### Description

_**Sipwise** hat on_

We noticed that pkg memory was getting exhausted and we found out that pv_cache_add() was the origin of the allocations. We are using ``$xavp(user_<UUID>)`` variables that, for sure, are kind of dynamic.

There is a pv_cache_drop() that tries to remove ``$sht()`` occurrences when the cache is about to be filled but in our case that's not helping.

#### Log Messages

``` WARNING: ROUTE_SET_CALLEE_DIALOG_TOTAL <core> [core/pvapi.c:340]: pv_cache_add(): pv cache limit is going to be exceeded - pkg memory may get filled with pv declarations WARNING: dialog:failed <core> [core/pvapi.c:340]: pv_cache_add(): pv cache limit is going to be exceeded - pkg memory may get filled with pv declarations ```

### Possible Solutions

Possible solutions that came on the top of my head:

- add a datetime member to struct _pv_cache so we can keep the last time it was accessed and search for the oldest and remove them in pv_cache_drop() - add pv module parameter to define a magic prefix, for instance '__' that will mark those vars as "temporal" should remove it from cache when needed. - add pv module parameter to control what types of variables will be added to cache

Any thoughts about this?