Delete expired SMS whenever we are done processing an SMS-related signal.
In order to minimize additional latency only one SMS is removed at a time.
Change-Id: I56cbe716e52b679c4b94f6cbb4a171306975be2e
Related: OS#2354
We already delete SMS which have been sent successfully. However, there
are plans to accept SMS for any subscriber in order to fix the problem
described in https://osmocom.org/issues/2354 ("SMSC: Store&Forward not
working for subscribed but unregistered MS").
This means we may end up storing SMS which never get sent, e.g. because
the B subscriber doesn't actually exist. This could lead to a higher
degree of SMS database growth over time, and therefore we need a way
to keep database size under control.
As a first step, introduce a DB function which removes an expired SMS,
and add a VTY command which removes all expired SMS from the DB.
Later commits will build upon this to remove expired SMS automatically.
The SMS expiry time period is currently hard-coded to 2 weeks.
We could make this configurable in the future if desired.
Change-Id: Icd6093b7b5d8db84b19a0aa47c68182566113ee2
Related: OS#2354
Currently the SMS database keeps accumulating entries for each SMS.
These entries are never deleted automatically. With this change, we
start deleting SMS which have successfully been sent to subscriber B.
Change-Id: I3749855fe25d9d4e37ec96b0c2bffbc692b66a78
Neels Hofmeyr