Reduce locking and improve concurrency on cache hits - #124
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August 4, 2026 07:35
this approach is similar to double-checked locking, we want to see if we can quickly use a cache hit before we do a full lock
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Description
This PR skips the intermediate-result cache key lock on cache hits.
This approach is similar to double-checked locking, we want to see if we can quickly use a cache hit before we do a full lock. I wrote a big comment on it and a test to try to make the approach more clear.
Improvement
I am trying to speed up the case where I switch branches in my IDE, because I do that a lot when checking various bugs.
I found that this area seems to be one that takes the most time, even though everything is cached, and I think it's because many files are hitting this lock and causing it to be a serial process.
Tests
I added one test to try to replicate switching branches in my IDE. It caches one version of Minecraft, then switches to another, etc, to try to exercise the code and make sure it's not getting blocked on clear cache hits.
Notes
restoreOutputsFromCacheused to have a side-effect of creating the intermediate cache directory if it was missing.I don't know if it really matters, but I moved that to the
saveOutputspath instead, so that's always done in the locked section.