本篇内容主要讲解“NacosNamingService中selectInstances的原理和作用”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“NacosNamingService中selectInstances的原理和作用”吧!
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本文主要研究一下NacosNamingService的selectInstances
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/NacosNamingService.java
public class NacosNamingService implements NamingService {
private static final String DEFAULT_PORT = "8080";
private static final long DEFAULT_HEART_BEAT_INTERVAL = TimeUnit.SECONDS.toMillis(5);
/**
* Each Naming instance should have different namespace.
*/
private String namespace;
private String endpoint;
private String serverList;
private String cacheDir;
private String logName;
private HostReactor hostReactor;
private BeatReactor beatReactor;
private EventDispatcher eventDispatcher;
private NamingProxy serverProxy;
//......
@Override
public List selectInstances(String serviceName, boolean healthy) throws NacosException {
return selectInstances(serviceName, new ArrayList(), healthy);
}
@Override
public List selectInstances(String serviceName, String groupName, boolean healthy) throws NacosException {
return selectInstances(serviceName, groupName, healthy, true);
}
@Override
public List selectInstances(String serviceName, boolean healthy, boolean subscribe)
throws NacosException {
return selectInstances(serviceName, new ArrayList(), healthy, subscribe);
}
@Override
public List selectInstances(String serviceName, String groupName, boolean healthy, boolean subscribe) throws NacosException {
return selectInstances(serviceName, groupName, new ArrayList(), healthy, subscribe);
}
@Override
public List selectInstances(String serviceName, List clusters, boolean healthy)
throws NacosException {
return selectInstances(serviceName, clusters, healthy, true);
}
@Override
public List selectInstances(String serviceName, String groupName, List clusters, boolean healthy) throws NacosException {
return selectInstances(serviceName, groupName, clusters, healthy, true);
}
@Override
public List selectInstances(String serviceName, List clusters, boolean healthy,
boolean subscribe) throws NacosException {
return selectInstances(serviceName, Constants.DEFAULT_GROUP, clusters, healthy, subscribe);
}
@Override
public List selectInstances(String serviceName, String groupName, List clusters, boolean healthy, boolean subscribe) throws NacosException {
ServiceInfo serviceInfo;
if (subscribe) {
serviceInfo = hostReactor.getServiceInfo(NamingUtils.getGroupedName(serviceName, groupName), StringUtils.join(clusters, ","));
} else {
serviceInfo = hostReactor.getServiceInfoDirectlyFromServer(NamingUtils.getGroupedName(serviceName, groupName), StringUtils.join(clusters, ","));
}
return selectInstances(serviceInfo, healthy);
}
private List selectInstances(ServiceInfo serviceInfo, boolean healthy) {
List list;
if (serviceInfo == null || CollectionUtils.isEmpty(list = serviceInfo.getHosts())) {
return new ArrayList();
}
Iterator iterator = list.iterator();
while (iterator.hasNext()) {
Instance instance = iterator.next();
if (healthy != instance.isHealthy() || !instance.isEnabled() || instance.getWeight() <= 0) {
iterator.remove();
}
}
return list;
}
//......
} selectInstances首先从hostReactor获取serviceInfo，然后再从serviceInfo.getHosts()剔除非healty、非enabled、weight小于等于0的instance再返回；如果subscribe为true，则执行hostReactor.getServiceInfo获取serviceInfo，否则执行hostReactor.getServiceInfoDirectlyFromServer获取serviceInfo
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/core/HostReactor.java
public class HostReactor {
private static final long DEFAULT_DELAY = 1000L;
private static final long UPDATE_HOLD_INTERVAL = 5000L;
private final Map> futureMap = new HashMap>();
private Map serviceInfoMap;
private Map updatingMap;
private PushReceiver pushReceiver;
private EventDispatcher eventDispatcher;
private NamingProxy serverProxy;
private FailoverReactor failoverReactor;
private String cacheDir;
private ScheduledExecutorService executor;
//......
public ServiceInfo getServiceInfo(final String serviceName, final String clusters) {
NAMING_LOGGER.debug("failover-mode: " + failoverReactor.isFailoverSwitch());
String key = ServiceInfo.getKey(serviceName, clusters);
if (failoverReactor.isFailoverSwitch()) {
return failoverReactor.getService(key);
}
ServiceInfo serviceObj = getServiceInfo0(serviceName, clusters);
if (null == serviceObj) {
serviceObj = new ServiceInfo(serviceName, clusters);
serviceInfoMap.put(serviceObj.getKey(), serviceObj);
updatingMap.put(serviceName, new Object());
updateServiceNow(serviceName, clusters);
updatingMap.remove(serviceName);
} else if (updatingMap.containsKey(serviceName)) {
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);
}
}
}
}
scheduleUpdateIfAbsent(serviceName, clusters);
return serviceInfoMap.get(serviceObj.getKey());
}
private ServiceInfo getServiceInfo0(String serviceName, String clusters) {
String key = ServiceInfo.getKey(serviceName, clusters);
return serviceInfoMap.get(key);
}
public void updateServiceNow(String serviceName, String clusters) {
ServiceInfo oldService = getServiceInfo0(serviceName, clusters);
try {
String result = serverProxy.queryList(serviceName, clusters, pushReceiver.getUDPPort(), false);
if (StringUtils.isNotEmpty(result)) {
processServiceJSON(result);
}
} catch (Exception e) {
NAMING_LOGGER.error("[NA] failed to update serviceName: " + serviceName, e);
} finally {
if (oldService != null) {
synchronized (oldService) {
oldService.notifyAll();
}
}
}
}
public void scheduleUpdateIfAbsent(String serviceName, String clusters) {
if (futureMap.get(ServiceInfo.getKey(serviceName, clusters)) != null) {
return;
}
synchronized (futureMap) {
if (futureMap.get(ServiceInfo.getKey(serviceName, clusters)) != null) {
return;
}
ScheduledFuture future = addTask(new UpdateTask(serviceName, clusters));
futureMap.put(ServiceInfo.getKey(serviceName, clusters), future);
}
}
public ServiceInfo getServiceInfoDirectlyFromServer(final String serviceName, final String clusters) throws NacosException {
String result = serverProxy.queryList(serviceName, clusters, 0, false);
if (StringUtils.isNotEmpty(result)) {
return JSON.parseObject(result, ServiceInfo.class);
}
return null;
}
//......
