第一步spring.factories:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.cloud.netflix.ribbon.RibbonAutoConfiguration
找到RibbonAutoConfiguration类
/**
* Auto configuration for Ribbon (client side load balancing).
*
* @author Spencer Gibb
* @author Dave Syer
* @author Biju Kunjummen
*/
@Configuration
@Conditional(RibbonAutoConfiguration.RibbonClassesConditions.class)
@RibbonClients
@AutoConfigureAfter(name = "org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration")
@AutoConfigureBefore({LoadBalancerAutoConfiguration.class, AsyncLoadBalancerAutoConfiguration.class})
@EnableConfigurationProperties({RibbonEagerLoadProperties.class, ServerIntrospectorProperties.class})
public class RibbonAutoConfiguration {
@Autowired(required = false)
private List<RibbonClientSpecification> configurations = new ArrayList<>();
@Autowired
private RibbonEagerLoadProperties ribbonEagerLoadProperties;
@Bean
public HasFeatures ribbonFeature() {
return HasFeatures.namedFeature("Ribbon", Ribbon.class);
}
@Bean
public SpringClientFactory springClientFactory() {
SpringClientFactory factory = new SpringClientFactory();
factory.setConfigurations(this.configurations);
return factory;
}
@Bean
@ConditionalOnMissingBean(LoadBalancerClient.class)
public LoadBalancerClient loadBalancerClient() {
return new RibbonLoadBalancerClient(springClientFactory());
}
@Bean
@ConditionalOnClass(name = "org.springframework.retry.support.RetryTemplate")
@ConditionalOnMissingBean
public LoadBalancedRetryFactory loadBalancedRetryPolicyFactory(final SpringClientFactory clientFactory) {
return new RibbonLoadBalancedRetryFactory(clientFactory);
}
@Bean
@ConditionalOnMissingBean
public PropertiesFactory propertiesFactory() {
return new PropertiesFactory();
}
@Bean
@ConditionalOnProperty(value = "ribbon.eager-load.enabled")
public RibbonApplicationContextInitializer ribbonApplicationContextInitializer() {
return new RibbonApplicationContextInitializer(springClientFactory(),
ribbonEagerLoadProperties.getClients());
}
@Configuration
@ConditionalOnClass(HttpRequest.class)
@ConditionalOnRibbonRestClient
protected static class RibbonClientHttpRequestFactoryConfiguration {
@Autowired
private SpringClientFactory springClientFactory;
@Bean
public RestTemplateCustomizer restTemplateCustomizer(
final RibbonClientHttpRequestFactory ribbonClientHttpRequestFactory) {
return restTemplate -> restTemplate.setRequestFactory(ribbonClientHttpRequestFactory);
}
@Bean
public RibbonClientHttpRequestFactory ribbonClientHttpRequestFactory() {
return new RibbonClientHttpRequestFactory(this.springClientFactory);
}
}
//TODO: support for autoconfiguring restemplate to use apache http client or okhttp
@Target({ ElementType.TYPE, ElementType.METHOD })
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Conditional(OnRibbonRestClientCondition.class)
@interface ConditionalOnRibbonRestClient { }
private static class OnRibbonRestClientCondition extends AnyNestedCondition {
public OnRibbonRestClientCondition() {
super(ConfigurationPhase.REGISTER_BEAN);
}
@Deprecated //remove in Edgware"
@ConditionalOnProperty("ribbon.http.client.enabled")
static class ZuulProperty {}
@ConditionalOnProperty("ribbon.restclient.enabled")
static class RibbonProperty {}
}
/**
* {@link AllNestedConditions} that checks that either multiple classes are present
*/
static class RibbonClassesConditions extends AllNestedConditions {
RibbonClassesConditions() {
super(ConfigurationPhase.PARSE_CONFIGURATION);
}
@ConditionalOnClass(IClient.class)
static class IClientPresent {
}
@ConditionalOnClass(RestTemplate.class)
static class RestTemplatePresent {
}
@ConditionalOnClass(AsyncRestTemplate.class)
static class AsyncRestTemplatePresent {
}
@ConditionalOnClass(Ribbon.class)
static class RibbonPresent {
}
}
}
首先关注创建工厂方法bean:
@Bean
public SpringClientFactory springClientFactory() {
SpringClientFactory factory = new SpringClientFactory();
factory.setConfigurations(this.configurations);
return factory;
}
SpringClientFactory构造方法：
public class SpringClientFactory extends NamedContextFactory<RibbonClientSpecification> {
static final String NAMESPACE = "ribbon";
public SpringClientFactory() {
super(RibbonClientConfiguration.class, NAMESPACE, "ribbon.client.name");
}
查看父类：NamedContextFactory实现了ApplicationContextAware，可以拿到容器上下文
public abstract class NamedContextFactory<C extends NamedContextFactory.Specification>
implements DisposableBean, ApplicationContextAware
private ApplicationContext parent;
@Override
public void setApplicationContext(ApplicationContext parent) throws BeansException {
this.parent = parent;
}
....
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) {
// Uses Environment from parent as well as beans
context.setParent(this.parent);
}
context.setDisplayName(generateDisplayName(name));
context.refresh();
return context;
}
看到createContext方法：new了一个AnnotationConfigApplicationContext，根据传入的name获取到this.configurations.containsKey是否已经有定义的service注册到context里，然后继续将其他的config注册到新创建的AnnotationConfigApplicationContext里，然后在讲AnnotationConfigApplicationContext设置到spring的context 里context.setParent(this.parent);类似springmvc和spring容器的关系。
回到RibbonAutoConfiguration,还定义了一个LoadBalancerClient值得关注：
@Bean
@ConditionalOnMissingBean(LoadBalancerClient.class)
public LoadBalancerClient loadBalancerClient() {
return new RibbonLoadBalancerClient(springClientFactory());
}
然后看下ribbon调用时做了些什么：
ServiceInstance serviceInstance = loadBalancerClient.choose("hello-server");
进入ZoneAwareLoadBalancer类
@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");
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);
}
}
判断是否有配置zone
private static final DynamicBooleanProperty ENABLED = DynamicPropertyFactory.getInstance().getBooleanProperty("ZoneAwareNIWSDiscoveryLoadBalancer.enabled", true);
没有配置zone调用父类chooseServer
/*
* Get the alive server dedicated to key
*
* @return the dedicated server
*/
public Server chooseServer(Object key) {
if (counter == null) {
counter = createCounter();
}
counter.increment();
if (rule == null) {
return null;
} else {
try {
return rule.choose(key);
} catch (Exception e) {
logger.warn("LoadBalancer [{}]: Error choosing server for key {}", name, key, e);
return null;
}
}
}
调用rule.choose(key);
rule定义默认
private final static IRule DEFAULT_RULE = new RoundRobinRule();
public interface IRule{
/*
* choose one alive server from lb.allServers or
* lb.upServers according to key
*
* @return choosen Server object. NULL is returned if none
* server is available
*/
public Server choose(Object key);
public void setLoadBalancer(ILoadBalancer lb);
public ILoadBalancer getLoadBalancer();
}
屏幕快照 2019-08-25 上午12.14.07.png
