ci/eval: improve api when calling in steps

Previously, `eval.full` organized the results for the supported systems
in a specific layout, i.e. with a folder with one subfolder per system.
Then, `eval.combine` relied on that.

When using `eval.singleSystem` and `eval.combine` directly, the caller
was responsible to recreate the same layout. This is annoying and
error-prone to do, when downloading artifacts from CI to recreate some
steps locally.

With this change, all the artifacts can be downloaded and extracted into
the same folder - because the result from `eval.singleSystem` already
contains the <system-name>/ subfolder.

.github/workflows/eval.yml

@@ -95,6 +95,7 @@ jobs:
         with:
           pattern: intermediate-*
           path: intermediate
+          merge-multiple: true
 
       - name: Check out the PR at the test merge commit
         uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
@@ -158,6 +159,7 @@ jobs:
         with:
           name: result
           path: targetResult
+          merge-multiple: true
           github-token: ${{ github.token }}
           run-id: ${{ steps.targetRunId.outputs.targetRunId }}
 

ci/eval/default.nix

@@ -3,7 +3,7 @@
   runCommand,
   writeShellScript,
   writeText,
-  linkFarm,
+  symlinkJoin,
   time,
   procps,
   nixVersions,
@@ -147,7 +147,7 @@ let
         chunkCount=$(( (attrCount - 1) / chunkSize + 1 ))
         echo "Chunk count: $chunkCount"
 
-        mkdir $out
+        mkdir -p $out/${evalSystem}
 
         # Record and print stats on free memory and swap in the background
         (
@@ -156,11 +156,11 @@ let
             freeSwap=$(free -b | grep Swap | awk '{print $4}')
             echo "Available memory: $(( availMemory / 1024 / 1024 )) MiB, free swap: $(( freeSwap / 1024 / 1024 )) MiB"
 
-            if [[ ! -f "$out/min-avail-memory" ]] || (( availMemory < $(<$out/min-avail-memory) )); then
-              echo "$availMemory" > $out/min-avail-memory
+            if [[ ! -f "$out/${evalSystem}/min-avail-memory" ]] || (( availMemory < $(<$out/${evalSystem}/min-avail-memory) )); then
+              echo "$availMemory" > $out/${evalSystem}/min-avail-memory
             fi
-            if [[ ! -f $out/min-free-swap ]] || (( availMemory < $(<$out/min-free-swap) )); then
-              echo "$freeSwap" > $out/min-free-swap
+            if [[ ! -f $out/${evalSystem}/min-free-swap ]] || (( availMemory < $(<$out/${evalSystem}/min-free-swap) )); then
+              echo "$freeSwap" > $out/${evalSystem}/min-free-swap
             fi
             sleep 4
           done
@@ -176,18 +176,18 @@ let
         mkdir "$chunkOutputDir"/{result,stats,timestats,stderr}
 
         seq -w 0 "$seq_end" |
-          command time -f "%e" -o "$out/total-time" \
+          command time -f "%e" -o "$out/${evalSystem}/total-time" \
           xargs -I{} -P"$cores" \
           ${singleChunk} "$chunkSize" {} "$evalSystem" "$chunkOutputDir"
 
-        cp -r "$chunkOutputDir"/stats $out/stats-by-chunk
+        cp -r "$chunkOutputDir"/stats $out/${evalSystem}/stats-by-chunk
 
         if (( chunkSize * chunkCount != attrCount )); then
           # A final incomplete chunk would mess up the stats, don't include it
           rm "$chunkOutputDir"/stats/"$seq_end"
         fi
 
-        cat "$chunkOutputDir"/result/* > $out/paths
+        cat "$chunkOutputDir"/result/* > $out/${evalSystem}/paths
       '';
 
   combine =
@@ -247,14 +247,15 @@ let
       quickTest ? false,
     }:
     let
-      results = linkFarm "results" (
-        map (evalSystem: {
-          name = evalSystem;
-          path = singleSystem {
+      results = symlinkJoin {
+        name = "results";
+        paths = map (
+          evalSystem:
+          singleSystem {
             inherit quickTest evalSystem chunkSize;
-          };
-        }) evalSystems
-      );
+          }
+        ) evalSystems;
+      };
     in
     combine {
       resultsDir = results;