1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.shardingsphere.db.protocol.mysql.packet.command.query.binary.execute;
19
20 import org.apache.shardingsphere.db.protocol.mysql.payload.MySQLPacketPayload;
21
22 import lombok.Getter;
23
24 /**
25 * Null bitmap for MySQL.
26 *
27 * @see <a href="https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_binary_resultset.html#sect_protocol_binary_resultset_row_null_bitmap">NULL-Bitmap</a>
28 */
29 public final class MySQLNullBitmap {
30
31 private final int offset;
32
33 @Getter
34 private final int[] nullBitmap;
35
36 public MySQLNullBitmap(final int columnsNumbers, final int offset) {
37 this.offset = offset;
38 nullBitmap = new int[calculateLength(columnsNumbers, offset)];
39 }
40
41 public MySQLNullBitmap(final int columnNumbers, final MySQLPacketPayload payload) {
42 offset = 0;
43 nullBitmap = new int[calculateLength(columnNumbers, 0)];
44 fillBitmap(payload);
45 }
46
47 private void fillBitmap(final MySQLPacketPayload payload) {
48 for (int i = 0; i < nullBitmap.length; i++) {
49 nullBitmap[i] = payload.readInt1();
50 }
51 }
52
53 private int calculateLength(final int columnsNumbers, final int offset) {
54 return (columnsNumbers + offset + 7) / 8;
55 }
56
57 /**
58 * Judge parameter is null or not null.
59 *
60 * @param index column index
61 * @return parameter is null or not null
62 */
63 public boolean isNullParameter(final int index) {
64 return (nullBitmap[getBytePosition(index)] & (1 << getBitPosition(index))) != 0;
65 }
66
67 /**
68 * Set null bit.
69 *
70 * @param index column index
71 */
72 public void setNullBit(final int index) {
73 nullBitmap[getBytePosition(index)] |= 1 << getBitPosition(index);
74 }
75
76 private int getBytePosition(final int index) {
77 return (index + offset) / 8;
78 }
79
80 private int getBitPosition(final int index) {
81 return (index + offset) % 8;
82 }
83 }