While doing a torture test with a very large combination of
the number of domains, campaigns and tenants (effectively
unbounded in any meaningful time period), using the smart sink
to generate bounces and suspensions, I found that the overhead
of tracking the set of bounces and suspensions by scheduled
queue was too high: each bounce lookup was O(number-of-bounces),
and when you can have 100k admin bounces configured, that is
not good for the miss case, which, despite the volume of admin
bounce records, is still the dominant case.
This commit introduces a helper map/multi-index type that
maintains indices for the common tuples:
* (domain, campaign, tenant),
* (domain, tenant)
* (domain)
* other
then uses an appropriate index based on the current context.
That reduces the the lookup cost to effectively constant time (3 x O(1)
lookups), unless there are admin bounces registered in the "other"
bucket, in which case there is an additional O(number-of-other) lookups.
Wez Furlong
d5decd1361