1.容器啟動 ribbon 的初始化
1.1 ribbon 入口
1.2 spring.factories 内容
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration
1.3 進入 RibbonAutoConfiguration.java
@Configuration
@ConditionalOnClass({IClient.class, RestTemplate.class, AsyncRestTemplate.class, Ribbon.class})
@RibbonClients
@AutoConfigureAfter(
name = {"org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration"}
)
@AutoConfigureBefore({LoadBalancerAutoConfiguration.class, AsyncLoadBalancerAutoConfiguration.class})
@EnableConfigurationProperties({RibbonEagerLoadProperties.class, ServerIntrospectorProperties.class})
public class RibbonAutoConfiguration {
@Bean
public SpringClientFactory springClientFactory() {
// 執行個體化一個工廠類進入這裡
SpringClientFactory factory = new SpringClientFactory();
factory.setConfigurations(this.configurations);
return factory;
}
}
1.4 SpringClientFactory.java
public class SpringClientFactory extends NamedContextFactory<RibbonClientSpecification> {
static final String NAMESPACE = "ribbon";
public SpringClientFactory() {
//SpringClientFactory 執行個體化，注入RibbonClientConfiguration.class
super(RibbonClientConfiguration.class, "ribbon", "ribbon.client.name");
}
}
1.5 NamedContextFactory.java
public abstract class NamedContextFactory<C extends NamedContextFactory.Specification>
implements DisposableBean, ApplicationContextAware {
private Class<?> defaultConfigType;
private final String propertySourceName;
private final String propertyName;
public NamedContextFactory(Class<?> defaultConfigType, String propertySourceName,
String propertyName) {
this.defaultConfigType = defaultConfigType;
this.propertySourceName = propertySourceName;
this.propertyName = propertyName;
}
}
小結：spring ioc 啟動時候會執行個體化SpringClientFactory， 同時 會執行個體化父類對象 NamedContextFactory。同時注入RibbonClientConfiguration.class 。這個類将來這ribbon 子容器中，會注入其他元件，後面詳細說明。
2.容器啟動 openFeign 的初始化
2.1 入口
進入到@EnableFeignClients 這個注解類
2.2 EnableFeignClients .java
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
// ioc 啟動時候 會加載 FeignClientsRegistrar.class
@Import(FeignClientsRegistrar.class)
public @interface EnableFeignClients {
}
2.3 進入到 FeignClientsRegistrar.java
class FeignClientsRegistrar implements ImportBeanDefinitionRegistrar,
ResourceLoaderAware, EnvironmentAware {
// 實作了 ImportBeanDefinitionRegistrar 接口 在ioc 中必然執行registerBeanDefinitions
@Override
public void registerBeanDefinitions(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
// 會注入一些 屬性資訊比如Client ，編解碼器 及其concat(參數綁定資訊)
registerDefaultConfiguration(metadata, registry);
// 會生成一些jdk 代理
registerFeignClients(metadata, registry);
}
}
2.3.1 registerDefaultConfiguration（）
private void registerDefaultConfiguration(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
// 擷取中繼資料資訊
Map<String, Object> defaultAttrs = metadata
.getAnnotationAttributes(EnableFeignClients.class.getName(), true);
if (defaultAttrs != null && defaultAttrs.containsKey("defaultConfiguration")) {
String name;
if (metadata.hasEnclosingClass()) {
name = "default." + metadata.getEnclosingClassName();
}
else {
name = "default." + metadata.getClassName();
}
// 跟進看一下
registerClientConfiguration(registry, name,
defaultAttrs.get("defaultConfiguration"));
}
}
2.3.1.1 registerClientConfiguration()
private void registerClientConfiguration(BeanDefinitionRegistry registry, Object name,
Object configuration) {
BeanDefinitionBuilder builder = BeanDefinitionBuilder
.genericBeanDefinition(FeignClientSpecification.class);
builder.addConstructorArgValue(name);
builder.addConstructorArgValue(configuration);
// 往ioc 中注入 name= "default." + metadata.getClassName()+"."+name = "default." + metadata.getClassName();
// value =FeignClientSpecification 的bean 對象
registry.registerBeanDefinition(
name + "." + FeignClientSpecification.class.getSimpleName(),
builder.getBeanDefinition());
}
2.3.2registerFeignClient()
回到 2.3 中的 registerFeignClients(metadata, registry) 方法。
public void registerFeignClients(AnnotationMetadata metadata,
BeanDefinitionRegistry registry) {
// 擷取 掃描對象 和 eureka 中 server 中注入9個 resouce 一樣
// 這裡掃描 帶@FeignClient 的接口
ClassPathScanningCandidateComponentProvider scanner = getScanner();
scanner.setResourceLoader(this.resourceLoader);
Set<String> basePackages;
Map<String, Object> attrs = metadata
.getAnnotationAttributes(EnableFeignClients.class.getName());
AnnotationTypeFilter annotationTypeFilter = new AnnotationTypeFilter(
FeignClient.class);
final Class<?>[] clients = attrs == null ? null
: (Class<?>[]) attrs.get("clients");
if (clients == null || clients.length == 0) {
scanner.addIncludeFilter(annotationTypeFilter);
// 擷取@EnableFeignClients的掃描包路徑
basePackages = getBasePackages(metadata);
}
else {
final Set<String> clientClasses = new HashSet<>();
basePackages = new HashSet<>();
for (Class<?> clazz : clients) {
basePackages.add(ClassUtils.getPackageName(clazz));
clientClasses.add(clazz.getCanonicalName());
}
AbstractClassTestingTypeFilter filter = new AbstractClassTestingTypeFilter() {
@Override
protected boolean match(ClassMetadata metadata) {
String cleaned = metadata.getClassName().replaceAll("\\$", ".");
return clientClasses.contains(cleaned);
}
};
scanner.addIncludeFilter(
new AllTypeFilter(Arrays.asList(filter, annotationTypeFilter)));
}
for (String basePackage : basePackages) {
Set<BeanDefinition> candidateComponents = scanner
.findCandidateComponents(basePackage);
for (BeanDefinition candidateComponent : candidateComponents) {
if (candidateComponent instanceof AnnotatedBeanDefinition) {
// 擷取到帶有 @FeignClient 的接口
AnnotatedBeanDefinition beanDefinition = (AnnotatedBeanDefinition) candidateComponent;
AnnotationMetadata annotationMetadata = beanDefinition.getMetadata();
Assert.isTrue(annotationMetadata.isInterface(),
"@FeignClient can only be specified on an interface");
Map<String, Object> attributes = annotationMetadata
.getAnnotationAttributes(
FeignClient.class.getCanonicalName());
String name = getClientName(attributes);
registerClientConfiguration(registry, name,
attributes.get("configuration"));
//跟進
registerFeignClient(registry, annotationMetadata, attributes);
}
}
}
}
2.3.2.1 registerFeignClient(registry, annotationMetadata, attributes)
private void registerFeignClient(BeanDefinitionRegistry registry,
AnnotationMetadata annotationMetadata, Map<String, Object> attributes) {
String className = annotationMetadata.getClassName();
//執行個體化一個 FeignClientFactoryBean 的bean 執行個體。一下是注入一些屬性
BeanDefinitionBuilder definition = BeanDefinitionBuilder
.genericBeanDefinition(FeignClientFactoryBean.class);
validate(attributes);
definition.addPropertyValue("url", getUrl(attributes));
definition.addPropertyValue("path", getPath(attributes));
String name = getName(attributes);
definition.addPropertyValue("name", name);
definition.addPropertyValue("type", className);
definition.addPropertyValue("decode404", attributes.get("decode404"));
definition.addPropertyValue("fallback", attributes.get("fallback"));
definition.addPropertyValue("fallbackFactory", attributes.get("fallbackFactory"));
definition.setAutowireMode(AbstractBeanDefinition.AUTOWIRE_BY_TYPE);
