canceled callers might linger around longer,
can potentially overwhelm the system. Instead
provider a caller context and canceled callers
don't hold on to them.
Bonus: we have no reason to cache errors, we should
never cache errors otherwise we can potentially have
quorum errors creeping in unexpectedly. We should
let the cache when invalidating hit the actual resources
instead.
* Remove lock for cached operations.
* Rename "Relax" to `ReturnLastGood`.
* Add `CacheError` to allow caching values even on errors.
* Add NoWait that will return current value with async fetching if within 2xTTL.
* Make benchmark somewhat representative.
```
Before: BenchmarkCache-12 16408370 63.12 ns/op 0 B/op
After: BenchmarkCache-12 428282187 2.789 ns/op 0 B/op
```
* Remove `storageRESTClient.scanning`. Nonsensical - RPC clients will not have any idea about scanning.
* Always fetch remote diskinfo metrics and cache them. Seems most calls are requesting metrics.
* Do async fetching of usage caches.
Harshavardhana
Aditya Manthramurthy
Klaus Post