/*
    * 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.writer;
  
  
  import java.net.InetAddress;
  import java.net.URI;
  import java.net.UnknownHostException;
  import java.util.Calendar;
  import java.util.List;
  import java.util.Timer;
  import java.util.TimerTask;
  import java.util.concurrent.Semaphore;
  import java.util.concurrent.TimeUnit;
  import java.io.IOException;
  
  import org.apache.hadoop.chukwa.ChukwaArchiveKey;
  import org.apache.hadoop.chukwa.Chunk;
  import org.apache.hadoop.chukwa.ChunkImpl;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataOutputStream;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.io.SequenceFile;
  import org.apache.log4j.Logger;
  
  /**
   * This class <b>is</b> thread-safe -- rotate() and save() both synchronize on
   * this object.
   * 
   */
  public class SeqFileWriter extends PipelineableWriter implements ChukwaWriter {
    static Logger log = Logger.getLogger(SeqFileWriter.class);
    private static boolean ENABLE_ROTATION_ON_CLOSE = true;
  
    protected int STAT_INTERVAL_SECONDS = 30;
    private int rotateInterval = 1000 * 60 * 5;
    private int offsetInterval = 1000 * 30;
    private boolean if_fixed_interval = false;
    static final int ACQ_WAIT_ON_TERM = 500; //ms to wait for lock on a SIGTERM before aborting
    
    public static final String STAT_PERIOD_OPT = "chukwaCollector.stats.period";
    public static final String ROTATE_INTERVAL_OPT = "chukwaCollector.rotateInterval";
    public static final String IF_FIXED_INTERVAL_OPT = "chukwaCollector.isFixedTimeRotatorScheme";
    public static final String FIXED_INTERVAL_OFFSET_OPT = "chukwaCollector.fixedTimeIntervalOffset";
    public static final String OUTPUT_DIR_OPT= "chukwaCollector.outputDir";
    public String localHostAddr = null;
    
    protected final Semaphore lock = new Semaphore(1, true);
    
    protected FileSystem fs = null;
    protected Configuration conf = null;
  
    protected String outputDir = null;
    private Calendar calendar = Calendar.getInstance();
  
    protected Path currentPath = null;
    protected String currentFileName = null;
    protected FSDataOutputStream currentOutputStr = null;
    protected SequenceFile.Writer seqFileWriter = null;
  
    protected long timePeriod = -1;
    protected long nextTimePeriodComputation = -1;
    
    protected Timer rotateTimer = null;  
    protected Timer statTimer = null;
    
    protected volatile long dataSize = 0;
    protected volatile long bytesThisRotate = 0;
    protected volatile boolean isRunning = false;
  
    public SeqFileWriter() {
      try {
        localHostAddr = "_" + InetAddress.getLocalHost().getHostName() + "_";
      } catch (UnknownHostException e) {
        localHostAddr = "-NA-";
      }
    }
    
    public long getBytesWritten() {
      return dataSize;
    }
    
   public void init(Configuration conf) throws WriterException {
     outputDir = conf.get(OUTPUT_DIR_OPT, "/chukwa");
 
     this.conf = conf;
 
     rotateInterval = conf.getInt(ROTATE_INTERVAL_OPT,rotateInterval);
     if_fixed_interval = conf.getBoolean(IF_FIXED_INTERVAL_OPT,if_fixed_interval);
     offsetInterval = conf.getInt(FIXED_INTERVAL_OFFSET_OPT,offsetInterval);
     
     STAT_INTERVAL_SECONDS = conf.getInt(STAT_PERIOD_OPT, STAT_INTERVAL_SECONDS);
 
     // check if they've told us the file system to use
     String fsname = conf.get("writer.hdfs.filesystem");
     if (fsname == null || fsname.equals("")) {
       // otherwise try to get the filesystem from hadoop
       fsname = conf.get("fs.defaultFS");
     }
 
     log.info("rotateInterval is " + rotateInterval);
     if(if_fixed_interval)
       log.info("using fixed time interval scheme, " +
               "offsetInterval is " + offsetInterval);
     else
       log.info("not using fixed time interval scheme");
     log.info("outputDir is " + outputDir);
     log.info("fsname is " + fsname);
     log.info("filesystem type from core-default.xml is "
         + conf.get("fs.hdfs.impl"));
 
     if (fsname == null) {
       log.error("no filesystem name");
       throw new WriterException("no filesystem");
     }
     try {
       fs = FileSystem.get(new URI(fsname), conf);
       if (fs == null) {
         log.error("can't connect to HDFS.");
       }
     } catch (Throwable e) {
       log.error(
           "can't connect to HDFS, trying default file system instead (likely to be local)",
           e);
     }
 
