001/*
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *     http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */
019
020package org.apache.hadoop.hbase.filter;
021
022import java.io.IOException;
023import java.util.ArrayList;
024
025import org.apache.hadoop.hbase.Cell;
026import org.apache.yetus.audience.InterfaceAudience;
027import org.apache.hadoop.hbase.exceptions.DeserializationException;
028import org.apache.hadoop.hbase.shaded.protobuf.generated.FilterProtos;
029
030import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
031import org.apache.hbase.thirdparty.com.google.protobuf.InvalidProtocolBufferException;
032
033/**
034 * Simple filter that returns first N columns on row only.
035 * This filter was written to test filters in Get and as soon as it gets
036 * its quota of columns, {@link #filterAllRemaining()} returns true.  This
037 * makes this filter unsuitable as a Scan filter.
038 */
039@InterfaceAudience.Public
040public class ColumnCountGetFilter extends FilterBase {
041  private int limit = 0;
042  private int count = 0;
043
044  public ColumnCountGetFilter(final int n) {
045    Preconditions.checkArgument(n >= 0, "limit be positive %s", n);
046    this.limit = n;
047  }
048
049  public int getLimit() {
050    return limit;
051  }
052
053  @Override
054  public boolean filterRowKey(Cell cell) throws IOException {
055    // Impl in FilterBase might do unnecessary copy for Off heap backed Cells.
056    if (filterAllRemaining()) return true;
057    return false;
058  }
059
060  @Override
061  public boolean filterAllRemaining() {
062    return this.count > this.limit;
063  }
064
065  @Deprecated
066  @Override
067  public ReturnCode filterKeyValue(final Cell c) {
068    return filterCell(c);
069  }
070
071  @Override
072  public ReturnCode filterCell(final Cell c) {
073    this.count++;
074    return filterAllRemaining() ? ReturnCode.NEXT_COL : ReturnCode.INCLUDE_AND_NEXT_COL;
075  }
076
077  @Override
078  public void reset() {
079    this.count = 0;
080  }
081
082  public static Filter createFilterFromArguments(ArrayList<byte []> filterArguments) {
083    Preconditions.checkArgument(filterArguments.size() == 1,
084                                "Expected 1 but got: %s", filterArguments.size());
085    int limit = ParseFilter.convertByteArrayToInt(filterArguments.get(0));
086    return new ColumnCountGetFilter(limit);
087  }
088
089  /**
090   * @return The filter serialized using pb
091   */
092  @Override
093  public byte [] toByteArray() {
094    FilterProtos.ColumnCountGetFilter.Builder builder =
095      FilterProtos.ColumnCountGetFilter.newBuilder();
096    builder.setLimit(this.limit);
097    return builder.build().toByteArray();
098  }
099
100  /**
101   * @param pbBytes A pb serialized {@link ColumnCountGetFilter} instance
102   * @return An instance of {@link ColumnCountGetFilter} made from <code>bytes</code>
103   * @throws org.apache.hadoop.hbase.exceptions.DeserializationException
104   * @see #toByteArray
105   */
106  public static ColumnCountGetFilter parseFrom(final byte [] pbBytes)
107  throws DeserializationException {
108    FilterProtos.ColumnCountGetFilter proto;
109    try {
110      proto = FilterProtos.ColumnCountGetFilter.parseFrom(pbBytes);
111    } catch (InvalidProtocolBufferException e) {
112      throw new DeserializationException(e);
113    }
114    return new ColumnCountGetFilter(proto.getLimit());
115  }
116
117  /**
118   * @param o the other filter to compare with
119   * @return true if and only if the fields of the filter that are serialized
120   * are equal to the corresponding fields in other.  Used for testing.
121   */
122  @Override
123  boolean areSerializedFieldsEqual(Filter o) {
124    if (o == this) return true;
125    if (!(o instanceof ColumnCountGetFilter)) return false;
126
127    ColumnCountGetFilter other = (ColumnCountGetFilter)o;
128    return this.getLimit() == other.getLimit();
129  }
130
131  @Override
132  public String toString() {
133    return this.getClass().getSimpleName() + " " + this.limit;
134  }
135}