/**
    *
    * 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 static org.apache.hadoop.hbase.regionserver.StripeStoreFileManager.OPEN_KEY;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.List;
  
  import com.google.common.collect.ImmutableList;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.KeyValue.KVComparator;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.regionserver.StoreConfigInformation;
  import org.apache.hadoop.hbase.regionserver.StoreFile;
  import org.apache.hadoop.hbase.regionserver.StoreUtils;
  import org.apache.hadoop.hbase.regionserver.StripeStoreConfig;
  import org.apache.hadoop.hbase.regionserver.StripeStoreFlusher;
  import org.apache.hadoop.hbase.regionserver.throttle.ThroughputController;
  import org.apache.hadoop.hbase.security.User;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.ConcatenatedLists;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  import org.apache.hadoop.hbase.util.Pair;
  
  /**
   * Stripe store implementation of compaction policy.
   */
  @InterfaceAudience.Private
  public class StripeCompactionPolicy extends CompactionPolicy {
    private final static Log LOG = LogFactory.getLog(StripeCompactionPolicy.class);
    // Policy used to compact individual stripes.
    private ExploringCompactionPolicy stripePolicy = null;
  
    private StripeStoreConfig config;
  
    public StripeCompactionPolicy(
        Configuration conf, StoreConfigInformation storeConfigInfo, StripeStoreConfig config) {
      super(conf, storeConfigInfo);
      this.config = config;
      stripePolicy = new ExploringCompactionPolicy(conf, storeConfigInfo);
    }
  
    public List<StoreFile> preSelectFilesForCoprocessor(StripeInformationProvider si,
        List<StoreFile> filesCompacting) {
      // We sincerely hope nobody is messing with us with their coprocessors.
      // If they do, they are very likely to shoot themselves in the foot.
      // We'll just exclude all the filesCompacting from the list.
      ArrayList<StoreFile> candidateFiles = new ArrayList<StoreFile>(si.getStorefiles());
      candidateFiles.removeAll(filesCompacting);
      return candidateFiles;
    }
  
    public StripeCompactionRequest createEmptyRequest(
        StripeInformationProvider si, CompactionRequest request) {
      // Treat as L0-ish compaction with fixed set of files, and hope for the best.
      if (si.getStripeCount() > 0) {
        return new BoundaryStripeCompactionRequest(request, si.getStripeBoundaries());
      }
      Pair<Long, Integer> targetKvsAndCount = estimateTargetKvs(
          request.getFiles(), this.config.getInitialCount());
      return new SplitStripeCompactionRequest(
          request, OPEN_KEY, OPEN_KEY, targetKvsAndCount.getSecond(), targetKvsAndCount.getFirst());
    }
  
    public StripeStoreFlusher.StripeFlushRequest selectFlush(KVComparator comparator,
        StripeInformationProvider si, int kvCount) {
      if (this.config.isUsingL0Flush()) {
        // L0 is used, return dumb request.
        return new StripeStoreFlusher.StripeFlushRequest(comparator);
      }
      if (si.getStripeCount() == 0) {
        // No stripes - start with the requisite count, derive KVs per stripe.
        int initialCount = this.config.getInitialCount();
        return new StripeStoreFlusher.SizeStripeFlushRequest(comparator, initialCount,
            kvCount / initialCount);
      }
     // There are stripes - do according to the boundaries.
     return new StripeStoreFlusher.BoundaryStripeFlushRequest(comparator, si.getStripeBoundaries());
   }
 
   public StripeCompactionRequest selectCompaction(StripeInformationProvider si,
       List<StoreFile> filesCompacting, boolean isOffpeak) throws IOException {
     // TODO: first cut - no parallel compactions. To have more fine grained control we
     //       probably need structure more sophisticated than a list.
     if (!filesCompacting.isEmpty()) {
       LOG.debug("Not selecting compaction: " + filesCompacting.size() + " files compacting");
       return null;
     }
 
     // We are going to do variations of compaction in strict order of preference.
     // A better/more advanced approach is to use a heuristic to see which one is "more
     // necessary" at current time.
 
