Does Update Reset the TTL?

[ShiromMakkad]

Hello, I'm wondering if updating the value inside the cache will reset the TTL. I'm specifically wondering about and_try_compute_with and and_upsert_with. Also, will it update the time to idle? I'm going to guess it's yes but I want to make sure.

[ShiromMakkad]

I wrote a test and confirmed that and_try_compute_with does update the ttl. One other question, do I need to run https://docs.rs/moka/latest/moka/future/struct.Cache.html#method.run_pending_tasks for the ttl to update? In my test, I didn't need to, but I'm not sure if that's just luck. What tasks does that run? Size based evictions?

[tatsuya6502]

Hi. Yes, and_try_compute_with and other insert like methods update the TTL and time to idle timers.

The following diagram (from #72) is a bit outdated, but last_modified field in the middle right box is for the TTL, and last_accessed field is for the time to idle.

The "Key" box and "Value" boxes (including the last_modified field) are updated when an insert like method is called, so you do not need to call run_pending_tasks. The boxes on the bottom will be updated by an implicit or explicit call on run_pending_tasks. They are used to evict entries when the cache is full.

The tasks ran by run_pending_tasks are documented here.

For example, it removes expired entries:

4. Remove expired entries.

And you would not have to call run_pending_tasks explicitly to remove expired entries:

Note that cache read methods such as the get, get_with and contains_key never return expired entries although they are not removed immediately from the cache when they expire. You will not need to call run_pending_tasks method to remove expired entries unless you want to remove them immediately (e.g. to free some resources).

(I should put the info to a better place in the document, but I have not found the time to do so yet.)

[ShiromMakkad]

This answers everything perfectly, thanks! I really appreciate your creation, support and maintenance of this repo; it's really well done.