Add development tools to generate flame graphs for nix-instantiate

shell.nix

@@ -6,10 +6,12 @@
 }:
 
 let
+  tools = pkgs.callPackage ./tools {};
 
 in
 pkgs.mkShell {
   buildInputs = [
+    tools.flamegraph
     pkgs.nixpkgs-fmt
     pkgs.poetry
   ];

tools/default.nix

@@ -0,0 +1,46 @@
+{ pkgs ? import <nixpkgs> {
+    overlays = [
+      (import ../overlay.nix)
+    ];
+  }
+}:
+
+let
+  inherit (pkgs) lib;
+
+in
+{
+
+  flamegraph = let
+    runtimeDeps = lib.makeBinPath [
+      pkgs.flamegraph
+      pkgs.python3
+      pkgs.nix
+    ];
+
+    nixSrc = pkgs.runCommandNoCC "${pkgs.nix.name}-sources" {} ''
+      mkdir $out
+      tar -x --strip=1 -f ${pkgs.nix.src} -C $out
+    '';
+
+    srcPath = builtins.toString ../.;
+
+  in
+    pkgs.writeScriptBin "poetry2nix-flamegraph" ''
+      #!${pkgs.runtimeShell}
+      export PATH=${runtimeDeps}:$PATH
+
+      workdir=$(mktemp -d)
+      function cleanup {
+        rm -rf "$workdir"
+      }
+      trap cleanup EXIT
+
+      # Run once to warm up
+      nix-instantiate --expr '(import <nixpkgs> { overlays = [ (import ${srcPath + "/overlay.nix"}) ]; })' -A poetry
+      nix-instantiate --trace-function-calls --expr '(import <nixpkgs> { overlays = [ (import ${srcPath + "/overlay.nix"}) ]; })' -A poetry 2> $workdir/traceFile
+      python3 ${nixSrc}/contrib/stack-collapse.py $workdir/traceFile > $workdir/traceFile.folded
+      flamegraph.pl $workdir/traceFile.folded > poetry2nix-flamegraph.svg
+    '';
+
+}