String alias = name + "FeignClient";
AbstractBeanDefinition beanDefinition = definition.getBeanDefinition();
boolean primary = (Boolean)attributes.get("primary"); // has a default, won't be null
beanDefinition.setPrimary(primary);
String qualifier = getQualifier(attributes);
if (StringUtils.hasText(qualifier)) {
alias = qualifier;
}
// 會往ioc 中注冊一個bean [email protected] 的接口 value 為FeignClientFactoryBean.class
BeanDefinitionHolder holder = new BeanDefinitionHolder(beanDefinition, className,
new String[] { alias });
BeanDefinitionReaderUtils.registerBeanDefinition(holder, registry);
}
2.3.2.2 FeignClientFactoryBean.java
class FeignClientFactoryBean implements FactoryBean<Object>, InitializingBean,
ApplicationContextAware {
// FeignClientFactoryBean 實作了FactoryBean 接口在@FeignClient 的接口 執行個體化的時候
//會調用getObject（）方法
@Override
public Object getObject() throws Exception {
return getTarget();
}
/**
* @param <T> the target type of the Feign client
* @return a {@link Feign} client created with the specified data and the context information
*/
<T> T getTarget() {
// 從 spring 容器中擷取FeignContext.class 對象
FeignContext context = applicationContext.getBean(FeignContext.class);
//
Feign.Builder builder = feign(context);
if (!StringUtils.hasText(this.url)) {
String url;
if (!this.name.startsWith("http")) {
url = "http://" + this.name;
}
else {
url = this.name;
}
// 預設走到 這個分支
url += cleanPath();
return (T) loadBalance(builder, context, new HardCodedTarget<>(this.type,
this.name, url));
}
if (StringUtils.hasText(this.url) && !this.url.startsWith("http")) {
this.url = "http://" + this.url;
}
String url = this.url + cleanPath();
Client client = getOptional(context, Client.class);
if (client != null) {
if (client instanceof LoadBalancerFeignClient) {
// not load balancing because we have a url,
// but ribbon is on the classpath, so unwrap
client = ((LoadBalancerFeignClient)client).getDelegate();
}
builder.client(client);
}
Targeter targeter = get(context, Targeter.class);
return (T) targeter.target(this, builder, context, new HardCodedTarget<>(
this.type, this.name, url));
}
}
2.3.2.3 feign()
2.3.2.2 中的 Feign.Builder builder = feign(context);
protected Feign.Builder feign(FeignContext context) {
// 更進 在子容器中注冊 FeignLoggerFactory 對象
FeignLoggerFactory loggerFactory = get(context, FeignLoggerFactory.class);
Logger logger = loggerFactory.create(this.type);
// 往子容器中注入其他屬性
Feign.Builder builder = get(context, Feign.Builder.class)
// required values
.logger(logger)
.encoder(get(context, Encoder.class))
.decoder(get(context, Decoder.class))
.contract(get(context, Contract.class));
// @formatter:on
configureFeign(context, builder);
return builder;
}
2.3.2.4 get（）
2.3.2.3 中的 FeignLoggerFactory loggerFactory = get(context, FeignLoggerFactory.class);
protected <T> T get(FeignContext context, Class<T> type) {
// 繼續跟進
T instance = context.getInstance(this.name, type);
if (instance == null) {
throw new IllegalStateException("No bean found of type " + type + " for "
+ this.name);
}
return instance;
}
2.3.2.5 getInstance()
2.3.2.4 中的 T instance = context.getInstance(this.name, type)
public <T> T getInstance(String name, Class<T> type) {
// 首先擷取到一個容器 完事從容器中擷取到對應的bean ，繼續跟進
AnnotationConfigApplicationContext context = getContext(name);
if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context,
type).length > 0) {
return context.getBean(type);
}
return null;
}
2.3.2.6 getContext()
2.3.2.5 中的 AnnotationConfigApplicationContext context = getContext(name);
// 這個name 是@FeignClient 的name 屬性 說明不同的name 回建立不同的createContext();
protected AnnotationConfigApplicationContext getContext(String name) {
if (!this.contexts.containsKey(name)) {
synchronized (this.contexts) {
if (!this.contexts.containsKey(name)) {
//private Map<String, AnnotationConfigApplicationContext> contexts = new ConcurrentHashMap<>();
// contexts 是一個 key 是 服務名 value 為一個容器的 map 對象
// 跟進 createContext()
this.contexts.put(name, createContext(name));
}
}
}
return this.contexts.get(name);
}
2.3.2.7 createContext（）
2.3.2.6 中的 createContext(name)
protected AnnotationConfigApplicationContext createContext(String name) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
if (this.configurations.containsKey(name)) {
for (Class<?> configuration : this.configurations.get(name)
.getConfiguration()) {
context.register(configuration);
}
}
for (Map.Entry<String, C> entry : this.configurations.entrySet()) {
if (entry.getKey().startsWith("default.")) {
for (Class<?> configuration : entry.getValue().getConfiguration()) {
context.register(configuration);
}
}
}
context.register(PropertyPlaceholderAutoConfiguration.class,
this.defaultConfigType);
context.getEnvironment().getPropertySources().addFirst(new MapPropertySource(
this.propertySourceName,
Collections.<String, Object> singletonMap(this.propertyName, name)));
if (this.parent != null) {
// 這個類實作了 ApplicationContextAware 接口 說明他講spring 的上下文容器設定成父容器
context.setParent(this.parent);
}
context.setDisplayName(generateDisplayName(name));
// 走的是spring 重新整理那一套
context.refresh();
return context;
}
這個方法是 建立一個容器同時将一些配置檔案 設定到該容器中 同時會重新整理 容器
2.3.2.8 loadBalance()
回到2.3.2.2 (T) loadBalance(builder, context, new HardCodedTarget<>(this.type,
this.name, url));
protected <T> T loadBalance(Feign.Builder builder, FeignContext context,
HardCodedTarget<T> target) {
// 會往容器中注入LoadBalancerFeignClient 這個Client 執行個體
Client client = getOptional(context, Client.class);
if (client != null) {
builder.client(client);
Targeter targeter = get(context, Targeter.class);
// 跟進 這個方法
return targeter.target(this, builder, context, target);
}
throw new IllegalStateException(
"No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-netflix-ribbon?");
}
2.3.2.9 target()
2.3.2.8 targeter.target(this, builder, context, target);
@Override
public <T> T target(FeignClientFactoryBean factory, Feign.Builder feign, FeignContext context,
Target.HardCodedTarget<T> target) {
if (!(feign instanceof feign.hystrix.HystrixFeign.Builder)) {
return feign.target(target);
}
feign.hystrix.HystrixFeign.Builder builder = (feign.hystrix.HystrixFeign.Builder) feign;
SetterFactory setterFactory = getOptional(factory.getName(), context,
SetterFactory.class);
if (setterFactory != null) {
builder.setterFactory(setterFactory);
}
Class<?> fallback = factory.getFallback();
if (fallback != void.class) {
return targetWithFallback(factory.getName(), context, target, builder, fallback);
}
Class<?> fallbackFactory = factory.getFallbackFactory();
if (fallbackFactory != void.class) {
return targetWithFallbackFactory(factory.getName(), context, target, builder, fallbackFactory);
}
// 預設走這個分支 繼續跟進去
return feign.target(target);
}
2.3.2.10 Feign.java ->target（）
2.3.2.9 feign.target(target);
public <T> T target(Target<T> target) {
return build().newInstance(target);
}
2.3.2.11 HystrixFeign.java ->build()
2.3.2.10 build()
@Override
public Feign build() {
return build(null);
}
2.3.2.12 HystrixFeign.java ->build()
2.3.2.11 build()
Feign build(final FallbackFactory<?> nullableFallbackFactory) {
