001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.filter;
019
020import java.util.ArrayList;
021import java.util.Arrays;
022import java.util.Comparator;
023import java.util.List;
024import java.util.Objects;
025import java.util.PriorityQueue;
026import org.apache.hadoop.hbase.Cell;
027import org.apache.hadoop.hbase.CellComparator;
028import org.apache.hadoop.hbase.PrivateCellUtil;
029import org.apache.hadoop.hbase.exceptions.DeserializationException;
030import org.apache.hadoop.hbase.unsafe.HBasePlatformDependent;
031import org.apache.hadoop.hbase.util.Bytes;
032import org.apache.hadoop.hbase.util.Pair;
033import org.apache.yetus.audience.InterfaceAudience;
034
035import org.apache.hbase.thirdparty.com.google.protobuf.InvalidProtocolBufferException;
036import org.apache.hbase.thirdparty.com.google.protobuf.UnsafeByteOperations;
037
038import org.apache.hadoop.hbase.shaded.protobuf.generated.FilterProtos;
039import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos.BytesBytesPair;
040
041/**
042 * This is optimized version of a standard FuzzyRowFilter Filters data based on fuzzy row key.
043 * Performs fast-forwards during scanning. It takes pairs (row key, fuzzy info) to match row keys.
044 * Where fuzzy info is a byte array with 0 or 1 as its values:
045 * <ul>
046 * <li>0 - means that this byte in provided row key is fixed, i.e. row key's byte at same position
047 * must match</li>
048 * <li>1 - means that this byte in provided row key is NOT fixed, i.e. row key's byte at this
049 * position can be different from the one in provided row key</li>
050 * </ul>
051 * Example: Let's assume row key format is userId_actionId_year_month. Length of userId is fixed and
052 * is 4, length of actionId is 2 and year and month are 4 and 2 bytes long respectively. Let's
053 * assume that we need to fetch all users that performed certain action (encoded as "99") in Jan of
054 * any year. Then the pair (row key, fuzzy info) would be the following: row key = "????_99_????_01"
055 * (one can use any value instead of "?") fuzzy info =
056 * "\x01\x01\x01\x01\x00\x00\x00\x00\x01\x01\x01\x01\x00\x00\x00" I.e. fuzzy info tells the matching
057 * mask is "????_99_????_01", where at ? can be any value.
058 */
059@InterfaceAudience.Public
060public class FuzzyRowFilter extends FilterBase {
061  private static final boolean UNSAFE_UNALIGNED = HBasePlatformDependent.unaligned();
062  private List<Pair<byte[], byte[]>> fuzzyKeysData;
063  private boolean done = false;
064
065  /**
066   * The index of a last successfully found matching fuzzy string (in fuzzyKeysData). We will start
067   * matching next KV with this one. If they do not match then we will return back to the one-by-one
068   * iteration over fuzzyKeysData.
069   */
070  private int lastFoundIndex = -1;
071
072  /**
073   * Row tracker (keeps all next rows after SEEK_NEXT_USING_HINT was returned)
074   */
075  private RowTracker tracker;
076
077  public FuzzyRowFilter(List<Pair<byte[], byte[]>> fuzzyKeysData) {
078    List<Pair<byte[], byte[]>> fuzzyKeyDataCopy = new ArrayList<>(fuzzyKeysData.size());
079
080    for (Pair<byte[], byte[]> aFuzzyKeysData : fuzzyKeysData) {
081      if (aFuzzyKeysData.getFirst().length != aFuzzyKeysData.getSecond().length) {
082        Pair<String, String> readable = new Pair<>(Bytes.toStringBinary(aFuzzyKeysData.getFirst()),
083          Bytes.toStringBinary(aFuzzyKeysData.getSecond()));
084        throw new IllegalArgumentException("Fuzzy pair lengths do not match: " + readable);
085      }
086
087      Pair<byte[], byte[]> p = new Pair<>();
088      // create a copy of pair bytes so that they are not modified by the filter.
089      p.setFirst(Arrays.copyOf(aFuzzyKeysData.getFirst(), aFuzzyKeysData.getFirst().length));
090      p.setSecond(Arrays.copyOf(aFuzzyKeysData.getSecond(), aFuzzyKeysData.getSecond().length));
091
092      // update mask ( 0 -> -1 (0xff), 1 -> 2)
093      p.setSecond(preprocessMask(p.getSecond()));
094      preprocessSearchKey(p);
095
096      fuzzyKeyDataCopy.add(p);
097    }
098    this.fuzzyKeysData = fuzzyKeyDataCopy;
099    this.tracker = new RowTracker();
100  }
101
102  private void preprocessSearchKey(Pair<byte[], byte[]> p) {
103    if (!UNSAFE_UNALIGNED) {
104      // do nothing
105      return;
106    }
107    byte[] key = p.getFirst();
108    byte[] mask = p.getSecond();
109    for (int i = 0; i < mask.length; i++) {
110      // set non-fixed part of a search key to 0.
