/**
    *
    * 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;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Comparator;
  import java.util.Iterator;
  import java.util.List;
  
  import com.google.common.collect.ImmutableCollection;
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.Lists;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.Cell;
  import org.apache.hadoop.hbase.KeyValue;
  import org.apache.hadoop.hbase.KeyValue.KVComparator;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.regionserver.compactions.CompactionConfiguration;
  
  /**
   * Default implementation of StoreFileManager. Not thread-safe.
   */
  @InterfaceAudience.Private
  class DefaultStoreFileManager implements StoreFileManager {
    private static final Log LOG = LogFactory.getLog(DefaultStoreFileManager.class);
  
    private final KVComparator kvComparator;
    private final CompactionConfiguration comConf;
    private final int blockingFileCount;
    private final Comparator<StoreFile> storeFileComparator;
    /**
     * List of store files inside this store. This is an immutable list that
     * is atomically replaced when its contents change.
     */
    private volatile ImmutableList<StoreFile> storefiles = null;
    /**
     * List of compacted files inside this store that needs to be excluded in reads
     * because further new reads will be using only the newly created files out of compaction.
     * These compacted files will be deleted/cleared once all the existing readers on these
     * compacted files are done.
     */
    private volatile List<StoreFile> compactedfiles = null;
  
    public DefaultStoreFileManager(KVComparator kvComparator,
        Comparator<StoreFile> storeFileComparator, Configuration conf,
        CompactionConfiguration comConf) {
      this.kvComparator = kvComparator;
      this.storeFileComparator = storeFileComparator;
      this.comConf = comConf;
      this.blockingFileCount =
          conf.getInt(HStore.BLOCKING_STOREFILES_KEY, HStore.DEFAULT_BLOCKING_STOREFILE_COUNT);
    }
  
    @Override
    public void loadFiles(List<StoreFile> storeFiles) {
      sortAndSetStoreFiles(storeFiles);
    }
  
    @Override
    public final Collection<StoreFile> getStorefiles() {
      // TODO: I can return a null list of StoreFiles? That'll mess up clients. St.Ack 20151111
      return storefiles;
    }
  
    @Override
    public Collection<StoreFile> getCompactedfiles() {
      return compactedfiles;
    }
  
    @Override
    public void insertNewFiles(Collection<StoreFile> sfs) throws IOException {
      ArrayList<StoreFile> newFiles = new ArrayList<StoreFile>(storefiles);
      newFiles.addAll(sfs);
      sortAndSetStoreFiles(newFiles);
    }
  
    @Override
   public ImmutableCollection<StoreFile> clearFiles() {
     ImmutableList<StoreFile> result = storefiles;
     storefiles = ImmutableList.of();
     return result;
   }
 
   @Override
   public Collection<StoreFile> clearCompactedFiles() {
     List<StoreFile> result = compactedfiles;
     compactedfiles = new ArrayList<StoreFile>();
     return result;
   }
 
   @Override
   public final int getStorefileCount() {
     return storefiles.size();
   }
 
   @Override
   public void addCompactionResults(
     Collection<StoreFile> newCompactedfiles, Collection<StoreFile> results) {
     ArrayList<StoreFile> newStoreFiles = Lists.newArrayList(storefiles);
     newStoreFiles.removeAll(newCompactedfiles);
     if (!results.isEmpty()) {
       newStoreFiles.addAll(results);
     }
     sortAndSetStoreFiles(newStoreFiles);
     ArrayList<StoreFile> updatedCompactedfiles = null;
     if (this.compactedfiles != null) {
       updatedCompactedfiles = new ArrayList<StoreFile>(this.compactedfiles);
       updatedCompactedfiles.addAll(newCompactedfiles);
     } else {
       updatedCompactedfiles = new ArrayList<StoreFile>(newCompactedfiles);
     }
     markCompactedAway(newCompactedfiles);
     this.compactedfiles = sortCompactedfiles(updatedCompactedfiles);
   }
 
