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本文主要研究一下 nacos NamingProxy 的 getServiceList
NamingProxy.initRefreshSrvIfNeed
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/net/NamingProxy.java
public class NamingProxy {
private static final int DEFAULT_SERVER_PORT = 8848;
private int serverPort = DEFAULT_SERVER_PORT;
private String namespaceId;
private String endpoint;
private String nacosDomain;
private List<String> serverList;
private List<String> serversFromEndpoint = new ArrayList<String>();
private long lastSrvRefTime = 0L;
private long vipSrvRefInterMillis = TimeUnit.SECONDS.toMillis(30);
private Properties properties;
public NamingProxy(String namespaceId, String endpoint, String serverList) {
this.namespaceId = namespaceId;
this.endpoint = endpoint;
if (StringUtils.isNotEmpty(serverList)) {this.serverList = Arrays.asList(serverList.split(","));
if (this.serverList.size() == 1) {this.nacosDomain = serverList;}
}
initRefreshSrvIfNeed();}
private void initRefreshSrvIfNeed() {if (StringUtils.isEmpty(endpoint)) {return;}
ScheduledExecutorService executorService = new ScheduledThreadPoolExecutor(1, new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {Thread t = new Thread(r);
t.setName("com.alibaba.nacos.client.naming.serverlist.updater");
t.setDaemon(true);
return t;
}
});
executorService.scheduleWithFixedDelay(new Runnable() {
@Override
public void run() {refreshSrvIfNeed();
}
}, 0, vipSrvRefInterMillis, TimeUnit.MILLISECONDS);
refreshSrvIfNeed();}
//......
private void refreshSrvIfNeed() {
try {if (!CollectionUtils.isEmpty(serverList)) {NAMING_LOGGER.debug("server list provided by user:" + serverList);
return;
}
if (System.currentTimeMillis() - lastSrvRefTime < vipSrvRefInterMillis) {return;}
List<String> list = getServerListFromEndpoint();
if (CollectionUtils.isEmpty(list)) {throw new Exception("Can not acquire Nacos list");
}
if (!CollectionUtils.isEqualCollection(list, serversFromEndpoint)) {NAMING_LOGGER.info("[SERVER-LIST] server list is updated:" + list);
}
serversFromEndpoint = list;
lastSrvRefTime = System.currentTimeMillis();} catch (Throwable e) {NAMING_LOGGER.warn("failed to update server list", e);
}
}
public List<String> getServerListFromEndpoint() {
try {
String urlString = "http://" + endpoint + "/nacos/serverlist";
List<String> headers = builderHeaders();
HttpClient.HttpResult result = HttpClient.httpGet(urlString, headers, null, UtilAndComs.ENCODING);
if (HttpURLConnection.HTTP_OK != result.code) {
throw new IOException("Error while requesting:" + urlString + "'. Server returned:"
+ result.code);
}
String content = result.content;
List<String> list = new ArrayList<String>();
for (String line : IoUtils.readLines(new StringReader(content))) {if (!line.trim().isEmpty()) {list.add(line.trim());
}
}
return list;
} catch (Exception e) {e.printStackTrace();
}
return null;
}
//......
}- NamingProxy 的构造器执行了 initRefreshSrvIfNeed 方法，该方法在 endpoint 不为空的时候，会注册一个定时任务，每隔 vipSrvRefInterMillis 时间执行一次 refreshSrvIfNeed 方法，同时立马调用了 refreshSrvIfNeed 方法
- refreshSrvIfNeed 方法在 serverList 为空，且距离 lastSrvRefTime 大于等于 vipSrvRefInterMillis 时会通过 getServerListFromEndpoint() 方法获取 serverList 更新 serversFromEndpoint 及 lastSrvRefTime
- getServerListFromEndpoint 方法会向 endpoint 请求 /serverlist 接口，获取 server 端返回的 serverList
NamingProxy.getServiceList
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/net/NamingProxy.java
public class NamingProxy {
private static final int DEFAULT_SERVER_PORT = 8848;
private int serverPort = DEFAULT_SERVER_PORT;
private String namespaceId;
private String endpoint;
private String nacosDomain;
private List<String> serverList;
private List<String> serversFromEndpoint = new ArrayList<String>();
private long lastSrvRefTime = 0L;
private long vipSrvRefInterMillis = TimeUnit.SECONDS.toMillis(30);
private Properties properties;
//......