111      if (mask[i] == 2) {
112        key[i] = 0;
113      }
114    }
115  }
116
117  /**
118   * We need to preprocess mask array, as since we treat 2's as unfixed positions and -1 (0xff) as
119   * fixed positions
120   * @return mask array
121   */
122  private byte[] preprocessMask(byte[] mask) {
123    if (!UNSAFE_UNALIGNED) {
124      // do nothing
125      return mask;
126    }
127    if (isPreprocessedMask(mask)) return mask;
128    for (int i = 0; i < mask.length; i++) {
129      if (mask[i] == 0) {
130        mask[i] = -1; // 0 -> -1
131      } else if (mask[i] == 1) {
132        mask[i] = 2;// 1 -> 2
133      }
134    }
135    return mask;
136  }
137
138  private boolean isPreprocessedMask(byte[] mask) {
139    for (int i = 0; i < mask.length; i++) {
140      if (mask[i] != -1 && mask[i] != 2) {
141        return false;
142      }
143    }
144    return true;
145  }
146
147  @Override
148  public ReturnCode filterCell(final Cell c) {
149    final int startIndex = lastFoundIndex >= 0 ? lastFoundIndex : 0;
150    final int size = fuzzyKeysData.size();
151    for (int i = startIndex; i < size + startIndex; i++) {
152      final int index = i % size;
153      Pair<byte[], byte[]> fuzzyData = fuzzyKeysData.get(index);
154      // This shift is idempotent - always end up with 0 and -1 as mask values.
155      for (int j = 0; j < fuzzyData.getSecond().length; j++) {
156        fuzzyData.getSecond()[j] >>= 2;
157      }
158      SatisfiesCode satisfiesCode = satisfies(isReversed(), c.getRowArray(), c.getRowOffset(),
159        c.getRowLength(), fuzzyData.getFirst(), fuzzyData.getSecond());
160      if (satisfiesCode == SatisfiesCode.YES) {
161        lastFoundIndex = index;
162        return ReturnCode.INCLUDE;
163      }
164    }
165    // NOT FOUND -> seek next using hint
166    lastFoundIndex = -1;
167
168    return ReturnCode.SEEK_NEXT_USING_HINT;
169
170  }
171
172  @Override
173  public Cell getNextCellHint(Cell currentCell) {
174    boolean result = tracker.updateTracker(currentCell);
175    if (result == false) {
176      done = true;
177      return null;
178    }
179    byte[] nextRowKey = tracker.nextRow();
180    return PrivateCellUtil.createFirstOnRow(nextRowKey, 0, (short) nextRowKey.length);
181  }
182
183  /**
184   * If we have multiple fuzzy keys, row tracker should improve overall performance. It calculates
185   * all next rows (one per every fuzzy key) and put them (the fuzzy key is bundled) into a priority
186   * queue so that the smallest row key always appears at queue head, which helps to decide the
187   * "Next Cell Hint". As scanning going on, the number of candidate rows in the RowTracker will
188   * remain the size of fuzzy keys until some of the fuzzy keys won't possibly have matches any
189   * more.
