Nacos7# Distro协议增量同步
引言
本文接着撸Distro协议，上文中分析了在Nacos server启动时会进行全量数据同步和数据校验，具体数据即客户端注册节点信息含命名空间、分组名称、服务名称、节点Instance信息等。什么时候会触发增量同步？增量同步都干了些啥，下文接着撸撸增量数据同步。
一、内容提要
增量数据同步
- 在Nacos节点启动时通过事件驱动模式订阅了ClientChangedEvent、ClientDisconnectEvent和ClientVerifyFailedEvent事件
- 当节点收到ClientChangedEvent事件时，会向集群中其他节点发送更新Client信息请求，其他节点收到后更新缓存
- 当节点收到ClientVerifyFailedEvent事件时，向该Event指定的目标节点发起新增该Event指定的Client信息请求，目标节点收到后更新到自己缓存中
- 当节点收到ClientDisconnectEvent事件时，会向集群中其他节点发送删除Client信息请求，其他节点收到后将该Client缓存删除
增量事件触发
- 当有服务注册或者注销时会触发ClientEvent.ClientChangedEvent事件，即客户端调用naming.registerInstance或者naming.deregisterInstance
- 定时任务每隔3秒钟定时检查缓存中的所有连接，如果超过保鲜期20秒则再次发起连接请求，连接未成功则注销关闭该连接并发布ClientEvent.ClientDisconnectEvent事件
- Nacos集群之间通过每5秒发送心跳校验数据请求（具体为本节点负责Client信息），其他节点接受到校验请求，如果缓存中存在该client表示校验成功，同时更新保鲜时间；否则校验失败，回调返回失败Response，请求节点收到失败的Response后会发布ClientVerifyFailedEvent事件
二、增量数据同步
将代码翻到DistroClientDataProcessor类中，该类继承了SmartSubscriber，遵循Subscriber/Notify模式，即事件驱动模式。该模式前面文章中分析过，当有订阅的事件时会进行回调通知。
订阅的事件
DistroClientDataProcessor订阅了ClientChangedEvent、ClientDisconnectEvent和ClientVerifyFailedEvent事件。
@Override
public List<Class<? extends Event>> subscribeTypes() {
List<Class<? extends Event>> result = new LinkedList<>();
result.add(ClientEvent.ClientChangedEvent.class);
result.add(ClientEvent.ClientDisconnectEvent.class);
result.add(ClientEvent.ClientVerifyFailedEvent.class);
return result;
}
当有上述三个事件产生时，DefaultPublisher回调onEvent方法。
public void onEvent(Event event) {
if (EnvUtil.getStandaloneMode()) {
return;
}
if (!upgradeJudgement.isUseGrpcFeatures()) {
return;
}
if (event instanceof ClientEvent.ClientVerifyFailedEvent) {
// 注解@1
syncToVerifyFailedServer((ClientEvent.ClientVerifyFailedEvent) event);
} else {
// 注解@2
syncToAllServer((ClientEvent) event);
}
}
注解@1 将ClientVerifyFailedEvent同步给校验失败的节点，操作类型为ADD
注解@2 将同步给集群中的其他节
private void syncToAllServer(ClientEvent event) {
Client client = event.getClient();
// Only ephemeral data sync by Distro, persist client should sync by raft.
