performance.yml

name: Performance Tests

on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]
    # Only run on release-plz PRs to document performance
    types: [ opened, synchronize ]
  workflow_dispatch:

permissions:
  contents: read
  issues: write
  pull-requests: write

env:
  CARGO_TERM_COLOR: always
  RUST_BACKTRACE: 1
  # Performance thresholds
  MAX_LATENCY_MS: 5
  MAX_REGRESSION_PERCENT: 10

jobs:
  performance:
    name: Performance Benchmarks
    runs-on: ubuntu-latest
    # Run on pushes to main or on release-plz PRs only
    if: |
      github.event_name == 'push' ||
      (github.event_name == 'pull_request' &&
       (startsWith(github.head_ref, 'release-plz-') ||
        github.event.pull_request.user.login == 'github-actions[bot]'))

    steps:
    - name: Checkout code
      uses: actions/checkout@v4
      with:
        fetch-depth: 0  # Need history for baseline comparison

    - name: Install Rust
      uses: dtolnay/rust-toolchain@stable

    - name: Cache dependencies
      uses: Swatinem/rust-cache@v2
      with:
        key: ${{ runner.os }}-cargo-bench-${{ hashFiles('**/Cargo.lock') }}

    - name: Install cargo-criterion
      run: |
        cargo install cargo-criterion --locked || true
        cargo install critcmp --locked || true

    - name: Run benchmark validation tests
      run: cargo test --test benchmark_validation

    - name: Get baseline benchmark results
      if: github.event_name == 'pull_request'
      run: |
        # Checkout base branch for comparison
        git fetch origin ${{ github.base_ref }}
        git checkout origin/${{ github.base_ref }}

        # Run benchmarks on base branch
        cargo bench --bench proxy_performance -- --save-baseline base --sample-size 50

        # Return to PR branch
        git checkout -

    - name: Run performance benchmarks
      run: |
        cargo bench --bench proxy_performance -- --save-baseline current --sample-size 50

    - name: Compare benchmark results
      if: github.event_name == 'pull_request'
      id: benchmark_comparison
      run: |
        # Compare results
        critcmp base current > comparison.txt || true

        # Check for regressions - look for increases above threshold
        # critcmp outputs format: "+12.34%" for regressions
        REGRESSION_FOUND=false

        # Extract percentage increases and check against threshold
        while IFS= read -r line; do
          if echo "$line" | grep -E '\+[0-9]+\.[0-9]+%' > /dev/null; then
            # Extract the percentage value
            PERCENT=$(echo "$line" | grep -oE '\+[0-9]+\.[0-9]+' | tr -d '+')

            # Check if it exceeds our threshold using awk for float comparison
            if awk -v p="$PERCENT" -v t="$MAX_REGRESSION_PERCENT" 'BEGIN { exit !(p >= t) }'; then
              echo "Regression found: +${PERCENT}% exceeds threshold of ${MAX_REGRESSION_PERCENT}%"
              REGRESSION_FOUND=true
            fi
          fi
        done < comparison.txt

        if [ "$REGRESSION_FOUND" = true ]; then
          echo "Performance regression detected!"
          echo "REGRESSION_DETECTED=true" >> $GITHUB_OUTPUT
        else
          echo "No significant regression detected"
          echo "REGRESSION_DETECTED=false" >> $GITHUB_OUTPUT
        fi

        # Save comparison for PR comment
        echo '```' > benchmark_report.md
        cat comparison.txt >> benchmark_report.md
        echo '```' >> benchmark_report.md

    - name: Run memory profiling
      run: |
        cargo bench --bench memory_profiling > memory_profile.txt 2>&1 || true

    - name: Post benchmark results to PR
      if: github.event_name == 'pull_request'
      uses: actions/github-script@v7
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }}
        script: |
          const fs = require('fs');

          let comment = '## 📊 Performance Benchmark Results\n\n';

          // Add comparison results if available
          try {
            const comparison = fs.readFileSync('benchmark_report.md', 'utf8');
            comment += '### Benchmark Comparison (base vs current)\n';
            comment += comparison + '\n\n';
          } catch (e) {
            comment += '### Benchmark Results\n';
            comment += 'No baseline comparison available.\n\n';
          }

          // Add memory profile summary
          try {
            const memProfile = fs.readFileSync('memory_profile.txt', 'utf8');
            const lines = memProfile.split('\n').slice(-20).join('\n');
            comment += '### Memory Profile Summary\n';
            comment += '```\n' + lines + '\n```\n\n';
          } catch (e) {
            console.log('No memory profile available');
          }

          // Check for regression
          const regressionDetected = '${{ steps.benchmark_comparison.outputs.REGRESSION_DETECTED }}' === 'true';
          if (regressionDetected) {
            comment += '⚠️ **Performance regression detected!** Please review the benchmark comparison above.\n';
            comment += 'Regressions exceeding ' + process.env.MAX_REGRESSION_PERCENT + '% require justification.\n';
          } else {
            comment += '✅ **No significant performance regressions detected.**\n';
          }

          comment += '\n<sub>All latency requirements (<' + process.env.MAX_LATENCY_MS + 'ms) are enforced by the test suite.</sub>';

          // Find existing comment or create new one
          const { data: comments } = await github.rest.issues.listComments({
            owner: context.repo.owner,
            repo: context.repo.repo,
            issue_number: context.issue.number,
          });

          const botComment = comments.find(comment =>
            comment.user.type === 'Bot' &&
            comment.body.includes('Performance Benchmark Results')
          );

          if (botComment) {
            await github.rest.issues.updateComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              comment_id: botComment.id,
              body: comment,
            });
          } else {
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: comment,
            });
          }

    - name: Fail if regression detected
      if: steps.benchmark_comparison.outputs.REGRESSION_DETECTED == 'true'
      run: |
        echo "Performance regression detected! See PR comment for details."
        exit 1