05e9b836

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Example: a source change that does not rebuild dependencies

Adds a module doc comment to lib/bombadil/src/lib.rs. The dependency
derivation (.#deps) is byte-identical before and after this commit:

  /nix/store/40jiv6rw28i2gaixwp66kdxxfan3f2fj-bombadil-deps-deps-0.0.0.drv

so dependencies are a cache hit and are not rebuilt. Reproduce with
./nix/experiments/deps-cache-stability.sh.

Suite timing

Time to Start Worker time Duration Time to finish Idle
Config 0s 2s 2s 2s 0s
Eval 1s 49s 49s 51s 0s
Build 5s 12m03s 6m03s 6m08s 11s
Suite 0s 12m54s 6m08s 6m08s 11s

Timeline

0s1m2m3m4m5m