Commit 4b4d4138 authored by adisbladis's avatar adisbladis
Browse files

lib.meta: Avoid attrset allocation in platformMatch 

Benchmarks (`nix-instantiate ./. -A python3`)

- Before
``` json
{
  "cpuTime": 0.30625399947166443,
  "envs": {
    "bytes": 4484216,
    "elements": 221443,
    "number": 169542
  },
  "gc": {
    "heapSize": 402915328,
    "totalBytes": 53091024
  },
  "list": {
    "bytes": 749424,
    "concats": 4242,
    "elements": 93678
  },
  "nrAvoided": 253991,
  "nrFunctionCalls": 149848,
  "nrLookups": 49614,
  "nrOpUpdateValuesCopied": 1588326,
  "nrOpUpdates": 10106,
  "nrPrimOpCalls": 130356,
  "nrThunks": 359013,
  "sets": {
    "bytes": 30432320,
    "elements": 1860540,
    "number": 41480
  },
  "sizes": {
    "Attr": 16,
    "Bindings": 16,
    "Env": 16,
    "Value": 24
  },
  "symbols": {
    "bytes": 236218,
    "number": 24459
  },
  "values": {
    "bytes": 10504632,
    "number": 437693
  }
}
```

- After
```
{
  "cpuTime": 0.29695799946784973,
  "envs": {
    "bytes": 3296712,
    "elements": 169055,
    "number": 121517
  },
  "gc": {
    "heapSize": 402915328,
    "totalBytes": 49044992
  },
  "list": {
    "bytes": 504928,
    "concats": 4242,
    "elements": 63116
  },
  "nrAvoided": 175403,
  "nrFunctionCalls": 110554,
  "nrLookups": 44907,
  "nrOpUpdateValuesCopied": 1588326,
  "nrOpUpdates": 10106,
  "nrPrimOpCalls": 82330,
  "nrThunks": 306625,
  "sets": {
    "bytes": 29943328,
    "elements": 1843076,
    "number": 28382
  },
  "sizes": {
    "Attr": 16,
    "Bindings": 16,
    "Env": 16,
    "Value": 24
  },
  "symbols": {
    "bytes": 236218,
    "number": 24459
  },
  "values": {
    "bytes": 90377526,
    "number": 376573
  }
}
```
parent 2819a35b

lib/meta.nix

+22 −10
Original line number Diff line number Diff line
@@ -3,6 +3,11 @@ 


{ lib }:



let

  inherit (lib) matchAttrs any all;

  inherit (builtins) isString;



in

rec {
@@ -83,14 +88,21 @@ rec { 
     We can inject these into a pattern for the whole of a structured platform,

     and then match that.

  */

  platformMatch = platform: elem: let

      pattern =

        if builtins.isString elem

        then { system = elem; }

        else if elem?parsed

        then elem

        else { parsed = elem; };

    in lib.matchAttrs pattern platform;

  platformMatch = platform: elem: (

    # Check with simple string comparison if elem was a string.

    #

    # The majority of comparisons done with this function will be against meta.platforms

    # which contains a simple platform string.

    #

    # Avoiding an attrset allocation results in significant  performance gains (~2-30) across the board in OfBorg

    # because this is a hot path for nixpkgs.

    if isString elem then platform ? system && elem == platform.system

    else matchAttrs (

      # Normalize platform attrset.

      if elem ? parsed then elem

      else { parsed = elem; }

    ) platform

  );



  /* Check if a package is available on a given platform.
@@ -102,8 +114,8 @@ rec { 
       2. None of `meta.badPlatforms` pattern matches the given platform.

  */

  availableOn = platform: pkg:

    ((!pkg?meta.platforms) || lib.any (platformMatch platform) pkg.meta.platforms) &&

    lib.all (elem: !platformMatch platform elem) (pkg.meta.badPlatforms or []);

    ((!pkg?meta.platforms) || any (platformMatch platform) pkg.meta.platforms) &&

    all (elem: !platformMatch platform elem) (pkg.meta.badPlatforms or []);



  /* Get the corresponding attribute in lib.licenses

     from the SPDX ID.

lib/tests/misc.nix

+20 −0
Original line number Diff line number Diff line
@@ -1948,4 +1948,24 @@ runTests { 
  testGetExe'FailureSecondArg = testingThrow (

    getExe' { type = "derivation"; } "dir/executable"

  );



  testPlatformMatch = {

    expr = meta.platformMatch { system = "x86_64-linux"; } "x86_64-linux";

    expected = true;

  };



  testPlatformMatchAttrs = {

    expr = meta.platformMatch (systems.elaborate "x86_64-linux") (systems.elaborate "x86_64-linux").parsed;

    expected = true;

  };



  testPlatformMatchNoMatch = {

    expr = meta.platformMatch { system = "x86_64-darwin"; } "x86_64-linux";

    expected = false;

  };



  testPlatformMatchMissingSystem = {

    expr = meta.platformMatch { } "x86_64-linux";

    expected = false;

  };

}