, listener, urls);
}
調用父類(AbstractRegistry)中的notify方法
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);
}
//對provider,configuations,routers,路徑下的進行刷新
for (Map.Entry<String, List<URL>> entry : result.entrySet()) {
String category = entry.getKey();
List<URL> categoryList = entry.getValue();
categoryNotified.put(category, categoryList);
saveProperties(url);
listener.notify(categoryList);
}
}
listener.notify(),調用的是RegisterDirectory類中的notify方法
public synchronized void notify(List<URL> urls) {
List<URL> invokerUrls = new ArrayList<URL>();
List<URL> routerUrls = new ArrayList<URL>();
List<URL> configuratorUrls = new ArrayList<URL>();
for (URL url : urls) {
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
refreshInvoker(invokerUrls);
}
RegisterDirectory類中的refreshInvoker方法
/**
* Convert the invokerURL list to the Invoker Map. The rules of the conversion are as follows:
* 1.If URL has been converted to invoker, it is no longer re-referenced and obtained directly from the cache, and notice that any parameter changes in the URL will be re-referenced.
* 2.If the incoming invoker list is not empty, it means that it is the latest invoker list
* 3.If the list of incoming invokerUrl is empty, It means that the rule is only a override rule or a route rule, which needs to be re-contrasted to decide whether to re-reference.
*
* @param invokerUrls this parameter can't be null
*/
private void refreshInvoker(List<URL> invokerUrls) {
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;
}
//核心部分：將url列表轉換爲Invoker map
Map<String, Invoker<T>> newUrlInvokerMap = 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);
}
}
}
RegisterDirectory類中的toInvokers方法
//Turn urls into invokers, and if url has been refer, will not re-reference.
//將urls轉爲invokers，並且如果url被映射，將不會再進行映射
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) {
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;
}
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