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.io.IOException;
021import java.util.ArrayList;
022import java.util.Objects;
023import org.apache.hadoop.hbase.Cell;
024import org.apache.hadoop.hbase.exceptions.DeserializationException;
025import org.apache.yetus.audience.InterfaceAudience;
026
027import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
028import org.apache.hbase.thirdparty.com.google.protobuf.InvalidProtocolBufferException;
029
030import org.apache.hadoop.hbase.shaded.protobuf.generated.FilterProtos;
031
032/**
033 * Simple filter that returns first N columns on row only. This filter was written to test filters
034 * in Get and as soon as it gets its quota of columns, {@link #filterAllRemaining()} returns true.
035 * This makes this filter unsuitable as a Scan filter.
036 */
037@InterfaceAudience.Public
038public class ColumnCountGetFilter extends FilterBase {
039  private int limit = 0;
040  private int count = 0;
041
042  public ColumnCountGetFilter(final int n) {
043    Preconditions.checkArgument(n >= 0, "limit be positive %s", n);
044    this.limit = n;
045  }
046
047  public int getLimit() {
048    return limit;
049  }
050
051  @Override
052  public boolean filterRowKey(Cell cell) throws IOException {
053    // Impl in FilterBase might do unnecessary copy for Off heap backed Cells.
054    if (filterAllRemaining()) return true;
055    return false;
056  }
057
058  @Override
059  public boolean filterAllRemaining() {
060    return this.count > this.limit;
061  }
062
063  @Deprecated
064  @Override
065  public ReturnCode filterKeyValue(final Cell c) {
066    return filterCell(c);
067  }
068
069  @Override
070  public ReturnCode filterCell(final Cell c) {
071    this.count++;
072    return filterAllRemaining() ? ReturnCode.NEXT_COL : ReturnCode.INCLUDE_AND_NEXT_COL;
073  }
074
075  @Override
076  public void reset() {
077    this.count = 0;
078  }
079
080  public static Filter createFilterFromArguments(ArrayList<byte[]> filterArguments) {
081    Preconditions.checkArgument(filterArguments.size() == 1, "Expected 1 but got: %s",
082      filterArguments.size());
083    int limit = ParseFilter.convertByteArrayToInt(filterArguments.get(0));
084    return new ColumnCountGetFilter(limit);
085  }
086
087  /** Returns The filter serialized using pb */
088  @Override
089  public byte[] toByteArray() {
090    FilterProtos.ColumnCountGetFilter.Builder builder =
091      FilterProtos.ColumnCountGetFilter.newBuilder();
092    builder.setLimit(this.limit);
093    return builder.build().toByteArray();
094  }
095
096  /**
097   * Parse a serialized representation of {@link ColumnCountGetFilter}
098   * @param pbBytes A pb serialized {@link ColumnCountGetFilter} instance
099   * @return An instance of {@link ColumnCountGetFilter} made from <code>bytes</code>
100   * @throws DeserializationException if an error occurred
101   * @see #toByteArray
102   */
103  public static ColumnCountGetFilter parseFrom(final byte[] pbBytes)
104    throws DeserializationException {
105    FilterProtos.ColumnCountGetFilter proto;
106    try {
107      proto = FilterProtos.ColumnCountGetFilter.parseFrom(pbBytes);
108    } catch (InvalidProtocolBufferException e) {
109      throw new DeserializationException(e);
110    }
111    return new ColumnCountGetFilter(proto.getLimit());
112  }
113
114  /**
115   * Returns true if and only if the fields of the filter that are serialized are equal to the
116   * corresponding fields in other. Used for testing.
117   */
118  @Override
119  boolean areSerializedFieldsEqual(Filter o) {
120    if (o == this) {
121      return true;
122    }
123    if (!(o instanceof ColumnCountGetFilter)) {
124      return false;
125    }
126    ColumnCountGetFilter other = (ColumnCountGetFilter) o;
127    return this.getLimit() == other.getLimit();
128  }
129
130  @Override
131  public String toString() {
132    return this.getClass().getSimpleName() + " " + this.limit;
133  }
134
135  @Override
136  public boolean equals(Object obj) {
137    return obj instanceof Filter && areSerializedFieldsEqual((Filter) obj);
138  }
139
140  @Override
141  public int hashCode() {
142    return Objects.hash(this.limit);
143  }
144}