content: /*
   * Copyright 1999-2018 Alibaba Group Holding Ltd.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.nacos.client.naming.core;
  
  import com.alibaba.nacos.api.PropertyKeyConst;
  import com.alibaba.nacos.api.exception.NacosException;
  import com.alibaba.nacos.api.naming.pojo.ServiceInfo;
  import com.alibaba.nacos.api.naming.utils.NamingUtils;
  import com.alibaba.nacos.client.env.NacosClientProperties;
  import com.alibaba.nacos.client.naming.cache.ServiceInfoHolder;
  import com.alibaba.nacos.client.naming.event.InstancesChangeNotifier;
  import com.alibaba.nacos.client.naming.remote.NamingClientProxy;
  import com.alibaba.nacos.common.executor.NameThreadFactory;
  import com.alibaba.nacos.common.lifecycle.Closeable;
  import com.alibaba.nacos.common.utils.CollectionUtils;
  import com.alibaba.nacos.common.utils.ConvertUtils;
  import com.alibaba.nacos.common.utils.ThreadUtils;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.ScheduledFuture;
  import java.util.concurrent.ScheduledThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  
  import static com.alibaba.nacos.client.utils.LogUtils.NAMING_LOGGER;
  
  /**
   * Service information update service.
   *
   * @author xiweng.yy
   */
  public class ServiceInfoUpdateService implements Closeable {
      
      private static final long DEFAULT_DELAY = 1000L;
      
      private static final int DEFAULT_UPDATE_CACHE_TIME_MULTIPLE = 6;
      
      private static final int MIN_THREAD_NUM = 1;
      
      private final Map<String, ScheduledFuture<?>> futureMap = new HashMap<>();
      
      private final ServiceInfoHolder serviceInfoHolder;
      
      private final ScheduledExecutorService executor;
      
      private final NamingClientProxy namingClientProxy;
      
      private final InstancesChangeNotifier changeNotifier;
      
      private final boolean asyncQuerySubscribeService;
      
      public ServiceInfoUpdateService(NacosClientProperties properties, ServiceInfoHolder serviceInfoHolder,
              NamingClientProxy namingClientProxy, InstancesChangeNotifier changeNotifier) {
          this.asyncQuerySubscribeService = isAsyncQueryForSubscribeService(properties);
          this.executor = new ScheduledThreadPoolExecutor(initPollingThreadCount(properties),
                  new NameThreadFactory("com.alibaba.nacos.client.naming.updater"));
          this.serviceInfoHolder = serviceInfoHolder;
          this.namingClientProxy = namingClientProxy;
          this.changeNotifier = changeNotifier;
      }
      
      private boolean isAsyncQueryForSubscribeService(NacosClientProperties properties) {
          if (properties == null || !properties.containsKey(PropertyKeyConst.NAMING_ASYNC_QUERY_SUBSCRIBE_SERVICE)) {
              return false;
          }
          return ConvertUtils.toBoolean(properties.getProperty(PropertyKeyConst.NAMING_ASYNC_QUERY_SUBSCRIBE_SERVICE),
                  false);
      }
      
      private int initPollingThreadCount(NacosClientProperties properties) {
          int count = ThreadUtils.getSuitableThreadCount(1) > 1 ? ThreadUtils.getSuitableThreadCount(1) / 2 : 1;
          if (properties == null) {
              return count;
          }
          count = Math.min(properties.getInteger(PropertyKeyConst.NAMING_POLLING_MAX_THREAD_COUNT, count), count);
          count = Math.max(count, MIN_THREAD_NUM);
          return properties.getInteger(PropertyKeyConst.NAMING_POLLING_THREAD_COUNT, count);
      }
      
      /**
       * Schedule update if absent.
       *
       * @param serviceName service name
       * @param groupName   group name
       * @param clusters    clusters
       */
      public void scheduleUpdateIfAbsent(String serviceName, String groupName, String clusters) {
          if (!asyncQuerySubscribeService) {
              return;
          }
          String serviceKey = ServiceInfo.getKey(NamingUtils.getGroupedName(serviceName, groupName), clusters);
          if (futureMap.get(serviceKey) != null) {
              return;
          }
          synchronized (futureMap) {
              if (futureMap.get(serviceKey) != null) {
                  return;
              }
              
              ScheduledFuture<?> future = addTask(new UpdateTask(serviceName, groupName, clusters));
              futureMap.put(serviceKey, future);
          }
      }
      
      private synchronized ScheduledFuture<?> addTask(UpdateTask task) {
          return executor.schedule(task, DEFAULT_DELAY, TimeUnit.MILLISECONDS);
      }
      
