Nacos源码分析-注册中心-Distro
Nacos 的AP
Nacos的AP模式，采用server之间互相的数据同步来实现数据在集群中的同步、复制操作
触发数据广播
public class DistroConsistencyServiceImpl implements EphemeralConsistencyService {
@Override
public void put(String key, Record value) throws NacosException {
onPut(key, value);
taskDispatcher.addTask(key);
}
}
当调用 ConsistencyService中定义的put、remove方法时，涉及到了server端数据的变更 此时会创建一个任务，将数据的key传入 taskDispatcher.addTask 方法中，用于后面数据变更时数据查找操作。
public class TaskDispatcher {
public void addTask(String key) {
taskSchedulerList.get(UtilsAndCommons.shakeUp(key, cpuCoreCount)).addTask(key);
}
}
这里有一个方法需要注意——shakeUp，查看官方代码注解可知这是将key（key可以看作是一次数据变更事件）这里应该是将任务均匀的路由到不同的TaskScheduler对象，确保每个TaskScheduler所承担的任务都差不多。
public class TaskScheduler implements Runnable {
....
private BlockingQueue<String> queue = new LinkedBlockingQueue<>(128 * 1024);
....
public void addTask(String key) {
queue.offer(key);
}
@Override
public void run() {
List<String> keys = new ArrayList<>();
while (true) {
try {
String key = queue.poll(partitionConfig.getTaskDispatchPeriod(), TimeUnit.MILLISECONDS);
if (Loggers.DISTRO.isDebugEnabled() && StringUtils.isNotBlank(key)) {
Loggers.DISTRO.debug("got key: {}", key);
}
if (dataSyncer.getServers() == null || dataSyncer.getServers().isEmpty()) {
continue;
}
if (StringUtils.isBlank(key)) {
continue;
}
if (dataSize == 0) {
keys = new ArrayList<>();
}
keys.add(key);
dataSize++;
if (dataSize == partitionConfig.getBatchSyncKeyCount()
|| (System.currentTimeMillis() - lastDispatchTime) > partitionConfig
.getTaskDispatchPeriod()) {
// bookmark 核心代码模块 将数据在nacos server 中进行广播操作
for (Member member : dataSyncer.getServers()) {
// bookmark 是自己的话 不需要广播操作
if (NetUtils.localServer().equals(member.getAddress())) {
continue;
}
// bookmark 创建SyncTask
SyncTask syncTask = new SyncTask();
// bookmark 设置事件集合（keys 集合）
syncTask.setKeys(keys);
// bookmark 将目标server信息设置到SyncTask中
syncTask.setTargetServer(member.getAddress());
if (Loggers.DISTRO.isDebugEnabled() && StringUtils.isNotBlank(key)) {
Loggers.DISTRO.debug("add sync task: {}", JacksonUtils.toJson(syncTask));
}
// bookmark 将数据广播任务提交到DataSync中
dataSyncer.submit(syncTask, 0);
}
lastDispatchTime = System.currentTimeMillis();
dataSize = 0;
}
} catch (Exception e) {
Loggers.DISTRO.error("dispatch sync task failed.", e);
}
}
}
}
核心代码就是for (Server member : dataSyncer.getServers()) {..}循环体内的代码，此处就是将数据在Nacos Server中进行广播操作；具体步骤如下：
- 创建
SyncTask，并设置事件集合（就是key集合） - 将目标
Server信息设置到SyncTask中——syncTask.setTargetServer(member.getKey()) - 将数据广播任务提交到
DataSyncer中
执行数据广播 DataSyncer
public class DataSyncer {
public void submit(SyncTask task, long delay) {
// If it's a new task:
// bookmark 是否是新任务
if (task.getRetryCount() == 0) {
// bookmark 遍历所有的keys
Iterator<String> iterator = task.getKeys().iterator();
while (iterator.hasNext()) {
String key = iterator.next();
// bookmark 添加进taskMap
if (StringUtils.isNotBlank(taskMap.putIfAbsent(buildKey(key, task.getTargetServer()), key))) {
// associated key already exist:
if (Loggers.DISTRO.isDebugEnabled()) {
Loggers.DISTRO.debug("sync already in process, key: {}", key);
}
iterator.remove();
}
}
}
if (task.getKeys().isEmpty()) {
// all keys are removed:
return;
}
// bookmark 提交一个数据广播任务
GlobalExecutor.submitDataSync(() -> {
// 1. check the server
if (getServers() == null || getServers().isEmpty()) {
Loggers.SRV_LOG.warn("try to sync data but server list is empty.");
return;
}
List<String> keys = task.getKeys();
if (Loggers.SRV_LOG.isDebugEnabled()) {
Loggers.SRV_LOG.debug("try to sync data for this keys {}.", keys);
}
// bookmark 通过SyncTask中的keys 去DataStore中去查询key所对一个的数据集合
// 2. get the datums by keys and check the datum is empty or not
Map<String, Datum> datumMap = dataStore.batchGet(keys);
if (datumMap == null || datumMap.isEmpty()) {
// clear all flags of this task:
