MySQL server plugins have access to server “services.” The services interface exposes server functionality that plugins can call. It complements the plugin API and has these characteristics:

Current services include the following, and others can be implemented:

The plugin services interface differs from the plugin API as follows:

For developers who wish to modify the server to add a new service, see MySQL Services for Plugins.

The remainder of this section describes how a plugin uses server functionality that is available as a service. See also the source for the “daemon” example plugin, which uses the my_snprintf service. Within a MySQL source distribution, that plugin is located in the plugin/daemon_example directory.

To determine what services exist and what functions they provide, look in the include/mysql directory of a MySQL source distribution. The relevant files are:

Each service-specific header should contain comments that provide full usage documentation for a given service, including what service functions are available, their calling sequences, and return values.

To use a service or services from within a plugin, the plugin source file must include the plugin.h header file to access service-related information:

#include <mysql/plugin.h>

This does not represent any additional setup cost. A plugin must include that file anyway because it contains definitions and structures that every plugin needs.

To access a service, a plugin calls service functions like any other function. For example, to format a string into a buffer for printing, call the my_snprintf() function provided by the service of the same name:

char buffer[BUFFER_SIZE];

my_snprintf(buffer, sizeof(buffer), format_string, argument_to_format, ...);

To report an error that the server will write to the error log, first choose an error level. mysql/service_my_plugin_log.h defines these levels:

enum plugin_log_level
{
  MY_ERROR_LEVEL,
  MY_WARNING_LEVEL,
  MY_INFORMATION_LEVEL
};  

Then invoke my_plugin_log_message():

int my_plugin_log_message(MYSQL_PLUGIN *plugin, enum plugin_log_level level,
                          const char *format, ...);

For example:

my_plugin_log_message(plugin_ptr, MY_ERROR_LEVEL, "Cannot initialize plugin");

When you build your plugin, you must link in the libmysqlservices library. Use the -lmysqlservices flag at link time. For example, for CMake, put this in the top-level CMakeLists.txt file:

FIND_LIBRARY(MYSQLSERVICES_LIB mysqlservices 
 PATHS "${MYSQL_SRCDIR}/libservices" NO_DEFAULT_PATH)

Put this in the CMakeLists.txt file in the directory containing the plugin source:

# the plugin needs the mysql services library for error logging
TARGET_LINK_LIBRARIES (your_plugin_library_name ${MYSQLSERVICES_LIB})