      /**
       * Stop to schedule update if contain task.
       *
       * @param serviceName service name
       * @param groupName   group name
       * @param clusters    clusters
       */
      public void stopUpdateIfContain(String serviceName, String groupName, String clusters) {
          String serviceKey = ServiceInfo.getKey(NamingUtils.getGroupedName(serviceName, groupName), clusters);
          if (!futureMap.containsKey(serviceKey)) {
              return;
          }
          synchronized (futureMap) {
              if (!futureMap.containsKey(serviceKey)) {
                  return;
              }
              futureMap.remove(serviceKey);
          }
      }
      
      @Override
      public void shutdown() throws NacosException {
          String className = this.getClass().getName();
          NAMING_LOGGER.info("{} do shutdown begin", className);
          ThreadUtils.shutdownThreadPool(executor, NAMING_LOGGER);
          NAMING_LOGGER.info("{} do shutdown stop", className);
      }
      
      public class UpdateTask implements Runnable {
          
          long lastRefTime = Long.MAX_VALUE;
          
          private boolean isCancel;
          
          private final String serviceName;
          
          private final String groupName;
          
          private final String clusters;
          
          private final String groupedServiceName;
          
          private final String serviceKey;
          
          /**
           * the fail situation. 1:can't connect to server 2:serviceInfo's hosts is empty
           */
          private int failCount = 0;
          
          public UpdateTask(String serviceName, String groupName, String clusters) {
              this.serviceName = serviceName;
              this.groupName = groupName;
              this.clusters = clusters;
              this.groupedServiceName = NamingUtils.getGroupedName(serviceName, groupName);
              this.serviceKey = ServiceInfo.getKey(groupedServiceName, clusters);
          }
          
          @Override
          public void run() {
              long delayTime = DEFAULT_DELAY;
              
              try {
                  if (!changeNotifier.isSubscribed(groupName, serviceName) && !futureMap.containsKey(
                          serviceKey)) {
                      NAMING_LOGGER.info("update task is stopped, service:{}, clusters:{}", groupedServiceName, clusters);
                      isCancel = true;
                      return;
                  }
                  
                  ServiceInfo serviceObj = serviceInfoHolder.getServiceInfoMap().get(serviceKey);
                  if (serviceObj == null) {
                      serviceObj = namingClientProxy.queryInstancesOfService(serviceName, groupName, clusters, false);
                      serviceInfoHolder.processServiceInfo(serviceObj);
                      // TODO multiple time can be configured.
                      delayTime = serviceObj.getCacheMillis() * DEFAULT_UPDATE_CACHE_TIME_MULTIPLE;
                      lastRefTime = serviceObj.getLastRefTime();
                      return;
                  }
                  
                  if (serviceObj.getLastRefTime() <= lastRefTime) {
                      serviceObj = namingClientProxy.queryInstancesOfService(serviceName, groupName, clusters, false);
                      serviceInfoHolder.processServiceInfo(serviceObj);
                  }
                  lastRefTime = serviceObj.getLastRefTime();
                  if (CollectionUtils.isEmpty(serviceObj.getHosts())) {
                      incFailCount();
                      return;
                  }
                  // TODO multiple time can be configured.
                  delayTime = serviceObj.getCacheMillis() * DEFAULT_UPDATE_CACHE_TIME_MULTIPLE;
                  resetFailCount();
              } catch (NacosException e) {
                  handleNacosException(e);
              } catch (Throwable e) {
                  handleUnknownException(e);
              } finally {
                  if (!isCancel) {
                      executor.schedule(this, Math.min(delayTime << failCount, DEFAULT_DELAY * 60),
                              TimeUnit.MILLISECONDS);
                  }
              }
          }
          
          private void handleNacosException(NacosException e) {
              incFailCount();
              int errorCode = e.getErrCode();
              if (NacosException.SERVER_ERROR == errorCode) {
                  handleUnknownException(e);
              }
              NAMING_LOGGER.warn("Can't update serviceName: {}, reason: {}", groupedServiceName, e.getErrMsg());
          }
          
          private void handleUnknownException(Throwable throwable) {
              incFailCount();
              NAMING_LOGGER.warn("[NA] failed to update serviceName: {}", groupedServiceName, throwable);
          }
          
          private void incFailCount() {
              int limit = 6;
              if (failCount == limit) {
                  return;
              }
              failCount++;
          }
          
          private void resetFailCount() {
              failCount = 0;
          }
      }
  }
  