     // This can happen due to region split. We can skip it later; for now preserve
     // compact-all-things behavior.
     Collection<StoreFile> allFiles = si.getStorefiles();
     if (StoreUtils.hasReferences(allFiles)) {
       LOG.debug("There are references in the store; compacting all files");
       long targetKvs = estimateTargetKvs(allFiles, config.getInitialCount()).getFirst();
       SplitStripeCompactionRequest request = new SplitStripeCompactionRequest(
           allFiles, OPEN_KEY, OPEN_KEY, targetKvs);
       request.setMajorRangeFull();
       request.getRequest().setAfterSplit(true);
       return request;
     }
 
     int stripeCount = si.getStripeCount();
     List<StoreFile> l0Files = si.getLevel0Files();
 
     // See if we need to make new stripes.
     boolean shouldCompactL0 = (this.config.getLevel0MinFiles() <= l0Files.size());
     if (stripeCount == 0) {
       if (!shouldCompactL0) return null; // nothing to do.
       return selectNewStripesCompaction(si);
     }
 
     boolean canDropDeletesNoL0 = l0Files.size() == 0;
     if (shouldCompactL0) {
       if (!canDropDeletesNoL0) {
         // If we need to compact L0, see if we can add something to it, and drop deletes.
         StripeCompactionRequest result = selectSingleStripeCompaction(
             si, true, canDropDeletesNoL0, isOffpeak);
         if (result != null) return result;
       }
       LOG.debug("Selecting L0 compaction with " + l0Files.size() + " files");
       return new BoundaryStripeCompactionRequest(l0Files, si.getStripeBoundaries());
     }
 
     // Try to delete fully expired stripes
     StripeCompactionRequest result = selectExpiredMergeCompaction(si, canDropDeletesNoL0);
     if (result != null) return result;
 
     // Ok, nothing special here, let's see if we need to do a common compaction.
     // This will also split the stripes that are too big if needed.
     return selectSingleStripeCompaction(si, false, canDropDeletesNoL0, isOffpeak);
   }
 
   public boolean needsCompactions(StripeInformationProvider si, List<StoreFile> filesCompacting) {
     // Approximation on whether we need compaction.
     return filesCompacting.isEmpty()
         && (StoreUtils.hasReferences(si.getStorefiles())
           || (si.getLevel0Files().size() >= this.config.getLevel0MinFiles())
           || needsSingleStripeCompaction(si));
   }
 
   @Override
   public boolean shouldPerformMajorCompaction(Collection<StoreFile> filesToCompact)
     throws IOException {
     return false; // there's never a major compaction!
   }
 
   @Override
   public boolean throttleCompaction(long compactionSize) {
     return compactionSize > comConf.getThrottlePoint();
   }
 
   /**
    * @param si StoreFileManager.
    * @return Whether any stripe potentially needs compaction.
    */
   protected boolean needsSingleStripeCompaction(StripeInformationProvider si) {
     int minFiles = this.config.getStripeCompactMinFiles();
     for (List<StoreFile> stripe : si.getStripes()) {
       if (stripe.size() >= minFiles) return true;
     }
     return false;
   }
 
   protected StripeCompactionRequest selectSingleStripeCompaction(StripeInformationProvider si,
       boolean includeL0, boolean canDropDeletesWithoutL0, boolean isOffpeak) throws IOException {
     ArrayList<ImmutableList<StoreFile>> stripes = si.getStripes();
 
     int bqIndex = -1;
     List<StoreFile> bqSelection = null;
     int stripeCount = stripes.size();
     long bqTotalSize = -1;
     for (int i = 0; i < stripeCount; ++i) {
       // If we want to compact L0 to drop deletes, we only want whole-stripe compactions.
       // So, pass includeL0 as 2nd parameter to indicate that.
       List<StoreFile> selection = selectSimpleCompaction(stripes.get(i),
           !canDropDeletesWithoutL0 && includeL0, isOffpeak);
       if (selection.isEmpty()) continue;
       long size = 0;
       for (StoreFile sf : selection) {
         size += sf.getReader().length();
       }
       if (bqSelection == null || selection.size() > bqSelection.size() ||
           (selection.size() == bqSelection.size() && size < bqTotalSize)) {
         bqSelection = selection;
         bqIndex = i;
         bqTotalSize = size;
       }
     }
     if (bqSelection == null) {
       LOG.debug("No good compaction is possible in any stripe");
       return null;
     }
     List<StoreFile> filesToCompact = new ArrayList<StoreFile>(bqSelection);
     // See if we can, and need to, split this stripe.
     int targetCount = 1;
     long targetKvs = Long.MAX_VALUE;
     boolean hasAllFiles = filesToCompact.size() == stripes.get(bqIndex).size();
     String splitString = "";
     if (hasAllFiles && bqTotalSize >= config.getSplitSize()) {
       if (includeL0) {
         // We want to avoid the scenario where we compact a stripe w/L0 and then split it.
         // So, if we might split, don't compact the stripe with L0.
         return null;
       }
       Pair<Long, Integer> kvsAndCount = estimateTargetKvs(filesToCompact, config.getSplitCount());
       targetKvs = kvsAndCount.getFirst();
       targetCount = kvsAndCount.getSecond();
       splitString = "; the stripe will be split into at most "
           + targetCount + " stripes with " + targetKvs + " target KVs";
     }
 