if (null == client || !client.isEphemeral() || !clientManager.isResponsibleClient(client)) {
return;
}
if (event instanceof ClientEvent.ClientDisconnectEvent) {
// 注解@3
DistroKey distroKey = new DistroKey(client.getClientId(), TYPE);
distroProtocol.sync(distroKey, DataOperation.DELETE);
} else if (event instanceof ClientEvent.ClientChangedEvent) {
// 注解@4
DistroKey distroKey = new DistroKey(client.getClientId(), TYPE);
distroProtocol.sync(distroKey, DataOperation.CHANGE);
}
}
注解@3 当客户端断开连接事件ClientDisconnectEvent时，向其他节点同步DELETE操作
注解@4 当客户端变更事件ClientChangedEvent时，向其他节点同步CHANGE操作
接着看下不同操作类型的处理
@Override
public boolean process(NacosTask task) {
if (!(task instanceof DistroDelayTask)) {
return true;
}
DistroDelayTask distroDelayTask = (DistroDelayTask) task;
DistroKey distroKey = distroDelayTask.getDistroKey();
switch (distroDelayTask.getAction()) {
case DELETE: // 删除操作
DistroSyncDeleteTask syncDeleteTask = new DistroSyncDeleteTask(distroKey, distroComponentHolder);
distroTaskEngineHolder.getExecuteWorkersManager().addTask(distroKey, syncDeleteTask);
return true;
case CHANGE:
case ADD: // 更新和新增操作
DistroSyncChangeTask syncChangeTask = new DistroSyncChangeTask(distroKey, distroComponentHolder);
distroTaskEngineHolder.getExecuteWorkersManager().addTask(distroKey, syncChangeTask);
return true;
default:
return false;
}
}
向指定的集群节点同步更新数据
@Override
public boolean syncData(DistroData data, String targetServer) {
if (isNoExistTarget(targetServer)) {
return true;
}
// 构造请求数据并设置数据类型
DistroDataRequest request = new DistroDataRequest(data, data.getType());
// 查找目标节点缓存数据
Member member = memberManager.find(targetServer);
// 节点状态检查需UP状态，即：可通信状态
if (checkTargetServerStatusUnhealthy(member)) {
Loggers.DISTRO.warn("[DISTRO] Cancel distro sync caused by target server {} unhealthy", targetServer);
return false;
}
try {
// 向目标节点发送数据
Response response = clusterRpcClientProxy.sendRequest(member, request);
return checkResponse(response);
} catch (NacosException e) {
Loggers.DISTRO.error("[DISTRO-FAILED] Sync distro data failed! ", e);
}
return false;
}
异步更新操作
@Override
public void syncData(DistroData data, String targetServer, DistroCallback callback) {
if (isNoExistTarget(targetServer)) {
callback.onSuccess();
}
DistroDataRequest request = new DistroDataRequest(data, data.getType());
Member member = memberManager.find(targetServer);
try {
// 异步更新操作
clusterRpcClientProxy.asyncRequest(member, request, new DistroRpcCallbackWrapper(callback, member));
} catch (NacosException nacosException) {
callback.onFailed(nacosException);
}
}
节点收到这些操作请求如何处理呢？
代码翻到DistroDataRequestHandler#handle()，集群中节点收到请求后处理逻辑在这里：
@Override
public DistroDataResponse handle(DistroDataRequest request, RequestMeta meta) throws NacosException {
try {
switch (request.getDataOperation()) {
case VERIFY:
return handleVerify(request.getDistroData(), meta);
case SNAPSHOT:
return handleSnapshot();
case ADD:
case CHANGE:
case DELETE:
return handleSyncData(request.getDistroData());
case QUERY:
return handleQueryData(request.getDistroData());
default:
return new DistroDataResponse();
}
} catch (Exception e) {
Loggers.DISTRO.error("[DISTRO-FAILED] distro handle with exception", e);
DistroDataResponse result = new DistroDataResponse();
result.setErrorCode(ResponseCode.FAIL.getCode());
result.setMessage("handle distro request with exception");
return result;
}
}
可以看出ADD、CHANGE和DELETE均由handleSyncData处理。
private DistroDataResponse handleSyncData(DistroData distroData) {
DistroDataResponse result = new DistroDataResponse();
if (!distroProtocol.onReceive(distroData)) {
result.setErrorCode(ResponseCode.FAIL.getCode());
result.setMessage("[DISTRO-FAILED] distro data handle failed");
}
return result;
}
@Override
public boolean processData(DistroData distroData) {
switch (distroData.getType()) {
case ADD:
case CHANGE:
