boulder: Add CCACHE_BASEDIR to improve cache hit rates #473
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Signed-off-by: Reilly Brogan <[email protected]>
ermo
requested changes
May 8, 2025
| - completionsdir : "%(datadir)/bash-completion/completions" | ||
| - zshcompletionsdir : "%(datadir)/zsh/site-functions" | ||
| - fishcompletionsdir : "%(datadir)/fish/vendor_completions.d" | ||
| - elvishcompletions : "%(datadir)/elvish/lib" |
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Does this macro omit the customary dir suffix for a specific reason...?
i.e. %(elvishcompletionsdir) vs. the current %(elvishcompletions)
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Yes, the specific reason is that that's the directory that elvish uses for vendor completions 🤷.
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But it's still a directory, right...?
(I've updated my original question to give it the proper context. Sorry that I didn't think to do that originally)
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ccache resolves absolute paths to source files and uses that path as part of the cache key. In practice this means that changing the build directory invalidates all builds using a previous build directory, and given that the source archive name typically ends up being part of the build path (for instance
/mason/build/x86_64/llvm-project-20.1.4.src.tar.xz/) the end result is that updating the version of a package is enough to invalidate all ccache entries from a previous version.To fix this we can use the CCACHE_BASEDIR environmental variable. If set ccache will strip the value of it from the cache key (for instance
/mason/build/x86_64/llvm-project-20.1.4.src.tar.xz/src/foo.cwith aCCACHE_BASEDIR=/mason/build/x86_64/llvm-project-20.1.4.src.tar.xz/will be stored assrc/foo.c) which means that ccache entries can persist between version updates. Given that ccache already hashes the file contents as part of the cache key this shouldn't cause any issues and should improve cache hit rates quite a bit.Also while we're at it add macro definitions for the zsh, fish, and elvish shell completions directories since that's a trivial change not really deserving of a separate PR.