     // Setup everything by rotating
 
     isRunning = true;
     rotate();
 
     statTimer = new Timer();
     statTimer.schedule(new StatReportingTask(), 1000,
         STAT_INTERVAL_SECONDS * 1000);
 
   }
 
   public class StatReportingTask extends TimerTask {
     private long lastTs = System.currentTimeMillis();
 
     public void run() {
 
       long time = System.currentTimeMillis();
       long currentDs = dataSize;
       dataSize = 0;
 
       long interval = time - lastTs;
       lastTs = time;
 
       long dataRate = 1000 * currentDs / interval; // kb/sec
       log.info("stat:datacollection.writer.hdfs dataSize=" + currentDs
           + " dataRate=" + dataRate);
     }
     
     public StatReportingTask() {}
   };
 
   void rotate() {
      if (rotateTimer != null) {
       rotateTimer.cancel();
     } 
      
     if(!isRunning)
       return;
     
     calendar.setTimeInMillis(System.currentTimeMillis());
 
     String newName = new java.text.SimpleDateFormat("yyyyMMddHHmmssSSS")
         .format(calendar.getTime());
     newName += localHostAddr + new java.rmi.server.UID().toString();
     newName = newName.replace("-", "");
     newName = newName.replace(":", "");
     newName = newName.replace(".", "");
     newName = outputDir + "/" + newName.trim();
 
     try {
       lock.acquire();
 
       FSDataOutputStream previousOutputStr = currentOutputStr;
       Path previousPath = currentPath;
       String previousFileName = currentFileName;
 
       if (previousOutputStr != null) {
         boolean closed = false;
         try {
           log.info("closing sink file" + previousFileName);
           previousOutputStr.close();
           closed = true;
         }catch (Throwable e) {
           log.error("couldn't close file" + previousFileName, e);
           //we probably have an orphaned 0 byte file at this point due to an
           //intermitant HDFS outage. Once HDFS comes up again we'll be able to
           //close it, although it will be empty.
         }
 
         if (bytesThisRotate > 0) {
           if (closed) {
             log.info("rotating sink file " + previousPath);
             fs.rename(previousPath, new Path(previousFileName + ".done"));
           }
           else {
             log.warn(bytesThisRotate + " bytes potentially lost, since " +
                     previousPath + " could not be closed.");
           }
         } else {
           log.info("no chunks written to " + previousPath + ", deleting");
           fs.delete(previousPath, false);
         }
       }
 
       Path newOutputPath = new Path(newName + ".chukwa");
       FSDataOutputStream newOutputStr = fs.create(newOutputPath);
       // Uncompressed for now
       seqFileWriter = SequenceFile.createWriter(conf, newOutputStr,
           ChukwaArchiveKey.class, ChunkImpl.class,
           SequenceFile.CompressionType.NONE, null);
 
       // reset these once we know that seqFileWriter was created
       currentOutputStr = newOutputStr;
       currentPath = newOutputPath;
       currentFileName = newName;
       bytesThisRotate = 0;
     } catch (Throwable e) {
       log.warn("Got an exception trying to rotate. Will try again in " +
               rotateInterval/1000 + " seconds." ,e);
     } finally {
       lock.release();
     }
     
     // Schedule the next timer
     scheduleNextRotation();
 
   }
 
   /**
    * Schedules the rotate task using either a fixed time interval scheme or a
    * relative time interval scheme as specified by the
    * chukwaCollector.isFixedTimeRotatorScheme configuration parameter. If the
    * value of this parameter is true then next rotation will be scheduled at a
    * fixed offset from the current rotateInterval. This fixed offset is
    * provided by chukwaCollector.fixedTimeIntervalOffset configuration
    * parameter.
    */
   void scheduleNextRotation(){
     long delay = rotateInterval;
     if (if_fixed_interval) {
       long currentTime = System.currentTimeMillis();
       delay = getDelayForFixedInterval(currentTime, rotateInterval, offsetInterval);
     }
     rotateTimer = new Timer();
     rotateTimer.schedule(new TimerTask() {
       public void run() {
         rotate();
       }
     }, delay);
   }
 
