Added benchmarking to the CI (#423)

* Added benchmarking to the CI

* Updated writing access of benchmark.yml

* Added benchmark-comment.yml that pushes the comment to the PR

* Added read permission

1 files changed, 90 insertions, 0 deletions

diff --git a/.github/workflows/benchmark-comment.yml b/.github/workflows/benchmark-comment.yml
new file mode 100644
index 00000000..c095162e
--- /dev/null
+++ b/.github/workflows/benchmark-comment.yml
@@ -0,0 +1,90 @@
+name: Benchmark Comment
+
+on:
+  workflow_run:
+    workflows: [Benchmark]
+    types: [completed]
+
+jobs:
+  comment-pr:
+    name: Post benchmark comment
+    # Only run when triggered by a pull_request event and the benchmark succeeded.
+    if: >
+      github.event.workflow_run.conclusion == 'success' &&
+      github.event.workflow_run.event == 'pull_request'
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      actions: read
+      pull-requests: write
+      issues: write
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Download benchmark results
+        uses: actions/download-artifact@v4
+        with:
+          run-id: ${{ github.event.workflow_run.id }}
+          name: benchmark-results
+          path: current-results
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Download PR number
+        uses: actions/download-artifact@v4
+        with:
+          run-id: ${{ github.event.workflow_run.id }}
+          name: pr-number
+          path: .
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Read PR number
+        id: pr
+        run: echo "number=$(cat pr-number.txt)" >> "$GITHUB_OUTPUT"
+
+      - name: Fetch baseline from benchmark-data branch
+        run: |
+          git fetch origin benchmark-data 2>/dev/null || true
+          git show origin/benchmark-data:benchmark-history.json > baseline.json 2>/dev/null \
+            || echo "[]" > baseline.json
+
+      - name: Generate comparison comment
+        run: |
+          python .github/scripts/compare_benchmarks.py \
+            current-results/results.json \
+            baseline.json \
+            > comment.md
+
+      - name: Post or update PR comment
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const fs = require('fs');
+            const body = fs.readFileSync('comment.md', 'utf8');
+            const marker = '<!-- opendc-benchmark-comment -->';
+            const fullBody = marker + '\n' + body;
+            const prNumber = parseInt(fs.readFileSync('pr-number.txt', 'utf8').trim());
+
+            const { data: comments } = await github.rest.issues.listComments({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: prNumber,
+            });
+
+            const existing = comments.find(c => c.body.includes(marker));
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: existing.id,
+                body: fullBody,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: prNumber,
+                body: fullBody,
+              });
+            }