190   */
191  private class RowTracker {
192    private final PriorityQueue<Pair<byte[], Pair<byte[], byte[]>>> nextRows;
193    private boolean initialized = false;
194
195    RowTracker() {
196      nextRows = new PriorityQueue<>(fuzzyKeysData.size(),
197        new Comparator<Pair<byte[], Pair<byte[], byte[]>>>() {
198          @Override
199          public int compare(Pair<byte[], Pair<byte[], byte[]>> o1,
200            Pair<byte[], Pair<byte[], byte[]>> o2) {
201            return isReversed()
202              ? Bytes.compareTo(o2.getFirst(), o1.getFirst())
203              : Bytes.compareTo(o1.getFirst(), o2.getFirst());
204          }
205        });
206    }
207
208    byte[] nextRow() {
209      if (nextRows.isEmpty()) {
210        throw new IllegalStateException("NextRows should not be empty, "
211          + "make sure to call nextRow() after updateTracker() return true");
212      } else {
213        return nextRows.peek().getFirst();
214      }
215    }
216
217    boolean updateTracker(Cell currentCell) {
218      if (!initialized) {
219        for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
220          updateWith(currentCell, fuzzyData);
221        }
222        initialized = true;
223      } else {
224        while (!nextRows.isEmpty() && !lessThan(currentCell, nextRows.peek().getFirst())) {
225          Pair<byte[], Pair<byte[], byte[]>> head = nextRows.poll();
226          Pair<byte[], byte[]> fuzzyData = head.getSecond();
227          updateWith(currentCell, fuzzyData);
228        }
229      }
230      return !nextRows.isEmpty();
231    }
232
233    boolean lessThan(Cell currentCell, byte[] nextRowKey) {
234      int compareResult =
235        CellComparator.getInstance().compareRows(currentCell, nextRowKey, 0, nextRowKey.length);
236      return (!isReversed() && compareResult < 0) || (isReversed() && compareResult > 0);
237    }
238
239    void updateWith(Cell currentCell, Pair<byte[], byte[]> fuzzyData) {
240      byte[] nextRowKeyCandidate =
241        getNextForFuzzyRule(isReversed(), currentCell.getRowArray(), currentCell.getRowOffset(),
242          currentCell.getRowLength(), fuzzyData.getFirst(), fuzzyData.getSecond());
243      if (nextRowKeyCandidate != null) {
244        nextRows.add(new Pair<>(nextRowKeyCandidate, fuzzyData));
245      }
246    }
247
248  }
249
250  @Override
251  public boolean filterAllRemaining() {
252    return done;
253  }
254
255  /** Returns The filter serialized using pb */
256  @Override
257  public byte[] toByteArray() {
258    FilterProtos.FuzzyRowFilter.Builder builder = FilterProtos.FuzzyRowFilter.newBuilder();
259    for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
260      BytesBytesPair.Builder bbpBuilder = BytesBytesPair.newBuilder();
261      bbpBuilder.setFirst(UnsafeByteOperations.unsafeWrap(fuzzyData.getFirst()));
262      bbpBuilder.setSecond(UnsafeByteOperations.unsafeWrap(fuzzyData.getSecond()));
263      builder.addFuzzyKeysData(bbpBuilder);
264    }
265    return builder.build().toByteArray();
266  }
267
268  /**
269   * Parse a serialized representation of {@link FuzzyRowFilter}
270   * @param pbBytes A pb serialized {@link FuzzyRowFilter} instance
271   * @return An instance of {@link FuzzyRowFilter} made from <code>bytes</code>
272   * @throws DeserializationException if an error occurred
273   * @see #toByteArray
274   */
275  public static FuzzyRowFilter parseFrom(final byte[] pbBytes) throws DeserializationException {
276    FilterProtos.FuzzyRowFilter proto;
277    try {
278      proto = FilterProtos.FuzzyRowFilter.parseFrom(pbBytes);
279    } catch (InvalidProtocolBufferException e) {
280      throw new DeserializationException(e);
281    }
282    int count = proto.getFuzzyKeysDataCount();
283    ArrayList<Pair<byte[], byte[]>> fuzzyKeysData = new ArrayList<>(count);
284    for (int i = 0; i < count; ++i) {
285      BytesBytesPair current = proto.getFuzzyKeysData(i);
286      byte[] keyBytes = current.getFirst().toByteArray();
287      byte[] keyMeta = current.getSecond().toByteArray();
288      fuzzyKeysData.add(new Pair<>(keyBytes, keyMeta));
289    }
290    return new FuzzyRowFilter(fuzzyKeysData);
291  }
292
293  @Override
294  public String toString() {
295    final StringBuilder sb = new StringBuilder();
296    sb.append("FuzzyRowFilter");
297    sb.append("{fuzzyKeysData=");
298    for (Pair<byte[], byte[]> fuzzyData : fuzzyKeysData) {
299      sb.append('{').append(Bytes.toStringBinary(fuzzyData.getFirst())).append(":");
300      sb.append(Bytes.toStringBinary(fuzzyData.getSecond())).append('}');
301    }
302    sb.append("}, ");
303    return sb.toString();
304  }
305
306  // Utility methods
307
308  static enum SatisfiesCode {
309    /** row satisfies fuzzy rule */
310    YES,
311    /** row doesn't satisfy fuzzy rule, but there's possible greater row that does */
