[389-devel] Implementing Referential Integrity by using a queue instead of a file

[Ilias Stamatis]

Hello,

A desire had been expressed to get rid of referint plugin's logfile:
https://pagure.io/389-ds-base/issue/49202

It finally turns out that this file is used for other purposes than real
logging.

The referint plugin currently works like that; When the delay update is set
to be more than 0 a new thread is created executing referential integrity
code every x seconds (set by delay update). When a delete or modrdn
operation happens, the plugin will write that down to its logfile. So,
every x seconds the plugin will check the logfile, see what happened and
apply the changes. Finally, it deletes the file, thus clearing the state
for the next time it reads from it.

After discussing this with William he suggested it's better to replace the
file with a queue, since the file involves excess fsync / sync, and has all
kinds of potential state/race issues. Using a queue will be much faster as
well.

William went even further and suggested that we could get rid of the async
referint update completely. This probably wouldn't happen soon though,
since likely customers are using it. For now we could provide a warning
such as "we recommend you set delay to 0".

Finally, the referint-logchanges attribute does absolutely nothing. It
seems to be completely ignored by the plugin, so we could remove this as
well.

I'll start working on these changes soon.

Any thoughts or objections on the above would be welcome.

Thanks,
Ilias