From a34bbb6b9cd5f511fb5d5cff7d2ceb12d927cffb Mon Sep 17 00:00:00 2001
From: Philip Taron <philip.taron@gmail.com>
Date: Fri, 12 Sep 2025 12:14:54 -0700
Subject: [PATCH] pkgs/top-level/metrics.nix: tidy up variables and quoting

We also allow the lines to be unbroken.
---
 pkgs/top-level/metrics.nix | 53 +++++++++++++++++++-------------------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/pkgs/top-level/metrics.nix b/pkgs/top-level/metrics.nix
index d2a755043aec..9b80d3d300e4 100644
--- a/pkgs/top-level/metrics.nix
+++ b/pkgs/top-level/metrics.nix
@@ -40,49 +40,48 @@ stdenvNoCC.mkDerivation {
       echo "running $@"
 
       case "$name" in
-        # Redirect stdout to /dev/null to avoid hitting "Output Limit
-        # Exceeded" on Hydra.
+        # Redirect stdout to /dev/null to avoid hitting "Output Limit Exceeded" on Hydra.
         nix-env.qaDrv|nix-env.qaDrvAggressive)
           NIX_SHOW_STATS=1 NIX_SHOW_STATS_PATH=stats-nix time -o stats-time "$@" >/dev/null ;;
         *)
           NIX_SHOW_STATS=1 NIX_SHOW_STATS_PATH=stats-nix time -o stats-time "$@" ;;
       esac
 
-      cat stats-nix; echo; cat stats-time; echo
+      # Show the Nix statistics and the `time` statistics.
+      cat stats-nix
+      echo
+      cat stats-time
+      echo
 
-      x=$(jq '.cpuTime' < stats-nix)
-      [[ -n $x ]] || exit 1
-      echo "$name.time $x s" >> $out/nix-support/hydra-metrics
+      cpuTime="$(jq '.cpuTime' < stats-nix)"
+      [[ -n $cpuTime ]] || exit 1
+      echo "$name.time $cpuTime s" >> $out/nix-support/hydra-metrics
 
-      x=$(sed -e 's/.* \([0-9]\+\)maxresident.*/\1/ ; t ; d' < stats-time)
-      [[ -n $x ]] || exit 1
-      echo "$name.maxresident $x KiB" >> $out/nix-support/hydra-metrics
+      maxresident="$(sed -e 's/.* \([0-9]\+\)maxresident.*/\1/ ; t ; d' < stats-time)"
+      [[ -n $maxresident ]] || exit 1
+      echo "$name.maxresident $maxresident KiB" >> $out/nix-support/hydra-metrics
 
-      # nix-2.2 also outputs .symbols.bytes but that wasn't summed originally
-      # https://github.com/NixOS/nix/pull/2392/files#diff-8e6ba8c21672fc1a5f6f606e1e101c74L1762
-      x=$(jq '[.envs,.list,.values,.sets] | map(.bytes) | add' < stats-nix)
-      [[ -n $x ]] || exit 1
-      echo "$name.allocations $x B" >> $out/nix-support/hydra-metrics
+      # Nix also outputs `.symbols.bytes` but since that wasn't summed originally, we don't count it here.
+      allocations="$(jq '[.envs,.list,.values,.sets] | map(.bytes) | add' < stats-nix)"
+      [[ -n $allocations ]] || exit 1
+      echo "$name.allocations $allocations B" >> $out/nix-support/hydra-metrics
 
-      x=$(jq '.values.number' < stats-nix)
-      [[ -n $x ]] || exit 1
-      echo "$name.values $x" >> $out/nix-support/hydra-metrics
+      values="$(jq '.values.number' < stats-nix)"
+      [[ -n $values ]] || exit 1
+      echo "$name.values $values" >> $out/nix-support/hydra-metrics
     }
 
-    run nixos.smallContainer nix-instantiate --dry-run ${nixpkgs}/nixos/release.nix \
-      -A closures.smallContainer.x86_64-linux --show-trace
-    run nixos.kde nix-instantiate --dry-run ${nixpkgs}/nixos/release.nix \
-      -A closures.kde.x86_64-linux --show-trace
-    run nixos.lapp nix-instantiate --dry-run ${nixpkgs}/nixos/release.nix \
-      -A closures.lapp.x86_64-linux --show-trace
+    run nixos.smallContainer nix-instantiate --dry-run ${nixpkgs}/nixos/release.nix -A closures.smallContainer.x86_64-linux --show-trace
+    run nixos.kde nix-instantiate --dry-run ${nixpkgs}/nixos/release.nix -A closures.kde.x86_64-linux --show-trace
+    run nixos.lapp nix-instantiate --dry-run ${nixpkgs}/nixos/release.nix -A closures.lapp.x86_64-linux --show-trace
     run nix-env.qa nix-env -f ${nixpkgs} -qa
     run nix-env.qaDrv nix-env -f ${nixpkgs} -qa --drv-path --meta --xml
 
     # It's slightly unclear which of the set to track: qaCount, qaCountDrv, qaCountBroken.
-    num=$(nix-env -f ${nixpkgs} -qa | wc -l)
+    num="$(nix-env -f ${nixpkgs} -qa | wc -l)"
     echo "nix-env.qaCount $num" >> $out/nix-support/hydra-metrics
-    qaCountDrv=$(nix-env -f ${nixpkgs} -qa --drv-path | wc -l)
-    num=$((num - $qaCountDrv))
+    qaCountDrv="$(nix-env -f ${nixpkgs} -qa --drv-path | wc -l)"
+    num="$((num - $qaCountDrv))"
     echo "nix-env.qaCountBroken $num" >> $out/nix-support/hydra-metrics
 
     # TODO: this has been ignored for some time
@@ -91,7 +90,7 @@ stdenvNoCC.mkDerivation {
     run nix-env.qaAggressive nix-env -f ${nixpkgs} -qa
     run nix-env.qaDrvAggressive nix-env -f ${nixpkgs} -qa --drv-path --meta --xml
 
-    lines=$(find ${nixpkgs} -name "*.nix" -type f | xargs cat | wc -l)
+    lines="$(find ${nixpkgs} -name "*.nix" -type f | xargs cat | wc -l)"
     echo "loc $lines" >> $out/nix-support/hydra-metrics
 
     runHook postInstall