super.invocationHandlerFactory(new InvocationHandlerFactory() {
@Override public InvocationHandler create(Target target,
Map<Method, MethodHandler> dispatch) {
return new HystrixInvocationHandler(target, dispatch, setterFactory, nullableFallbackFactory);
}
});
super.contract(new HystrixDelegatingContract(contract));
return super.build();
}
這是一個 匿名方法 ，會建立一個 HystrixInvocationHandler 的動态代理 對象工廠 ，同時建立
contract 這個是方法入參和形參綁定的插件
2.3.2.13 Feign.java ->newInstance（）
2.3.2.10 newInstance()
public <T> T newInstance(Target<T> target) {
// 擷取到 帶有@FeignClient 接口的所有方法 将參數類型進行綁定 ，并建立一個map對象
Map<String, MethodHandler> nameToHandler = targetToHandlersByName.apply(target);
Map<Method, MethodHandler> methodToHandler = new LinkedHashMap<Method, MethodHandler>();
List<DefaultMethodHandler> defaultMethodHandlers = new LinkedList<DefaultMethodHandler>();
for (Method method : target.type().getMethods()) {
if (method.getDeclaringClass() == Object.class) {
continue;
} else if(Util.isDefault(method)) {
DefaultMethodHandler handler = new DefaultMethodHandler(method);
defaultMethodHandlers.add(handler);
methodToHandler.put(method, handler);
} else {
methodToHandler.put(method, nameToHandler.get(Feign.configKey(target.type(), method)));
}
}
InvocationHandler handler = factory.create(target, methodToHandler);
// 通過工廠方法建立 HystrixInvocationHandler的代理對象
T proxy = (T) Proxy.newProxyInstance(target.type().getClassLoader(), new Class<?>[]{target.type()}, handler);
// 将方法的map 和改動态代理進行綁定
for(DefaultMethodHandler defaultMethodHandler : defaultMethodHandlers) {
defaultMethodHandler.bindTo(proxy);
}
return proxy;
}
小結：
容器啟動後，會自動掃描指定目錄下的帶有@FeignClient 的接口，同時會為不同執行個體建立一個容器，并将 log，編解碼器 參數綁定器 注入到容器中。同時會建立 jdk 代理類，bean 的那麼為@FeignClient 的接口的bean,同時 每個方法會建立一個RequestTemplate ，儲存在map 中，key 為完成的方法名稱，
最後将jdk 動态代理和map 綁定。
3.服務的調用過程
容器中注入HystrixInvocationHandler 代理類，同時調用的時候會執行 其invoke()
3.1 HystrixInvocationHandler.java
@Override
public Object invoke(final Object proxy, final Method method, final Object[] args)
throws Throwable {
// early exit if the invoked method is from java.lang.Object
// code is the same as ReflectiveFeign.FeignInvocationHandler
if ("equals".equals(method.getName())) {
try {
Object otherHandler =
args.length > 0 && args[0] != null ? Proxy.getInvocationHandler(args[0]) : null;
return equals(otherHandler);
} catch (IllegalArgumentException e) {
return false;
}
} else if ("hashCode".equals(method.getName())) {
return hashCode();
} else if ("toString".equals(method.getName())) {
return toString();
}
HystrixCommand<Object> hystrixCommand = new HystrixCommand<Object>(setterMethodMap.get(method)) {
@Override
protected Object run() throws Exception {
try {
// 這個方法是通過 hystrixCommand.execute();觸發的 跟進看一下invoke()
return HystrixInvocationHandler.this.dispatch.get(method).invoke(args);
} catch (Exception e) {
throw e;
} catch (Throwable t) {
throw (Error) t;
}
}
@Override
protected Object getFallback() {
if (fallbackFactory == null) {
return super.getFallback();
}
try {
Object fallback = fallbackFactory.create(getExecutionException());
Object result = fallbackMethodMap.get(method).invoke(fallback, args);
if (isReturnsHystrixCommand(method)) {
return ((HystrixCommand) result).execute();
} else if (isReturnsObservable(method)) {
// Create a cold Observable
return ((Observable) result).toBlocking().first();
} else if (isReturnsSingle(method)) {
// Create a cold Observable as a Single
return ((Single) result).toObservable().toBlocking().first();
} else if (isReturnsCompletable(method)) {
((Completable) result).await();
return null;
} else {
return result;
}
} catch (IllegalAccessException e) {
// shouldn't happen as method is public due to being an interface
throw new AssertionError(e);
} catch (InvocationTargetException e) {
// Exceptions on fallback are tossed by Hystrix
throw new AssertionError(e.getCause());
}
}
};
if (Util.isDefault(method)) {
return hystrixCommand.execute();
} else if (isReturnsHystrixCommand(method)) {
return hystrixCommand;
} else if (isReturnsObservable(method)) {
// Create a cold Observable
return hystrixCommand.toObservable();
} else if (isReturnsSingle(method)) {
// Create a cold Observable as a Single
return hystrixCommand.toObservable().toSingle();
} else if (isReturnsCompletable(method)) {
return hystrixCommand.toObservable().toCompletable();
}
return hystrixCommand.execute();
}
3.2 SynchronousMethodHandler.java ->invoke
@Override
public Object invoke(Object[] argv) throws Throwable {
// 将入參塞入到方法中的 requestTemplate 中，同時傳回一個RequestTemplate
RequestTemplate template = buildTemplateFromArgs.create(argv);
Retryer retryer = this.retryer.clone();
while (true) {
try {
// 跟進 這個方法
return executeAndDecode(template);
} catch (RetryableException e) {
retryer.continueOrPropagate(e);
if (logLevel != Logger.Level.NONE) {
logger.logRetry(metadata.configKey(), logLevel);
}
continue;
}
}
}
3.3 SynchronousMethodHandler.java ->executeAndDecode
3.2 中的 executeAndDecode(template);
Object executeAndDecode(RequestTemplate template) throws Throwable {
Request request = targetRequest(template);
if (logLevel != Logger.Level.NONE) {
logger.logRequest(metadata.configKey(), logLevel, request);
}
Response response;
long start = System.nanoTime();
try {
// client 是初始化注冊的 LoadBalancerFeignClient.java
response = client.execute(request, options);
// ensure the request is set. TODO: remove in Feign 10
response.toBuilder().request(request).build();
} catch (IOException e) {
if (logLevel != Logger.Level.NONE) {
logger.logIOException(metadata.configKey(), logLevel, e, elapsedTime(start));
}
throw errorExecuting(request, e);
}
long elapsedTime = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start);
boolean shouldClose = true;
try {
if (logLevel != Logger.Level.NONE) {
response =
logger.logAndRebufferResponse(metadata.configKey(), logLevel, response, elapsedTime);
// ensure the request is set. TODO: remove in Feign 10
response.toBuilder().request(request).build();
}
if (Response.class == metadata.returnType()) {
if (response.body() == null) {
return response;
}
if (response.body().length() == null ||
response.body().length() > MAX_RESPONSE_BUFFER_SIZE) {
shouldClose = false;
return response;
}
// Ensure the response body is disconnected
byte[] bodyData = Util.toByteArray(response.body().asInputStream());
return response.toBuilder().body(bodyData).build();
}
if (response.status() >= 200 && response.status() < 300) {
if (void.class == metadata.returnType()) {
return null;
} else {
Object result = decode(response);
shouldClose = closeAfterDecode;
return result;
}
} else if (decode404 && response.status() == 404 && void.class != metadata.returnType()) {
Object result = decode(response);
shouldClose = closeAfterDecode;
return result;
} else {
throw errorDecoder.decode(metadata.configKey(), response);
}
} catch (IOException e) {
if (logLevel != Logger.Level.NONE) {
logger.logIOException(metadata.configKey(), logLevel, e, elapsedTime);
}
throw errorReading(request, response, e);
} finally {
if (shouldClose) {
