1 /* 2 * Copyright 2010 The Apache Software Foundation 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, software 15 * distributed under the License is distributed on an "AS IS" BASIS, 16 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 17 * See the License for the specific language governing permissions and 18 * limitations under the License. 19 */ 20 21 package org.apache.hadoop.hbase.filter; 22 23 import org.apache.hadoop.hbase.KeyValue; 24 25 import java.io.DataInput; 26 import java.io.DataOutput; 27 import java.io.IOException; 28 29 /** 30 * Simple filter that returns first N columns on row only. 31 * This filter was written to test filters in Get and as soon as it gets 32 * its quota of columns, {@link #filterAllRemaining()} returns true. This 33 * makes this filter unsuitable as a Scan filter. 34 */ 35 public class ColumnCountGetFilter extends FilterBase { 36 private int limit = 0; 37 private int count = 0; 38 39 /** 40 * Used during serialization. 41 * Do not use. 42 */ 43 public ColumnCountGetFilter() { 44 super(); 45 } 46 47 public ColumnCountGetFilter(final int n) { 48 this.limit = n; 49 } 50 51 public int getLimit() { 52 return limit; 53 } 54 55 @Override 56 public boolean filterAllRemaining() { 57 return this.count > this.limit; 58 } 59 60 @Override 61 public ReturnCode filterKeyValue(KeyValue v) { 62 this.count++; 63 return filterAllRemaining() ? ReturnCode.SKIP: ReturnCode.INCLUDE; 64 } 65 66 @Override 67 public void reset() { 68 this.count = 0; 69 } 70 71 @Override 72 public void readFields(DataInput in) throws IOException { 73 this.limit = in.readInt(); 74 } 75 76 @Override 77 public void write(DataOutput out) throws IOException { 78 out.writeInt(this.limit); 79 } 80 }