Package proposal: a query cache plugin for mysqlnd

Hi,

we would like to add a query cache plugin extension for mysqlnd to PECL [1].

As of PHP 5.3.2 the MySQL native driver for PHP (mysqlnd), which can be 
used with ext/mysql, ext/mysqli and PDO_MYSQL, features an internal C 
plugin API [2, 3]. The proposed query cache plugin is a mysqlnd plugin. 
It is written in C and comes as a PHP extension. C gives you the best 
possible performance.

*Basic usage* example (see also [1]):

   $mysqli = new mysqli($host, $user, $password, $db, $port, $socket);
   // Will be cached because of the SQL hint
   $res = $mysqli->query("/*qc=on*/SELECT id FROM test WHERE id = 1");
   var_dump($res->fetch_assoc());
   $res->free();

The plugin hooks internal mysqlnd C calls. From a user space point of 
view it is virtually transparent because it does not change existing 
APIs. Like every other mysqlnd plugin it can be used with every PHP 
MySQL API (ext/mysql, ext/mysqli, PDO_MySQL).

*Key feaures* of the query cache [1]:

   - works with ext/mysql, ext/mysqli and PDO_MySQL
   - supports unbuffered queries

   - controlled through SQL hints

   - default invalidation strategy: Time-to-live (TTL)
     - TTL can be set globally or per query
     - user space storage handler can implement any other
       more sophisticated invalidation strategy

   - built-in storage handler:
       - default (PHP hashes)
       - APC
       - Memcache
       - SQLite
       - user

*License*:

    PHP License

*Source* download, build instructions, requirements, ... :

   [1] http://forge.mysql.com/wiki/MySQLnd_Query_Cache_Plugin_for_PHP

*Testing/QA status*:

We officially call it a "prototype".

However, that is the official description. The extension comes with 58 
*.phpt tests which should cover more than 85% of the extensions source 
code, if you run the tests against all storage handler before generating 
code coverage figures.

All tests pass.

The code has been build and tested on some 30 platforms:

  - FreeBSD 6 (x86, x86_64)
  - FreeBSD 7 (x86, x86_64)
  - Linux ia64
  - Linux RHEL 4, 5 (ia64, x86, x86_64)
  - Linux SLES 9, 10 (ia64, x86, x86_64)
  - Solaris 11 (x86, x86_64)
  - a couple of Ubuntu and OpenSuSE x86/x86_64 used for development
  - Win XP, VC9, x86

Valgrind likes the code with the exception of (my) APC handler. No 
valgrind warnings when using default, Memcache, SQLite and user space 
handler.

The package.xml calls the API "beta".

*Documentation*:

    Prepared, see [1] and [4].

*TODO*:

  - check almost untested package.xml
  - align config.win32 and config.m4
  - fix APC handler valgrind warnings
  - write documentation in PECL/php.net format

Ulf

[1] http://forge.mysql.com/wiki/MySQLnd_Query_Cache_Plugin_for_PHP
[2] http://blog.ulf-wendel.de/mysqlnd_plugin_ipc2010.html
[3] http://www.slideshare.net/nixnutz/the-mysql
[4]
http://www.slideshare.net/nixnutz/buildin-query-caching-for-all-php-mysql-extensionsapis