• MySQL Native Driver Plugin
  • The mysqlnd plugin API

  • The mysqlnd plugin API
  • The mysqlnd plugin API

    The mysqlnd plugin API

    The following is a list of functions provided in
    the mysqlnd plugin API:

    • mysqlnd_plugin_register()

    • mysqlnd_plugin_count()

    • mysqlnd_plugin_get_plugin_connection_data()

    • mysqlnd_plugin_get_plugin_result_data()

    • mysqlnd_plugin_get_plugin_stmt_data()

    • mysqlnd_plugin_get_plugin_net_data()

    • mysqlnd_plugin_get_plugin_protocol_data()

    • mysqlnd_conn_get_methods()

    • mysqlnd_result_get_methods()

    • mysqlnd_result_meta_get_methods()

    • mysqlnd_stmt_get_methods()

    • mysqlnd_net_get_methods()

    • mysqlnd_protocol_get_methods()

    There is no formal definition of what a plugin is
    and how a plugin mechanism works.

    Components often found in plugins mechanisms

    • A plugin manager

    • A plugin API

    • Application services (or modules)

    • Application service APIs (or module APIs)

    The mysqlnd plugin concept employs these
    features, and additionally enjoys an open architecture.

    No Restrictions

    A plugin has full access to the inner workings of
    mysqlnd. There are no security limits or restrictions.
    Everything can be overwritten to implement friendly or hostile
    algorithms. It is recommended you only deploy plugins from a
    trusted source.

    As discussed previously, plugins can use pointers
    freely. These pointers are not restricted in any way, and can point
    into another plugin’s data. Simple offset arithmetic can be used to
    read another plugin’s data.

    It is recommended that you write cooperative
    plugins, and that you always call the parent method. The plugins
    should always cooperate with mysqlnd itself.

    Issues: an example of chaining and
    Extension mysqlnd.query() pointer call stack if calling parent
    ext/mysqlnd mysqlnd.query() mysqlnd.query
    ext/mysqlnd_cache mysqlnd_cache.query()
    1. mysqlnd_cache.query()

    2. mysqlnd.query

    ext/mysqlnd_monitor mysqlnd_monitor.query()
    1. mysqlnd_monitor.query()

    2. mysqlnd_cache.query()

    3. mysqlnd.query

    In this scenario, a cache
    (ext/mysqlnd_cache) and a monitor
    (ext/mysqlnd_monitor) plugin are loaded. Both subclass
    Connection::query(). Plugin registration happens at
    MINIT using the logic shown previously. PHP calls
    extensions in alphabetical order by default. Plugins are not aware
    of each other and do not set extension dependencies.

    By default the plugins call the parent
    implementation of the query method in their derived version of the

    PHP Extension Recap

    This is a recap of what happens when using an
    example plugin, ext/mysqlnd_plugin, which exposes the
    mysqlnd C plugin API to PHP:

    • Any PHP MySQL application tries to establish a
      connection to

    • The PHP application will either use
      ext/mysql, ext/mysqli or PDO_MYSQL. All
      three PHP MySQL extensions use mysqlnd to establish the
      connection to

    • Mysqlnd calls its connect method, which
      has been subclassed by ext/mysqlnd_plugin.

    • ext/mysqlnd_plugin calls the userspace
      hook proxy::connect() registered by the user.

    • The userspace hook changes the connection host IP
      from to and returns the connection
      established by parent::connect().

    • ext/mysqlnd_plugin performs the equivalent
      of parent::connect( by calling the original
      mysqlnd method for establishing a connection.

    • ext/mysqlnd establishes a connection and
      returns to ext/mysqlnd_plugin. ext/mysqlnd_plugin
      returns as well.

    • Whatever PHP MySQL extension had been used by the
      application, it receives a connection to The PHP MySQL
      extension itself returns to the PHP application. The circle is