312    NEXT_EXISTS,
313    /** row doesn't satisfy fuzzy rule and there's no greater row that does */
314    NO_NEXT
315  }
316
317  static SatisfiesCode satisfies(byte[] row, byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
318    return satisfies(false, row, 0, row.length, fuzzyKeyBytes, fuzzyKeyMeta);
319  }
320
321  static SatisfiesCode satisfies(boolean reverse, byte[] row, byte[] fuzzyKeyBytes,
322    byte[] fuzzyKeyMeta) {
323    return satisfies(reverse, row, 0, row.length, fuzzyKeyBytes, fuzzyKeyMeta);
324  }
325
326  static SatisfiesCode satisfies(boolean reverse, byte[] row, int offset, int length,
327    byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
328
329    if (!UNSAFE_UNALIGNED) {
330      return satisfiesNoUnsafe(reverse, row, offset, length, fuzzyKeyBytes, fuzzyKeyMeta);
331    }
332
333    if (row == null) {
334      // do nothing, let scan to proceed
335      return SatisfiesCode.YES;
336    }
337    length = Math.min(length, fuzzyKeyBytes.length);
338    int numWords = length / Bytes.SIZEOF_LONG;
339
340    int j = numWords << 3; // numWords * SIZEOF_LONG;
341
342    for (int i = 0; i < j; i += Bytes.SIZEOF_LONG) {
343      long fuzzyBytes = Bytes.toLong(fuzzyKeyBytes, i);
344      long fuzzyMeta = Bytes.toLong(fuzzyKeyMeta, i);
345      long rowValue = Bytes.toLong(row, offset + i);
346      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
347        // We always return NEXT_EXISTS
348        return SatisfiesCode.NEXT_EXISTS;
349      }
350    }
351
352    int off = j;
353
354    if (length - off >= Bytes.SIZEOF_INT) {
355      int fuzzyBytes = Bytes.toInt(fuzzyKeyBytes, off);
356      int fuzzyMeta = Bytes.toInt(fuzzyKeyMeta, off);
357      int rowValue = Bytes.toInt(row, offset + off);
358      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
359        // We always return NEXT_EXISTS
360        return SatisfiesCode.NEXT_EXISTS;
361      }
362      off += Bytes.SIZEOF_INT;
363    }
364
365    if (length - off >= Bytes.SIZEOF_SHORT) {
366      short fuzzyBytes = Bytes.toShort(fuzzyKeyBytes, off);
367      short fuzzyMeta = Bytes.toShort(fuzzyKeyMeta, off);
368      short rowValue = Bytes.toShort(row, offset + off);
369      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
370        // We always return NEXT_EXISTS
371        // even if it does not (in this case getNextForFuzzyRule
372        // will return null)
373        return SatisfiesCode.NEXT_EXISTS;
374      }
375      off += Bytes.SIZEOF_SHORT;
376    }
377
378    if (length - off >= Bytes.SIZEOF_BYTE) {
379      int fuzzyBytes = fuzzyKeyBytes[off] & 0xff;
380      int fuzzyMeta = fuzzyKeyMeta[off] & 0xff;
381      int rowValue = row[offset + off] & 0xff;
382      if ((rowValue & fuzzyMeta) != fuzzyBytes) {
383        // We always return NEXT_EXISTS
384        return SatisfiesCode.NEXT_EXISTS;
385      }
386    }
387    return SatisfiesCode.YES;
388  }
389
390  static SatisfiesCode satisfiesNoUnsafe(boolean reverse, byte[] row, int offset, int length,
391    byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
392    if (row == null) {
393      // do nothing, let scan to proceed
394      return SatisfiesCode.YES;
395    }
396
397    Order order = Order.orderFor(reverse);
398    boolean nextRowKeyCandidateExists = false;
399
400    for (int i = 0; i < fuzzyKeyMeta.length && i < length; i++) {
401      // First, checking if this position is fixed and not equals the given one
402      boolean byteAtPositionFixed = fuzzyKeyMeta[i] == 0;
403      boolean fixedByteIncorrect = byteAtPositionFixed && fuzzyKeyBytes[i] != row[i + offset];
404      if (fixedByteIncorrect) {
405        // in this case there's another row that satisfies fuzzy rule and bigger than this row
406        if (nextRowKeyCandidateExists) {
407          return SatisfiesCode.NEXT_EXISTS;
408        }
409
410        // If this row byte is less than fixed then there's a byte array bigger than
411        // this row and which satisfies the fuzzy rule. Otherwise there's no such byte array:
412        // this row is simply bigger than any byte array that satisfies the fuzzy rule
413        boolean rowByteLessThanFixed = (row[i + offset] & 0xFF) < (fuzzyKeyBytes[i] & 0xFF);
414        if (rowByteLessThanFixed && !reverse) {
415          return SatisfiesCode.NEXT_EXISTS;
416        } else if (!rowByteLessThanFixed && reverse) {
417          return SatisfiesCode.NEXT_EXISTS;
418        } else {
419          return SatisfiesCode.NO_NEXT;
420        }
421      }
422
423      // Second, checking if this position is not fixed and byte value is not the biggest. In this
424      // case there's a byte array bigger than this row and which satisfies the fuzzy rule. To get
425      // bigger byte array that satisfies the rule we need to just increase this byte
426      // (see the code of getNextForFuzzyRule below) by one.