     LOG.debug("Found compaction in a stripe with end key ["
         + Bytes.toString(si.getEndRow(bqIndex)) + "], with "
         + filesToCompact.size() + " files of total size " + bqTotalSize + splitString);
 
     // See if we can drop deletes.
     StripeCompactionRequest req;
     if (includeL0) {
       assert hasAllFiles;
       List<StoreFile> l0Files = si.getLevel0Files();
       LOG.debug("Adding " + l0Files.size() + " files to compaction to be able to drop deletes");
       ConcatenatedLists<StoreFile> sfs = new ConcatenatedLists<StoreFile>();
       sfs.addSublist(filesToCompact);
       sfs.addSublist(l0Files);
       req = new BoundaryStripeCompactionRequest(sfs, si.getStripeBoundaries());
     } else {
       req = new SplitStripeCompactionRequest(
           filesToCompact, si.getStartRow(bqIndex), si.getEndRow(bqIndex), targetCount, targetKvs);
     }
     if (hasAllFiles && (canDropDeletesWithoutL0 || includeL0)) {
       req.setMajorRange(si.getStartRow(bqIndex), si.getEndRow(bqIndex));
     }
     req.getRequest().setOffPeak(isOffpeak);
     return req;
   }
 
   /**
    * Selects the compaction of a single stripe using default policy.
    * @param sfs Files.
    * @param allFilesOnly Whether a compaction of all-or-none files is needed.
    * @return The resulting selection.
    */
   private List<StoreFile> selectSimpleCompaction(
       List<StoreFile> sfs, boolean allFilesOnly, boolean isOffpeak) {
     int minFilesLocal = Math.max(
         allFilesOnly ? sfs.size() : 0, this.config.getStripeCompactMinFiles());
     int maxFilesLocal = Math.max(this.config.getStripeCompactMaxFiles(), minFilesLocal);
     return stripePolicy.applyCompactionPolicy(sfs, false, isOffpeak, minFilesLocal, maxFilesLocal);
   }
 
   /**
    * Selects the compaction that compacts all files (to be removed later).
    * @param si StoreFileManager.
    * @param targetStripeCount Target stripe count.
    * @param targetSize Target stripe size.
    * @return The compaction.
    */
   private StripeCompactionRequest selectCompactionOfAllFiles(StripeInformationProvider si,
       int targetStripeCount, long targetSize) {
     Collection<StoreFile> allFiles = si.getStorefiles();
     SplitStripeCompactionRequest request = new SplitStripeCompactionRequest(
         allFiles, OPEN_KEY, OPEN_KEY, targetStripeCount, targetSize);
     request.setMajorRangeFull();
     LOG.debug("Selecting a compaction that includes all " + allFiles.size() + " files");
     return request;
   }
 
   private StripeCompactionRequest selectNewStripesCompaction(StripeInformationProvider si) {
     List<StoreFile> l0Files = si.getLevel0Files();
     Pair<Long, Integer> kvsAndCount = estimateTargetKvs(l0Files, config.getInitialCount());
     LOG.debug("Creating " + kvsAndCount.getSecond() + " initial stripes with "
         + kvsAndCount.getFirst() + " kvs each via L0 compaction of " + l0Files.size() + " files");
     SplitStripeCompactionRequest request = new SplitStripeCompactionRequest(
         si.getLevel0Files(), OPEN_KEY, OPEN_KEY, kvsAndCount.getSecond(), kvsAndCount.getFirst());
     request.setMajorRangeFull(); // L0 only, can drop deletes.
     return request;
   }
 