ensureClosed(response.body());
}
}
}
3.4 LoadBalancerFeignClient.java ->execute（）
3.3 中的 response = client.execute(request, options);
@Override
public Response execute(Request request, Request.Options options) throws IOException {
try {
URI asUri = URI.create(request.url());
String clientName = asUri.getHost();
URI uriWithoutHost = cleanUrl(request.url(), clientName);
FeignLoadBalancer.RibbonRequest ribbonRequest = new FeignLoadBalancer.RibbonRequest(
this.delegate, request, uriWithoutHost);
//進入這裡 這是和 ribbon 有關的入口
IClientConfig requestConfig = getClientConfig(options, clientName);
return lbClient(clientName).executeWithLoadBalancer(ribbonRequest,
requestConfig).toResponse();
}
catch (ClientException e) {
IOException io = findIOException(e);
if (io != null) {
throw io;
}
throw new RuntimeException(e);
}
}
3.4.1 LoadBalancerFeignClient.java->getClientConfig
3.4 IClientConfig requestConfig = getClientConfig(options, clientName);
IClientConfig getClientConfig(Request.Options options, String clientName) {
IClientConfig requestConfig;
if (options == DEFAULT_OPTIONS) {
// 預設進入這個分支 clientName 為服務名稱(注冊到eureka上的)
requestConfig = this.clientFactory.getClientConfig(clientName);
} else {
requestConfig = new FeignOptionsClientConfig(options);
}
return requestConfig;
}
3.4.1.1 SpringClientFactory.java ->getClientConfig
3.4.1 requestConfig = this.clientFactory.getClientConfig(clientName);
public IClientConfig getClientConfig(String name) {
return (IClientConfig)this.getInstance(name, IClientConfig.class);
}
3.4.1.2 SpringClientFactory.java ->getInstance
public <C> C getInstance(String name, Class<C> type) {
// 預設走這個分支
C instance = super.getInstance(name, type);
if (instance != null) {
return instance;
} else {
IClientConfig config = (IClientConfig)this.getInstance(name, IClientConfig.class);
return instantiateWithConfig(this.getContext(name), type, config);
}
}
3.4.1.3 NamedContextFactory.java ->getInstance
3.4.1.2 C instance = super.getInstance(name, type);
public <T> T getInstance(String name, Class<T> type) {
// 進入
AnnotationConfigApplicationContext context = getContext(name);
if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context,
type).length > 0) {
return context.getBean(type);
}
return null;
}
3.4.1.4 SpringClientFactory.java ->getContext
3.4.13 AnnotationConfigApplicationContext context = getContext(name);
protected AnnotationConfigApplicationContext getContext(String name) {
// 繼續跟進
return super.getContext(name);
}
3.4.1.5 NamedContextFactory.java ->getContext
3.4.1.4 super.getContext(name);
protected AnnotationConfigApplicationContext getContext(String name) {
if (!this.contexts.containsKey(name)) {
synchronized (this.contexts) {
if (!this.contexts.containsKey(name)) {
// private Map<String, AnnotationConfigApplicationContext> contexts = new ConcurrentHashMap<>();
// key 為注冊到eueka的服務名稱 value 為一個容器
// 第一次跟進這個容器看一下
this.contexts.put(name, createContext(name));
}
}
}
return this.contexts.get(name);
}
3.4.1.6 NamedContextFactory.java ->createContext(name)
3.4.1.5 createContext(name)
protected AnnotationConfigApplicationContext createContext(String name) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
if (this.configurations.containsKey(name)) {
for (Class<?> configuration : this.configurations.get(name)
.getConfiguration()) {
context.register(configuration);
}
}
for (Map.Entry<String, C> entry : this.configurations.entrySet()) {
if (entry.getKey().startsWith("default.")) {
for (Class<?> configuration : entry.getValue().getConfiguration()) {
context.register(configuration);
}
}
}
context.register(PropertyPlaceholderAutoConfiguration.class,
this.defaultConfigType);
// 這個propertyName 為1.4 RibbonClientConfiguration.class
// ribbon 在啟動時候 将 propertySourceName 屬性指派的
context.getEnvironment().getPropertySources().addFirst(new MapPropertySource(
this.propertySourceName,
Collections.<String, Object> singletonMap(this.propertyName, name)));
if (this.parent != null) {
// Uses Environment from parent as well as beans
context.setParent(this.parent);
}
context.setDisplayName(generateDisplayName(name));
// 重新整理容器
context.refresh();
return context;
}
從以上代碼可以看書 每個eurek 注冊的服務會增加一個 容器，容器中是ribbon 相關的屬性，第一次調用的時候會建立 容器。容器重新整理的時候 會執行個體化RibbonClientConfiguration.class
。暫時進入到RibbonClientConfiguration.class 看一下裡面有哪些屬性
@Configuration
@EnableConfigurationProperties
@Import({HttpClientConfiguration.class, OkHttpRibbonConfiguration.class, RestClientRibbonConfiguration.class, HttpClientRibbonConfiguration.class})
public class RibbonClientConfiguration {
@Bean
@ConditionalOnMissingBean
public ILoadBalancer ribbonLoadBalancer(IClientConfig config, ServerList<Server> serverList, ServerListFilter<Server> serverListFilter, IRule rule, IPing ping, ServerListUpdater serverListUpdater) {
return (ILoadBalancer)(this.propertiesFactory.isSet(ILoadBalancer.class, this.name) ?
(ILoadBalancer)this.propertiesFactory.get(ILoadBalancer.class, config, this.name) :
// 預設走的是 new ZoneAwareLoadBalancer 這個分支
new ZoneAwareLoadBalancer(config, rule, ping, serverList, serverListFilter, serverListUpdater));
}
}
跟進 new ZoneAwareLoadBalancer(config, rule, ping, serverList, serverListFilter, serverListUpdater));
進入 ZoneAwareLoadBalancer.java 看一下執行個體化的過程
public ZoneAwareLoadBalancer(IClientConfig clientConfig, IRule rule,
IPing ping, ServerList<T> serverList, ServerListFilter<T> filter,
ServerListUpdater serverListUpdater) {
super(clientConfig, rule, ping, serverList, filter, serverListUpdater);
}
跟進 super(clientConfig, rule, ping, serverList, filter, serverListUpdater);
執行個體化 ZoneAwareLoadBalancer 之前 必定先執行個體化 父類DynamicServerListLoadBalancer.java。
public DynamicServerListLoadBalancer(IClientConfig clientConfig, IRule rule, IPing ping,
ServerList<T> serverList, ServerListFilter<T> filter,
ServerListUpdater serverListUpdater) {
// 一大坨 繼續跟進
super(clientConfig, rule, ping);
this.serverListImpl = serverList;
this.filter = filter;
this.serverListUpdater = serverListUpdater;
if (filter instanceof AbstractServerListFilter) {
((AbstractServerListFilter) filter).setLoadBalancerStats(getLoadBalancerStats());
}
// 這個地方打個标記 一會回來看一下
restOfInit(clientConfig);
}
跟進 super(clientConfig, rule, ping)
BaseLoadBalancer.java 的執行個體化方法
public BaseLoadBalancer(IClientConfig config, IRule rule, IPing ping) {
// 執行個體化 會執行他 看起來像是一個 配置 負載政策及其ping 的規則
initWithConfig(config, rule, ping);
}
void initWithConfig(IClientConfig clientConfig, IRule rule, IPing ping) {
this.config = clientConfig;
String clientName = clientConfig.getClientName();
this.name = clientName;
int pingIntervalTime = Integer.parseInt(""
+ clientConfig.getProperty(
CommonClientConfigKey.NFLoadBalancerPingInterval,
Integer.parseInt("30")));
int maxTotalPingTime = Integer.parseInt(""
+ clientConfig.getProperty(
CommonClientConfigKey.NFLoadBalancerMaxTotalPingTime,
Integer.parseInt("2")));
setPingInterval(pingIntervalTime);
setMaxTotalPingTime(maxTotalPingTime);
// cross associate with each other
// i.e. Rule,Ping meet your container LB
// LB, these are your Ping and Rule guys ...
