hbase-client/src/main/java/org/apache/hadoop/hbase/filter/MultipleColumnPrefixFilter.java

/*
 * 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.filter;


import com.google.protobuf.HBaseZeroCopyByteString;
import com.google.protobuf.InvalidProtocolBufferException;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.exceptions.DeserializationException;
import org.apache.hadoop.hbase.protobuf.generated.FilterProtos;
import org.apache.hadoop.hbase.util.Bytes;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.TreeSet;

/**
 * This filter is used for selecting only those keys with columns that matches
 * a particular prefix. For example, if prefix is 'an', it will pass keys will
 * columns like 'and', 'anti' but not keys with columns like 'ball', 'act'.
 */
@InterfaceAudience.Public
@InterfaceStability.Stable
public class MultipleColumnPrefixFilter extends FilterBase {
  protected byte [] hint = null;
  protected TreeSet<byte []> sortedPrefixes = createTreeSet();
  private final static int MAX_LOG_PREFIXES = 5;

  public MultipleColumnPrefixFilter(final byte [][] prefixes) {
    if (prefixes != null) {
      for (int i = 0; i < prefixes.length; i++) {
        if (!sortedPrefixes.add(prefixes[i]))
          throw new IllegalArgumentException ("prefixes must be distinct");
      }
    }
  }

  public byte [][] getPrefix() {
    int count = 0;
    byte [][] temp = new byte [sortedPrefixes.size()][];
    for (byte [] prefixes : sortedPrefixes) {
      temp [count++] = prefixes;
    }
    return temp;
  }

  @Override
  public ReturnCode filterKeyValue(Cell kv) {
    if (sortedPrefixes.size() == 0 || kv.getQualifierArray() == null) {
      return ReturnCode.INCLUDE;
    } else {
      return filterColumn(kv.getQualifierArray(), kv.getQualifierOffset(), kv.getQualifierLength());
    }
  }

  public ReturnCode filterColumn(byte[] buffer, int qualifierOffset, int qualifierLength) {
    byte [] qualifier = Arrays.copyOfRange(buffer, qualifierOffset,
                                           qualifierLength + qualifierOffset);
    TreeSet<byte []> lesserOrEqualPrefixes =
      (TreeSet<byte []>) sortedPrefixes.headSet(qualifier, true);

    if (lesserOrEqualPrefixes.size() != 0) {
      byte [] largestPrefixSmallerThanQualifier = lesserOrEqualPrefixes.last();
      
      if (Bytes.startsWith(qualifier, largestPrefixSmallerThanQualifier)) {
        return ReturnCode.INCLUDE;
      }
      
      if (lesserOrEqualPrefixes.size() == sortedPrefixes.size()) {
        return ReturnCode.NEXT_ROW;
      } else {
        hint = sortedPrefixes.higher(largestPrefixSmallerThanQualifier);
        return ReturnCode.SEEK_NEXT_USING_HINT;
      }
    } else {
      hint = sortedPrefixes.first();
      return ReturnCode.SEEK_NEXT_USING_HINT;
    }
  }

  public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
    byte [][] prefixes = new byte [filterArguments.size()][];
    for (int i = 0 ; i < filterArguments.size(); i++) {
      byte [] columnPrefix = ParseFilter.removeQuotesFromByteArray(filterArguments.get(i));
      prefixes[i] = columnPrefix;
    }
    return new MultipleColumnPrefixFilter(prefixes);
  }

  /**
   * @return The filter serialized using pb
   */
  public byte [] toByteArray() {
    FilterProtos.MultipleColumnPrefixFilter.Builder builder =
      FilterProtos.MultipleColumnPrefixFilter.newBuilder();
    for (byte [] element : sortedPrefixes) {
      if (element != null) builder.addSortedPrefixes(HBaseZeroCopyByteString.wrap(element));
    }
    return builder.build().toByteArray();
  }

  /**
   * @param pbBytes A pb serialized {@link MultipleColumnPrefixFilter} instance
   * @return An instance of {@link MultipleColumnPrefixFilter} made from <code>bytes</code>
   * @throws DeserializationException
   * @see #toByteArray
   */
  public static MultipleColumnPrefixFilter parseFrom(final byte [] pbBytes)
  throws DeserializationException {
    FilterProtos.MultipleColumnPrefixFilter proto;
    try {
      proto = FilterProtos.MultipleColumnPrefixFilter.parseFrom(pbBytes);
    } catch (InvalidProtocolBufferException e) {
      throw new DeserializationException(e);
    }
    int numPrefixes = proto.getSortedPrefixesCount();
    byte [][] prefixes = new byte[numPrefixes][];
    for (int i = 0; i < numPrefixes; ++i) {
      prefixes[i] = proto.getSortedPrefixes(i).toByteArray();
    }

    return new MultipleColumnPrefixFilter(prefixes);
  }

  /**
   * @param other
   * @return true if and only if the fields of the filter that are serialized
   * are equal to the corresponding fields in other.  Used for testing.
   */
  boolean areSerializedFieldsEqual(Filter o) {
    if (o == this) return true;
    if (!(o instanceof MultipleColumnPrefixFilter)) return false;

    MultipleColumnPrefixFilter other = (MultipleColumnPrefixFilter)o;
    return this.sortedPrefixes.equals(other.sortedPrefixes);
  }

  @Override
  public Cell getNextCellHint(Cell kv) {
    return KeyValue.createFirstOnRow(
      kv.getRowArray(), kv.getRowOffset(), kv.getRowLength(), kv.getFamilyArray(),
      kv.getFamilyOffset(), kv.getFamilyLength(), hint, 0, hint.length);
  }

  public TreeSet<byte []> createTreeSet() {
    return new TreeSet<byte []>(new Comparator<Object>() {
        @Override
          public int compare (Object o1, Object o2) {
          if (o1 == null || o2 == null)
            throw new IllegalArgumentException ("prefixes can't be null");

          byte [] b1 = (byte []) o1;
          byte [] b2 = (byte []) o2;
          return Bytes.compareTo (b1, 0, b1.length, b2, 0, b2.length);
        }
      });
  }

  @Override
  public String toString() {
    return toString(MAX_LOG_PREFIXES);
  }

  protected String toString(int maxPrefixes) {
    StringBuilder prefixes = new StringBuilder();

    int count = 0;
    for (byte[] ba : this.sortedPrefixes) {
      if (count >= maxPrefixes) {
        break;
      }
      ++count;
      prefixes.append(Bytes.toStringBinary(ba));
      if (count < this.sortedPrefixes.size() && count < maxPrefixes) {
        prefixes.append(", ");
      }
    }

    return String.format("%s (%d/%d): [%s]", this.getClass().getSimpleName(),
        count, this.sortedPrefixes.size(), prefixes.toString());
  }
}