New syslog module for Drizzle DB

One of the long-time continuing complaints against using MySQL in an enterprise or large scale environment is it's logging system. The query log, slow query log, and error log all get written to the server's local filesystem, which is difficult and awkward to hook up to enterprise log collection and analysis systems. A recurring feature request is to be able to use the UNIX syslog instead.

One of the first things I did to Drizzle was tear out the existing logging code. This also removed a number of mutex locks, one of which was completely unnecessary, and one that got constantly hit even if logging was turned off.

In it's place I put two of the first Drizzle plugin interfaces, one for the query logging, which combined the features of the old MySQL query log and the slow query log, and one for error message reporting. I then wrote a plugin that took the query log, and sent it to the syslog.

At the last MySQL Conference, during the Drizzle Developer Day, Monty Taylor pointed out that we were missing something. There was no "send error messages to the syslog" plugin. Oops.

Now there is.

I've completely replaced the plugin/logging_syslog module with a new plugin/syslog module that contains three plugins. In addition to a rewritten "query log to syslog", there is "error messages to syslog", and also a new SQL function SYSLOG(facility, priority, text).

I've pushed the work up to launchpad, and I'm confident that after review and possibly some tweaks, it will be integrated with Drizzle.

Documentation and examples for using this new module are in upcoming posts.