Eureka-server原始碼分析
阿新 • • 發佈：2018-11-03
作者：陳剛，叩丁狼高階講師。本文為原創文章，轉載請註明出處。
我們在分析eureka-client的時候發現他是通過Http Rest 的方式做請求的，那麼eureka-server一定是基於Rest風格 類似SpringMvc一樣的模式接受處理請求。在 EurekaServerAutoConfiguration 自動配置類中有一個 jerseyFilterRegistration方法，這個方法表明eureka-server使用了Jersey實現Rest
/** * Register the Jersey filter */ @Bean public FilterRegistrationBean jerseyFilterRegistration( javax.ws.rs.core.Application eurekaJerseyApp) { FilterRegistrationBean bean = new FilterRegistrationBean(); bean.setFilter(new ServletContainer(eurekaJerseyApp)); bean.setOrder(Ordered.LOWEST_PRECEDENCE); bean.setUrlPatterns( Collections.singletonList(EurekaConstants.DEFAULT_PREFIX + "/*")); return bean; }
這裡在註冊一個 Jersey 的 filter ，配置好相應的Filter 和 url對映等
Eureka Server對於Eureka client的REST請求的定義都位於com.netflix.eureka.resources包下，我們先來看
com.netflix.eureka.resources.ApplicationResource下面的addInstance方法，看名字就知道是新增服務例項
@POST @Consumes({"application/json", "application/xml"}) public Response addInstance(InstanceInfo info, @HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication) { logger.debug("Registering instance {} (replication={})", info.getId(), isReplication); // validate that the instanceinfo contains all the necessary required fields if (isBlank(info.getId())) { return Response.status(400).entity("Missing instanceId").build(); } else if (isBlank(info.getHostName())) { return Response.status(400).entity("Missing hostname").build(); } else if (isBlank(info.getIPAddr())) { return Response.status(400).entity("Missing ip address").build(); } else if (isBlank(info.getAppName())) { return Response.status(400).entity("Missing appName").build(); } else if (!appName.equals(info.getAppName())) { return Response.status(400).entity("Mismatched appName, expecting " + appName + " but was " + info.getAppName()).build(); } else if (info.getDataCenterInfo() == null) { return Response.status(400).entity("Missing dataCenterInfo").build(); } else if (info.getDataCenterInfo().getName() == null) { return Response.status(400).entity("Missing dataCenterInfo Name").build(); } // handle cases where clients may be registering with bad DataCenterInfo with missing data DataCenterInfo dataCenterInfo = info.getDataCenterInfo(); if (dataCenterInfo instanceof UniqueIdentifier) { String dataCenterInfoId = ((UniqueIdentifier) dataCenterInfo).getId(); if (isBlank(dataCenterInfoId)) { boolean experimental = "true".equalsIgnoreCase(serverConfig.getExperimental("registration.validation.dataCenterInfoId")); if (experimental) { String entity = "DataCenterInfo of type " + dataCenterInfo.getClass() + " must contain a valid id"; return Response.status(400).entity(entity).build(); } else if (dataCenterInfo instanceof AmazonInfo) { AmazonInfo amazonInfo = (AmazonInfo) dataCenterInfo; String effectiveId = amazonInfo.get(AmazonInfo.MetaDataKey.instanceId); if (effectiveId == null) { amazonInfo.getMetadata().put(AmazonInfo.MetaDataKey.instanceId.getName(), info.getId()); } } else { logger.warn("Registering DataCenterInfo of type {} without an appropriate id", dataCenterInfo.getClass()); } } } registry.register(info, "true".equals(isReplication)); return Response.status(204).build(); // 204 to be backwards compatible
InstanceInfo 引數就是客戶端提交的服務元配置資訊，
做了一大堆判斷後呼叫了com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl.register： 進行註冊，我們跟蹤進去
@Override public void register(final InstanceInfo info, final boolean isReplication) { int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS; if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) { leaseDuration = info.getLeaseInfo().getDurationInSecs(); } super.register(info, leaseDuration, isReplication); replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication); }
繼續跟蹤 super.register ：呼叫了父類的註冊方法。
/**
* Registers a new instance with a given duration.