// 預設配置 ZoneAvoidanceRule.java 這種負載均衡政策
setRule(rule);
//
setPing(ping);
setLoadBalancerStats(new LoadBalancerStats(clientName));
rule.setLoadBalancer(this);
if (ping instanceof AbstractLoadBalancerPing) {
((AbstractLoadBalancerPing) ping).setLoadBalancer(this);
}
logger.info("Client: {} instantiated a LoadBalancer: {}", name, this);
boolean enablePrimeConnections = clientConfig.get(
CommonClientConfigKey.EnablePrimeConnections, DefaultClientConfigImpl.DEFAULT_ENABLE_PRIME_CONNECTIONS);
if (enablePrimeConnections) {
this.setEnablePrimingConnections(true);
PrimeConnections primeConnections = new PrimeConnections(
this.getName(), clientConfig);
this.setPrimeConnections(primeConnections);
}
init();
}
跟進setPing(ping);
BaseLoadBalancer.java->setping（）
public void setPing(IPing ping) {
if (ping != null) {
if (!ping.equals(this.ping)) {
this.ping = ping;
// 預設走這個分支
setupPingTask(); // since ping data changed
}
} else {
this.ping = null;
// cancel the timer task
lbTimer.cancel();
}
}
setupPingTask();
void setupPingTask() {
// 預設走 false 分支
if (canSkipPing()) {
return;
}
if (lbTimer != null) {
lbTimer.cancel();
}
lbTimer = new ShutdownEnabledTimer("NFLoadBalancer-PingTimer-" + name,
true);
// 建立一個定時job
lbTimer.schedule(new PingTask(), 0, pingIntervalSeconds * 1000);
// 強制執行
forceQuickPing();
}
跟進 new PingTask()
定時job 30s 回執行一次 runPinger()
class PingTask extends TimerTask {
public void run() {
try {
new Pinger(pingStrategy).runPinger();
} catch (Exception e) {
logger.error("LoadBalancer [{}]: Error pinging", name, e);
}
}
}
setupPingTask() 中， forceQuickPing()
public void forceQuickPing() {
if (canSkipPing()) {
return;
}
logger.debug("LoadBalancer [{}]: forceQuickPing invoking", name);
try {
// 也會執行 runPinger()
new Pinger(pingStrategy).runPinger();
} catch (Exception e) {
logger.error("LoadBalancer [{}]: Error running forceQuickPing()", name, e);
}
}
說明 第一次會強制執行runPinger() ,完事啟動一個定時job 每隔30s執行一次
public void runPinger() throws Exception {
if (!pingInProgress.compareAndSet(false, true)) {
return; // Ping in progress - nothing to do
}
// we are "in" - we get to Ping
Server[] allServers = null;
boolean[] results = null;
Lock allLock = null;
Lock upLock = null;
try {
/*
* The readLock should be free unless an addServer operation is
* going on...
*/
allLock = allServerLock.readLock();
allLock.lock();
allServers = allServerList.toArray(new Server[allServerList.size()]);
allLock.unlock();
int numCandidates = allServers.length;
// 檢查 allServers 中的狀态,跟進一下 pingServers（）
results = pingerStrategy.pingServers(ping, allServers);
final List<Server> newUpList = new ArrayList<Server>();
final List<Server> changedServers = new ArrayList<Server>();
for (int i = 0; i < numCandidates; i++) {
boolean isAlive = results[i];
Server svr = allServers[i];
boolean oldIsAlive = svr.isAlive();
svr.setAlive(isAlive);
if (oldIsAlive != isAlive) {
changedServers.add(svr);
logger.debug("LoadBalancer [{}]: Server [{}] status changed to {}",
name, svr.getId(), (isAlive ? "ALIVE" : "DEAD"));
}
if (isAlive) {
newUpList.add(svr);
}
}
upLock = upServerLock.writeLock();
upLock.lock();
upServerList = newUpList;
upLock.unlock();
notifyServerStatusChangeListener(changedServers);
} finally {
pingInProgress.set(false);
}
}
}
跟進 results = pingerStrategy.pingServers(ping, allServers);
/**
* Default implementation for <c>IPingStrategy</c>, performs ping
* serially, which may not be desirable, if your <c>IPing</c>
* implementation is slow, or you have large number of servers.
*/
private static class SerialPingStrategy implements IPingStrategy {
@Override
public boolean[] pingServers(IPing ping, Server[] servers) {
int numCandidates = servers.length;
boolean[] results = new boolean[numCandidates];
logger.debug("LoadBalancer: PingTask executing [{}] servers configured", numCandidates);
for (int i = 0; i < numCandidates; i++) {
results[i] = false; /* Default answer is DEAD. */
try {
// NOTE: IFF we were doing a real ping
// assuming we had a large set of servers (say 15)
// the logic below will run them serially
// hence taking 15 times the amount of time it takes
// to ping each server
// A better method would be to put this in an executor
// pool
// But, at the time of this writing, we dont REALLY
// use a Real Ping (its mostly in memory eureka call)
// hence we can afford to simplify this design and run
// this
// serially
if (ping != null) {
// 逐一檢查 檢視狀态
results[i] = ping.isAlive(servers[i]);
}
} catch (Exception e) {
logger.error("Exception while pinging Server: '{}'", servers[i], e);
}
}
return results;
}
}
跟進 results[i] = ping.isAlive(servers[i]);
NIWSDiscoveryPing.java -> isAlive（）
public boolean isAlive(Server server) {
boolean isAlive = true;
if (server!=null && server instanceof DiscoveryEnabledServer){
DiscoveryEnabledServer dServer = (DiscoveryEnabledServer)server;
// eureka 執行個體
InstanceInfo instanceInfo = dServer.getInstanceInfo();
if (instanceInfo!=null){
InstanceStatus status = instanceInfo.getStatus();
if (status!=null){
isAlive = status.equals(InstanceStatus.UP);
}
}
}
return isAlive;
}
小結一下：
每隔30s 檢查一次 ，檢視每隔服務在eureka 中的狀态資訊。對于存活的就放在 servList 中。
回到 前面 DynamicServerListLoadBalancer.java -> restOfInit(clientConfig);
void restOfInit(IClientConfig clientConfig) {
boolean primeConnection = this.isEnablePrimingConnections();
// turn this off to avoid duplicated asynchronous priming done in BaseLoadBalancer.setServerList()
this.setEnablePrimingConnections(false);
// 第一次會拉取eureka 全量資訊服務資訊
enableAndInitLearnNewServersFeature();
// 跟新server 資訊 server 那邊服務的保護政策 有些下線的服務沒有剔除
updateListOfServers();
if (primeConnection && this.getPrimeConnections() != null) {
this.getPrimeConnections()
.primeConnections(getReachableServers());
}
this.setEnablePrimingConnections(primeConnection);
LOGGER.info("DynamicServerListLoadBalancer for client {} initialized: {}", clientConfig.getClientName(), this.toString());
}
跟進 enableAndInitLearnNewServersFeature()
DynamicServerListLoadBalancer.java ->enableAndInitLearnNewServersFeature
public void enableAndInitLearnNewServersFeature() {
LOGGER.info("Using serverListUpdater {}", serverListUpdater.getClass().getSimpleName());
serverListUpdater.start(updateAction);
}
PollingServerListUpdater.java ->start
跟進 serverListUpdater.start(updateAction);
@Override
public synchronized void start(final UpdateAction updateAction) {
if (isActive.compareAndSet(false, true)) {
final Runnable wrapperRunnable = new Runnable() {
@Override
public void run() {
if (!isActive.get()) {
if (scheduledFuture != null) {
scheduledFuture.cancel(true);
}
return;
}
try {
// 跟進看一下這個方法
updateAction.doUpdate();
lastUpdated = System.currentTimeMillis();
} catch (Exception e) {
