Canal+Otter - Canal篇（1）

Canal是阿里开源产品之一，是用java开发的基于数据库增量日志解析，提供增量数据订阅&消费的中间件。目前，Canal主要支持了MySQL的binlog解析。

为何要解析binlog： binlog中含有许多我们需要的信息，基于这些信息，我们可以实现很多功能：

异构数据库同步

数据库事件触发实现分布式事务

数据检效与监控

等等

基本原理：

MySQL主从同步原理：

master将改变记录到二进制日志(binary log)中（这些记录叫做二进制日志事件，binary log events，可以通过show binlog events进行查看）；

slave将master的binary log events拷贝到它的中继日志(relay log)；

slave重做中继日志中的事件，将改变反映它自己的数据。

Canal模拟binlog用的传输协议，把自己伪装成slave，抓取日志：

canal模拟mysql slave的交互协议，伪装自己为mysql slave，向mysql master发送dump协议

mysql master收到dump请求，开始推送binary log给slave(也就是canal)

canal解析binary log对象(原始为byte流)

快速使用：

目前最新的版本是Canal1.0.21，在这个版本修复了几个bug

修复mysql协议读取 #127 [BUG]

mysql 5.6版本 datetime值为null时 sqltype解析异常 #130 [BUG]

值由Null变为空字符串时，isUpdated属性为false #135 [BUG]

多表rename ddl解析出现NPE #122 #128 #137 [BUG]

这几个bug比较重要，所以最好用最新版的canal。之后的otter最新版的默认内置canal版本为1.0.20，最好在这里自己编译下并替换。

git clone https://github.com/alibaba/canal.git mvn clean install -Dmaven.test.skip -Denv=release

配置测试数据库，开启binlog：

log-bin=mysql-bin #添加这一行就ok
binlog-format=ROW #选择row模式，虽然Canal支持各种模式，但是想用otter，必须用ROW模式
server_id=1 #配置mysql replaction需要定义，不能和canal的slaveId重复

添加Canal用户：

CREATE USER canal IDENTIFIED BY 'canal';
GRANT SELECT, REPLICATION SLAVE, REPLICATION CLIENT ON *.* TO 'canal'@'%';
FLUSH PRIVILEGES;

在编译好的目录下的target中找到canal.deployer-1.0.21-SNAPSHOT.tar.gz，解压

mkdir /usr/local/canal
tar zxvf canal.deployer-1.0.21-SNAPSHOT.tar.gz -C /usr/local/canal

配置conf/example/instance.properties:

#################################################
## mysql serverId
## 这个id不能和目标源数据库的id一样
canal.instance.mysql.slaveId = 1234

# 数据库地址，binlog订阅开始点
canal.instance.master.address = 10.202.4.39:3308
canal.instance.master.journal.name = mysql-binlog.000005
canal.instance.master.position = 126596922
canal.instance.master.timestamp =

# 配置备用源数据库
#canal.instance.standby.address =
#canal.instance.standby.journal.name =
#canal.instance.standby.position =
#canal.instance.standby.timestamp =

# username/password
canal.instance.dbUsername = canal
canal.instance.dbPassword = canal
canal.instance.defaultDatabaseName =
canal.instance.connectionCharset = UTF-8

# 订阅哪些表的binlog，支持正则表达式
canal.instance.filter.regex = .*\\..*
# 过滤掉的表的正则表达式
canal.instance.filter.black.regex =

#################################################

订阅起始点可自定义，查看当前binlog状态：

show master status;

一般的，binlog通过文件名和position就可以定位到，timestamp一般可以不用填。

配置conf/canal.properties:

#################################################
######### common argument #############
#################################################
canal.id= 1000001
canal.ip= 10.202.44.205
canal.port= 20999
# canal通过zk做负载均衡
canal.zkServers= 127.0.0.1:2181
# flush data to zk
canal.zookeeper.flush.period = 1000
# flush meta cursor/parse position to file
canal.file.data.dir = ${canal.conf.dir}
canal.file.flush.period = 1000
## memory store RingBuffer size, should be Math.pow(2,n)
canal.instance.memory.buffer.size = 16384
## memory store RingBuffer used memory unit size , default 1kb
canal.instance.memory.buffer.memunit = 1024
## meory store gets mode used MEMSIZE or ITEMSIZE
canal.instance.memory.batch.mode = MEMSIZE

## detecing config
canal.instance.detecting.enable = false
#canal.instance.detecting.sql = insert into retl.xdual values(1,now()) on duplicate key update x=now()
canal.instance.detecting.sql = select 1
canal.instance.detecting.interval.time = 3
canal.instance.detecting.retry.threshold = 3
canal.instance.detecting.heartbeatHaEnable = false

# support maximum transaction size, more than the size of the transaction will be cut into multiple transactions delivery
canal.instance.transaction.size =  1024
# mysql fallback connected to new master should fallback times
canal.instance.fallbackIntervalInSeconds = 60

# network config
canal.instance.network.receiveBufferSize = 16384
canal.instance.network.sendBufferSize = 16384
canal.instance.network.soTimeout = 30

