Installing a proxy
The extension provides two built-in classes: MysqlndUhConnection
and MysqlndUhPreparedStatement. The classes are used
for hooking mysqlnd library calls. Their methods correspond
to mysqlnd internal functions. By default they act like
a transparent proxy and do nothing but call their mysqlnd counterparts.
By subclassing the classes you can install your own proxy to monitor mysqlnd.
See also the How it works guide to learn about the inner workings of this extension.
Connection proxies are objects of the type MysqlndUhConnection. Connection proxy objects are installed by mysqlnd_uh_set_connection_proxy(). If you install the built-in class MysqlndUhConnection as a proxy, nothing happens. It behaves like a transparent proxy.
Example #1 Proxy registration, mysqlnd_uh.enable=1
<?php
mysqlnd_uh_set_connection_proxy(new MysqlndUhConnection());
$mysqli = new mysqli("localhost", "root", "", "test");
?>
The PHP_INI_SYSTEM configuration setting
mysqlnd_uh.enable
controls whether a proxy may be set. If disabled, the extension
will throw errors of type E_WARNING
Example #2 Proxy installation disabled
mysqlnd_uh.enable=0
<?php
mysqlnd_uh_set_connection_proxy(new MysqlndUhConnection());
$mysqli = new mysqli("localhost", "root", "", "test");
?>
The above example will output:
PHP Warning: MysqlndUhConnection::__construct(): (Mysqlnd User Handler) The plugin has been disabled by setting the configuration parameter mysqlnd_uh.enabled = false. You must not use any of the base classes in %s on line %d PHP Warning: mysqlnd_uh_set_connection_proxy(): (Mysqlnd User Handler) The plugin has been disabled by setting the configuration parameter mysqlnd_uh.enable = false. The proxy has not been installed in %s on line %d
To monitor mysqlnd, you have to write your own
proxy object subclassing MysqlndUhConnection.
Please, see the function reference for a the list of methods that
can be subclassed. Alternatively, you can use reflection to inspect
the built-in MysqlndUhConnection.
Create a new class proxy. Derive it from the
built-in class MysqlndUhConnection.
Replace the
MysqlndUhConnection::connect().
method. Print out the host parameter value passed to the method.
Make sure that you call the parent implementation of the connect
method. Failing to do so may give unexpected and undesired results, including
memory leaks and crashes.
Register your proxy and open three connections using the PHP MySQL
extensions mysqli,
mysql,
PDO_MYSQL. If the extensions have been
compiled to use the mysqlnd library, the
proxy::connect method will be called three times, once
for each connection opened.
Example #3 Connection proxy
<?php
class proxy extends MysqlndUhConnection {
public function connect($res, $host, $user, $passwd, $db, $port, $socket, $mysql_flags) {
printf("Connection opened to '%s'\n", $host);
/* Always call the parent implementation! */
return parent::connect($res, $host, $user, $passwd, $db, $port, $socket, $mysql_flags);
}
}
mysqlnd_uh_set_connection_proxy(new proxy());
$mysqli = new mysqli("localhost", "root", "", "test");
$mysql = mysql_connect("localhost", "root", "");
$pdo = new PDO("mysql:host=localhost;dbname=test", "root", "");
?>
The above example will output:
Connection opened to 'localhost' Connection opened to 'localhost' Connection opened to 'localhost'
The use of prepared statement proxies follows the same pattern: create a proxy object of the type MysqlndUhPreparedStatement and install the proxy using mysqlnd_uh_set_statement_proxy().
Example #4 Prepared statement proxy
<?php
class stmt_proxy extends MysqlndUhPreparedStatement {
public function prepare($res, $query) {
printf("%s(%s)\n", __METHOD__, $query);
return parent::prepare($res, $query);
}
}
mysqlnd_uh_set_statement_proxy(new stmt_proxy());
$mysqli = new mysqli("localhost", "root", "", "test");
$stmt = $mysqli->prepare("SELECT 'mysqlnd hacking made easy' AS _msg FROM DUAL");
?>
The above example will output:
stmt_proxy::prepare(SELECT 'mysqlnd hacking made easy' AS _msg FROM DUAL)
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