logger.warn("Failed one update cycle", e);
}
}
};
// 啟動後 1s 後執行 預設30s 會執行一次 updateAction.doUpdate(); 方法
scheduledFuture = getRefreshExecutor().scheduleWithFixedDelay(
wrapperRunnable,
initialDelayMs,
refreshIntervalMs,
TimeUnit.MILLISECONDS
);
} else {
logger.info("Already active, no-op");
}
}
跟進 updateAction.doUpdate();
DynamicServerListLoadBalancer.java ->doUpdate
class NamelessClass_1 implements UpdateAction {
NamelessClass_1() {
}
public void doUpdate() {
DynamicServerListLoadBalancer.this.updateListOfServers();
}
}
跟進 updateListOfServers()
DynamicServerListLoadBalancer.java ->updateListOfServers
@VisibleForTesting
public void updateListOfServers() {
List<T> servers = new ArrayList<T>();
// 會進到這個分支
if (serverListImpl != null) {
// 先進到這裡
servers = serverListImpl.getUpdatedListOfServers();
LOGGER.debug("List of Servers for {} obtained from Discovery client: {}",
getIdentifier(), servers);
if (filter != null) {
servers = filter.getFilteredListOfServers(servers);
LOGGER.debug("Filtered List of Servers for {} obtained from Discovery client: {}",
getIdentifier(), servers);
}
}
updateAllServerList(servers);
}
servers = serverListImpl.getUpdatedListOfServers();
DomainExtractingServerList.java ->getUpdatedListOfServers
@Override
public List<DiscoveryEnabledServer> getUpdatedListOfServers() {
List<DiscoveryEnabledServer> servers = setZones(this.list
.getUpdatedListOfServers());
return servers;
}
DiscoveryEnabledNIWSServerList.java->getUpdatedListOfServers（）
@Override
public List<DiscoveryEnabledServer> getUpdatedListOfServers(){
return obtainServersViaDiscovery();
}
// 在obtainServersViaDiscovery 調用的
private List<DiscoveryEnabledServer> obtainServersViaDiscovery() {
List<DiscoveryEnabledServer> serverList = new ArrayList<DiscoveryEnabledServer>();
if (eurekaClientProvider == null || eurekaClientProvider.get() == null) {
logger.warn("EurekaClient has not been initialized yet, returning an empty list");
return new ArrayList<DiscoveryEnabledServer>();
}
EurekaClient eurekaClient = eurekaClientProvider.get();
if (vipAddresses!=null){
for (String vipAddress : vipAddresses.split(",")) {
// if targetRegion is null, it will be interpreted as the same region of client
List<InstanceInfo> listOfInstanceInfo = eurekaClient.getInstancesByVipAddress(vipAddress, isSecure, targetRegion);
for (InstanceInfo ii : listOfInstanceInfo) {
if (ii.getStatus().equals(InstanceStatus.UP)) {
if(shouldUseOverridePort){
if(logger.isDebugEnabled()){
logger.debug("Overriding port on client name: " + clientName + " to " + overridePort);
}
// copy is necessary since the InstanceInfo builder just uses the original reference,
// and we don't want to corrupt the global eureka copy of the object which may be
// used by other clients in our system
InstanceInfo copy = new InstanceInfo(ii);
if(isSecure){
ii = new InstanceInfo.Builder(copy).setSecurePort(overridePort).build();
}else{
ii = new InstanceInfo.Builder(copy).setPort(overridePort).build();
}
}
DiscoveryEnabledServer des = new DiscoveryEnabledServer(ii, isSecure, shouldUseIpAddr);
des.setZone(DiscoveryClient.getZone(ii));
serverList.add(des);
}
}
if (serverList.size()>0 && prioritizeVipAddressBasedServers){
break; // if the current vipAddress has servers, we dont use subsequent vipAddress based servers
}
}
}
return serverList;
}
小結:
每隔30s 會執行一下 ，從eureka 拉取 server 資訊，或從用戶端直接擷取或者從server 拉取。
回到DynamicServerListLoadBalancer.java -> restOfInit(clientConfig); 中的 updateListOfServers();
protected void updateAllServerList(List<T> ls) {
// other threads might be doing this - in which case, we pass
if (serverListUpdateInProgress.compareAndSet(false, true)) {
try {
for (T s : ls) {
s.setAlive(true); // set so that clients can start using these
// servers right away instead
// of having to wait out the ping cycle.
}
setServersList(ls);
// 強制檢查每一個server 看他的狀态是不是down
super.forceQuickPing();
} finally {
serverListUpdateInProgress.set(false);
}
}
}
小結一下：
容器在重新整理的時候會注入DynamicServerListLoadBalancer 對象到子容器，同時在執行個體化的時候，會建立兩個定時任務，預設都是30s 執行一次，會通過eurek client 擷取執行個體資訊，領完一個定時任務會 重新整理執行個體清單，檢查是不是down 狀态。
回到3.4 中
3.4.2 AbstractLoadBalancerAwareClient.java ->executeWithLoadBalancer
回到 LoadBalancerFeignClient.java 中的 execute 中的executeWithLoadBalancer
// 這個方法有兩個目的 1； 根據服務名及其負載政策定位及其
// 實作遠端調用
public T executeWithLoadBalancer(final S request, final IClientConfig requestConfig) throws ClientException {
LoadBalancerCommand<T> command = buildLoadBalancerCommand(request, requestConfig);
try {
// 這裡是一個匿名函數
return command.submit(
new ServerOperation<T>() {
@Override
public Observable<T> call(Server server) {
URI finalUri = reconstructURIWithServer(server, request.getUri());
S requestForServer = (S) request.replaceUri(finalUri);
try {
return Observable.just(AbstractLoadBalancerAwareClient.this.execute(requestForServer, requestConfig));
}
catch (Exception e) {
return Observable.error(e);
}
}
})
.toBlocking()
.single();
} catch (Exception e) {
Throwable t = e.getCause();
if (t instanceof ClientException) {
throw (ClientException) t;
} else {
throw new ClientException(e);
}
}
}
3.4.2.1 LoadBalancerCommand.java ->submit（）
這裡是選擇server
// 整體采用Rxjava 1.0 響應式程式設計 實作的
public Observable<T> submit(final ServerOperation<T> operation) {
final ExecutionInfoContext context = new ExecutionInfoContext();
if (listenerInvoker != null) {
try {
listenerInvoker.onExecutionStart();
} catch (AbortExecutionException e) {
return Observable.error(e);
}
}
final int maxRetrysSame = retryHandler.getMaxRetriesOnSameServer();
final int maxRetrysNext = retryHandler.getMaxRetriesOnNextServer();
// Use the load balancer
Observable<T> o =
// 建立觀察這的時候 selectServer() 負載原理 進去看一下
(server == null ? selectServer() : Observable.just(server))
.concatMap(new Func1<Server, Observable<T>>() {
@Override
// Called for each server being selected
public Observable<T> call(Server server) {
context.setServer(server);
final ServerStats stats = loadBalancerContext.getServerStats(server);
// Called for each attempt and retry
Observable<T> o = Observable
.just(server)
.concatMap(new Func1<Server, Observable<T>>() {
@Override
public Observable<T> call(final Server server) {
context.incAttemptCount();
loadBalancerContext.noteOpenConnection(stats);
if (listenerInvoker != null) {
try {
listenerInvoker.onStartWithServer(context.toExecutionInfo());
} catch (AbortExecutionException e) {
return Observable.error(e);
}
}
final Stopwatch tracer = loadBalancerContext.getExecuteTracer().start();
return operation.call(server).doOnEach(new Observer<T>() {
private T entity;
@Override
public void onCompleted() {
recordStats(tracer, stats, entity, null);
// TODO: What to do if onNext or onError are never called?
