lix-project/lix-releng-staging
0
0
Fork 0
Code Packages Activity

* Cache the result of file evaluation (i.e, memoize evalFile()). This

Browse source 
prevents files from being evaluated and stored as values multiple
  times.  For instance, evaluation of the ‘system’ attribute in NixOS
  causes ‘nixpkgs/pkgs/lib/lists.nix’ to be evaluated 2019 times.

  Caching gives a modest speedup and a decent memory footprint
  reduction (e.g., from 1.44s to 1.28s, and from 81 MiB to 59 MiB with
  GC_INITIAL_HEAP_SIZE=100000 on my system).
This commit is contained in:
Eelco Dolstra 2011-08-06 19:45:43 +00:00
parent 510033e783
commit 2d663b502d
2 changed files with 22 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
src/libexpr/eval.cc
View file

@ -431,17 +431,19 @@ Value * EvalState::maybeThunk(Env & env, Expr * expr)
void EvalState::evalFile(const Path & path, Value & v)
{
startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path);
Expr * e = parseExprFromFile(path);
try {
/* !!! Maybe we should cache the evaluation result. */
eval(e, v);
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the file `%1%':\n", path);
throw;
}
FileEvalCache::iterator i = fileEvalCache.find(path);
if (i == fileEvalCache.end()) {
startNest(nest, lvlTalkative, format("evaluating file `%1%'") % path);
Expr * e = parseExprFromFile(path);
try {
eval(e, v);
} catch (Error & e) {
addErrorPrefix(e, "while evaluating the file `%1%':\n", path);
throw;
}
fileEvalCache[path] = v;
} else
v = i->second;
}

9
src/libexpr/eval.hh
View file

@ -211,8 +211,17 @@ private:
bool allowUnsafeEquality;
/* A cache from path names to parse trees. */
std::map<Path, Expr *> parseTrees;
/* A cache from path names to values. */
#if HAVE_BOEHMGC
typedef std::map<Path, Value, std::less<Path>, gc_allocator<std::pair<const Path, Value> > > FileEvalCache;
#else
typedef std::map<Path, Value> FileEvalCache;
#endif
FileEvalCache fileEvalCache;
typedef list<std::pair<string, Path> > SearchPath;
SearchPath searchPath;
SearchPath::iterator searchPathInsertionPoint;