nordic-dev.net/nix
nordic-dev.net/nix
2
0
Fork 0
mirror of https://github.com/NixOS/nix.git synced 2024-11-22 14:52:55 +00:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #5809 from pennae/small-perf-improvements

Browse Source 
small perf improvements
This commit is contained in:
Théophane Hufschmitt 2021-12-21 08:50:29 +01:00 committed by GitHub
commit de273bbff2
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 19 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
src/libexpr/eval.cc
View File

@ -821,8 +821,23 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
Value * EvalState::allocValue()
{
/* We use the boehm batch allocator to speed up allocations of Values (of which there are many).
GC_malloc_many returns a linked list of objects of the given size, where the first word
of each object is also the pointer to the next object in the list. This also means that we
have to explicitly clear the first word of every object we take. */
if (!valueAllocCache) {
valueAllocCache = GC_malloc_many(sizeof(Value));
if (!valueAllocCache) throw std::bad_alloc();
}
/* GC_NEXT is a convenience macro for accessing the first word of an object.
Take the first list item, advance the list to the next item, and clear the next pointer. */
void * p = valueAllocCache;
GC_PTR_STORE_AND_DIRTY(&valueAllocCache, GC_NEXT(p));
GC_NEXT(p) = nullptr;
nrValues++;
auto v = (Value *) allocBytes(sizeof(Value));
auto v = (Value *) p;
return v;
}

3
src/libexpr/eval.hh
View File

@ -133,6 +133,9 @@ private:
/* Cache used by prim_match(). */
std::shared_ptr<RegexCache> regexCache;
/* Allocation cache for GC'd Value objects. */
void * valueAllocCache = nullptr;
public:
EvalState(