A Hello World! Daemon plugin

Now, let's look at our first complete plugin example. This plugin is probably the most basic plugin we can have. It simply prints a message into the MySQL error log when loaded:

#include <stdio.h>
#include <mysql/plugin.h>
#include <mysql_version.h>

These are the basic includes required for most Daemon plugins. The most important being mysql/plugin.h, which contains macros and data structures necessary for a MySQL plugin.

static int hello_world_plugin_init(void *p)
{
fprintf(stderr, "Hello World: "
"This is a static text daemon example plugin!\n");
return 0;
}

In the plugin initialization function we simply write a message to stderr. MySQL redirects stderr to the error log (if there is one) so our message will end up there. We then return 0 to indicate that the initialization was successful.

struct st_mysql_daemon hello_world_info =
{ MYSQL_DAEMON_INTERFACE_VERSION };

This structure is used for the info part of the plugin declaration. In Daemon...