| /* |
| * Copyright 2010 The Apache Software Foundation |
| * |
| * 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 org.apache.hadoop.hbase.KeyValue; |
| import org.apache.hadoop.hbase.util.Bytes; |
| |
| import java.io.DataOutput; |
| import java.io.IOException; |
| import java.io.DataInput; |
| |
| /** |
| * 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'. |
| */ |
| public class ColumnPrefixFilter extends FilterBase { |
| protected byte [] prefix = null; |
| |
| public ColumnPrefixFilter() { |
| super(); |
| } |
| |
| public ColumnPrefixFilter(final byte [] prefix) { |
| this.prefix = prefix; |
| } |
| |
| public byte[] getPrefix() { |
| return prefix; |
| } |
| |
| @Override |
| public ReturnCode filterKeyValue(KeyValue kv) { |
| if (this.prefix == null || kv.getBuffer() == null) { |
| return ReturnCode.INCLUDE; |
| } else { |
| return filterColumn(kv.getBuffer(), kv.getQualifierOffset(), kv.getQualifierLength()); |
| } |
| } |
| |
| public ReturnCode filterColumn(byte[] buffer, int qualifierOffset, int qualifierLength) { |
| if (qualifierLength < prefix.length) { |
| int cmp = Bytes.compareTo(buffer, qualifierOffset, qualifierLength, this.prefix, 0, |
| qualifierLength); |
| if (cmp <= 0) { |
| return ReturnCode.SEEK_NEXT_USING_HINT; |
| } else { |
| return ReturnCode.NEXT_ROW; |
| } |
| } else { |
| int cmp = Bytes.compareTo(buffer, qualifierOffset, this.prefix.length, this.prefix, 0, |
| this.prefix.length); |
| if (cmp < 0) { |
| return ReturnCode.SEEK_NEXT_USING_HINT; |
| } else if (cmp > 0) { |
| return ReturnCode.NEXT_ROW; |
| } else { |
| return ReturnCode.INCLUDE; |
| } |
| } |
| } |
| |
| public void write(DataOutput out) throws IOException { |
| Bytes.writeByteArray(out, this.prefix); |
| } |
| |
| public void readFields(DataInput in) throws IOException { |
| this.prefix = Bytes.readByteArray(in); |
| } |
| |
| public KeyValue getNextKeyHint(KeyValue kv) { |
| return KeyValue.createFirstOnRow( |
| kv.getBuffer(), kv.getRowOffset(), kv.getRowLength(), kv.getBuffer(), |
| kv.getFamilyOffset(), kv.getFamilyLength(), prefix, 0, prefix.length); |
| } |
| } |