1, 环境

CentOS, MySQL, Redis, Nodejs

2, Redis简介

Redis是一个开源的K-V内存数据库，它的key可以是string/set/hash/list/...，因为是基于内存的，所在访问速度相当快。

3, Gearman简介

Gearman是一个开源的Map/Reduce分布式计算框架，具有丰富的client sdk，而且它支持MySQL UDF。

Gearman工作图

Gearman调用流程

Gearman集群

从图中可以看出貌似Gearman的集群功能比较弱，Job Server之间没啥关系好像。

4, MySQL - Redis配合使用方案

首先我们以MySQL数据为主，将insert/update/delete交给MySQL，而select交给redis；
当有数据发生变化时，通过MySQL Trigger实时异步调用Gearman的UDF提交一个job给Job Server，当job执行的时候会去更新redis；从而保证redis与MySQL中的数据是同步的。

4, 软件安装

安装gearman

//安装依赖
$ yum install -y boost-devel gperf libevent-devel libuuid-devel//下载gearman
$ wget https://launchpad.net/gearmand/1.2/1.1.12/+download/gearmand-1.1.12.tar.gz
$ tar zxvf gearmand-1.1.12.tar.gz//编译安装，指定mysqlclient的链接路径
$ ./configure LDFLAGS=-L/usr/lib64/mysql/
$ make
$ make install//启动gearmand服务端
$ /usr/local/sbin/gearmand -l /var/log/gearmand.log -d//查看是否安装成功，查看gearman版本
$ /usr/local/sbin/gearmand -V

gearman client

gearman client有很多种：PHP, Perl, Python, Ruby, Nodejs, Go, Java, C#...，我们选择GearmaNode(Nodejs库)作为实验用的gearman client

Nodejs的安装省略

GearmaNode的安装及测试

安装GearmaNode

//安装GearmaNode
$ npm install gearmanode

启动Gearman Job Server

//确保gearman的job server已经启动, job server默认监听4730端口
$ netstat -nplt | grep 4730//如果没有，则启动job server（-d表示启动, -l指定log的位置）
$ /usr/local/sbin/gearmand -l /var/log/gearmand.log -d

worker.js (Gearman Job Worker)

var gearmanode = require('gearmanode');
var worker = gearmanode.worker();
//对job client传递过来的字符串执行reverse倒序操作
worker.addFunction('reverse', function (job) {job.sendWorkData(job.payload); // mirror input as partial resultjob.workComplete(job.payload.toString().split("").reverse().join(""));
});

//启动job worker
$ node worker.js

client.js (Gearman Job Client)

var gearmanode = require('gearmanode');
var client = gearmanode.client();
//提交job
var job = client.submitJob('reverse', 'hello world!');
job.on('workData', function(data) {console.log('WORK_DATA >>> ' + data);
});
//结果回调函数
job.on('complete', function() {console.log('RESULT >>> ' + job.response);client.close();
});

//执行client.js
$ node client.js
//查看控制台打印输出

WORK_DATA >>> hello world!
RESULT >>> !dlrow olleh

可以看到gearman安装成功，运行正常。

5, MySQL UDF + Trigger同步数据到Gearman

安装lib_mysqludf_json

lib_mysqludf_json可以把MySQL表的数据以json数据格式输出

//下载lib_mysqludf_json
$ git clone https://github.com/mysqludf/lib_mysqludf_json.git
$ cd lib_mysqludf_json//编译
$ gcc $(mysql_config --cflags) -shared -fPIC -o lib_mysqludf_json.so lib_mysqludf_json.c//拷贝lib_mysqludf_json.so到MySQL的plugin目录
//可以登陆MySQL，输入命令"show variables like '%plugin%'"查看plugin位置
$ cp lib_mysqludf_json.so /usr/lib64/mysql/plugin///演示lib_mysqludf_json功能
$ mysql -uname -hhost -ppwd
//首先注册UDF函数
mysql> CREATE FUNCTION json_object RETURNS STRING SONAME "lib_mysqludf_json.so";
//json_array|json_members|json_values函数注册方式与json_object一样.
mysql> use test;
mysql> select * from user_list;
+------+----------+
| NAME | PASSWORD |
+------+----------+
| troy | pwd      |
+------+----------+
mysql> select json_object(name,password) as user from user_list;
+----------------------------------+
| user                             |
+----------------------------------+
| {"name":"troy","password":"pwd"} |
+----------------------------------+

