benchmark.yml

name: benchmark

on:
  pull_request:
    branches:
      - master
    types: [opened, synchronize, reopened]

permissions:
  pull-requests: write
  issues: write

jobs:
  benchmark:

    runs-on: ubuntu-latest

    steps:
      # Step 1: Checkout the PR branch
      - name: Checkout PR branch
        uses: actions/checkout@v6
        with:
          fetch-depth: 0  # Fetch all history for comparison

      # Step 2: Setup PHP
      - name: Setup PHP
        uses: shivammathur/setup-php@bf6b4fbd49ca58e4608c9c89fba0b8d90bd2a39f
        with:
          php-version: '8.5'
          extensions: zip, curl, mbstring, xml
          coverage: none
          tools: composer:v2

      # Step 2.1: Install PHPBench globally
      - name: Install PHPBench
        run: |
          composer global require phpbench/phpbench:^1.6 --prefer-dist --no-progress --no-interaction
          PHPBENCH_BIN="$(composer global config bin-dir --absolute)/phpbench"
          echo "PHPBENCH_BIN=$PHPBENCH_BIN" >> "$GITHUB_ENV"
          "$PHPBENCH_BIN" --version

      # Step 3: Install dependencies for PR branch
      - name: Install Composer dependencies
        run: |
          # Remove dependency artifacts that can leak across branch switches in CI
          git clean -ffdx -- composer.lock vendor
          composer install --prefer-dist --no-progress

      # Step 4: Run benchmarks on PR branch
      - name: Run benchmarks on PR branch
        run: |
          mkdir -p tests/Benchmark
          "$PHPBENCH_BIN" run tests/Benchmark \
            --report=default \
            --tag=pr \
            --retry-threshold=5 \
            --iterations=10

      # Step 5: Checkout base branch
      - name: Checkout base branch
        run: |
          git fetch origin "$BASE_REF"
          git checkout "origin/$BASE_REF"
        env:
          BASE_REF: ${{ github.base_ref }}

      # Step 5.1: Diagnose Composer state on base branch
      - name: Diagnose Composer state (base)
        run: |
          echo "Commit: $(git rev-parse --short HEAD)"
          echo "Base ref: origin/$BASE_REF"
          echo "phpunit/phpunit constraint in composer.json:"
          grep -n '"phpunit/phpunit"' composer.json || true

          if [ -f composer.lock ]; then
            echo "composer.lock present before cleanup"
            php -r '$lock = json_decode(file_get_contents("composer.lock"), true); $version = "not-found"; foreach (($lock["packages-dev"] ?? []) as $pkg) { if (($pkg["name"] ?? "") === "phpunit/phpunit") { $version = $pkg["version"] ?? "unknown"; break; } } echo "locked phpunit/phpunit: {$version}\n";'
          else
            echo "composer.lock missing before cleanup"
          fi

          echo "ignore status for composer.lock:"
          git check-ignore -v composer.lock || true

          echo "git status snapshot:"
          git status --short -- composer.json composer.lock vendor || true
        env:
          BASE_REF: ${{ github.base_ref }}

      # Step 6: Install dependencies for base branch
      - name: Install Composer dependencies (base)
        run: |
          # Ensure install uses only files from the checked out base branch
          git clean -ffdx -- composer.lock vendor
          composer install --prefer-dist --no-progress

      # Step 7: Run benchmarks on base branch
      - name: Run benchmarks on base branch
        run: |
          mkdir -p tests/Benchmark
          "$PHPBENCH_BIN" run tests/Benchmark \
            --report=default \
            --tag=base \
            --retry-threshold=5 \
            --iterations=10

      # Step 8: Checkout PR branch again
      - name: Checkout PR branch again
        run: git checkout "$HEAD_REF"
        env:
          HEAD_REF: ${{ github.head_ref }}

      # Step 8.1: Reinstall dependencies for PR branch
      - name: Install Composer dependencies (PR, comparison)
        run: |
          # Prevent base branch dependency artifacts from affecting PR comparison run
          git clean -ffdx -- composer.lock vendor
          composer install --prefer-dist --no-progress

      # Step 9: Compare benchmarks
      - name: Compare benchmarks with baseline
        id: compare
        run: |
          mkdir -p tests/Benchmark
          "$PHPBENCH_BIN" run tests/Benchmark \
            --report=aggregate \
            --ref=base \
            --retry-threshold=5 \
            --iterations=10 \
            --tag=pr \
            --assert="mode(variant.time.avg) <= mode(baseline.time.avg) +/- 2%" \
          | tee benchmark-comparison.txt
        continue-on-error: true

      # Step 10: Post results as PR comment
      - name: Comment PR with benchmark results
        if: ${{ github.actor != 'dependabot[bot]' }}
        uses: actions/github-script@v9
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            const fs = require('fs');
            const results = fs.readFileSync('benchmark-comparison.txt', 'utf8');

            const body = `## 📊 Benchmark Results\n\n\`\`\`\n${results}\n\`\`\`\n\n**Note:** Benchmarks compare PR against \`${{ github.base_ref }}\` branch.\nPerformance regression threshold: ±2%`;

            github.rest.issues.createComment({
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body: body
            });

      # Step 11: Fail if performance degrades
      - name: Check benchmark assertions
        if: steps.compare.outcome == 'failure'
        run: |
          echo "::error::Performance regression detected! Benchmarks exceeded acceptable threshold."
          exit 1