   // Mark the files as compactedAway once the storefiles and compactedfiles list is finalised
   // Let a background thread close the actual reader on these compacted files and also
   // ensure to evict the blocks from block cache so that they are no longer in
   // cache
   private void markCompactedAway(Collection<StoreFile> compactedFiles) {
     for (StoreFile file : compactedFiles) {
       file.markCompactedAway();
     }
   }
 
   @Override
   public void removeCompactedFiles(Collection<StoreFile> removedCompactedfiles) throws IOException {
     ArrayList<StoreFile> updatedCompactedfiles = null;
     if (this.compactedfiles != null) {
       updatedCompactedfiles = new ArrayList<StoreFile>(this.compactedfiles);
       updatedCompactedfiles.removeAll(removedCompactedfiles);
       this.compactedfiles = sortCompactedfiles(updatedCompactedfiles);
     }
   }
 
   @Override
   public final Iterator<StoreFile> getCandidateFilesForRowKeyBefore(final KeyValue targetKey) {
     return new ArrayList<StoreFile>(Lists.reverse(this.storefiles)).iterator();
   }
 
   @Override
   public Iterator<StoreFile> updateCandidateFilesForRowKeyBefore(
       Iterator<StoreFile> candidateFiles, final KeyValue targetKey, final Cell candidate) {
     // Default store has nothing useful to do here.
     // TODO: move this comment when implementing Level:
     // Level store can trim the list by range, removing all the files which cannot have
     // any useful candidates less than "candidate".
     return candidateFiles;
   }
 
   @Override
   public final byte[] getSplitPoint() throws IOException {
     if (this.storefiles.isEmpty()) {
       return null;
     }
     return StoreUtils.getLargestFile(this.storefiles).getFileSplitPoint(this.kvComparator);
   }
 
   @Override
   public final Collection<StoreFile> getFilesForScanOrGet(byte[] startRow, boolean includeStartRow,
       byte[] stopRow, boolean includeStopRow) {
     // We cannot provide any useful input and already have the files sorted by seqNum.
     return getStorefiles();
   }
 
   @Override
   public int getStoreCompactionPriority() {
     int priority = blockingFileCount - storefiles.size();
     return (priority == HStore.PRIORITY_USER) ? priority + 1 : priority;
   }
 
   @Override
   public Collection<StoreFile> getUnneededFiles(long maxTs, List<StoreFile> filesCompacting) {
     Collection<StoreFile> expiredStoreFiles = null;
     ImmutableList<StoreFile> files = storefiles;
     // 1) We can never get rid of the last file which has the maximum seqid.
     // 2) Files that are not the latest can't become one due to (1), so the rest are fair game.
     for (int i = 0; i < files.size() - 1; ++i) {
       StoreFile sf = files.get(i);
       long fileTs = sf.getReader().getMaxTimestamp();
       if (fileTs < maxTs && !filesCompacting.contains(sf)) {
         LOG.info("Found an expired store file: " + sf.getPath()
             + " whose maxTimeStamp is " + fileTs + ", which is below " + maxTs);
         if (expiredStoreFiles == null) {
           expiredStoreFiles = new ArrayList<StoreFile>();
         }
         expiredStoreFiles.add(sf);
       }
     }
     return expiredStoreFiles;
   }
 
   private void sortAndSetStoreFiles(List<StoreFile> storeFiles) {
     Collections.sort(storeFiles, storeFileComparator);
     storefiles = ImmutableList.copyOf(storeFiles);
   }
 
   private List<StoreFile> sortCompactedfiles(List<StoreFile> storefiles) {
     // Sorting may not be really needed here for the compacted files?
     Collections.sort(storefiles, storeFileComparator);
     return new ArrayList<StoreFile>(storefiles);
   }
 
   @Override
   public double getCompactionPressure() {
     int storefileCount = getStorefileCount();
     int minFilesToCompact = comConf.getMinFilesToCompact();
     if (storefileCount <= minFilesToCompact) {
       return 0.0;
     }
     return (double) (storefileCount - minFilesToCompact) / (blockingFileCount - minFilesToCompact);
   }
 
   @Override
   public Comparator<StoreFile> getStoreFileComparator() {
     return storeFileComparator;
   }
 }