Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Use std::unordered_map for the EvalState caches #11092

Merged
merged 2 commits into from
Jul 16, 2024
Merged

Use std::unordered_map for the EvalState caches #11092

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
cdc23b6
Provide std::hash<SourcePath>
edolstra Jun 6, 2024
550b347
Include the accessor in the SourcePath hash
edolstra Jul 15, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 3 additions & 3 deletions src/libexpr/eval.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1011,7 +1011,7 @@ void EvalState::evalFile(const SourcePath & path, Value & v, bool mustBeTrivial)
if (!e)
e = parseExprFromFile(resolvedPath);

fileParseCache[resolvedPath] = e;
fileParseCache.emplace(resolvedPath, e);

try {
auto dts = debugRepl
Expand All @@ -1034,8 +1034,8 @@ void EvalState::evalFile(const SourcePath & path, Value & v, bool mustBeTrivial)
throw;
}

fileEvalCache[resolvedPath] = v;
if (path != resolvedPath) fileEvalCache[path] = v;
fileEvalCache.emplace(resolvedPath, v);
if (path != resolvedPath) fileEvalCache.emplace(path, v);
}


Expand Down
10 changes: 5 additions & 5 deletions src/libexpr/eval.hh
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -307,25 +307,25 @@ private:

/* Cache for calls to addToStore(); maps source paths to the store
paths. */
Sync<std::map<SourcePath, StorePath>> srcToStore;
Sync<std::unordered_map<SourcePath, StorePath>> srcToStore;

/**
* A cache from path names to parse trees.
*/
#if HAVE_BOEHMGC
typedef std::map<SourcePath, Expr *, std::less<SourcePath>, traceable_allocator<std::pair<const SourcePath, Expr *>>> FileParseCache;
typedef std::unordered_map<SourcePath, Expr *, std::hash<SourcePath>, std::equal_to<SourcePath>, traceable_allocator<std::pair<const SourcePath, Expr *>>> FileParseCache;
#else
typedef std::map<SourcePath, Expr *> FileParseCache;
typedef std::unordered_map<SourcePath, Expr *> FileParseCache;
#endif
FileParseCache fileParseCache;

/**
* A cache from path names to values.
*/
#if HAVE_BOEHMGC
typedef std::map<SourcePath, Value, std::less<SourcePath>, traceable_allocator<std::pair<const SourcePath, Value>>> FileEvalCache;
typedef std::unordered_map<SourcePath, Value, std::hash<SourcePath>, std::equal_to<SourcePath>, traceable_allocator<std::pair<const SourcePath, Value>>> FileEvalCache;
#else
typedef std::map<SourcePath, Value> FileEvalCache;
typedef std::unordered_map<SourcePath, Value> FileEvalCache;
#endif
FileEvalCache fileEvalCache;

Expand Down
15 changes: 15 additions & 0 deletions src/libutil/source-path.hh
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,8 @@
#include "canon-path.hh"
#include "source-accessor.hh"

#include <boost/functional/hash.hpp> // for boost::hash_combine

Comment on lines +12 to +13
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This wasn't actually used; removing in #11113

Question though: the version in I got from boost was less capable, accepting only two arguments. Did you copy hash_combine from a newer version of boost than our dependency?

namespace nix {

/**
Expand Down Expand Up @@ -115,8 +117,21 @@ struct SourcePath
{
return {accessor, accessor->resolveSymlinks(path, mode)};
}

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

std::ostream & operator << (std::ostream & str, const SourcePath & path);

}

template<>
struct std::hash<nix::SourcePath>
{
std::size_t operator()(const nix::SourcePath & s) const noexcept
{
std::size_t hash = 0;
hash_combine(hash, s.accessor->number, s.path);
return hash;
}
};
14 changes: 14 additions & 0 deletions src/libutil/util.hh
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -360,4 +360,18 @@ inline std::string operator + (std::string_view s1, const char * s2)
return s;
}

/**
* hash_combine() from Boost. Hash several hashable values together
* into a single hash.
*/
inline void hash_combine(std::size_t & seed) { }

template <typename T, typename... Rest>
inline void hash_combine(std::size_t & seed, const T & v, Rest... rest)
{
std::hash<T> hasher;
seed ^= hasher(v) + 0x9e3779b9 + (seed<<6) + (seed>>2);
hash_combine(seed, rest...);
}

}
Loading