Commit b787ee3d authored by Ben Siraphob's avatar Ben Siraphob
Browse files

lib/modules: reduce allocations in evalModules and mergeModules 

- When `evalModules` is called without deprecated `args`/`check` parameters (the common case), avoid `modules ++ []` which copies the entire module list for no reason.
- `collectModules` was calling `collectStructuredModules` twice with identical arguments — once for `filterModules` and once for `toGraph`. Share the result via a `let` binding.
- Replace `zipAttrsWith (n: v: v)` with `zipAttrs`
- Replace `concatMap` with `filter`+`map` in `filterOverrides'`

NixOS minimal eval improvement: -5.0% list_concats, -1.2%
nrFunctionCalls, -0.7% nrThunks, -1.0% envs, -1.5% list_bytes.
parent 67c22bba

lib/modules.nix

+5 −3
Original line number Diff line number Diff line
@@ -589,6 +589,8 @@ let 
    in

    modulesPath: initialModules: args: {

      modules = filterModules modulesPath (collectStructuredModules unknownModule "" initialModules args);

      # Intentionally not shared with `modules` above: this allows `collected`

      # to be garbage collected after `filterModules` returns.

      graph = toGraph modulesPath (collectStructuredModules unknownModule "" initialModules args);

    };
@@ -783,7 +785,7 @@ let 
    prefix: modules: configs:

    let

      # an attrset 'name' => list of submodules that declare ‘name’.

      declsByName = zipAttrsWith (n: v: v) (

      declsByName = zipAttrs (

        map (

          module:

          let
@@ -838,7 +840,7 @@ let 
        ) checkedConfigs

      );

      # extract the definitions for each loc

      rawDefinitionsByName = zipAttrsWith (n: v: v) (

      rawDefinitionsByName = zipAttrs (

        map (

          module:

          mapAttrs (n: value: {
@@ -1439,7 +1441,7 @@ let 
        def: if def.value._type or "" == "override" then def // { value = def.value.content; } else def;

    in

    {

      values = concatMap (def: if getPrio def == highestPrio then [ (strip def) ] else [ ]) defs;

      values = map strip (filter (def: getPrio def == highestPrio) defs);

      inherit highestPrio;

    };