ClientSyncData clientSyncData = ApplicationUtils.getBean(Serializer.class)
.deserialize(distroData.getContent(), ClientSyncData.class);
handlerClientSyncData(clientSyncData); // 注解@5
return true;
case DELETE:
String deleteClientId = distroData.getDistroKey().getResourceKey();
Loggers.DISTRO.info("[Client-Delete] Received distro client sync data {}", deleteClientId);
clientManager.clientDisconnected(deleteClientId); // 注解@6
return true;
default:
return false;
}
}
注解@5 将同步过来的Client信息进行缓存
private void handlerClientSyncData(ClientSyncData clientSyncData) {
Loggers.DISTRO.info("[Client-Add] Received distro client sync data {}", clientSyncData.getClientId());
clientManager.syncClientConnected(clientSyncData.getClientId(), clientSyncData.getAttributes());
Client client = clientManager.getClient(clientSyncData.getClientId());
// 注解@5.1
upgradeClient(client, clientSyncData);
}
需要的是从其他节点通过过来的Client信息，ConnectionBasedClient属性isNative为false表示该连接时从其他节点同步过来的；true表示该连接客户端直接连接的。
public boolean syncClientConnected(String clientId, ClientSyncAttributes attributes) {
String type = attributes.getClientAttribute(ClientConstants.CONNECTION_TYPE);
ClientFactory clientFactory = ClientFactoryHolder.getInstance().findClientFactory(type);
return clientConnected(clientFactory.newSyncedClient(clientId, attributes));
}
@Override
public ConnectionBasedClient newSyncedClient(String clientId, ClientSyncAttributes attributes) {
return new ConnectionBasedClient(clientId, false); // false表示从其他节点同步过来的client
}
@Override
public boolean clientConnected(Client client) {
Loggers.SRV_LOG.info("Client connection {} connect", client.getClientId());
if (!clients.containsKey(client.getClientId())) {
clients.putIfAbsent(client.getClientId(), (ConnectionBasedClient) client); // 缓存client
}
return true;
}
注解@5.1 更新Client的Service以及Instance信息。
private void upgradeClient(Client client, ClientSyncData clientSyncData) {
List<String> namespaces = clientSyncData.getNamespaces();
List<String> groupNames = clientSyncData.getGroupNames();
List<String> serviceNames = clientSyncData.getServiceNames();
List<InstancePublishInfo> instances = clientSyncData.getInstancePublishInfos();
Set<Service> syncedService = new HashSet<>();
for (int i = 0; i < namespaces.size(); i++) {
Service service = Service.newService(namespaces.get(i), groupNames.get(i), serviceNames.get(i));
Service singleton = ServiceManager.getInstance().getSingleton(service);
syncedService.add(singleton);
InstancePublishInfo instancePublishInfo = instances.get(i);
if (!instancePublishInfo.equals(client.getInstancePublishInfo(singleton))) {
client.addServiceInstance(singleton, instancePublishInfo);
NotifyCenter.publishEvent(
new ClientOperationEvent.ClientRegisterServiceEvent(singleton, client.getClientId()));
}
}
for (Service each : client.getAllPublishedService()) {
if (!syncedService.contains(each)) {
client.removeServiceInstance(each);
NotifyCenter.publishEvent(
new ClientOperationEvent.ClientDeregisterServiceEvent(each, client.getClientId()));
}
}
}
注解@6 响应删除操作，从clients缓存中移除。
@Override
public boolean clientDisconnected(String clientId) {
Loggers.SRV_LOG.info("Client connection {} disconnect, remove instances and subscribers", clientId);
ConnectionBasedClient client = clients.remove(clientId);
if (null == client) {
return true;
}
client.release();
NotifyCenter.publishEvent(new ClientEvent.ClientDisconnectEvent(client));
return true;
}
小结： 增量同步的逻辑如下：当本节点DistroClientDataProcessor收到ClientChangedEvent、ClientDisconnectEvent和ClientVerifyFailedEvent事件时，会向Nacos集群的其他节点同步Client信息；集群中其他节点收到同步信息后更新或者删除本地缓存的Client信息；通过增量同步的Client信息isNative为false表示不是由客户端直连的。
三、增量事件触发
在Nacos server启动时从运行时内存信息可以看出，总共缓存了17个事件类型。当然也包括ClientChangedEvent、ClientDisconnectEvent和ClientVerifyFailedEvent。
ClientChangedEvent事件触发
当处理服务注册和注销事件时会触发ClientChangeEvent事件，详见InstanceRequestHandler#handle处理逻辑。