427      // Note: if non-fixed byte is already at biggest value, this doesn't allow us to say there's
428      // bigger one that satisfies the rule as it can't be increased.
429      if (fuzzyKeyMeta[i] == 1 && !order.isMax(fuzzyKeyBytes[i])) {
430        nextRowKeyCandidateExists = true;
431      }
432    }
433    return SatisfiesCode.YES;
434  }
435
436  static byte[] getNextForFuzzyRule(byte[] row, byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
437    return getNextForFuzzyRule(false, row, 0, row.length, fuzzyKeyBytes, fuzzyKeyMeta);
438  }
439
440  static byte[] getNextForFuzzyRule(boolean reverse, byte[] row, byte[] fuzzyKeyBytes,
441    byte[] fuzzyKeyMeta) {
442    return getNextForFuzzyRule(reverse, row, 0, row.length, fuzzyKeyBytes, fuzzyKeyMeta);
443  }
444
445  /** Abstracts directional comparisons based on scan direction. */
446  private enum Order {
447    ASC {
448      @Override
449      public boolean lt(int lhs, int rhs) {
450        return lhs < rhs;
451      }
452
453      @Override
454      public boolean gt(int lhs, int rhs) {
455        return lhs > rhs;
456      }
457
458      @Override
459      public byte inc(byte val) {
460        // TODO: what about over/underflow?
461        return (byte) (val + 1);
462      }
463
464      @Override
465      public boolean isMax(byte val) {
466        return val == (byte) 0xff;
467      }
468
469      @Override
470      public byte min() {
471        return 0;
472      }
473    },
474    DESC {
475      @Override
476      public boolean lt(int lhs, int rhs) {
477        return lhs > rhs;
478      }
479
480      @Override
481      public boolean gt(int lhs, int rhs) {
482        return lhs < rhs;
483      }
484
485      @Override
486      public byte inc(byte val) {
487        // TODO: what about over/underflow?
488        return (byte) (val - 1);
489      }
490
491      @Override
492      public boolean isMax(byte val) {
493        return val == 0;
494      }
495
496      @Override
497      public byte min() {
498        return (byte) 0xFF;
499      }
500    };
501
502    public static Order orderFor(boolean reverse) {
503      return reverse ? DESC : ASC;
504    }
505
506    /** Returns true when {@code lhs < rhs}. */
507    public abstract boolean lt(int lhs, int rhs);
508
509    /** Returns true when {@code lhs > rhs}. */
510    public abstract boolean gt(int lhs, int rhs);
511
512    /** Returns {@code val} incremented by 1. */
513    public abstract byte inc(byte val);
514
515    /** Return true when {@code val} is the maximum value */
516    public abstract boolean isMax(byte val);
517
518    /** Return the minimum value according to this ordering scheme. */
519    public abstract byte min();
520  }
521
522  /**
523   * @return greater byte array than given (row) which satisfies the fuzzy rule if it exists, null
524   *         otherwise
525   */
526  static byte[] getNextForFuzzyRule(boolean reverse, byte[] row, int offset, int length,
527    byte[] fuzzyKeyBytes, byte[] fuzzyKeyMeta) {
528    // To find out the next "smallest" byte array that satisfies fuzzy rule and "greater" than
529    // the given one we do the following:
530    // 1. setting values on all "fixed" positions to the values from fuzzyKeyBytes
531    // 2. if during the first step given row did not increase, then we increase the value at
532    // the first "non-fixed" position (where it is not maximum already)
533
534    // It is easier to perform this by using fuzzyKeyBytes copy and setting "non-fixed" position
535    // values than otherwise.
