Override Time in CacheLib for Accurate Benchmarking

[hazelnut-99]

Hi!

I'm benchmarking different slab rebalance strategies in CacheLib and noticed that several components are time-dependent:

1. PoolRebalancer wakes up periodically (default: 1s).
2. LRU tail age checker relies on time

I was trying to figure out ways to 1) implement a mock timer that ticks according to the trace time 2) override the concept of time in CacheLib with the mock timer.

After reading the code, it feels like all time-relate functionalities in cachelib use real wall clock time via std::chrono, and the current implementation doesn’t seem to support override timer easily.

Does anyone have suggestions on how to approach this? (I think it'd help with testing TTL-related logics as well.

Cheers!