RemoteFSAccessor: Make the local NAR cache content-addressed #14948
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Do we need to bump a cache version? |
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@Ericson2314 There is no version at the moment. There shouldn't be any upgrade issues since the new file names in the cache have a different length. |
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There is no version at the moment. There shouldn't be any upgrade issues since the new file names in the cache have a different length.
sounds good
OK generally looks good, but I would make it a double map (see final comment) so we don't end up opening multiple NAR accessors for the same NAR.
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Use double-indirection for better NAR accessor caching Co-authored-by: John Ericson <[email protected]>
It was not pulling its weight. (Only used once, optional paths are confusing, we already have an `if` / branch fit-for-purpose.)
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Motivation
Previously, the local NAR cache was indexed by the store path hash. Making it content-addressed (i.e. indexed by NAR hash) provides some potential deduplication, but more importantly, makes it possible to substitute NARs from the local NAR cache with fewer trust issues (see DeterminateSystems#279).
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