# binlog filter config
canal.instance.filter.query.dcl = false
canal.instance.filter.query.dml = false
canal.instance.filter.query.ddl = false
canal.instance.filter.table.error = false

# binlog format/image check
canal.instance.binlog.format = ROW,STATEMENT,MIXED
canal.instance.binlog.image = FULL,MINIMAL,NOBLOB

# binlog ddl isolation
canal.instance.get.ddl.isolation = false

#################################################
######### destinations #############
#################################################
canal.destinations= example
# conf root dir
canal.conf.dir = ../conf
# auto scan instance dir add/remove and start/stop instance
canal.auto.scan = true
canal.auto.scan.interval = 5

canal.instance.global.mode = spring
canal.instance.global.lazy = false
#canal.instance.global.manager.address = 127.0.0.1:1099
#canal.instance.global.spring.xml = classpath:spring/memory-instance.xml
canal.instance.global.spring.xml = classpath:spring/file-instance.xml
#canal.instance.global.spring.xml = classpath:spring/default-instance.xml

剩下的配置我在Canal源代码分析中会细讲，敬请期待。
配置好，启动：

./bin/startup.sh

查看日志，启动成功。



之后利用客户端程序测试：

import java.net.InetSocketAddress;
import java.util.List;

import com.alibaba.otter.canal.client.CanalConnector;
import com.alibaba.otter.canal.client.CanalConnectors;
import com.alibaba.otter.canal.common.utils.AddressUtils;
import com.alibaba.otter.canal.protocol.Message;
import com.alibaba.otter.canal.protocol.CanalEntry.Column;
import com.alibaba.otter.canal.protocol.CanalEntry.Entry;
import com.alibaba.otter.canal.protocol.CanalEntry.EntryType;
import com.alibaba.otter.canal.protocol.CanalEntry.EventType;
import com.alibaba.otter.canal.protocol.CanalEntry.RowChange;
import com.alibaba.otter.canal.protocol.CanalEntry.RowData;

/** * Created by 862911 on 2016/3/8. */
public class CanalClientUtil {
public static void main(String args[]) {
// 创建链接
CanalConnector connector = CanalConnectors.newSingleConnector(new InetSocketAddress("10.202.44.205",
20999), "example", "", "");
int batchSize = 1000;
int emptyCount = 0;
try {
connector.connect();
connector.subscribe(".*\\..*");
connector.rollback();
int totalEmtryCount = 120;
while (emptyCount < totalEmtryCount) {
Message message = connector.getWithoutAck(batchSize); // 获取指定数量的数据
long batchId = message.getId();
int size = message.getEntries().size();
if (batchId == -1 || size == 0) {
emptyCount++;
System.out.println("empty count : " + emptyCount);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
}
} else {
emptyCount = 0;
// System.out.printf("message[batchId=%s,size=%s] \n", batchId, size);
printEntry(message.getEntries());
}

connector.ack(batchId); // 提交确认
// connector.rollback(batchId); // 处理失败, 回滚数据
}

System.out.println("empty too many times, exit");
} finally {
connector.disconnect();
}
}

private static void printEntry(List<Entry> entrys) {
for (Entry entry : entrys) {
if (entry.getEntryType() == EntryType.TRANSACTIONBEGIN || entry.getEntryType() == EntryType.TRANSACTIONEND) {
continue;
}

RowChange rowChage = null;
try {
rowChage = RowChange.parseFrom(entry.getStoreValue());
} catch (Exception e) {
throw new RuntimeException("ERROR ## parser of eromanga-event has an error , data:" + entry.toString(),
e);
}

EventType eventType = rowChage.getEventType();
System.out.println(String.format("================> binlog[%s:%s] , name[%s,%s] , eventType : %s",
entry.getHeader().getLogfileName(), entry.getHeader().getLogfileOffset(),
entry.getHeader().getSchemaName(), entry.getHeader().getTableName(),
eventType));

for (RowData rowData : rowChage.getRowDatasList()) {
if (eventType == EventType.DELETE) {
printColumn(rowData.getBeforeColumnsList());
} else if (eventType == EventType.INSERT) {
printColumn(rowData.getAfterColumnsList());
} else {
System.out.println("-------> before");
printColumn(rowData.getBeforeColumnsList());
System.out.println("-------> after");
printColumn(rowData.getAfterColumnsList());
}
}
}
}

private static void printColumn(List<Column> columns) {
for (Column column : columns) {
System.out.println(column.getName() + " : " + column.getValue() + " update=" + column.getUpdated());
}
}
}