}
@Override
public void onError(Throwable e) {
recordStats(tracer, stats, null, e);
logger.debug("Got error {} when executed on server {}", e, server);
if (listenerInvoker != null) {
listenerInvoker.onExceptionWithServer(e, context.toExecutionInfo());
}
}
@Override
public void onNext(T entity) {
this.entity = entity;
if (listenerInvoker != null) {
listenerInvoker.onExecutionSuccess(entity, context.toExecutionInfo());
}
}
private void recordStats(Stopwatch tracer, ServerStats stats, Object entity, Throwable exception) {
tracer.stop();
loadBalancerContext.noteRequestCompletion(stats, entity, exception, tracer.getDuration(TimeUnit.MILLISECONDS), retryHandler);
}
});
}
});
if (maxRetrysSame > 0)
o = o.retry(retryPolicy(maxRetrysSame, true));
return o;
}
});
// 重試
if (maxRetrysNext > 0 && server == null)
o = o.retry(retryPolicy(maxRetrysNext, false));
return o.onErrorResumeNext(new Func1<Throwable, Observable<T>>() {
@Override
public Observable<T> call(Throwable e) {
if (context.getAttemptCount() > 0) {
if (maxRetrysNext > 0 && context.getServerAttemptCount() == (maxRetrysNext + 1)) {
e = new ClientException(ClientException.ErrorType.NUMBEROF_RETRIES_NEXTSERVER_EXCEEDED,
"Number of retries on next server exceeded max " + maxRetrysNext
+ " retries, while making a call for: " + context.getServer(), e);
}
else if (maxRetrysSame > 0 && context.getAttemptCount() == (maxRetrysSame + 1)) {
e = new ClientException(ClientException.ErrorType.NUMBEROF_RETRIES_EXEEDED,
"Number of retries exceeded max " + maxRetrysSame
+ " retries, while making a call for: " + context.getServer(), e);
}
}
if (listenerInvoker != null) {
listenerInvoker.onExecutionFailed(e, context.toFinalExecutionInfo());
}
return Observable.error(e);
}
});
}
3.4.2.2 LoadBalancerCommand.java ->selectServer（）
3.4.2.1 selectServer()
private Observable<Server> selectServer() {
return Observable.create(new OnSubscribe<Server>() {
@Override
public void call(Subscriber<? super Server> next) {
try {
//跟進這個方法，loadBalancerKey 為null,loadBalancerURI:不帶服務名的uri
Server server = loadBalancerContext.getServerFromLoadBalancer(loadBalancerURI, loadBalancerKey);
next.onNext(server);
next.onCompleted();
} catch (Exception e) {
next.onError(e);
}
}
});
}
3.4.2.3 LoadBalancerContext.java ->getServerFromLoadBalancer（）
public Server getServerFromLoadBalancer(@Nullable URI original, @Nullable Object loadBalancerKey) throws ClientException {
String host = null;
int port = -1;
if (original != null) {
host = original.getHost();
}
if (original != null) {
Pair<String, Integer> schemeAndPort = deriveSchemeAndPortFromPartialUri(original);
port = schemeAndPort.second();
}
// 注入的DynamicServerListLoadBalancer.java bean對象
ILoadBalancer lb = getLoadBalancer();
if (host == null) {
// Partial URI or no URI Case
// well we have to just get the right instances from lb - or we fall back
if (lb != null){
// 選server的部分
Server svc = lb.chooseServer(loadBalancerKey);
if (svc == null){
throw new ClientException(ClientException.ErrorType.GENERAL,
"Load balancer does not have available server for client: "
+ clientName);
}
host = svc.getHost();
if (host == null){
throw new ClientException(ClientException.ErrorType.GENERAL,
"Invalid Server for :" + svc);
}
logger.debug("{} using LB returned Server: {} for request {}", new Object[]{clientName, svc, original});
return svc;
} else {
// No Full URL - and we dont have a LoadBalancer registered to
// obtain a server
// if we have a vipAddress that came with the registration, we
// can use that else we
// bail out
if (vipAddresses != null && vipAddresses.contains(",")) {
throw new ClientException(
ClientException.ErrorType.GENERAL,
"Method is invoked for client " + clientName + " with partial URI of ("
+ original
+ ") with no load balancer configured."
+ " Also, there are multiple vipAddresses and hence no vip address can be chosen"
+ " to complete this partial uri");
} else if (vipAddresses != null) {
try {
Pair<String,Integer> hostAndPort = deriveHostAndPortFromVipAddress(vipAddresses);
host = hostAndPort.first();
port = hostAndPort.second();
} catch (URISyntaxException e) {
throw new ClientException(
ClientException.ErrorType.GENERAL,
"Method is invoked for client " + clientName + " with partial URI of ("
+ original
+ ") with no load balancer configured. "
+ " Also, the configured/registered vipAddress is unparseable (to determine host and port)");
}
} else {
throw new ClientException(
ClientException.ErrorType.GENERAL,
this.clientName
+ " has no LoadBalancer registered and passed in a partial URL request (with no host:port)."
+ " Also has no vipAddress registered");
}
}
} else {
// Full URL Case
// This could either be a vipAddress or a hostAndPort or a real DNS
// if vipAddress or hostAndPort, we just have to consult the loadbalancer
// but if it does not return a server, we should just proceed anyways
// and assume its a DNS
// For restClients registered using a vipAddress AND executing a request
// by passing in the full URL (including host and port), we should only
// consult lb IFF the URL passed is registered as vipAddress in Discovery
boolean shouldInterpretAsVip = false;
if (lb != null) {
shouldInterpretAsVip = isVipRecognized(original.getAuthority());
}
if (shouldInterpretAsVip) {
Server svc = lb.chooseServer(loadBalancerKey);
if (svc != null){
host = svc.getHost();
if (host == null){
throw new ClientException(ClientException.ErrorType.GENERAL,
"Invalid Server for :" + svc);
}
logger.debug("using LB returned Server: {} for request: {}", svc, original);
return svc;
} else {
// just fall back as real DNS
logger.debug("{}:{} assumed to be a valid VIP address or exists in the DNS", host, port);
}
} else {
// consult LB to obtain vipAddress backed instance given full URL
//Full URL execute request - where url!=vipAddress
logger.debug("Using full URL passed in by caller (not using load balancer): {}", original);
}
}
// end of creating final URL
if (host == null){
throw new ClientException(ClientException.ErrorType.GENERAL,"Request contains no HOST to talk to");
}
// just verify that at this point we have a full URL
return new Server(host, port);
}
3.4.2.4 ZoneAwareLoadBalancer.java ->chooseServer
3.4.2.3 Server svc = lb.chooseServer(loadBalancerKey);
@Override
public Server chooseServer(Object key) {
if (!ENABLED.get() || getLoadBalancerStats().getAvailableZones().size() <= 1) {
logger.debug("Zone aware logic disabled or there is only one zone");
// 預設走這個分支
return super.chooseServer(key);
}
Server server = null;
try {
LoadBalancerStats lbStats = getLoadBalancerStats();
Map<String, ZoneSnapshot> zoneSnapshot = ZoneAvoidanceRule.createSnapshot(lbStats);
logger.debug("Zone snapshots: {}", zoneSnapshot);
if (triggeringLoad == null) {
triggeringLoad = DynamicPropertyFactory.getInstance().getDoubleProperty(
"ZoneAwareNIWSDiscoveryLoadBalancer." + this.getName() + ".triggeringLoadPerServerThreshold", 0.2d);
}
if (triggeringBlackoutPercentage == null) {
triggeringBlackoutPercentage = DynamicPropertyFactory.getInstance().getDoubleProperty(
"ZoneAwareNIWSDiscoveryLoadBalancer." + this.getName() + ".avoidZoneWithBlackoutPercetage", 0.99999d);
}
Set<String> availableZones = ZoneAvoidanceRule.getAvailableZones(zoneSnapshot, triggeringLoad.get(), triggeringBlackoutPercentage.get());
logger.debug("Available zones: {}", availableZones);
if (availableZones != null && availableZones.size() < zoneSnapshot.keySet().size()) {
String zone = ZoneAvoidanceRule.randomChooseZone(zoneSnapshot, availableZones);
logger.debug("Zone chosen: {}", zone);
if (zone != null) {
BaseLoadBalancer zoneLoadBalancer = getLoadBalancer(zone);
server = zoneLoadBalancer.chooseServer(key);
}
}
} catch (Exception e) {
logger.error("Error choosing server using zone aware logic for load balancer={}", name, e);
}
if (server != null) {
return server;
} else {
logger.debug("Zone avoidance logic is not invoked.");
return super.chooseServer(key);
}
}
3.4.2.5 BaseLoadBalancer.java ->chooseServer
3.4.2.4 return super.chooseServer(key);
public Server chooseServer(Object key) {
if (counter == null) {
counter = createCounter();
}
counter.increment();
if (rule == null) {
return null;
} else {
try {
// 進入看一下
return rule.choose(key);
} catch (Exception e) {
logger.warn("LoadBalancer [{}]: Error choosing server for key {}", name, key, e);
return null;
}
}
}
3.4.2.6 PredicateBasedRule.java->choose
public Server choose(Object key) {
ILoadBalancer lb = getLoadBalancer();
Optional<Server> server = getPredicate().chooseRoundRobinAfterFiltering(lb.getAllServers(), key);
if (server.isPresent()) {
return server.get();
} else {
return null;
}
}
3.4.2.7 AbstractServerPredicate.java ->chooseRoundRobinAfterFiltering
/**
* Choose a server in a round robin fashion after the predicate filters a given list of servers and load balancer key.