安装gearman-mysql-udf

//下载
$ wget https://launchpad.net/gearman-mysql-udf/trunk/0.6/+download/gearman-mysql-udf-0.6.tar.gz
$ tar zxvf gearman-mysql-udf-0.6.tar.gz
$ cd gearman-mysql-udf-0.6//安装libgearman-devel
$ yum install libgearman-devel//编译安装
$ ./configure --with-mysql=/usr/bin/mysql_config --libdir=/usr/lib64/mysql/plugin/
$ make && make install//登录MySQL注册UDF函数
mysql> CREATE FUNCTION gman_do_background RETURNS STRINGSONAME "libgearman_mysql_udf.so";
mysql> CREATE FUNCTION gman_servers_set RETURNS STRINGSONAME "libgearman_mysql_udf.so";
//函数gman_do|gman_do_high|gman_do_low|gman_do_high_background|gman_do_low_background|gman_sum注册方式类似，请参考gearman-mysql-udf-0.6/README//指定gearman job server地址
mysql> SELECT gman_servers_set('127.0.0.1:4730');

如果出现异常信息：
ERROR 1126 (HY000): Can't open shared library 'libgearman_mysql_udf.so' (errno: 11 libgearman.so.8: cannot open shared object file: No such file or directory)
表示系统找不到 libgearman.so 文件，一般so都在/usr/local/lib目录下，修改配置文件/etc/ld.so.conf，将/usr/local/lib目录加入进去即可:

$ cat /etc/ld.so.conf
include ld.so.conf.d/*.conf
/usr/local/lib
$ /sbin/ldconfig -v | grep gearman*

MySQL Trigger调用Gearman UDF实现同步

DELIMITER $$
CREATE TRIGGER user_list_data_to_redis AFTER UPDATE ON user_listFOR EACH ROW BEGINSET @ret=gman_do_background('syncToRedis', json_object(NEW.name as 'name', NEW.password as 'password')); END$$
DELIMITER ;

Gearman Nodejs Worker将数据异步复制到redis

redis的安装步骤省略
启动redis-server

$ redis-server

安装redis的Nodejs client:

npm install hiredis redis

redis-worker.js (Gearman Nodejs worker)

var redis = require("redis");
var gearmanode = require('gearmanode');
var worker = gearmanode.worker();//添加gearman函数syncToRedis
//当MySQL表记录更改时，此函数会被调用
worker.addFunction('syncToRedis', function (job) {job.sendWorkData(job.payload);console.log("-------job.payload: " + job.payload.toString());//将字符串转换成json object, 然后调用更新redisupdateRedis(eval('(' + job.payload.toString() + ')'));job.workComplete("Successed!");
});//些函数只是简单的将MySQL表中的一行的记录按单个字段更新到redis中。可根据实际情况自行扩展
function updateRedis(json)
{var client = redis.createClient();client.on("error", function (err) {console.log("Error " + err);});for(var key in json){client.set(key, json[key], redis.print);}client.quit();
}

启动worder:

node redis-worker.js

更新MySQL

mysql> select * from user_list;
+------+----------+
| NAME | PASSWORD |
+------+----------+
| troy | jane     |
+------+----------+
mysql> update user_list set name='hello', password='world';

redis-worker控制台输出：

-------job.payload: {"name":"hello","password":"world"}

查看redis数据

$ redis-cli
127.0.0.1:6379> keys *
1) "password"
2) "name"
127.0.0.1:6379> get name
"hello"
127.0.0.1:6379> get password
"world"

可以看到只要MySQL中user_list表的数据被update了，redis中的数据也会被更新。

6, 参考资料

Gearman+PHP+MySQL UDF的组合异步实现MySQL到Redis的数据复制