【一起学源码-微服务】Ribbon 源码三:Ribbon与Eureka整合原理分析
一枝花算不算浪漫 人气:1前言
前情回顾
上一篇讲了Ribbon的初始化过程,从LoadBalancerAutoConfiguration
到RibbonAutoConfiguration
再到RibbonClientConfiguration
,我们找到了ILoadBalancer
默认初始化的对象等。
本讲目录
这一讲我们会进一步往下探究Ribbon和Eureka是如何结合的。
通过上一讲ILoadBalancer
我们已经可以拿到一个服务所有的服务节点信息了,这里面是怎么把服务的名称转化为对应的具体host请求信息的呢?
通过这一讲 我们来一探究竟
目录如下:
- EurekaClientAutoConfiguration.getLoadBalancer()回顾
- 再次梳理Ribbon初始化过程
- ServerList实现类初始化过程
- getUpdatedListOfServers()获取注册表列表分析
- ribbon如何更新自己保存的注册表信息?
说明
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源码阅读
EurekaClientAutoConfiguration.getLoadBalancer()回顾
上一讲我们已经深入的讲解过getLoadBalancer()
方法的实现,每个serviceName都对应一个自己的SpringContext上下文信息,然后通过ILoadBalancer.class
从上下文信息中获取默认的LoadBalancer:ZoneAwareLoadBalancer
, 我们看下这个类的构造函数:
public ZoneAwareLoadBalancer(IClientConfig clientConfig, IRule rule,
IPing ping, ServerList<T> serverList, ServerListFilter<T> filter,
ServerListUpdater serverListUpdater) {
super(clientConfig, rule, ping, serverList, filter, serverListUpdater);
}
继续跟父类DynamicServerListLoadBalancer
的初始化方法:
public class DynamicServerListLoadBalancer<T extends Server> extends BaseLoadBalancer {
volatile ServerList<T> serverListImpl;
volatile ServerListFilter<T> filter;
public DynamicServerListLoadBalancer(IClientConfig clientConfig, IRule rule, IPing ping,
ServerList<T> serverList, ServerListFilter<T> filter,
ServerListUpdater serverListUpdater) {
super(clientConfig, rule, ping);
this.serverListImpl = serverList;
this.filter = filter;
this.serverListUpdater = serverListUpdater;
if (filter instanceof AbstractServerListFilter) {
((AbstractServerListFilter) filter).setLoadBalancerStats(getLoadBalancerStats());
}
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);
enableAndInitLearnNewServersFeature();
updateListOfServers();
if (primeConnection && this.getPrimeConnections() != null) {
this.getPrimeConnections()
.primeConnections(getReachableServers());
}
this.setEnablePrimingConnections(primeConnection);
LOGGER.info("DynamicServerListLoadBalancer for client {} initialized: {}", clientConfig.getClientName(), this.toString());
}
@VisibleForTesting
public void updateListOfServers() {
List<T> servers = new ArrayList<T>();
if (serverListImpl != null) {
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);
}
}
构造方法中有个restOfInit()
方法,进去后又会有updateListOfServers()
方法,看方法名就知道这个肯定是和server注册表相关的,继续往后看,servers = serverListImpl.getUpdatedListOfServers();
,这里直接调用getUpdatedListOfServers()
就获取到了所有的注册表信息。
可以看到ServerList
有四个实现类,这个到底是该调用哪个实现类的getUpdatedListOfServers()
方法呢?接着往下看。
再次梳理Ribbon初始化过程
第二讲我们已经见过Ribbon的初始化过程,并画了图整理,这里针对于之前的图再更新一下:
这里主要是增加了RibbonEurekaAutoConfiguration
和EurekaRibbonClientConfiguration
两个配置类的初始化。
ServerList实现类初始化过程
上面已经梳理过 Ribbon
初始化的过程,其中在EurekaRibbonClientConfiguration
会初始化RibbonServerList
,代码如下:
@Configuration
public class EurekaRibbonClientConfiguration {
@Bean
@ConditionalOnMissingBean
public ServerList<?> ribbonServerList(IClientConfig config, Provider<EurekaClient> eurekaClientProvider) {
if (this.propertiesFactory.isSet(ServerList.class, serviceId)) {
return this.propertiesFactory.get(ServerList.class, config, serviceId);
}
DiscoveryEnabledNIWSServerList discoveryServerList = new DiscoveryEnabledNIWSServerList(
config, eurekaClientProvider);
DomainExtractingServerList serverList = new DomainExtractingServerList(
discoveryServerList, config, this.approximateZoneFromHostname);
return serverList;
}
}
这里实际的ServerList
实际就是DiscoveryEnabledNIWSServerList
,我们看下这个类:
public class DiscoveryEnabledNIWSServerList extends AbstractServerList<DiscoveryEnabledServer>{
}
public abstract class AbstractServerList<T extends Server> implements ServerList<T>, IClientConfigAware {
}
所以可以看出来ServerList
实际就是在这里进行初始化的,上面那个serverListImpl.getUpdatedListOfServers();
即为调用DiscoveryEnabledNIWSServerList.getUpdatedListOfServers()
方法了,继续往下看。
getUpdatedListOfServers()获取注册表分析
直接看DiscoveryEnabledNIWSServerList.getUpdatedListOfServers()
源代码:
@Override
public List<DiscoveryEnabledServer> getUpdatedListOfServers(){
return obtainServersViaDiscovery();
}
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;
}
看到这里代码就已经很明显了,我们来解读下这段代码:
- 通过eurekaClientProvider获取对应EurekaClient
- 通过vipAdress(实际就是serviceName)获取对应注册表集合信息
- 将注册信息组装成
DiscoveryEnabledServer
列表
再回到DynamicServerListLoadBalancer.updateListOfServers()
中,这里获取到对应的DiscoveryEnabledServer list后调用updateAllServerList()
方法,一路跟踪这里最终会调用BaseLoadBalancer.setServersList()
public class BaseLoadBalancer extends AbstractLoadBalancer implements
