Examples
How it works
How it works
How it works
This describes the background and inner workings of
the mysqlnd_uh extension.
Two classes are provided by the extension: MysqlndUhConnection and MysqlndUhPreparedStatement. MysqlndUhConnection lets you access almost all
methods of the mysqlnd internal connection class.
The latter exposes some selected methods of the mysqlnd
internal statement class. For example, MysqlndUhConnection::connect() maps to the
mysqlnd library C function
mysqlnd_conn__connect.
As a mysqlnd plugin, the PECL/mysqlnd_uh extension
replaces mysqlnd library C functions with its own
functions. Whenever a PHP MySQL extension compiled to use
mysqlnd calls a mysqlnd function, the functions installed
by the plugin are executed instead of the original mysqlnd
ones. For example, mysqli_connect() invokes
mysqlnd_conn__connect, so the connect function installed
by PECL/mysqlnd_uh will be called. The functions installed by
PECL/mysqlnd_uh are the methods of the built-in classes.
The built-in PHP classes and their methods do
nothing but call their mysqlnd C library counterparts, to
behave exactly like the original mysqlnd function they
replace. The code below illustrates in pseudo-code what the
extension does.
Example #1 Pseudo-code: what a built-in class
does
class MysqlndUhConnection {
public function connect(($conn, $host, $user, $passwd, $db, $port, $socket, $mysql_flags) {
MYSQLND* c_mysqlnd_connection = convert_from_php_to_c($conn);
...
return call_c_function(mysqlnd_conn__connect(c_mysqlnd_connection, ...));
}
}
The build-in classes behave like a transparent
proxy. It is possible for you to replace the proxy with your own.
This is done by subclassing MysqlndUhConnection or MysqlndUhPreparedStatement to extend the
functionality of the proxy, followed by registering a new proxy
object. Proxy objects are installed by mysqlnd_uh_set_connection_proxy() and
mysqlnd_uh_set_statement_proxy().
Example #2 Installing a proxy
<?php
class proxy extends MysqlndUhConnection {
public function connect($res, $host, $user, $passwd, $db, $port, $socket, $mysql_flags) {
printf("%s(%s)\n", __METHOD__, var_export(func_get_args(), true));
$ret = parent::connect($res, $host, $user, $passwd, $db, $port, $socket, $mysql_flags);
printf("%s returns %s\n", __METHOD__, var_export($ret, true));
return $ret;
}
}
mysqlnd_uh_set_connection_proxy(new proxy());
$mysqli = new mysqli("localhost", "root", "", "test");
?>The above example will output:
proxy::connect(array ( 0 => NULL, 1 => 'localhost', 2 => 'root', 3 => '', 4 => 'test', 5 => 3306, 6 => NULL, 7 => 131072, )) proxy::connect returns true