mysql 插件开发

最新推荐文章于 2025-07-02 23:45:35 发布

翻译最新推荐文章于 2025-07-02 23:45:35 发布 · 746 阅读

本文详细介绍了如何使用C语言开发MySQL监控插件，并通过mysql_config命令进行编译和链接，最终实现插件的加载与运行。重点阐述了插件的初始化、退出流程以及与MySQL核心函数库的交互。

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1.代码demo

#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <plugin.h>
#include <mysql_version.h>
#include <my_global.h>
#include <my_sys.h>
#include <pthread.h>
extern ulong       thread_id;
extern uint       thread_count;
extern ulong       max_connections;
static pthread_t   G_thread;
pthread_t ntid;

pthread_handler_t func(void *p)
{
    while(1) {
         sleep(5);
         fprintf(stderr, "Thread id [%ld] Max_connections:%lu\n",
             thread_id, max_connections);
         }
}

static int monitor_plugin_init(void *p)
{

   if (pthread_create(&G_thread,NULL,func, NULL) != 0) {}

    fprintf(stderr, "%s", "Monitor plugin init\n");
    return 0;
}

static int monitor_plugin_deinit(void *p)
{
    pthread_cancel(G_thread);
    pthread_join(G_thread, NULL);
    fprintf(stderr, "%s", "Monitor_plugin deinit\n");

    return 0;
}

struct st_mysql_daemon monitor_plugin =
{
    MYSQL_DAEMON_INTERFACE_VERSION
};

mysql_declare_plugin(monitor_plugin)
{
    MYSQL_DAEMON_PLUGIN,
    &monitor_plugin,
    "monitor",
    "hoterran",
    "test",
    PLUGIN_LICENSE_GPL,
    monitor_plugin_init,
    monitor_plugin_deinit,
    0x0100,
    NULL,
    NULL,
    NULL,
}
mysql_declare_plugin_end;

编译前查看mysql函数库的路经。

/usr/local/mysql/bin/mysql_config --cflags
-I/usr/local/mysql/include -g -fabi-version=2 -fno-omit-frame-pointer -fno-strict-aliasing
[root@localhost demo]#

编译：

#gcc -o monitor.o monitor.c -shared '/usr/local/mysql/bin/mysql_config --cflags'

gcc -g -Wall -I/usr/local/mysql/include/ -DMYSQL_DYNAMIC_PLUGIN -c -o monitor.o monit
or.c

64位系统：

错误：/usr/bin/ld: monitor.o: relocation R_X86_64_32 against `.rodata' can not be used when making a shared object; recompile with -fPIC

在编译时加－fPIC

gcc -g -Wall -I/usr/local/mysql/include/ -DMYSQL_DYNAMIC_PLUGIN -c -fPIC -o monitor.o
monitor.c

gcc -shared -o libmonitor.so monitor.o

拷贝monitor.o

cp monitor.o /usr/local/mysql/lib/plugin/

show variables like 'plugin_dir';

进入mysql：

加载：

install plugin monitor soname 'libmonitor.so';

show plugins;

select * from mysql.plugin