maria-developers team mailing list archive

[Piotr Jurkiewicz <piotr.jerzy.jurkiewicz@xxxxxxxxx>]

Hi all,

as the midterm is approaching, I am posting a report on what I have done 
so far.

The project is going as scheduled. You can see the timeline in my proposal:

http://www.google-melange.com/gsoc/proposal/public/google/gsoc2015/piotrjurkiewicz/5743522325987328

All goals planned before the midterm have been reached. InnoDB Memcached 
plugin ported from MySQL works now with MariaDB (both with InnoDB and 
XtraDB engines). That means that MariaDB is now on par with MySQL on 
this issue.

My repository with the code is available here: 
https://github.com/piotrjurkiewicz/mariadb-server

What have been done in details:

1. Code of InnoDB Memcached plugin has been imported from MySQL into the 
MariaDB tree.

2. There were some differences between MariaDB and MySQL, which blocked 
the plugin from out-of-the-box compilation and correct operation. They 
have been resolved.

3. Test suite for the plugin has been imported from MySQL. Compatibility 
changes were introduced into these test cases which required them. The 
test suite was modified to assign memcached port number dynamically from 
mtr worker's pool, what allows to run the same test in parallel for many 
combinations.

The plugin fully passes the test suite, both for 'innodb_plugin' and 
'xtradb' combinations.

4. Some enhancements and bug fixes have been introduced into the plugin:

- detection of memcached daemon initialization has been fixed -- this 
eliminated unnecessary wait (15 seconds) on plugin shutdown and memory 
leak (in cases when plugin failed to initialize properly before)

- memcached arithmetic commands (incr/decr) handling has been improved 
-- now numeric columns values are handled in a consistent and 
predictable way

- incorrect handling of unsigned not null integers columns has been fixed

For details of all changes please see commit messages associated with 
them: 
https://github.com/piotrjurkiewicz/mariadb-server/commits/10.1-memcached

After the midterm, I plan to focus on further enhancements of the 
plugin, as stated in my proposal:

1. Change plugin architecture to "one table per socket", as originally 
proposed in MDEV-4674 bug report. This will allow usage of well known 
security solutions (firewalls, unix file permissions) to restrict access 
to different tables for different users.

2. Implement a new interface inside the Memcached plugin, which will use 
Handler API for database access. This will make possible to use the 
plugin with database engines other than InnoDB/XtraDB. Ultimately, this 
interface will replace existing InnoDB direct API interface (if there 
will be no significant performance differences).

Therefore, I would like to as you to point me to Handler API 
documentation (if documentation such exists). I know that HandlerSocket 
plugin uses the Handler API to access databases. Is HandlerSocket plugin 
a good example of Handler API usage to follow?

Piotr