public ListView<String> getServiceList(int pageNo, int pageSize, String groupName) throws NacosException {return getServiceList(pageNo, pageSize, groupName, null);
}
public ListView<String> getServiceList(int pageNo, int pageSize, String groupName, AbstractSelector selector) throws NacosException {Map<String, String> params = new HashMap<String, String>(4);
params.put("pageNo", String.valueOf(pageNo));
params.put("pageSize", String.valueOf(pageSize));
params.put(CommonParams.NAMESPACE_ID, namespaceId);
params.put(CommonParams.GROUP_NAME, groupName);
if (selector != null) {switch (SelectorType.valueOf(selector.getType())) {
case none:
break;
case label:
ExpressionSelector expressionSelector = (ExpressionSelector) selector;
params.put("selector", JSON.toJSONString(expressionSelector));
break;
default:
break;
}
}
String result = reqAPI(UtilAndComs.NACOS_URL_BASE + "/service/list", params);
JSONObject json = JSON.parseObject(result);
ListView<String> listView = new ListView<String>();
listView.setCount(json.getInteger("count"));
listView.setData(JSON.parseObject(json.getString("doms"), new TypeReference<List<String>>() {}));
return listView;
}
public String reqAPI(String api, Map<String, String> params) throws NacosException {
List<String> snapshot = serversFromEndpoint;
if (!CollectionUtils.isEmpty(serverList)) {snapshot = serverList;}
return reqAPI(api, params, snapshot);
}
public String reqAPI(String api, Map<String, String> params, List<String> servers) {return reqAPI(api, params, servers, HttpMethod.GET);
}
public String reqAPI(String api, Map<String, String> params, List<String> servers, String method) {params.put(CommonParams.NAMESPACE_ID, getNamespaceId());
if (CollectionUtils.isEmpty(servers) && StringUtils.isEmpty(nacosDomain)) {throw new IllegalArgumentException("no server available");
}
Exception exception = new Exception();
if (servers != null && !servers.isEmpty()) {Random random = new Random(System.currentTimeMillis());
int index = random.nextInt(servers.size());
for (int i = 0; i < servers.size(); i++) {String server = servers.get(index);
try {return callServer(api, params, server, method);
} catch (NacosException e) {
exception = e;
NAMING_LOGGER.error("request {} failed.", server, e);
} catch (Exception e) {
exception = e;
NAMING_LOGGER.error("request {} failed.", server, e);
}
index = (index + 1) % servers.size();}
throw new IllegalStateException("failed to req API:" + api + "after all servers(" + servers + ") tried:"
+ exception.getMessage());
}
for (int i = 0; i < UtilAndComs.REQUEST_DOMAIN_RETRY_COUNT; i++) {
try {return callServer(api, params, nacosDomain);
} catch (Exception e) {
exception = e;
NAMING_LOGGER.error("[NA] req api:" + api + "failed, server(" + nacosDomain, e);
}
}
throw new IllegalStateException("failed to req API:/api/" + api + "after all servers(" + servers + ") tried:"
+ exception.getMessage());
}
//......
}- getServiceList 方法有个 AbstractSelector 参数，它会往请求的参数里头添加 selector 参数，目前 label 类型会添加 ExpressionSelector，之后调用 reqAPI 方法请求 /service/list 接口
- reqAPI 方法首先将 serversFromEndpoint 赋值给 snapshot，但是 serverList 不为空的情况下会重置 snapshot 为 serverList，然后进行 reqAPI 请求
- reqAPI 方法会根据 servers.size() 随机一个 index，然后以 servers.size() 为最大循环次数开始 for 循环，循环里头根据 index 获取 server 然后通过 callServer 请求，请求成功则跳出循环返回，请求失败则递增 index 并对 servers.size() 取余继续下次循环，如果都请求失败则最后抛出 IllegalStateException
小结
- NamingProxy 的构造器执行了 initRefreshSrvIfNeed 方法，该方法在 endpoint 不为空的时候，会注册一个定时任务，每隔 vipSrvRefInterMillis 时间执行一次 refreshSrvIfNeed 方法
- refreshSrvIfNeed 方法在 serverList 为空，且距离 lastSrvRefTime 大于等于 vipSrvRefInterMillis 时会通过 getServerListFromEndpoint() 方法获取 serverList 更新 serversFromEndpoint 及 lastSrvRefTime
- getServiceList 方法优先以 serverList 作为 server 端地址列表，如果它为空再以 serversFromEndpoint 为准，然后通过 reqAPI 方法请求的时候，随机选择一个 server 进行请求，最多请求 server.size() 次，请求成功则跳出循环返回，请求失败则递增 index 并对 servers.size() 取余继续下次循环，如果都请求失败则最后抛出 IllegalStateException
doc
- NamingProxy