*/
public Optional<Server> chooseRoundRobinAfterFiltering(List<Server> servers, Object loadBalancerKey) {
List<Server> eligible = getEligibleServers(servers, loadBalancerKey);
if (eligible.size() == 0) {
return Optional.absent();
}
// 看一下 incrementAndGetModulo()
return Optional.of(eligible.get(incrementAndGetModulo(eligible.size())));
}
3.4.2.8 AbstractServerPredicate.java-> incrementAndGetModulo（）
private int incrementAndGetModulo(int modulo) {
for (;;) {
int current = nextIndex.get();
int next = (current + 1) % modulo;
if (nextIndex.compareAndSet(current, next) && current < modulo)
return current;
}
}
小結 ; 這裡是負載均衡 輪訓的實作 ，代碼很簡單 文字不好描述。大概就是 每次除以serverlist 求餘，然後從List 中擷取.
3.4.3 RetryableFeignLoadBalancer.java->execute
3.4.2 AbstractLoadBalancerAwareClient.this.execute(requestForServer, requestConfig)
public RibbonResponse execute(final RibbonRequest request, IClientConfig configOverride)
throws IOException {
final Request.Options options;
if (configOverride != null) {
RibbonProperties ribbon = RibbonProperties.from(configOverride);
options = new Request.Options(
ribbon.connectTimeout(this.connectTimeout),
ribbon.readTimeout(this.readTimeout));
}
else {
options = new Request.Options(this.connectTimeout, this.readTimeout);
}
final LoadBalancedRetryPolicy retryPolicy = loadBalancedRetryFactory.createRetryPolicy(this.getClientName(), this);
RetryTemplate retryTemplate = new RetryTemplate();
BackOffPolicy backOffPolicy = loadBalancedRetryFactory.createBackOffPolicy(this.getClientName());
retryTemplate.setBackOffPolicy(backOffPolicy == null ? new NoBackOffPolicy() : backOffPolicy);
RetryListener[] retryListeners = this.loadBalancedRetryFactory.createRetryListeners(this.getClientName());
if (retryListeners != null && retryListeners.length != 0) {
retryTemplate.setListeners(retryListeners);
}
retryTemplate.setRetryPolicy(retryPolicy == null ? new NeverRetryPolicy()
: new FeignRetryPolicy(request.toHttpRequest(), retryPolicy, this, this.getClientName()));
return retryTemplate.execute(new RetryCallback<RibbonResponse, IOException>() {
@Override
public RibbonResponse doWithRetry(RetryContext retryContext) throws IOException {
Request feignRequest = null;
//on retries the policy will choose the server and set it in the context
//extract the server and update the request being made
if (retryContext instanceof LoadBalancedRetryContext) {
ServiceInstance service = ((LoadBalancedRetryContext) retryContext).getServiceInstance();
if (service != null) {
feignRequest = ((RibbonRequest) request.replaceUri(reconstructURIWithServer(new Server(service.getHost(), service.getPort()), request.getUri()))).toRequest();
}
}
if (feignRequest == null) {
feignRequest = request.toRequest();
}
// 這裡發起http 請求
Response response = request.client().execute(feignRequest, options);
if (retryPolicy.retryableStatusCode(response.status())) {
byte[] byteArray = response.body() == null ? new byte[]{} : StreamUtils.copyToByteArray(response.body().asInputStream());
response.close();
throw new RibbonResponseStatusCodeException(RetryableFeignLoadBalancer.this.clientName, response,
byteArray, request.getUri());
}
return new RibbonResponse(request.getUri(), response);
}
}, new LoadBalancedRecoveryCallback<RibbonResponse, Response>() {
@Override
protected RibbonResponse createResponse(Response response, URI uri) {
return new RibbonResponse(uri, response);
}
});
}
3.4.3.1 Default.java ->execute
@Override
public Response execute(Request request, Options options) throws IOException {
HttpURLConnection connection = convertAndSend(request, options);
return convertResponse(connection).toBuilder().request(request).build();
}
HttpURLConnection convertAndSend(Request request, Options options) throws IOException {
final HttpURLConnection
connection =
(HttpURLConnection) new URL(request.url()).openConnection();
if (connection instanceof HttpsURLConnection) {
HttpsURLConnection sslCon = (HttpsURLConnection) connection;
if (sslContextFactory != null) {
sslCon.setSSLSocketFactory(sslContextFactory);
}
if (hostnameVerifier != null) {
sslCon.setHostnameVerifier(hostnameVerifier);
}
}
connection.setConnectTimeout(options.connectTimeoutMillis());
connection.setReadTimeout(options.readTimeoutMillis());
connection.setAllowUserInteraction(false);
connection.setInstanceFollowRedirects(options.isFollowRedirects());
connection.setRequestMethod(request.method());
Collection<String> contentEncodingValues = request.headers().get(CONTENT_ENCODING);
boolean
gzipEncodedRequest =
contentEncodingValues != null && contentEncodingValues.contains(ENCODING_GZIP);
boolean
deflateEncodedRequest =
contentEncodingValues != null && contentEncodingValues.contains(ENCODING_DEFLATE);
boolean hasAcceptHeader = false;
Integer contentLength = null;
for (String field : request.headers().keySet()) {
if (field.equalsIgnoreCase("Accept")) {
hasAcceptHeader = true;
}
for (String value : request.headers().get(field)) {
if (field.equals(CONTENT_LENGTH)) {
if (!gzipEncodedRequest && !deflateEncodedRequest) {
contentLength = Integer.valueOf(value);
connection.addRequestProperty(field, value);
}
} else {
connection.addRequestProperty(field, value);
}
}
}
// Some servers choke on the default accept string.
if (!hasAcceptHeader) {
connection.addRequestProperty("Accept", "*/*");
}
if (request.body() != null) {
if (contentLength != null) {
connection.setFixedLengthStreamingMode(contentLength);
} else {
connection.setChunkedStreamingMode(8196);
}
connection.setDoOutput(true);
OutputStream out = connection.getOutputStream();
if (gzipEncodedRequest) {
out = new GZIPOutputStream(out);
} else if (deflateEncodedRequest) {
out = new DeflaterOutputStream(out);
}
try {
out.write(request.body());
} finally {
try {
out.close();
} catch (IOException suppressed) { // NOPMD
}
}
}
return connection;
}
Response convertResponse(HttpURLConnection connection) throws IOException {
int status = connection.getResponseCode();
String reason = connection.getResponseMessage();
if (status < 0) {
throw new IOException(format("Invalid status(%s) executing %s %s", status,
connection.getRequestMethod(), connection.getURL()));
}
Map<String, Collection<String>> headers = new LinkedHashMap<String, Collection<String>>();
for (Map.Entry<String, List<String>> field : connection.getHeaderFields().entrySet()) {
// response message
if (field.getKey() != null) {
headers.put(field.getKey(), field.getValue());
}
}
Integer length = connection.getContentLength();
if (length == -1) {
length = null;
}
InputStream stream;
if (status >= 400) {
stream = connection.getErrorStream();
} else {
stream = connection.getInputStream();
}
return Response.builder()
.status(status)
.reason(reason)
.headers(headers)
.body(stream, length)
.build();
}
}
以上是client 發起請求，過程 包括序列化。
總結:
容器啟動時候，會為每一個eureka 注冊的執行個體 注冊一個openfeigin 的配置容器，同時建立一個jdk 生成的動态代理，同時将每個方法 放到map 中，同時每個方法就是一個requestTemplate.
ribbbon 啟動時候 會在容器中 生成SpringClientFactory 對象。找到動态代理的invoke 方法，并且比對map中的方法，在服務第一次調用的時候 對每個eureka執行個體，生成一個容器，容器在重新整理的時候，會生成兩個30s 執行一次的定時任務。一個是30s從eureka 拉取執行個體資訊，另外一個将下線的服務剔除服務清單。最後根據ribbon 容器總的負載政策選擇一個server,最後發起服務調用。