public InstanceResponse handle(InstanceRequest request, RequestMeta meta) throws NacosException {
Service service = Service
.newService(request.getNamespace(), request.getGroupName(), request.getServiceName(), true);
switch (request.getType()) {
// 注解@7
case NamingRemoteConstants.REGISTER_INSTANCE:
return registerInstance(service, request, meta);
// 注解@8
case NamingRemoteConstants.DE_REGISTER_INSTANCE:
return deregisterInstance(service, request, meta);
default:
throw new NacosException(NacosException.INVALID_PARAM,
String.format("Unsupported request type %s", request.getType()));
}
}
注解@7 处理注册请求，会调用到addServiceInstance方法，该方法中发布了ClientEvent.ClientChangedEvent事件。
public boolean addServiceInstance(Service service, InstancePublishInfo instancePublishInfo) {
if (null == publishers.put(service, instancePublishInfo)) {
MetricsMonitor.incrementInstanceCount();
}
NotifyCenter.publishEvent(new ClientEvent.ClientChangedEvent(this));
Loggers.SRV_LOG.info("Client change for service {}, {}", service, getClientId());
return true;
}
注解@8 处理注销请求，会调用到removeServiceInstance方法，该方法中发布了ClientEvent.ClientChangedEvent事件
public InstancePublishInfo removeServiceInstance(Service service) {
InstancePublishInfo result = publishers.remove(service);
if (null != result) {
MetricsMonitor.decrementInstanceCount();
NotifyCenter.publishEvent(new ClientEvent.ClientChangedEvent(this));
}
Loggers.SRV_LOG.info("Client remove for service {}, {}", service, getClientId());
return result;
}
小结： 当有服务注册或者注销时会触发ClientEvent.ClientChangedEvent事件。
ClientDisconnectEvent事件触发
下面一段代码通过检测连接是否超过保鲜期，超过保鲜期的会被注销关闭，翻到代码ConnectionManager#start()。
@PostConstruct
public void start() {
// 定时任务每3秒执行一次
RpcScheduledExecutor.COMMON_SERVER_EXECUTOR.scheduleWithFixedDelay(new Runnable() {
@Override
public void run() {
try {
// 获取缓存连接
int totalCount = connections.size();
Loggers.REMOTE_DIGEST.info("Connection check task start");
MetricsMonitor.getLongConnectionMonitor().set(totalCount);
// 所有连接集合
Set<Map.Entry<String, Connection>> entries = connections.entrySet();
// 获取通过SDK连接的数量
int currentSdkClientCount = currentSdkClientCount();
boolean isLoaderClient = loadClient >= 0;
int currentMaxClient = isLoaderClient ? loadClient : connectionLimitRule.countLimit;
int expelCount = currentMaxClient < 0 ? 0 : Math.max(currentSdkClientCount - currentMaxClient, 0);
List<String> expelClient = new LinkedList<>();
Map<String, AtomicInteger> expelForIp = new HashMap<>(16);
// 1. calculate expel count of ip.
// 加载Connection ConnectionLimitRule
// 默认路径为 ${usr.home}/nacos/data/loader/limitRule
for (Map.Entry<String, Connection> entry : entries) {
Connection client = entry.getValue();
String appName = client.getMetaInfo().getAppName();
String clientIp = client.getMetaInfo().getClientIp();
if (client.getMetaInfo().isSdkSource() && !expelForIp.containsKey(clientIp)) {
//get limit for current ip.
// 默认无limit限制
int countLimitOfIp = connectionLimitRule.getCountLimitOfIp(clientIp);
// 默认无limit限制
if (countLimitOfIp < 0) {
int countLimitOfApp = connectionLimitRule.getCountLimitOfApp(appName);
countLimitOfIp = countLimitOfApp < 0 ? countLimitOfIp : countLimitOfApp;
}
if (countLimitOfIp < 0) { // 默认无限制
countLimitOfIp = connectionLimitRule.getCountLimitPerClientIpDefault();
}
if (countLimitOfIp >= 0 && connectionForClientIp.containsKey(clientIp)) {
AtomicInteger currentCountIp = connectionForClientIp.get(clientIp);
if (currentCountIp != null && currentCountIp.get() > countLimitOfIp) {
expelForIp.put(clientIp, new AtomicInteger(currentCountIp.get() - countLimitOfIp));
}
}
}
}
if (expelForIp.size() > 0) { // 默认等于0
Loggers.REMOTE_DIGEST.info("Over limit ip expel info,", expelForIp);
}
Set<String> outDatedConnections = new HashSet<>();
long now = System.currentTimeMillis();
// 2.get expel connection for ip limit.
