例項列表獲取主要是HostReactor#getServiceInfo方法。Nacos - 啟動中namingService.subscribe註冊監聽的時候，也會呼叫這個方法。
getServiceInfo
public ServiceInfo getServiceInfo(final String serviceName, final String clusters) {
// 如果發生故障轉移，就從檔案快取裡取
NAMING_LOGGER.debug("failover-mode: " + failoverReactor.isFailoverSwitch());
String key = ServiceInfo.getKey(serviceName, clusters);
if (failoverReactor.isFailoverSwitch()) {
return failoverReactor.getService(key);
}
// 從serviceInfoMap裡取
ServiceInfo serviceObj = getServiceInfo0(serviceName, clusters);
// serviceInfoMap沒有
if (null == serviceObj) {
serviceObj = new ServiceInfo(serviceName, clusters);
serviceInfoMap.put(serviceObj.getKey(), serviceObj);
updatingMap.put(serviceName, new Object());
// 記憶體沒有，從伺服器取
updateServiceNow(serviceName, clusters);
updatingMap.remove(serviceName);
} else if (updatingMap.containsKey(serviceName)) {
// 如果正在更新，則wait，避免多執行緒同時呼叫伺服器
if (UPDATE_HOLD_INTERVAL > 0) {
// hold a moment waiting for update finish
synchronized (serviceObj) {
try {
serviceObj.wait(UPDATE_HOLD_INTERVAL);
} catch (InterruptedException e) {
NAMING_LOGGER
.error("[getServiceInfo] serviceName:" + serviceName + ", clusters:" + clusters, e);
}
}
}
}
// 開啟定時任務更新服務列表
scheduleUpdateIfAbsent(serviceName, clusters);
// 從記憶體裡取
return serviceInfoMap.get(serviceObj.getKey());
}updateServiceNow
從伺服器獲取，NamingProxy會呼叫NamingProxy#reqApi，他會隨機取一個server，呼叫NamingProxy#callServer。NamingProxy的程式碼就略了。
private void updateServiceNow(String serviceName, String clusters) {
try {
updateService(serviceName, clusters);
} catch (NacosException e) {
NAMING_LOGGER.error("[NA] failed to update serviceName: " + serviceName, e);
}
}
public void updateService(String serviceName, String clusters) throws NacosException {
ServiceInfo oldService = getServiceInfo0(serviceName, clusters);
try {
// 從伺服器取
String result = serverProxy.queryList(serviceName, clusters, pushReceiver.getUdpPort(), false);
if (StringUtils.isNotEmpty(result)) {
// 解析返回的字串
processServiceJson(result);
}
} finally {
if (oldService != null) {
synchronized (oldService) {
oldService.notifyAll();
}
}
}
}processServiceJson
主要是判斷是否有更新，有更新傳送給serviceChanged，並寫入檔案
public ServiceInfo processServiceJson(String json) {
ServiceInfo serviceInfo = JacksonUtils.toObj(json, ServiceInfo.class);
ServiceInfo oldService = serviceInfoMap.get(serviceInfo.getKey());
if (serviceInfo.getHosts() == null || !serviceInfo.validate()) {
return oldService;
}
boolean changed = false;
if (oldService != null) {
if (oldService.getLastRefTime() > serviceInfo.getLastRefTime()) {
NAMING_LOGGER.warn("out of date data received, old-t: " + oldService.getLastRefTime() + ", new-t: "
+ serviceInfo.getLastRefTime());
}
serviceInfoMap.put(serviceInfo.getKey(), serviceInfo);
Map<String, Instance> oldHostMap = new HashMap<String, Instance>(oldService.getHosts().size());
for (Instance host : oldService.getHosts()) {
oldHostMap.put(host.toInetAddr(), host);
}
Map<String, Instance> newHostMap = new HashMap<String, Instance>(serviceInfo.getHosts().size());
for (Instance host : serviceInfo.getHosts()) {
newHostMap.put(host.toInetAddr(), host);
}
Set<Instance> modHosts = new HashSet<Instance>();
Set<Instance> newHosts = new HashSet<Instance>();
Set<Instance> remvHosts = new HashSet<Instance>();
// 下面是修改、新增、移除的篩選。
List<Map.Entry<String, Instance>> newServiceHosts = new ArrayList<Map.Entry<String, Instance>>(
newHostMap.entrySet());
for (Map.Entry<String, Instance> entry : newServiceHosts) {
Instance host = entry.getValue();
String key = entry.getKey();
if (oldHostMap.containsKey(key) && !StringUtils
.equals(host.toString(), oldHostMap.get(key).toString())) {
modHosts.add(host);
continue;