测试结果：

================> binlog[mysql-binlog.000005:126600892] , name[express2,exp_data_waybill] , eventType : INSERT
waybill_no : 444502894553    update=true
delivery_tel : jHR4SS2qWgxxAntO1y1HVA==    update=true
delivery_mobile : sKBkAB0Z3LGVCbVfS1YOZQ==    update=true
delivery_contact : FdVG8RGFYwtWL9MU6QoMxg==    update=true
delivery_addr : CW4QuCFWXlDZdTQCGgJLPe+LiC3hKPV7ykvdB7qx7dE=    update=true
delivery_company : -    update=true
delivery_addr_lat : 0.0    update=true
delivery_addr_lng : 0.0    update=true
consignee_tel : kcObfcMJkQ+uAh2RtAZ6cQ==    update=true
consignee_mobile : b0mwnXp6/YKX/MKXX6S8CQ==    update=true
consignee_contact : b0mwnXp6/YKX/MKXX6S8CQ==    update=true
consignee_addr : XESDfeSycHu4VHDE/ns1QksFDEmfVhkUgGWZ/+ea+tpU4Dq+d1/Rez4RGvRdALOS    update=true
consignee_company : sf-express    update=true
source_zone_code :     update=true
dest_zone_code : 010    update=true
meterage_weight_qty : 20.0    update=true
real_weight_qty : 1.0    update=true
quantity : 1.0    update=true
consignee_emp_code : 000212    update=true
consigned_tm : 2016-03-04 17:25:42    update=true
deliver_emp_code :     update=true
subscriber_name :     update=true
signin_tm : 0000-00-00 00:00:00    update=true
cargo_type_code : C201    update=true
limit_type_code : T4    update=true
distance_type_code : R10102    update=true
transport_type_code : TR2    update=true
express_type_code : B1    update=true
bill_long :     update=true
bill_width :     update=true
bill_high :     update=true
volume : 120000.0    update=true
last_modified_tm : 2016-03-08 11:15:24    update=true
is_child_waybill : N    update=true
is_deleted : 0    update=true
created_time : 2016-03-08 11:15:27    update=true
inputer_emp_code : BSP    update=true
modified_time : 2016-03-08 11:15:27    update=true
================> binlog[mysql-binlog.000005:126601605] , name[express2,exp_data_waybill] , eventType : UPDATE
-------> before
waybill_no : 906501983434    update=false
delivery_tel : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
delivery_mobile : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
delivery_contact : +nSsYUguIjG7al33EaPDzA==    update=false
delivery_addr : AfdjSlmWTbKQgeqVaQgDvw==    update=false
delivery_company : 啊啊啊啊啊啊    update=false
delivery_addr_lat : 0.0    update=false
delivery_addr_lng : 0.0    update=false
consignee_tel : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
consignee_mobile : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
consignee_contact : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
consignee_addr : qoPgg0MX3wMoT1g9JpRQFA==    update=false
consignee_company : soreufgd    update=false
source_zone_code :     update=false
dest_zone_code : 010A    update=false
meterage_weight_qty : 100.0    update=false
real_weight_qty : 100.0    update=false
quantity : 1.0    update=false
consignee_emp_code : 002776    update=false
consigned_tm : 2016-03-01 10:45:00    update=false
deliver_emp_code :     update=false
subscriber_name :     update=false
signin_tm : 0000-00-00 00:00:00    update=false
cargo_type_code : C201    update=false
limit_type_code : T4    update=false
distance_type_code : R10102    update=false
transport_type_code : TR2    update=false
express_type_code : B1    update=false
bill_long :     update=false
bill_width :     update=false
bill_high :     update=false
volume :     update=false
last_modified_tm : 2016-03-01 14:22:09    update=false
is_child_waybill : N    update=false
is_deleted : 0    update=false
created_time : 2016-03-04 19:59:20    update=false
inputer_emp_code : 000000    update=false
modified_time : 2016-03-04 19:59:20    update=false
-------> after
waybill_no : 906501983434    update=false
delivery_tel : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
delivery_mobile : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
delivery_contact : +nSsYUguIjG7al33EaPDzA==    update=false
delivery_addr : AfdjSlmWTbKQgeqVaQgDvw==    update=false
delivery_company : 啊啊啊啊啊啊    update=false
delivery_addr_lat : 0.0    update=false
delivery_addr_lng : 0.0    update=false
consignee_tel : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
consignee_mobile : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
consignee_contact : 9BxLJQjsg8u0y5T4Prf0Hg==    update=false
consignee_addr : qoPgg0MX3wMoT1g9JpRQFA==    update=false
consignee_company : soreufgd    update=false
source_zone_code :     update=false
dest_zone_code : 010A    update=false
meterage_weight_qty : 100.0    update=false
real_weight_qty : 100.0    update=false
quantity : 1.0    update=false
consignee_emp_code : 002776    update=false
consigned_tm : 2016-03-01 10:45:00    update=false
deliver_emp_code :     update=false
subscriber_name :     update=false
signin_tm : 0000-00-00 00:00:00    update=false
cargo_type_code : C201    update=false
limit_type_code : T4    update=false
distance_type_code : R10102    update=false
transport_type_code : TR2    update=false
express_type_code : B1    update=false
bill_long :     update=false
bill_width :     update=false
bill_high :     update=false
volume :     update=false
last_modified_tm : 2016-03-08 11:18:25    update=true
is_child_waybill : N    update=false
is_deleted : 0    update=false
created_time : 2016-03-04 19:59:20    update=false
inputer_emp_code : 000000    update=false
modified_time : 2016-03-08 11:18:27    update=true

可以看出，基于ROW格式的binlog解析，我们可以解析出是何种语句，以及每条记录是怎么更新的。