for (String key : keys) {
taskMap.remove(buildKey(key, task.getTargetServer()));
}
return;
}
// bookmark 对数据进行序列化操作，转化为 byte[]数组
byte[] data = serializer.serialize(datumMap);
long timestamp = System.currentTimeMillis();
// bookmark 内部会发起http请求 进行数据广播
boolean success = NamingProxy.syncData(data, task.getTargetServer());
if (!success) {
// bookmark 如果数据广播失败，
// bookmark 将任务重新打包再次压入GlobalExecutor中
SyncTask syncTask = new SyncTask();
syncTask.setKeys(task.getKeys());
syncTask.setRetryCount(task.getRetryCount() + 1);
syncTask.setLastExecuteTime(timestamp);
syncTask.setTargetServer(task.getTargetServer());
retrySync(syncTask);
} else {
// clear all flags of this task:
for (String key : task.getKeys()) {
taskMap.remove(buildKey(key, task.getTargetServer()));
}
}
}, delay);
}
}
GlobalExecutor.submitDataSync(Runnable runnable)提交一个数据广播任务；首先通过SyncTask中的key集合去DataStore中去查询key所对应的数据集合，然后对数据进行序列化操作，转为byte[]数组后，执行Http请求操作——NamingProxy.syncData(data, task.getTargetServer())；如果数据广播失败，则将任务重新打包再次压入GlobalExecutor中。
NamingProxy.syncData 方法：
public class NamingProxy {
public static boolean syncData(byte[] data, String curServer) {
Map<String, String> headers = new HashMap<>(128);
headers.put(HttpHeaderConsts.CLIENT_VERSION_HEADER, VersionUtils.version);
headers.put(HttpHeaderConsts.USER_AGENT_HEADER, UtilsAndCommons.SERVER_VERSION);
headers.put("Accept-Encoding", "gzip,deflate,sdch");
headers.put("Connection", "Keep-Alive");
headers.put("Content-Encoding", "gzip");
try {
/** bookmark PUT http://ip:port/nacos/v1/ns//distro/datum 该url的处理器为{@link com.alibaba.nacos.naming.controllers.DistroController#onSyncDatum(Map)}*/
HttpClient.HttpResult result = HttpClient.httpPutLarge(
"http://" + curServer + ApplicationUtils.getContextPath() + UtilsAndCommons.NACOS_NAMING_CONTEXT
+ DATA_ON_SYNC_URL, headers, data);
if (HttpURLConnection.HTTP_OK == result.code) {
return true;
}
if (HttpURLConnection.HTTP_NOT_MODIFIED == result.code) {
return true;
}
throw new IOException("failed to req API:" + "http://" + curServer + ApplicationUtils.getContextPath()
+ UtilsAndCommons.NACOS_NAMING_CONTEXT + DATA_ON_SYNC_URL + ". code:" + result.code + " msg: "
+ result.content);
} catch (Exception e) {
Loggers.SRV_LOG.warn("NamingProxy", e);
}
return false;
}
}
这里将数据提交到了URL为PUT http://ip:port/nacos/v1/ns//distro/datum中，而该URL对应的处理位置是com.alibaba.nacos.naming.controllers.DistroController#onSyncDatum(Map)。
public class DistroController {
@PutMapping("/datum")
public ResponseEntity onSyncDatum(@RequestBody Map<String, Datum<Instances>> dataMap) throws Exception {
if (dataMap.isEmpty()) {
Loggers.DISTRO.error("[onSync] receive empty entity!");
throw new NacosException(NacosException.INVALID_PARAM, "receive empty entity!");
}
for (Map.Entry<String, Datum<Instances>> entry : dataMap.entrySet()) {
if (KeyBuilder.matchEphemeralInstanceListKey(entry.getKey())) {
String namespaceId = KeyBuilder.getNamespace(entry.getKey());
String serviceName = KeyBuilder.getServiceName(entry.getKey());
if (!serviceManager.containService(namespaceId, serviceName) && switchDomain
.isDefaultInstanceEphemeral()) {
serviceManager.createEmptyService(namespaceId, serviceName, true);
}
// bookmark 进行数据的更新操作，onPut方法不会涉及 taskDispatcher.addTask操作，而是将数据更新压入了Notifier的Task列表中
consistencyService.onPut(entry.getKey(), entry.getValue().value);
}
}
return ResponseEntity.ok("ok");
}
}
public class DistroConsistencyServiceImpl implements EphemeralConsistencyService {
public void onPut(String key, Record value) {
if (KeyBuilder.matchEphemeralInstanceListKey(key)) {
Datum<Instances> datum = new Datum<>();
datum.value = (Instances) value;
datum.key = key;
datum.timestamp.incrementAndGet();
dataStore.put(key, datum);
}
if (!listeners.containsKey(key)) {
return;
}
notifier.addTask(key, ApplyAction.CHANGE);
}
}
数据同步操作
