.github/workflows/benchmark-comment.yml

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name: PR benchmark comment

on:
  workflow_run:
    workflows: ['PR benchmark']
    types: [completed]

permissions:
  actions: read
  pull-requests: write

concurrency:
  group: benchmark-comment-${{ github.event.workflow_run.head_repository.id }}-${{ github.event.workflow_run.head_branch }}
  cancel-in-progress: false

jobs:
  comment:
    if: ${{ github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion != 'cancelled' }}
    runs-on: ubuntu-24.04
    timeout-minutes: 5
    steps:
      # Never check out PR code, restore its caches, or execute artifact contents.
      - name: Download this run's comment input
        uses: actions/download-artifact@v4
        with:
          name: benchmark-comment-${{ github.event.workflow_run.run_attempt }}
          run-id: ${{ github.event.workflow_run.id }}
          github-token: ${{ github.token }}
          path: report

      - name: Create or update benchmark comment
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const { owner, repo } = context.repo;
            const run = context.payload.workflow_run;
            if (run.path !== '.github/workflows/benchmark-pr.yml') {
              throw new Error('Unexpected source workflow');
            }
            // Artifact fields are untrusted: bind the requested PR to GitHub's run data.
            const input = JSON.parse(fs.readFileSync('report/benchmark-context.json', 'utf8'));
            if (!Number.isSafeInteger(input.number) || input.number <= 0) {
              throw new Error('Invalid PR number');
            }
            const { data: pr } = await github.rest.pulls.get({ owner, repo, pull_number: input.number });
            if (pr.state !== 'open' || pr.base.repo.full_name !== `${owner}/${repo}`
                || pr.head.repo?.id !== run.head_repository.id
                || pr.head.ref !== run.head_branch || pr.head.sha !== run.head_sha
                || input.head !== pr.head.sha || input.base !== pr.base.sha) {
              core.info('Skipping unrelated or stale benchmark result');
              return;
            }
            // A delayed delivery from an earlier rerun must not replace the latest result.
            const { data: current } = await github.rest.actions.getWorkflowRun({ owner, repo, run_id: run.id });
            if (current.run_attempt !== run.run_attempt) return;
            const marker = '<!-- paimon-pr-benchmark -->';
            const path = 'report/results/summary.md';
            const report = fs.existsSync(path)
              ? fs.readFileSync(path, 'utf8')
              : 'Benchmark did not produce a report. See the workflow logs.';
            if (Buffer.byteLength(report, 'utf8') > 60000) throw new Error('Report too large');
            const body = `${marker}\n[Benchmark run](${run.html_url}) · ${run.conclusion} · attempt ${run.run_attempt}\n\n${report}`;
            const comments = await github.paginate(github.rest.issues.listComments, {
              owner, repo, issue_number: pr.number, per_page: 100,
            });
            const existing = comments.find(comment =>
              comment.user.login === 'github-actions[bot]' && comment.body?.startsWith(marker));
            if (existing) {
              await github.rest.issues.updateComment({ owner, repo, comment_id: existing.id, body });
            } else {
              await github.rest.issues.createComment({ owner, repo, issue_number: pr.number, body });
            }