/*
    * 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.hadoop.chukwa.tools.backfilling;
  
  import java.util.LinkedList;
  import java.util.List;
  
  import org.apache.hadoop.chukwa.Chunk;
  import org.apache.hadoop.chukwa.datacollection.ChunkQueue;
  import org.apache.hadoop.chukwa.datacollection.DataFactory;
  import org.apache.hadoop.chukwa.datacollection.agent.ChukwaAgent;
  import org.apache.hadoop.chukwa.datacollection.connector.Connector;
  import org.apache.hadoop.chukwa.datacollection.writer.ChukwaWriter;
  import org.apache.hadoop.chukwa.datacollection.writer.SeqFileWriter;
  import org.apache.hadoop.chukwa.util.DaemonWatcher;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.log4j.Logger;
  
  public class QueueToWriterConnector implements Connector, Runnable {
    static Logger log = Logger.getLogger(QueueToWriterConnector.class);
    static final int MAX_SIZE_PER_POST = 2 * 1024 * 1024;
  
    protected Configuration conf = null;
    protected volatile boolean isRunning = true;
    protected ChunkQueue chunkQueue = DataFactory.getInstance().getEventQueue();
    protected ChukwaWriter writer = null;
    protected Thread runner = null;
    protected boolean isBackfilling = false;
    public QueueToWriterConnector(Configuration conf,boolean isBackfilling) {
      this.conf = conf;
      this.isBackfilling = isBackfilling;
    }
  
    @Override
    public void reloadConfiguration() {
      // do nothing here
    }
  
    @Override
    public void shutdown() {
      isRunning = false;
      
      log.info("Shutdown in progress ...");
      while (isAlive()) {
        try {
          Thread.sleep(1000);
        } catch (InterruptedException e) {}
      }
     
      try {
        if (writer != null) {
          writer.close();
        }
      } catch(Exception e) {
        log.warn("Exception while closing writer: ", e);
      }
      log.info("Shutdown done.");
    }
  
    @Override
    public void start() {
      log.info("Starting QueueToWriterConnector thread");
      runner = new Thread(this, "QueueToWriterConnectorThread");
      runner.start();
    }
  
    protected boolean isAlive() {
      return this.runner.isAlive();
    }
    
    @Override
    public void run() {
  
      log.info("initializing QueueToWriterConnector");
      try {
        String writerClassName = conf.get("chukwaCollector.writerClass",
            SeqFileWriter.class.getCanonicalName());
        Class<?> writerClass = Class.forName(writerClassName);
        if (writerClass != null
            && ChukwaWriter.class.isAssignableFrom(writerClass)) {
          writer = (ChukwaWriter) writerClass.newInstance();
        } else {
          throw new RuntimeException("Wrong class type");
       }
       writer.init(conf);
 
     } catch (Throwable e) {
       log.warn("failed to use user-chosen writer class, Bail out!", e);
       DaemonWatcher.bailout(-1);
     }
 
     
     List<Chunk> chunks = new LinkedList<Chunk>();
     ChukwaAgent agent = null;// ChukwaAgent.getAgent();
     
     log.info("processing data for QueueToWriterConnector");
     
     while ( isRunning ||  chunkQueue.size() != 0 || chunks.size() != 0) {
       try {
         if (chunks.size() == 0) {
           
           if (isBackfilling && chunkQueue.size() == 0) {
             Thread.sleep(300);
             continue;
           }
           chunkQueue.collect(chunks, MAX_SIZE_PER_POST);
           log.info("Got " + chunks.size() + " chunks back from the queue");
         }       
         
         writer.add(chunks);
         
         if (agent != null) {
           for(Chunk chunk: chunks) {
             agent.reportCommit(chunk.getInitiator(), chunk.getSeqID());
           }
         }
         
         chunks.clear();
         
       }
       catch (Throwable e) {
         log.warn("Could not save some chunks");
         e.printStackTrace();
         try {
           Thread.sleep(5000);
         } catch (InterruptedException e1) {}
       } 
     }
   }
 
 }