   private StripeCompactionRequest selectExpiredMergeCompaction(
       StripeInformationProvider si, boolean canDropDeletesNoL0) {
     long cfTtl = this.storeConfigInfo.getStoreFileTtl();
     if (cfTtl == Long.MAX_VALUE) {
       return null; // minversion might be set, cannot delete old files
     }
     long timestampCutoff = EnvironmentEdgeManager.currentTime() - cfTtl;
     // Merge the longest sequence of stripes where all files have expired, if any.
     int start = -1, bestStart = -1, length = 0, bestLength = 0;
     ArrayList<ImmutableList<StoreFile>> stripes = si.getStripes();
     OUTER: for (int i = 0; i < stripes.size(); ++i) {
       for (StoreFile storeFile : stripes.get(i)) {
         if (storeFile.getReader().getMaxTimestamp() < timestampCutoff) continue;
         // Found non-expired file, this stripe has to stay.
         if (length > bestLength) {
           bestStart = start;
           bestLength = length;
         }
         start = -1;
         length = 0;
         continue OUTER;
       }
       if (start == -1) {
         start = i;
       }
       ++length;
     }
     if (length > bestLength) {
       bestStart = start;
       bestLength = length;
     }
     if (bestLength == 0) return null;
     if (bestLength == 1) {
       // This is currently inefficient. If only one stripe expired, we will rewrite some
       // entire stripe just to delete some expired files because we rely on metadata and it
       // cannot simply be updated in an old file. When we either determine stripe dynamically
       // or move metadata to manifest, we can just drop the "expired stripes".
       if (bestStart == (stripes.size() - 1)) return null;
       ++bestLength;
     }
     LOG.debug("Merging " + bestLength + " stripes to delete expired store files");
     int endIndex = bestStart + bestLength - 1;
     ConcatenatedLists<StoreFile> sfs = new ConcatenatedLists<StoreFile>();
     sfs.addAllSublists(stripes.subList(bestStart, endIndex + 1));
     SplitStripeCompactionRequest result = new SplitStripeCompactionRequest(sfs,
         si.getStartRow(bestStart), si.getEndRow(endIndex), 1, Long.MAX_VALUE);
     if (canDropDeletesNoL0) {
       result.setMajorRangeFull();
     }
     return result;
   }
 
   private static long getTotalKvCount(final Collection<StoreFile> candidates) {
     long totalSize = 0;
     for (StoreFile storeFile : candidates) {
       totalSize += storeFile.getReader().getEntries();
     }
     return totalSize;
   }
 
   public static long getTotalFileSize(final Collection<StoreFile> candidates) {
     long totalSize = 0;
     for (StoreFile storeFile : candidates) {
       totalSize += storeFile.getReader().length();
     }
     return totalSize;
   }
 
   private Pair<Long, Integer> estimateTargetKvs(Collection<StoreFile> files, double splitCount) {
     // If the size is larger than what we target, we don't want to split into proportionally
     // larger parts and then have to split again very soon. So, we will increase the multiplier
     // by one until we get small enough parts. E.g. 5Gb stripe that should have been split into
     // 2 parts when it was 3Gb will be split into 3x1.67Gb parts, rather than 2x2.5Gb parts.
     long totalSize = getTotalFileSize(files);
     long targetPartSize = config.getSplitPartSize();
     assert targetPartSize > 0 && splitCount > 0;
     double ratio = totalSize / (splitCount * targetPartSize); // ratio of real to desired size
     while (ratio > 1.0) {
       // Ratio of real to desired size if we increase the multiplier.
       double newRatio = totalSize / ((splitCount + 1.0) * targetPartSize);
       if ((1.0 / newRatio) >= ratio) break; // New ratio is < 1.0, but further than the last one.
       ratio = newRatio;
       splitCount += 1.0;
     }
     long kvCount = (long)(getTotalKvCount(files) / splitCount);
     return new Pair<Long, Integer>(kvCount, (int)Math.ceil(splitCount));
   }
 
   /** Stripe compaction request wrapper. */
   public abstract static class StripeCompactionRequest {
     protected CompactionRequest request;
     protected byte[] majorRangeFromRow = null, majorRangeToRow = null;
 
     public List<Path> execute(StripeCompactor compactor,
       ThroughputController throughputController) throws IOException {
       return execute(compactor, throughputController, null);
     }
     /**
      * Executes the request against compactor (essentially, just calls correct overload of
      * compact method), to simulate more dynamic dispatch.
      * @param compactor Compactor.
      * @return result of compact(...)
      */
     public abstract List<Path> execute(StripeCompactor compactor,
         ThroughputController throughputController, User user) throws IOException;
 
     public StripeCompactionRequest(CompactionRequest request) {
       this.request = request;
     }
 
     /**
      * Sets compaction "major range". Major range is the key range for which all
      * the files are included, so they can be treated like major-compacted files.
      * @param startRow Left boundary, inclusive.
      * @param endRow Right boundary, exclusive.
      */
     public void setMajorRange(byte[] startRow, byte[] endRow) {
       this.majorRangeFromRow = startRow;
       this.majorRangeToRow = endRow;
     }
 
     public CompactionRequest getRequest() {
       return this.request;
     }
 
     public void setRequest(CompactionRequest request) {
       assert request != null;
       this.request = request;
       this.majorRangeFromRow = this.majorRangeToRow = null;
     }
   }
 
