feat(popcount): Add new narinfo-based popcount implementation

Adds an implementation of popcount that, instead of realising
derivations locally, just queries the cache's narinfo files.

The downside of this is that calculating popularity for arbitrary Nix
package sets is not possible with this implementation. The upside is
that calculating the popularity for an entire Nix channel can now be
done in ~10 seconds[0].

This fixes #65.

[0]: Assuming a /fast/ internet connection.

1 files changed, 0 insertions, 53 deletions

diff --git a/tools/nixery/popcount/popcount.nix b/tools/nixery/popcount/popcount.nix
deleted file mode 100644
index 54fd2ad589ee..000000000000
--- a/tools/nixery/popcount/popcount.nix
+++ /dev/null
@@ -1,53 +0,0 @@
-# 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)