//
for (Map.Entry<String, Connection> entry : entries) {
Connection client = entry.getValue();
String clientIp = client.getMetaInfo().getClientIp();
AtomicInteger integer = expelForIp.get(clientIp);
if (integer != null && integer.intValue() > 0) {
integer.decrementAndGet();
expelClient.add(client.getMetaInfo().getConnectionId());
expelCount--;
} else if (now - client.getMetaInfo().getLastActiveTime() >= KEEP_ALIVE_TIME) { // 保鲜时间超过20秒放入outDatedConnections集合
outDatedConnections.add(client.getMetaInfo().getConnectionId());
}
}
// 3. if total count is still over limit.
// expelCount 默认为0
if (expelCount > 0) {
for (Map.Entry<String, Connection> entry : entries) {
Connection client = entry.getValue();
if (!expelForIp.containsKey(client.getMetaInfo().clientIp) && client.getMetaInfo()
.isSdkSource() && expelCount > 0) {
expelClient.add(client.getMetaInfo().getConnectionId());
expelCount--;
outDatedConnections.remove(client.getMetaInfo().getConnectionId());
}
}
}
String serverIp = null;
String serverPort = null;
if (StringUtils.isNotBlank(redirectAddress) && redirectAddress.contains(Constants.COLON)) {
String[] split = redirectAddress.split(Constants.COLON);
serverIp = split[0];
serverPort = split[1];
}
for (String expelledClientId : expelClient) { // 默认空集合
try {
Connection connection = getConnection(expelledClientId);
if (connection != null) {
ConnectResetRequest connectResetRequest = new ConnectResetRequest();
connectResetRequest.setServerIp(serverIp);
connectResetRequest.setServerPort(serverPort);
connection.asyncRequest(connectResetRequest, null);
}
} catch (ConnectionAlreadyClosedException e) {
unregister(expelledClientId);
} catch (Exception e) {
Loggers.REMOTE_DIGEST.error("Error occurs when expel connection :", expelledClientId, e);
}
}
//4.client active detection.
Loggers.REMOTE_DIGEST.info("Out dated connection ,size={}", outDatedConnections.size());
// 超过保鲜期的链接集合
if (CollectionUtils.isNotEmpty(outDatedConnections)) {
Set<String> successConnections = new HashSet<>();
final CountDownLatch latch = new CountDownLatch(outDatedConnections.size());
for (String outDateConnectionId : outDatedConnections) {
try {
Connection connection = getConnection(outDateConnectionId);
if (connection != null) {
ClientDetectionRequest clientDetectionRequest = new ClientDetectionRequest();
// 超过保鲜时间的连接，重新异步发起连接
connection.asyncRequest(clientDetectionRequest, new RequestCallBack() {
@Override
public Executor getExecutor() {
return null;
}
@Override
public long getTimeout() {
return 1000L;
}
@Override
public void onResponse(Response response) {
latch.countDown();
if (response != null && response.isSuccess()) {
// 刷新激活时间
connection.freshActiveTime();
successConnections.add(outDateConnectionId);
}
}
@Override
public void onException(Throwable e) {
latch.countDown();
}
});
} else {
latch.countDown();
}
} catch (ConnectionAlreadyClosedException e) {
latch.countDown();
} catch (Exception e) {
// ...
latch.countDown();
}
}
latch.await(3000L, TimeUnit.MILLISECONDS);
Loggers.REMOTE_DIGEST
.info("Out dated connection check successCount={}", successConnections.size());
// 无效连接集合
for (String outDateConnectionId : outDatedConnections) {
if (!successConnections.contains(outDateConnectionId)) {
Loggers.REMOTE_DIGEST
.info("[{}]Unregister Out dated connection....", outDateConnectionId);
// 注销关闭connection
unregister(outDateConnectionId);
}
}
}
if (isLoaderClient) { // 重置
loadClient = -1;
redirectAddress = null;
}
} catch (Throwable e) {
}
}
}, 1000L, 3000L, TimeUnit.MILLISECONDS);
}
public synchronized void unregister(String connectionId) {
Connection remove = this.connections.remove(connectionId);
if (remove != null) {
String clientIp = remove.getMetaInfo().clientIp;
