tvl-depot/tools/nixery/popcount/popcount.nix

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# Copyright 2019 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# This script, given a target attribute in `nixpkgs`, builds the
# target derivations' runtime closure and returns its reference graph.
#
# This is invoked by popcount.sh for each package in nixpkgs to
# collect all package references, so that package popularity can be
# tracked.
#
# Check out build-image/group-layers.go for an in-depth explanation of
# what the popularity counts are used for.
{ pkgs ? import <nixpkgs> { config.allowUnfree = false; }, target }:
let
inherit (pkgs) coreutils runCommand writeText;
inherit (builtins) readFile toFile fromJSON toJSON listToAttrs;
# graphJSON abuses feature in Nix that makes structured runtime
# closure information available to builders. This data is imported
# back via IFD to process it for layering data.
graphJSON = path:
runCommand "build-graph" {
__structuredAttrs = true;
exportReferencesGraph.graph = path;
PATH = "${coreutils}/bin";
builder = toFile "builder" ''
. .attrs.sh
cat .attrs.json > ''${outputs[out]}
'';
} "";
buildClosures = paths: (fromJSON (readFile (graphJSON paths)));
buildGraph = paths:
listToAttrs (map (c: {
name = c.path;
value = { inherit (c) closureSize references; };
}) (buildClosures paths));
in writeText "${target}-graph"
(toJSON (buildClosures [ pkgs."${target}" ]).graph)