   /**
    * Calculates delay for scheduling the next rotation in case of
    * FixedTimeRotatorScheme. This delay is the time difference between the
    * currentTimestamp (t1) and the next time the collector should rotate the
    * sequence files (t2). t2 is the time when the current rotateInterval ends
    * plus an offset (as set by chukwaCollector.FixedTimeIntervalOffset).
    * So, delay = t2 - t1
    *
    * @param currentTime - the current timestamp
    * @param rotateInterval - chukwaCollector.rotateInterval
    * @param offsetInterval - chukwaCollector.fixedTimeIntervalOffset
    * @return delay for scheduling next rotation
    */
   long getDelayForFixedInterval(long currentTime, long rotateInterval, long offsetInterval){
     // time since last rounded interval
     long remainder = (currentTime % rotateInterval);
     long prevRoundedInterval = currentTime - remainder;
     long nextRoundedInterval = prevRoundedInterval + rotateInterval;
     long delay = nextRoundedInterval - currentTime + offsetInterval;
 
     if (log.isInfoEnabled()) {
      log.info("currentTime="+currentTime+" prevRoundedInterval="+
              prevRoundedInterval+" nextRoundedInterval" +
             "="+nextRoundedInterval+" delay="+delay);
     }
 
     return delay;
   }
 
 
   protected void computeTimePeriod() {
     synchronized (calendar) {
       calendar.setTimeInMillis(System.currentTimeMillis());
       calendar.set(Calendar.MINUTE, 0);
       calendar.set(Calendar.SECOND, 0);
       calendar.set(Calendar.MILLISECOND, 0);
       timePeriod = calendar.getTimeInMillis();
       calendar.add(Calendar.HOUR, 1);
       nextTimePeriodComputation = calendar.getTimeInMillis();
     }
   }
   
   @Override
   public CommitStatus add(List<Chunk> chunks) throws WriterException {
     COMMIT_PENDING result = new COMMIT_PENDING(chunks.size());
     if (!isRunning) {
       log.info("Collector not ready");
       throw new WriterException("Collector not ready");
     }
 
     ChukwaArchiveKey archiveKey = new ChukwaArchiveKey();
     
     if (System.currentTimeMillis() >= nextTimePeriodComputation) {
       computeTimePeriod();
     }
     try {
       lock.acquire();
       for (Chunk chunk : chunks) {
         archiveKey.setTimePartition(timePeriod);
         archiveKey.setDataType(chunk.getDataType());
         archiveKey.setStreamName(chunk.getTags() + "/" + chunk.getSource()
             + "/" + chunk.getStreamName());
         archiveKey.setSeqId(chunk.getSeqID());
 
         seqFileWriter.append(archiveKey, chunk);
 
         // compute size for stats only if append succeeded. Note though that
         // seqFileWriter.append can continue taking data for quite some time
         // after HDFS goes down while the client is trying to reconnect. Hence
         // these stats might not reflect reality during an HDFS outage.
         dataSize += chunk.getData().length;
         bytesThisRotate += chunk.getData().length;
 
         String futureName = currentPath.getName().replace(".chukwa", ".done");
         result.addPend(futureName, currentOutputStr.getPos());
 
       }
     }
     catch (IOException e) {
       log.error("IOException when trying to write a chunk, Collector will return error and keep running.", e);
       return COMMIT_FAIL;
     }
     catch (Throwable e) {
       // We don't want to loose anything
       log.fatal("IOException when trying to write a chunk, Collector is going to exit!", e);
       isRunning = false;
     } finally {
       lock.release();
     }
     return result;
   }
 
   public void close() {
     
     isRunning = false;
 
     if (statTimer != null) {
       statTimer.cancel();
     }
 
     if (rotateTimer != null) {
       rotateTimer.cancel();
     }
 
     // If we are here it's either because of an HDFS exception
     // or Collector has received a kill -TERM
     boolean gotLock = false;
     try {
       gotLock = lock.tryAcquire(ACQ_WAIT_ON_TERM, TimeUnit.MILLISECONDS);
       if(gotLock) {
         
         if (this.currentOutputStr != null) {
           this.currentOutputStr.close();
         }
         if(ENABLE_ROTATION_ON_CLOSE)
           if(bytesThisRotate > 0)
             fs.rename(currentPath, new Path(currentFileName + ".done"));
           else
             fs.delete(currentPath, false);
       }
     } catch (Throwable e) {
      log.warn("cannot rename dataSink file:" + currentPath,e);
     } finally {
       if(gotLock)
         lock.release();
     }
   }
   
   public static void setEnableRotationOnClose(boolean b) {
     ENABLE_ROTATION_ON_CLOSE = b;
   }
 
 }