/**
    * 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.hbase.regionserver.compactions;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.List;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.regionserver.InternalScanner;
  import org.apache.hadoop.hbase.regionserver.ScanType;
  import org.apache.hadoop.hbase.regionserver.Store;
  import org.apache.hadoop.hbase.regionserver.StoreFile;
  import org.apache.hadoop.hbase.regionserver.StoreFileScanner;
  import org.apache.hadoop.hbase.security.User;
  
  /**
   * Compact passed set of files. Create an instance and then call
   * {@link #compact(CompactionRequest, CompactionThroughputController, User)}
   */
  @InterfaceAudience.Private
  public class DefaultCompactor extends Compactor {
    private static final Log LOG = LogFactory.getLog(DefaultCompactor.class);
  
    public DefaultCompactor(final Configuration conf, final Store store) {
      super(conf, store);
    }
  
    /**
     * Do a minor/major compaction on an explicit set of storefiles from a Store.
     */
    public List<Path> compact(final CompactionRequest request,
        CompactionThroughputController throughputController, User user) throws IOException {
      FileDetails fd = getFileDetails(request.getFiles(), request.isAllFiles());
      this.progress = new CompactionProgress(fd.maxKeyCount);
  
      // Find the smallest read point across all the Scanners.
      long smallestReadPoint = getSmallestReadPoint();
  
      List<StoreFileScanner> scanners;
      Collection<StoreFile> readersToClose;
      if (this.conf.getBoolean("hbase.regionserver.compaction.private.readers", true)) {
        // clone all StoreFiles, so we'll do the compaction on a independent copy of StoreFiles,
        // HFileFiles, and their readers
        readersToClose = new ArrayList<StoreFile>(request.getFiles().size());
        for (StoreFile f : request.getFiles()) {
          readersToClose.add(new StoreFile(f));
        }
        scanners = createFileScanners(readersToClose, smallestReadPoint,
            store.throttleCompaction(request.getSize()));
      } else {
        readersToClose = Collections.emptyList();
        scanners = createFileScanners(request.getFiles(), smallestReadPoint,
            store.throttleCompaction(request.getSize()));
      }
  
      StoreFile.Writer writer = null;
      List<Path> newFiles = new ArrayList<Path>();
      boolean cleanSeqId = false;
      IOException e = null;
      try {
        InternalScanner scanner = null;
        try {
          /* Include deletes, unless we are doing a compaction of all files */
          ScanType scanType = request.isRetainDeleteMarkers() ? ScanType.COMPACT_RETAIN_DELETES
              : ScanType.COMPACT_DROP_DELETES;
          scanner = preCreateCoprocScanner(request, scanType, fd.earliestPutTs, scanners, user);
          if (scanner == null) {
            scanner = createScanner(store, scanners, scanType, smallestReadPoint, fd.earliestPutTs);
          }
          scanner = postCreateCoprocScanner(request, scanType, scanner, user);
          if (scanner == null) {
            // NULL scanner returned from coprocessor hooks means skip normal processing.
            return newFiles;
          }
          // Create the writer even if no kv(Empty store file is also ok),
          // because we need record the max seq id for the store file, see HBASE-6059
         if(fd.minSeqIdToKeep > 0) {
           smallestReadPoint = Math.min(fd.minSeqIdToKeep, smallestReadPoint);
           cleanSeqId = true;
         }
 
         writer = createTmpWriter(fd, store.throttleCompaction(request.getSize()));
         boolean finished = performCompaction(fd, scanner, writer, smallestReadPoint, cleanSeqId,
           throughputController, request.isAllFiles());
 
         if (!finished) {
           writer.close();
           store.getFileSystem().delete(writer.getPath(), false);
           writer = null;
           throw new InterruptedIOException("Aborting compaction of store " + store +
               " in region " + store.getRegionInfo().getRegionNameAsString() +
               " because it was interrupted.");
          }
        } finally {
          if (scanner != null) {
            scanner.close();
          }
       }
     } catch (IOException ioe) {
       e = ioe;
       // Throw the exception
       throw ioe;
     }
     finally {
       try {
         if (writer != null) {
           if (e != null) {
             writer.close();
           } else {
             writer.appendMetadata(fd.maxSeqId, request.isAllFiles());
             writer.close();
             newFiles.add(writer.getPath());
           }
         }
       } finally {
         for (StoreFile f : readersToClose) {
           try {
             f.closeReader(true);
           } catch (IOException ioe) {
             LOG.warn("Exception closing " + f, ioe);
           }
         }
       }
     }
     return newFiles;
   }
 
   /**
    * Creates a writer for a new file in a temporary directory.
    * @param fd The file details.
    * @return Writer for a new StoreFile in the tmp dir.
    * @throws IOException
    */
   protected StoreFile.Writer createTmpWriter(FileDetails fd, boolean shouldDropBehind)
     throws IOException {
 
       // When all MVCC readpoints are 0, don't write them.
       // See HBASE-8166, HBASE-12600, and HBASE-13389.
 
       return store.createWriterInTmp(fd.maxKeyCount, this.compactionCompression,
             /* isCompaction = */ true,
             /* includeMVCCReadpoint = */ fd.maxMVCCReadpoint > 0,
             /* includesTags = */ fd.maxTagsLength > 0,
             /* shouldDropBehind = */ shouldDropBehind);
   }
 
   /**
    * Compact a list of files for testing. Creates a fake {@link CompactionRequest} to pass to
    * {@link #compact(CompactionRequest, CompactionThroughputController, User)};
    * @param filesToCompact the files to compact. These are used as the compactionSelection for
    *          the generated {@link CompactionRequest}.
    * @param isMajor true to major compact (prune all deletes, max versions, etc)
    * @return Product of compaction or an empty list if all cells expired or deleted and nothing \
    *         made it through the compaction.
    * @throws IOException
    */
   public List<Path> compactForTesting(final Collection<StoreFile> filesToCompact, boolean isMajor)
       throws IOException {
     CompactionRequest cr = new CompactionRequest(filesToCompact);
     cr.setIsMajor(isMajor, isMajor);
     return this.compact(cr, NoLimitCompactionThroughputController.INSTANCE, null);
   }
 }