PrimeConnections.PrimeConnectionListener, IClientConfigAware {
@Monitor(name = PREFIX + "AllServerList", type = DataSourceType.INFORMATIONAL)
protected volatile List<Server> allServerList = Collections
.synchronizedList(new ArrayList<Server>());
public void setServersList(List lsrv) {
Lock writeLock = allServerLock.writeLock();
logger.debug("LoadBalancer [{}]: clearing server list (SET op)", name);
ArrayList<Server> newServers = new ArrayList<Server>();
writeLock.lock();
try {
ArrayList<Server> allServers = new ArrayList<Server>();
for (Object server : lsrv) {
if (server == null) {
continue;
}
if (server instanceof String) {
server = new Server((String) server);
}
if (server instanceof Server) {
logger.debug("LoadBalancer [{}]: addServer [{}]", name, ((Server) server).getId());
allServers.add((Server) server);
} else {
throw new IllegalArgumentException(
"Type String or Server expected, instead found:"
+ server.getClass());
}
}
boolean listChanged = false;
if (!allServerList.equals(allServers)) {
listChanged = true;
if (changeListeners != null && changeListeners.size() > 0) {
List<Server> oldList = ImmutableList.copyOf(allServerList);
List<Server> newList = ImmutableList.copyOf(allServers);
for (ServerListChangeListener l: changeListeners) {
try {
l.serverListChanged(oldList, newList);
} catch (Exception e) {
logger.error("LoadBalancer [{}]: Error invoking server list change listener", name, e);
}
}
}
}
if (isEnablePrimingConnections()) {
for (Server server : allServers) {
if (!allServerList.contains(server)) {
server.setReadyToServe(false);
newServers.add((Server) server);
}
}
if (primeConnections != null) {
primeConnections.primeConnectionsAsync(newServers, this);
}
}
// This will reset readyToServe flag to true on all servers
// regardless whether
// previous priming connections are success or not
allServerList = allServers;
if (canSkipPing()) {
for (Server s : allServerList) {
s.setAlive(true);
}
upServerList = allServerList;
} else if (listChanged) {
forceQuickPing();
}
} finally {
writeLock.unlock();
}
}
}
这个过程最后用一张图总结为:
ribbon如何更新自己保存的注册表信息?
上面已经讲了 Ribbon是如何通过serviceName拉取到注册表的,我们知道EurekaClient默认是30s拉取一次注册表信息的,因为Ribbon要关联注册表信息,那么Ribbon该如何更新自己存储的注册表信息呢?
继续回到DynamicSeverListLoadBalancer.restOfInit()
方法中:
public class DynamicServerListLoadBalancer<T extends Server> extends BaseLoadBalancer {
protected volatile ServerListUpdater serverListUpdater;
void restOfInit(IClientConfig clientConfig) {
boolean primeConnection = this.isEnablePrimingConnections();
// turn this off to avoid duplicated asynchronous priming done in BaseLoadBalancer.setServerList()
this.setEnablePrimingConnections(false);
enableAndInitLearnNewServersFeature();
updateListOfServers();
if (primeConnection && this.getPrimeConnections() != null) {
this.getPrimeConnections()
.primeConnections(getReachableServers());
}
this.setEnablePrimingConnections(primeConnection);
LOGGER.info("DynamicServerListLoadBalancer for client {} initialized: {}", clientConfig.getClientName(), this.toString());
}
public void enableAndInitLearnNewServersFeature() {
LOGGER.info("Using serverListUpdater {}", serverListUpdater.getClass().getSimpleName());
serverListUpdater.start(updateAction);
}
}
重点查看enableAndInitLearnNewServersFeature()
方法,从名字我们就可以看出来这意思为激活和初始化学习新服务的功能,这里实际上就启动serverListUpdater
中的一个线程。
在最上面Ribbon初始化的过程中我们知道,在RibbonClientConfiguration
中默认初始化的ServerListUpdater
为 PollingServreListUpdater
,我们继续跟这个类的start方法:
@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 {
updateAction.doUpdate();
lastUpdated = System.currentTimeMillis();
} catch (Exception e) {
logger.warn("Failed one update cycle", e);
}
}
};
scheduledFuture = getRefreshExecutor().scheduleWithFixedDelay(
wrapperRunnable,
initialDelayMs,
refreshIntervalMs,
TimeUnit.MILLISECONDS
);
} else {
logger.info("Already active, no-op");
}
}
这里只要是执行updateAction.doUpdate();
,然后后面启动了一个调度任务,默认30s执行一次。
继续往后跟doUpdate()
方法:
public class DynamicServerListLoadBalancer<T extends Server> extends BaseLoadBalancer {
protected final ServerListUpdater.UpdateAction updateAction = new ServerListUpdater.UpdateAction() {
@Override
public void doUpdate() {
updateListOfServers();
}
};
}
这里又调用了之前通过serviceName获取对应注册服务列表的方法了。
总结到一张图如下:
总结
本文主要是重新梳理了Ribbon的初始化过程,主要是几个Configure初始化的过程,然后是Ribbon与Eureka的整合,这里也涉及到了注册表的更新逻辑。
看到这里真是被Spring的各种AutoConfigure绕晕了,哈哈,但是最后分析完 还是觉得挺清晰的,对于复杂的业务画张流程图还挺容易理解的。
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