   /**
    * Request for stripe compactor that will cause it to split the source files into several
    * separate files at the provided boundaries.
    */
   private static class BoundaryStripeCompactionRequest extends StripeCompactionRequest {
     private final List<byte[]> targetBoundaries;
 
     /**
      * @param request Original request.
      * @param targetBoundaries New files should be written with these boundaries.
      */
     public BoundaryStripeCompactionRequest(CompactionRequest request,
         List<byte[]> targetBoundaries) {
       super(request);
       this.targetBoundaries = targetBoundaries;
     }
 
     public BoundaryStripeCompactionRequest(Collection<StoreFile> files,
         List<byte[]> targetBoundaries) {
       this(new CompactionRequest(files), targetBoundaries);
     }
 
     @Override
     public List<Path> execute(StripeCompactor compactor,
         ThroughputController throughputController, User user) throws IOException {
       return compactor.compact(this.request, this.targetBoundaries, this.majorRangeFromRow,
         this.majorRangeToRow, throughputController, user);
     }
   }
 
   /**
    * Request for stripe compactor that will cause it to split the source files into several
    * separate files into based on key-value count, as well as file count limit.
    * Most of the files will be roughly the same size. The last file may be smaller or larger
    * depending on the interplay of the amount of data and maximum number of files allowed.
    */
   private static class SplitStripeCompactionRequest extends StripeCompactionRequest {
     private final byte[] startRow, endRow;
     private final int targetCount;
     private final long targetKvs;
 
     /**
      * @param request Original request.
      * @param startRow Left boundary of the range to compact, inclusive.
      * @param endRow Right boundary of the range to compact, exclusive.
      * @param targetCount The maximum number of stripe to compact into.
      * @param targetKvs The KV count of each segment. If targetKvs*targetCount is less than
      *                  total number of kvs, all the overflow data goes into the last stripe.
      */
     public SplitStripeCompactionRequest(CompactionRequest request,
         byte[] startRow, byte[] endRow, int targetCount, long targetKvs) {
       super(request);
       this.startRow = startRow;
       this.endRow = endRow;
       this.targetCount = targetCount;
       this.targetKvs = targetKvs;
     }
 
     public SplitStripeCompactionRequest(
         CompactionRequest request, byte[] startRow, byte[] endRow, long targetKvs) {
       this(request, startRow, endRow, Integer.MAX_VALUE, targetKvs);
     }
 
     public SplitStripeCompactionRequest(
         Collection<StoreFile> files, byte[] startRow, byte[] endRow, long targetKvs) {
       this(files, startRow, endRow, Integer.MAX_VALUE, targetKvs);
     }
 
     public SplitStripeCompactionRequest(Collection<StoreFile> files,
         byte[] startRow, byte[] endRow, int targetCount, long targetKvs) {
       this(new CompactionRequest(files), startRow, endRow, targetCount, targetKvs);
     }
 
     @Override
     public List<Path> execute(StripeCompactor compactor,
         ThroughputController throughputController, User user) throws IOException {
       return compactor.compact(this.request, this.targetCount, this.targetKvs, this.startRow,
         this.endRow, this.majorRangeFromRow, this.majorRangeToRow, throughputController, user);
     }
 
     /** Set major range of the compaction to the entire compaction range.
      * See {@link #setMajorRange(byte[], byte[])}. */
     public void setMajorRangeFull() {
       setMajorRange(this.startRow, this.endRow);
     }
   }
 
   /** The information about stripes that the policy needs to do its stuff */
   public static interface StripeInformationProvider {
     public Collection<StoreFile> getStorefiles();
 
     /**
      * Gets the start row for a given stripe.
      * @param stripeIndex Stripe index.
      * @return Start row. May be an open key.
      */
     public byte[] getStartRow(int stripeIndex);
 
     /**
      * Gets the end row for a given stripe.
      * @param stripeIndex Stripe index.
      * @return End row. May be an open key.
      */
     public byte[] getEndRow(int stripeIndex);
 
     /**
      * @return Level 0 files.
      */
     public List<StoreFile> getLevel0Files();
 
     /**
      * @return All stripe boundaries; including the open ones on both ends.
      */
     public List<byte[]> getStripeBoundaries();
 
     /**
      * @return The stripes.
      */
     public ArrayList<ImmutableList<StoreFile>> getStripes();
 
     /**
      * @return Stripe count.
      */
     public int getStripeCount();
   }
 }