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defer formals duplicate check for incresed efficiency all round

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if we defer the duplicate argument check for lambda formals we can use more
efficient data structures for the formals set, and we can get rid of the
duplication of formals names to boot. instead of a list of formals we've seen
and a set of names we'll keep a vector instead and run a sort+dupcheck step
before moving the parsed formals into a newly created lambda. this improves
performance on search and rebuild by ~1%, pure parsing gains more (about 4%).

this does reorder lambda arguments in the xml output, but the output is still
stable. this shouldn't be a problem since argument order is not semantically
important anyway.

 before

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.550 s ±  0.060 s    [User: 6.470 s, System: 1.664 s]
    Range (min … max):    8.435 s …  8.666 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     346.7 ms ±   2.1 ms    [User: 312.4 ms, System: 34.2 ms]
    Range (min … max):   343.8 ms … 353.4 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.720 s ±  0.031 s    [User: 2.415 s, System: 0.231 s]
    Range (min … max):    2.662 s …  2.780 s    20 runs

 after

  nix search --no-eval-cache --offline ../nixpkgs hello
    Time (mean ± σ):      8.462 s ±  0.063 s    [User: 6.398 s, System: 1.661 s]
    Range (min … max):    8.339 s …  8.542 s    20 runs

  nix eval -f ../nixpkgs/pkgs/development/haskell-modules/hackage-packages.nix
    Time (mean ± σ):     329.1 ms ±   1.4 ms    [User: 296.8 ms, System: 32.3 ms]
    Range (min … max):   326.1 ms … 330.8 ms    20 runs

  nix eval --raw --impure --expr 'with import <nixpkgs/nixos> {}; system'
    Time (mean ± σ):      2.687 s ±  0.035 s    [User: 2.392 s, System: 0.228 s]
    Range (min … max):    2.626 s …  2.754 s    20 runs
This commit is contained in:
pennae 2022-01-19 16:49:02 +01:00
parent 9ac836d1d6
commit 7d4cc5515c
7 changed files with 71 additions and 26 deletions
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2
src/libexpr/value-to-xml.cc
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@ -142,7 +142,7 @@ static void printValueAsXML(EvalState & state, bool strict, bool location,
if (!v.lambda.fun->arg.empty()) attrs["name"] = v.lambda.fun->arg;
if (v.lambda.fun->formals->ellipsis) attrs["ellipsis"] = "1";
XMLOpenElement _(doc, "attrspat", attrs);
for (auto & i : v.lambda.fun->formals->formals)
for (auto & i : v.lambda.fun->formals->lexicographicOrder())
doc.writeEmptyElement("attr", singletonAttrs("name", i.name));
} else
doc.writeEmptyElement("varpat", singletonAttrs("name", v.lambda.fun->arg));