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.common.task.engine;
  
  import com.alibaba.nacos.api.exception.NacosException;
  import com.alibaba.nacos.common.executor.ExecutorFactory;
  import com.alibaba.nacos.common.executor.NameThreadFactory;
  import com.alibaba.nacos.common.task.AbstractDelayTask;
  import com.alibaba.nacos.common.task.NacosTaskProcessor;
  import org.slf4j.Logger;
  
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.locks.ReentrantLock;
  
  /**
   * Nacos delay task execute engine.
   *
   * @author xiweng.yy
   */
  public class NacosDelayTaskExecuteEngine extends AbstractNacosTaskExecuteEngine<AbstractDelayTask> {
      
      private final ScheduledExecutorService processingExecutor;
      
      protected final ConcurrentHashMap<Object, AbstractDelayTask> tasks;
      
      protected final ReentrantLock lock = new ReentrantLock();
      
      public NacosDelayTaskExecuteEngine(String name) {
          this(name, null);
      }
      
      public NacosDelayTaskExecuteEngine(String name, Logger logger) {
          this(name, 32, logger, 100L);
      }
      
      public NacosDelayTaskExecuteEngine(String name, int initCapacity, Logger logger, long processInterval) {
          super(logger);
          tasks = new ConcurrentHashMap<>(initCapacity);
          processingExecutor = ExecutorFactory.newSingleScheduledExecutorService(new NameThreadFactory(name));
          processingExecutor
                  .scheduleWithFixedDelay(new ProcessRunnable(), processInterval, processInterval, TimeUnit.MILLISECONDS);
      }
      
      @Override
      public int size() {
          lock.lock();
          try {
              return tasks.size();
          } finally {
              lock.unlock();
          }
      }
      
      @Override
      public boolean isEmpty() {
          lock.lock();
          try {
              return tasks.isEmpty();
          } finally {
              lock.unlock();
          }
      }
      
      @Override
      public AbstractDelayTask removeTask(Object key) {
          lock.lock();
          try {
              AbstractDelayTask task = tasks.get(key);
              if (null != task && task.shouldProcess()) {
                  return tasks.remove(key);
              } else {
                  return null;
              }
          } finally {
              lock.unlock();
          }
      }
      
      @Override
      public Collection<Object> getAllTaskKeys() {
          Collection<Object> keys = new HashSet<>();
          lock.lock();
          try {
              keys.addAll(tasks.keySet());
          } finally {
              lock.unlock();
          }
          return keys;
      }
      
      @Override
      public void shutdown() throws NacosException {
          tasks.clear();
          processingExecutor.shutdown();
      }
      
      @Override
      public void addTask(Object key, AbstractDelayTask newTask) {
          lock.lock();
          try {
              AbstractDelayTask existTask = tasks.get(key);
              if (null != existTask) {
                  newTask.merge(existTask);
              }
              tasks.put(key, newTask);
          } finally {
              lock.unlock();
          }
      }
      
      /**
       * process tasks in execute engine.
       */
      protected void processTasks() {
          Collection<Object> keys = getAllTaskKeys();
          for (Object taskKey : keys) {
              AbstractDelayTask task = removeTask(taskKey);
              if (null == task) {
                  continue;
              }
              NacosTaskProcessor processor = getProcessor(taskKey);
              try {
                  // ReAdd task if process failed
                  if (!processor.process(task)) {
                      retryFailedTask(taskKey, task);
                  }
              } catch (Throwable e) {
                  getEngineLog().error("Nacos task execute error ", e);
                  retryFailedTask(taskKey, task);
              }
          }
      }
      
      private void retryFailedTask(Object key, AbstractDelayTask task) {
          task.setLastProcessTime(System.currentTimeMillis());
          addTask(key, task);
      }
      
      private class ProcessRunnable implements Runnable {
          
          @Override
          public void run() {
              try {
                  processTasks();
              } catch (Throwable e) {
                  getEngineLog().error(e.toString(), e);
              }
          }
      }
  }
  