code: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 org.apache.skywalking.oap.server.library.datacarrier.consumer;
  
  import java.util.ArrayList;
  import java.util.List;
  import org.apache.skywalking.oap.server.library.datacarrier.buffer.Buffer;
  import org.apache.skywalking.oap.server.library.datacarrier.buffer.QueueBuffer;
  
  public class ConsumerThread<T> extends Thread {
      private volatile boolean running;
      private IConsumer<T> consumer;
      private List<DataSource> dataSources;
      private long consumeCycle;
  
      ConsumerThread(String threadName, IConsumer<T> consumer, long consumeCycle) {
          super(threadName);
          this.consumer = consumer;
          running = false;
          dataSources = new ArrayList<DataSource>(1);
          this.consumeCycle = consumeCycle;
      }
  
      /**
       * add whole buffer to consume
       */
      void addDataSource(QueueBuffer<T> sourceBuffer) {
          this.dataSources.add(new DataSource(sourceBuffer));
      }
  
      @Override
      public void run() {
          running = true;
  
          final List<T> consumeList = new ArrayList<T>(1500);
          while (running) {
              if (!consume(consumeList)) {
                  try {
                      Thread.sleep(consumeCycle);
                  } catch (InterruptedException e) {
                  }
              }
          }
  
          // consumer thread is going to stop
          // consume the last time
          consume(consumeList);
  
          consumer.onExit();
      }
  
      private boolean consume(List<T> consumeList) {
          for (DataSource dataSource : dataSources) {
              dataSource.obtain(consumeList);
          }
  
          if (!consumeList.isEmpty()) {
              try {
                  consumer.consume(consumeList);
              } catch (Throwable t) {
                  consumer.onError(consumeList, t);
              } finally {
                  consumeList.clear();
              }
              return true;
          }
          consumer.nothingToConsume();
          return false;
      }
  
      void shutdown() {
          running = false;
      }
  
      /**
       * DataSource is a refer to {@link Buffer}.
       */
      class DataSource {
          private QueueBuffer<T> sourceBuffer;
  
          DataSource(QueueBuffer<T> sourceBuffer) {
              this.sourceBuffer = sourceBuffer;
          }
  
          void obtain(List<T> consumeList) {
              sourceBuffer.obtain(consumeList);
          }
      }
  }
  