AtomicInteger atomicInteger = connectionForClientIp.get(clientIp);
if (atomicInteger != null) {
int count = atomicInteger.decrementAndGet();
if (count <= 0) {
connectionForClientIp.remove(clientIp);
}
}
remove.close();
Loggers.REMOTE_DIGEST.info("[{}]Connection unregistered successfully. ", connectionId);
clientConnectionEventListenerRegistry.notifyClientDisConnected(remove); // 异步
}
}
public void notifyClientDisConnected(final Connection connection) {
for (ClientConnectionEventListener clientConnectionEventListener : clientConnectionEventListeners) {
try {
clientConnectionEventListener.clientDisConnected(connection);
} catch (Throwable throwable) {
Loggers.REMOTE.info("[NotifyClientDisConnected] failed for listener {}",
clientConnectionEventListener.getName(), throwable);
}
}
}
@Override
public boolean clientDisconnected(String clientId) {
Loggers.SRV_LOG.info("Client connection {} disconnect, remove instances and subscribers", clientId);
ConnectionBasedClient client = clients.remove(clientId);
if (null == client) {
return true;
}
client.release();
NotifyCenter.publishEvent(new ClientEvent.ClientDisconnectEvent(client)); // 发布ClientDisconnectEvent事件
return true;
}
小结： 连接可以配置限制规则具体在${usr.home}/nacos/data/loader/limitRule文件配置，默认无限制；通过定时任务每隔3秒钟定时检查缓存中的所有连接包括通过来源sdk的连接和集群的连接；如果连接超过保鲜期20秒，并再次发起连接请求，未能连接成功则注销关闭该连接；注销关闭时发布ClientEvent.ClientDisconnectEvent事件。
ClientVerifyFailedEvent事件触发
上一篇文章中梳理了Nacos集群中，每个节点会对集群中其他节点每隔5秒发送校验数据，也就是心跳。当校验的结果会进行回调（gRPC为例），我们翻着看看这部分。
public void syncVerifyData(DistroData verifyData, String targetServer, DistroCallback callback) {
if (isNoExistTarget(targetServer)) {
callback.onSuccess();
}
DistroDataRequest request = new DistroDataRequest(verifyData, DataOperation.VERIFY);
Member member = memberManager.find(targetServer);
try {
DistroVerifyCallbackWrapper wrapper = new DistroVerifyCallbackWrapper(targetServer,
verifyData.getDistroKey().getResourceKey(), callback, member);
clusterRpcClientProxy.asyncRequest(member, request, wrapper); // 向其他节点发送本节点负责的cleintId信息
} catch (NacosException nacosException) {
callback.onFailed(nacosException);
}
}
重点看下DistroVerifyCallbackWrapper部分，校验失败发布ClientVerifyFailedEvent事件。
@Override
public void onResponse(Response response) {
if (checkResponse(response)) {
NamingTpsMonitor.distroVerifySuccess(member.getAddress(), member.getIp());
distroCallback.onSuccess();
} else {
Loggers.DISTRO.info("Target {} verify client {} failed, sync new client", targetServer, clientId);
// 校验失败发布ClientVerifyFailedEvent事件
NotifyCenter.publishEvent(new ClientEvent.ClientVerifyFailedEvent(clientId, targetServer));
NamingTpsMonitor.distroVerifyFail(member.getAddress(), member.getIp());
distroCallback.onFailed(null);
}
}
最后看下ClientVerifyFailedEvent这个类，关注下成员变量包含了clientId和targetServer。当收到ClientVerifyFailedEvent时用于向targetServer目标节点添加客户端clientId信息。
public static class ClientVerifyFailedEvent extends ClientEvent {
private static final long serialVersionUID = 2023951686223780851L;
private final String clientId;
private final String targetServer;
public ClientVerifyFailedEvent(String clientId, String targetServer) {
super(null);
this.clientId = clientId;
this.targetServer = targetServer;
}
public String getClientId() {
return clientId;
}
public String getTargetServer() {
return targetServer;
}
}
小结： Nacos集群之间通过每5秒发送心跳校验数据请求（具体为本节点负责Client信息），其他节点接受到校验请求，如果缓存中存在该client表示校验成功，同时更新保鲜时间；否则校验失败，回调返回失败Response，请求节点收到失败的Response后会发布ClientVerifyFailedEvent事件。
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原始发表：2021-07-05，如有侵权请联系 cloudcommunity@tencent.com 删除
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对象存储
对象存储（Cloud Object Storage，COS）是由腾讯云推出的无目录层次结构、无数据格式限制，可容纳海量数据且支持 HTTP/HTTPS 协议访问的分布式存储服务。腾讯云 COS 的存储桶空间无容量上限，无需分区管理，适用于 CDN 数据分发、数据万象处理或大数据计算与分析的数据湖等多种场景。