*
* @see com.netflix.eureka.lease.LeaseManager#register(java.lang.Object, int, boolean)
*/
public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
try {
read.lock();
Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName());
REGISTER.increment(isReplication);
if (gMap == null) {
final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>();
gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap);
if (gMap == null) {
gMap = gNewMap;
}
}
這裡我們看到 ConcurrentHashMap<String, Lease<InstanceInfo>> 這樣的一個 執行緒安全的map去存放客戶端註冊的服務，
它是一個兩層Map結構，第一層的key儲存服務名：InstanceInfo中的appName屬性，第二層的key儲存例項名：InstanceInfo中的instanceId屬性。
服務續約在 com.netflix.eureka.resources.InstanceResource#renewLease方法中
@PUT
public Response renewLease(
@HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication,
@QueryParam("overriddenstatus") String overriddenStatus,
@QueryParam("status") String status,
@QueryParam("lastDirtyTimestamp") String lastDirtyTimestamp) {
boolean isFromReplicaNode = "true".equals(isReplication);
boolean isSuccess = registry.renew(app.getName(), id, isFromReplicaNode);
獲取到客戶端服務名字 呼叫registry.renew實現續約 ，我們跟蹤進去最終會呼叫 com.netflix.eureka.registry.AbstractInstanceRegistry#renew方法
public boolean renew(String appName, String id, boolean isReplication) {
RENEW.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
Lease<InstanceInfo> leaseToRenew = null;
if (gMap != null) {
leaseToRenew = gMap.get(id);
}
if (leaseToRenew == null) {
RENEW_NOT_FOUND.increment(isReplication);
logger.warn("DS: Registry: lease doesn't exist, registering resource: {} - {}", appName, id);
return false;
} else {
InstanceInfo instanceInfo = leaseToRenew.getHolder();
if (instanceInfo != null) {
// touchASGCache(instanceInfo.getASGName());
InstanceStatus overriddenInstanceStatus = this.getOverriddenInstanceStatus(
instanceInfo, leaseToRenew, isReplication);
if (overriddenInstanceStatus == InstanceStatus.UNKNOWN) {
logger.info("Instance status UNKNOWN possibly due to deleted override for instance {}"
+ "; re-register required", instanceInfo.getId());
RENEW_NOT_FOUND.increment(isReplication);
return false;
}
if (!instanceInfo.getStatus().equals(overriddenInstanceStatus)) {
logger.info(
"The instance status {} is different from overridden instance status {} for instance {}. "
+ "Hence setting the status to overridden status", instanceInfo.getStatus().name(),
instanceInfo.getOverriddenStatus().name(),
instanceInfo.getId());
instanceInfo.setStatusWithoutDirty(overriddenInstanceStatus);
}
}
renewsLastMin.increment();
leaseToRenew.renew();
return true;
}
Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
leaseToRenew = gMap.get(id); 在獲取註冊的服務例項
instanceInfo.setStatusWithoutDirty(overriddenInstanceStatus); 在修改服務例項的狀態
leaseToRenew.renew(); 在增加租約時間
public void renew() {
lastUpdateTimestamp = System.currentTimeMillis() + duration;
}
追蹤 InstanceResource#cancelLease() 方法,最終會呼叫 com.netflix.eureka.registry.AbstractInstanceRegistry#internalCancel
protected boolean internalCancel(String appName, String id, boolean isReplication) {
boolean var7;
try {
this.read.lock();
EurekaMonitors.CANCEL.increment(isReplication);
Map<String, Lease<InstanceInfo>> gMap = (Map)this.registry.get(appName);
Lease<InstanceInfo> leaseToCancel = null;
if (gMap != null) {
leaseToCancel = (Lease)gMap.remove(id);
}
......
gMap.remove(id); 就是獲取當前要下線的服務id，然後從註冊的map中移除掉
服務端的請求接收差不多，對於其他的服務端處理這裡就不在多說，可執行斷點跟蹤。
