/*
    * 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.datacollection.connector;
  
  /**
   * This class is responsible for setting up connections with configured
   * storage writers base on configuration of chukwa_agent.xml.
   * 
   * On error, tries the list of available storage writers, pauses for a minute, 
   * and then repeats.
   *
   */
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Timer;
  import java.util.TimerTask;
  
  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.ChukwaWriter.CommitStatus;
  import org.apache.hadoop.chukwa.datacollection.writer.PipelineStageWriter;
  import org.apache.hadoop.chukwa.datacollection.writer.WriterException;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.log4j.Logger;
  
  public class PipelineConnector implements Connector, Runnable {
  
    static Logger log = Logger.getLogger(PipelineConnector.class);
  
    Timer statTimer = null;
    volatile int chunkCount = 0;
    
    int MAX_SIZE_PER_POST = 2 * 1024 * 1024;
    int MIN_POST_INTERVAL = 5 * 1000;
    public static final String MIN_POST_INTERVAL_OPT = "pipelineConnector.minPostInterval";
    public static final String MAX_SIZE_PER_POST_OPT = "pipelineConnector.maxPostSize";
    public static final String ASYNC_ACKS_OPT = "pipelineConnector.asyncAcks";
  
    ChunkQueue chunkQueue;
  
    private ChukwaAgent agent = null;
  
    private volatile boolean stopMe = false;
    protected ChukwaWriter writers = null;
  
    public PipelineConnector() {
      //instance initializer block
      statTimer = new Timer();
      statTimer.schedule(new TimerTask() {
        public void run() {
          int count = chunkCount;
          chunkCount = 0;
          log.info("# Data chunks sent since last report: " + count);
        }
      }, 100, 60 * 1000);
    }
    
    public void start() {
      chunkQueue = DataFactory.getInstance().getEventQueue();
      agent = ChukwaAgent.getAgent();
      Configuration conf = agent.getConfiguration();
      MAX_SIZE_PER_POST = conf.getInt(MAX_SIZE_PER_POST_OPT, MAX_SIZE_PER_POST);
      MIN_POST_INTERVAL = conf.getInt(MIN_POST_INTERVAL_OPT, MIN_POST_INTERVAL);
      try {
        writers = new PipelineStageWriter(conf);
        (new Thread(this, "Pipeline connector thread")).start();
      } catch(Exception e) {
        log.error("Pipeline initialization error: ", e);
      }
    }
  
    public void shutdown() {
      stopMe = true;
      try {
        writers.close();
      } catch (WriterException e) {
        log.warn("Shutdown error: ",e);
      }
   }
 
   public void run() {
     log.info("PipelineConnector started at time:" + System.currentTimeMillis());
 
     try {
       long lastPost = System.currentTimeMillis();
       while (!stopMe) {
         List<Chunk> newQueue = new ArrayList<Chunk>();
         try {
           // get all ready chunks from the chunkQueue to be sent
           chunkQueue.collect(newQueue, MAX_SIZE_PER_POST);
           CommitStatus result = writers.add(newQueue);
           if(result.equals(ChukwaWriter.COMMIT_OK)) {
             chunkCount = newQueue.size();
             for (Chunk c : newQueue) {
               agent.reportCommit(c.getInitiator(), c.getSeqID());
             }          
           }
         } catch (WriterException e) {
           log.warn("PipelineStageWriter Exception: ", e);
         } catch (InterruptedException e) {
           log.warn("thread interrupted during addChunks(ChunkQueue)");
           Thread.currentThread().interrupt();
           break;
         }
         long now = System.currentTimeMillis();
         long delta = MIN_POST_INTERVAL - now + lastPost;
         if(delta > 0) {
           Thread.sleep(delta); // wait for stuff to accumulate
         }
         lastPost = now;
       } // end of try forever loop
       log.info("received stop() command so exiting run() loop to shutdown connector");
     } catch (OutOfMemoryError e) {
       log.warn("Bailing out", e);
       throw new RuntimeException("Shutdown pipeline connector.");
     } catch (InterruptedException e) {
       // do nothing, let thread die.
       log.warn("Bailing out", e);
       throw new RuntimeException("Shutdown pipeline connector.");
     } catch (Throwable e) {
       log.error("connector failed; shutting down agent: ", e);
       throw new RuntimeException("Shutdown pipeline connector.");
     }
   }
 
   @Override
   public void reloadConfiguration() {
   }
   
 }