FORMS-1677: add user caching

[usingtechnology]

To reduce the number of hits to the db for user (login user - parsed token + db id) add a caching layer.

Cache the login user (parsed token + db fields). Caching is limited to 5 minutes - same as our token.

A few important things happen before we read from the cache:

• the token is parsed
• the token is verified

If we have a valid token, we can then check the cache. If we get a cache hit, we check to see that the cache version matches the token (token may have been refreshed). If that cache hit is stale, then we discard it and do the normal refresh and hydration of the login user and then cache it.

The login user (current user) is called on nearly all endpoints and currently invokes 2 db hits. Short term caching will reduce db load and therefore improve performance. This caching strategy is not aggressive and has safeguards to prevent returning an invalid user.

This relates to #1579 where we remove forms from the current user and use explicit form queries instead of always making those 2 db hits.

Description

Type of Change

feat (a new feature)

perf (change to improve performance)

Checklist

• I have read the CONTRIBUTING doc
• I have checked that unit tests pass locally with my changes
• I have run the npm script lint on the frontend and backend
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• I have approval from the product owner for the contribution in this pull request

Further comments

[WalterMoar]

I think that as a team we need to discuss this sort of thing before work starts on it.

[usingtechnology]

I think that as a team we need to discuss this sort of thing before work starts on it.

I have no idea when we are going to have a prioritized list of tasks, so got to work on something. Performance is an issue and has been raised by clients. Some analysis has been done on this (no metrics, but when are we going to get metrics?) so good thing as any to get cracking on. This isn't a "look at the files and approve" PR. At least there is something to kick around and test out.

[github-actions]

Release 2dcf1ae deployed at https://chefs-dev.apps.silver.devops.gov.bc.ca/pr-1577