[opendmarc-dev] Delayed DB writes

[Murray S. Kucherawy]

I'm planning to have the opendmarc filter write records to an SQL database 
for each message it receives, to allow report generation.

In the event the database is unavailable, we have a few options:

1) Temp-fail messages when the DB is unavailable

2) Write things to a flat text file which then gets batch-imported when 
the database is available (maybe by cron, maybe by a separate filter 
thread); if the flat file can't be written (disk full or such), fall back 
to 1

3) Queue some number of events internally and then replay the queue into 
the DB when it's available; when the queue gets too large, fall back to 1

I'm leaning toward having a separate thread that does all of the DB 
insertions, accepting and queueing requests from the other thread(s).  It 
would otherwise implement option 3 above.  Any comments?

-MSK