}
if (!oldHostMap.containsKey(key)) {
newHosts.add(host);
}
}
for (Map.Entry<String, Instance> entry : oldHostMap.entrySet()) {
Instance host = entry.getValue();
String key = entry.getKey();
if (newHostMap.containsKey(key)) {
continue;
}
if (!newHostMap.containsKey(key)) {
remvHosts.add(host);
}
}
if (newHosts.size() > 0) {
changed = true;
NAMING_LOGGER.info("new ips(" + newHosts.size() + ") service: " + serviceInfo.getKey() + " -> "
+ JacksonUtils.toJson(newHosts));
}
if (remvHosts.size() > 0) {
changed = true;
NAMING_LOGGER.info("removed ips(" + remvHosts.size() + ") service: " + serviceInfo.getKey() + " -> "
+ JacksonUtils.toJson(remvHosts));
}
if (modHosts.size() > 0) {
changed = true;
updateBeatInfo(modHosts);
NAMING_LOGGER.info("modified ips(" + modHosts.size() + ") service: " + serviceInfo.getKey() + " -> "
+ JacksonUtils.toJson(modHosts));
}
serviceInfo.setJsonFromServer(json);
// 有更新傳送給serviceChanged，並寫入檔案
if (newHosts.size() > 0 || remvHosts.size() > 0 || modHosts.size() > 0) {
eventDispatcher.serviceChanged(serviceInfo);
DiskCache.write(serviceInfo, cacheDir);
}
} else {
changed = true;
NAMING_LOGGER.info("init new ips(" + serviceInfo.ipCount() + ") service: " + serviceInfo.getKey() + " -> "
+ JacksonUtils.toJson(serviceInfo.getHosts()));
serviceInfoMap.put(serviceInfo.getKey(), serviceInfo);
// 有更新傳送給serviceChanged，並寫入檔案
eventDispatcher.serviceChanged(serviceInfo);
serviceInfo.setJsonFromServer(json);
DiskCache.write(serviceInfo, cacheDir);
}
MetricsMonitor.getServiceInfoMapSizeMonitor().set(serviceInfoMap.size());
if (changed) {
NAMING_LOGGER.info("current ips:(" + serviceInfo.ipCount() + ") service: " + serviceInfo.getKey() + " -> "
+ JacksonUtils.toJson(serviceInfo.getHosts()));
}
return serviceInfo;
}scheduleUpdateIfAbsent
把任務加入執行緒池
public void scheduleUpdateIfAbsent(String serviceName, String clusters) {
// 任務已經有了就不加了
if (futureMap.get(ServiceInfo.getKey(serviceName, clusters)) != null) {
return;
}
synchronized (futureMap) {
// // 任務已經有了就不加了
if (futureMap.get(ServiceInfo.getKey(serviceName, clusters)) != null) {
return;
}
// 把任務加入執行緒池
ScheduledFuture<?> future = addTask(new UpdateTask(serviceName, clusters));
// 加入任務
futureMap.put(ServiceInfo.getKey(serviceName, clusters), future);
}
}UpdateTask.run
定時任務更新，預設每10秒更新，如果失敗了，就每次乘以2，比如第一次1秒，第二次2秒，第三次4秒，最多是2的6次方，最大等待60秒。
public void run() {
long delayTime = DEFAULT_DELAY;
try {
ServiceInfo serviceObj = serviceInfoMap.get(ServiceInfo.getKey(serviceName, clusters));
// serviceInfoMap沒有就直接更新
if (serviceObj == null) {
updateService(serviceName, clusters);
return;
}
if (serviceObj.getLastRefTime() <= lastRefTime) {
updateService(serviceName, clusters);
serviceObj = serviceInfoMap.get(ServiceInfo.getKey(serviceName, clusters));
} else {
// if serviceName already updated by push, we should not override it
// since the push data may be different from pull through force push
refreshOnly(serviceName, clusters);
}
lastRefTime = serviceObj.getLastRefTime();
if (!eventDispatcher.isSubscribed(serviceName, clusters) && !futureMap
.containsKey(ServiceInfo.getKey(serviceName, clusters))) {
// abort the update task
NAMING_LOGGER.info("update task is stopped, service:" + serviceName + ", clusters:" + clusters);
return;
}
// 失敗了就增加失敗次數
if (CollectionUtils.isEmpty(serviceObj.getHosts())) {
incFailCount();
return;
}
delayTime = serviceObj.getCacheMillis();
// 成功就重置為1
resetFailCount();
} catch (Throwable e) {
incFailCount();
NAMING_LOGGER.warn("[NA] failed to update serviceName: " + serviceName, e);
} finally {
// 重新到執行緒池
executor.schedule(this, Math.min(delayTime << failCount, DEFAULT_DELAY * 60), TimeUnit.MILLISECONDS);
}
}總結
