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SourceAccessor: Allow the lstat cache to be invalidated #14957

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Merged
edolstra merged 1 commit into from
Feb 4, 2026
+41 −3
Merged

SourceAccessor: Allow the lstat cache to be invalidated #14957

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5 changes: 5 additions & 0 deletions src/libfetchers/filtering-source-accessor.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,11 @@ std::pair<CanonPath, std::optional<std::string>> FilteringSourceAccessor::getFin
return next->getFingerprint(prefix / path);
}

void FilteringSourceAccessor::invalidateCache(const CanonPath & path)
{
next->invalidateCache(prefix / path);
}

void FilteringSourceAccessor::checkAccess(const CanonPath & path)
{
if (!isAllowed(path))
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2 changes: 2 additions & 0 deletions src/libfetchers/include/nix/fetchers/filtering-source-accessor.hh
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Expand Up @@ -52,6 +52,8 @@ struct FilteringSourceAccessor : SourceAccessor

std::pair<CanonPath, std::optional<std::string>> getFingerprint(const CanonPath & path) override;

void invalidateCache(const CanonPath & path) override;

/**
* Call `makeNotAllowedError` to throw a `RestrictedPathError`
* exception if `isAllowed()` returns `false` for `path`.
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2 changes: 2 additions & 0 deletions src/libflake/flake.cc
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Expand Up @@ -876,6 +876,8 @@ lockFlake(const Settings & settings, EvalState & state, const FlakeRef & topRef,
CanonPath((topRef.subdir == "" ? "" : topRef.subdir + "/") + "flake.lock"),
newLockFileS,
commitMessage);

flake.lockFilePath().invalidateCache();
}

/* Rewriting the lockfile changed the top-level
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2 changes: 2 additions & 0 deletions src/libutil/include/nix/util/posix-source-accessor.hh
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Expand Up @@ -80,6 +80,8 @@ public:
return trackLastModified ? std::optional{mtime} : std::nullopt;
}

void invalidateCache(const CanonPath & path) override;

private:

/**
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5 changes: 5 additions & 0 deletions src/libutil/include/nix/util/source-accessor.hh
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Expand Up @@ -213,6 +213,11 @@ struct SourceAccessor : std::enable_shared_from_this<SourceAccessor>
{
return std::nullopt;
}

/**
* Invalidate any cached value the accessor may have for the specified path.
*/
virtual void invalidateCache(const CanonPath & path) {}
};

/**
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5 changes: 5 additions & 0 deletions src/libutil/include/nix/util/source-path.hh
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Expand Up @@ -114,6 +114,11 @@ struct SourcePath
return {accessor, accessor->resolveSymlinks(path, mode)};
}

void invalidateCache() const
{
accessor->invalidateCache(path);
}

friend class std::hash<nix::SourcePath>;
};

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6 changes: 6 additions & 0 deletions src/libutil/mounted-source-accessor.cc
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Expand Up @@ -99,6 +99,12 @@ struct MountedSourceAccessorImpl : MountedSourceAccessor
auto [accessor, subpath] = resolve(path);
return accessor->getFingerprint(subpath);
}

void invalidateCache(const CanonPath & path) override
{
auto [accessor, subpath] = resolve(path);
accessor->invalidateCache(subpath);
}
};

ref<MountedSourceAccessor> makeMountedSourceAccessor(std::map<CanonPath, ref<SourceAccessor>> mounts)
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11 changes: 8 additions & 3 deletions src/libutil/posix-source-accessor.cc
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Expand Up @@ -85,11 +85,11 @@ bool PosixSourceAccessor::pathExists(const CanonPath & path)
return nix::pathExists(makeAbsPath(path).string());
}

using Cache = boost::concurrent_flat_map<Path, std::optional<PosixStat>>;
static Cache cache;

std::optional<PosixStat> PosixSourceAccessor::cachedLstat(const CanonPath & path)
{
using Cache = boost::concurrent_flat_map<Path, std::optional<PosixStat>>;
static Cache cache;

// Note: we convert std::filesystem::path to Path because the
// former is not hashable on libc++.
Path absPath = makeAbsPath(path).string();
Expand All @@ -106,6 +106,11 @@ std::optional<PosixStat> PosixSourceAccessor::cachedLstat(const CanonPath & path
return st;
}

void PosixSourceAccessor::invalidateCache(const CanonPath & path)
{
cache.erase(makeAbsPath(path).string());
}

std::optional<SourceAccessor::Stat> PosixSourceAccessor::maybeLstat(const CanonPath & path)
{
if (auto parent = path.parent())
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6 changes: 6 additions & 0 deletions src/libutil/union-source-accessor.cc
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Expand Up @@ -90,6 +90,12 @@ struct UnionSourceAccessor : SourceAccessor
}
return {path, std::nullopt};
}

void invalidateCache(const CanonPath & path) override
{
for (auto & accessor : accessors)
accessor->invalidateCache(path);
}
};

ref<SourceAccessor> makeUnionSourceAccessor(std::vector<ref<SourceAccessor>> && accessors)
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