} getServiceInfo首先判断failoverReactor.isFailoverSwitch()，如果是则返回failoverReactor.getService(key)；接着通过getServiceInfo0从serviceInfoMap查找，如果找不到则创建一个新的然后放入serviceInfoMap，同时放入updatingMap，执行updateServiceNow，再从updatingMap移除；如果从serviceInfoMap找出来的serviceObj在updatingMap中则等待UPDATE_HOLD_INTERVAL；最后执行scheduleUpdateIfAbsent，再从serviceInfoMap取出serviceInfo
updateServiceNow则从serverProxy.queryList获取结果，然后通过processServiceJSON解析并根据需要更新serviceInfoMap；scheduleUpdateIfAbsent方法判断futureMap是否有该任务，如果没有则添加一个UpdateTask
getServiceInfoDirectlyFromServer方法则直接请求serverProxy.queryList获取ServiceInfo
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/naming/core/HostReactor.java
public class UpdateTask implements Runnable {
long lastRefTime = Long.MAX_VALUE;
private String clusters;
private String serviceName;
public UpdateTask(String serviceName, String clusters) {
this.serviceName = serviceName;
this.clusters = clusters;
}
@Override
public void run() {
try {
ServiceInfo serviceObj = serviceInfoMap.get(ServiceInfo.getKey(serviceName, clusters));
if (serviceObj == null) {
updateServiceNow(serviceName, clusters);
executor.schedule(this, DEFAULT_DELAY, TimeUnit.MILLISECONDS);
return;
}
if (serviceObj.getLastRefTime() <= lastRefTime) {
updateServiceNow(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);
}
executor.schedule(this, serviceObj.getCacheMillis(), TimeUnit.MILLISECONDS);
lastRefTime = serviceObj.getLastRefTime();
} catch (Throwable e) {
NAMING_LOGGER.warn("[NA] failed to update serviceName: " + serviceName, e);
}
}
}
public void refreshOnly(String serviceName, String clusters) {
try {
serverProxy.queryList(serviceName, clusters, pushReceiver.getUDPPort(), false);
} catch (Exception e) {
NAMING_LOGGER.error("[NA] failed to update serviceName: " + serviceName, e);
}
}UpdateTask实现了Runnable接口，其run方法首先从serviceInfoMap获取serviceObj，获取不到则执行updateServiceNow，然后再次延时调度UpdateTask；可以从serviceInfoMap获取serviceObj的话则判断serviceObj.getLastRefTime()是否小于等于lastRefTime，是的话则执行updateServiceNow，否则执行refreshOnly；最后再次延时调度UpdateTask，并更新lastRefTime
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 serverList;
private List serversFromEndpoint = new ArrayList();
private long lastSrvRefTime = 0L;
private long vipSrvRefInterMillis = TimeUnit.SECONDS.toMillis(30);
private Properties properties;
//......
public String queryList(String serviceName, String clusters, int udpPort, boolean healthyOnly)
throws NacosException {
final Map params = new HashMap(8);
params.put(CommonParams.NAMESPACE_ID, namespaceId);
params.put(CommonParams.SERVICE_NAME, serviceName);
params.put("clusters", clusters);
params.put("udpPort", String.valueOf(udpPort));
params.put("clientIP", NetUtils.localIP());
params.put("healthyOnly", String.valueOf(healthyOnly));
return reqAPI(UtilAndComs.NACOS_URL_BASE + "/instance/list", params, HttpMethod.GET);
}
//......
} queryList方法会往/instance/list接口发送GET请求查询服务实例列表
selectInstances首先从hostReactor获取serviceInfo，然后再从serviceInfo.getHosts()剔除非healty、非enabled、weight小于等于0的instance再返回；如果subscribe为true，则执行hostReactor.getServiceInfo获取serviceInfo，否则执行hostReactor.getServiceInfoDirectlyFromServer获取serviceInfo
到此，相信大家对“NacosNamingService中selectInstances的原理和作用”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