536    byte[] result =
537      Arrays.copyOf(fuzzyKeyBytes, length > fuzzyKeyBytes.length ? length : fuzzyKeyBytes.length);
538    if (reverse && length > fuzzyKeyBytes.length) {
539      // we need trailing 0xff's instead of trailing 0x00's
540      for (int i = fuzzyKeyBytes.length; i < result.length; i++) {
541        result[i] = (byte) 0xFF;
542      }
543    }
544    int toInc = -1;
545    final Order order = Order.orderFor(reverse);
546
547    boolean increased = false;
548    for (int i = 0; i < result.length; i++) {
549      if (i >= fuzzyKeyMeta.length || fuzzyKeyMeta[i] == 0 /* non-fixed */) {
550        result[i] = row[offset + i];
551        if (!order.isMax(row[offset + i])) {
552          // this is "non-fixed" position and is not at max value, hence we can increase it
553          toInc = i;
554        }
555      } else if (i < fuzzyKeyMeta.length && fuzzyKeyMeta[i] == -1 /* fixed */) {
556        if (order.lt((row[i + offset] & 0xFF), (fuzzyKeyBytes[i] & 0xFF))) {
557          // if setting value for any fixed position increased the original array,
558          // we are OK
559          increased = true;
560          break;
561        }
562
563        if (order.gt((row[i + offset] & 0xFF), (fuzzyKeyBytes[i] & 0xFF))) {
564          // if setting value for any fixed position makes array "smaller", then just stop:
565          // in case we found some non-fixed position to increase we will do it, otherwise
566          // there's no "next" row key that satisfies fuzzy rule and "greater" than given row
567          break;
568        }
569      }
570    }
571
572    if (!increased) {
573      if (toInc < 0) {
574        return null;
575      }
576      result[toInc] = order.inc(result[toInc]);
577
578      // Setting all "non-fixed" positions to zeroes to the right of the one we increased so
579      // that found "next" row key is the smallest possible
580      for (int i = toInc + 1; i < result.length; i++) {
581        if (i >= fuzzyKeyMeta.length || fuzzyKeyMeta[i] == 0 /* non-fixed */) {
582          result[i] = order.min();
583        }
584      }
585    }
586
587    return reverse ? result : trimTrailingZeroes(result, fuzzyKeyMeta, toInc);
588  }
589
590  /**
591   * For forward scanner, next cell hint should not contain any trailing zeroes unless they are part
592   * of fuzzyKeyMeta hint = '\x01\x01\x01\x00\x00' will skip valid row '\x01\x01\x01'
593   * @param toInc - position of incremented byte
594   * @return trimmed version of result
595   */
596
597  private static byte[] trimTrailingZeroes(byte[] result, byte[] fuzzyKeyMeta, int toInc) {
598    int off = fuzzyKeyMeta.length >= result.length ? result.length - 1 : fuzzyKeyMeta.length - 1;
599    for (; off >= 0; off--) {
600      if (fuzzyKeyMeta[off] != 0) break;
601    }
602    if (off < toInc) off = toInc;
603    byte[] retValue = new byte[off + 1];
604    System.arraycopy(result, 0, retValue, 0, retValue.length);
605    return retValue;
606  }
607
608  /**
609   * Returns true if and only if the fields of the filter that are serialized are equal to the
610   * corresponding fields in other. Used for testing.
611   */
612  @Override
613  boolean areSerializedFieldsEqual(Filter o) {
614    if (o == this) {
615      return true;
616    }
617    if (!(o instanceof FuzzyRowFilter)) {
618      return false;
619    }
620    FuzzyRowFilter other = (FuzzyRowFilter) o;
621    if (this.fuzzyKeysData.size() != other.fuzzyKeysData.size()) return false;
622    for (int i = 0; i < fuzzyKeysData.size(); ++i) {
623      Pair<byte[], byte[]> thisData = this.fuzzyKeysData.get(i);
624      Pair<byte[], byte[]> otherData = other.fuzzyKeysData.get(i);
625      if (
626        !(Bytes.equals(thisData.getFirst(), otherData.getFirst())
627          && Bytes.equals(thisData.getSecond(), otherData.getSecond()))
628      ) {
629        return false;
630      }
631    }
632    return true;
633  }
634
635  @Override
636  public boolean equals(Object obj) {
637    return obj instanceof Filter && areSerializedFieldsEqual((Filter) obj);
638  }
639
640  @Override
641  public int hashCode() {
642    return Objects.hash(this.fuzzyKeysData);
643  }
644}