Timer to group calls to appDb store() method

Calls to store() are now non-blocking, and a timer is set to perform the write to persistent storage 5 seconds after the latest store() call. This makes persistent storage writes much less frequent.

This is the first attempt at a solution - a better approach is to put calls into a queue, the other end of which will be serviced by a worker task. Working on that next...

Looks good to me! Thanks for keeping our codebase clean.

However, I'm only a bot - so a human will still have to approve this request.

We know that it is not ideal to do this inside a timer, but we believe that it will improve the situation. Worker task coming up.

merged

mentioned in commit 05b94cac