benchmark.yml

name: benchmark
on:
  workflow_dispatch:
  pull_request_review:
    types: [submitted]
  pull_request:
    branches: [main]
    types: [synchronize]
    paths:
      - Sources/*.swift
      - .github/workflows/benchmark.yml

jobs:
  benchmark-vs-thresholds:
    if: github.event_name == 'workflow_dispatch' || github.event.review.state == 'approved'

    # https://runs-on.com/features/custom-runners/
    runs-on:
      labels:
        - runs-on
        - runner=2cpu-4ram
        - run-id=${{ github.run_id }}

    container: swift:noble

    defaults:
      run:
        shell: bash

    env:
      PR_COMMENT: null # will be populated later

    steps:
      - name: Check out code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Configure git
        run: git config --global --add safe.directory "${GITHUB_WORKSPACE}"

      # jemalloc is a dependency of the Benchmarking package
      # actions/cache will detect zstd and will become much faster.
      - name: Install jemalloc, curl, jq and zstd
        run: |
          set -eu

          apt-get update -y
          apt-get install -y libjemalloc-dev curl jq zstd

      - name: Restore .build
        id: restore-cache
        uses: runs-on/cache/restore@v4
        with:
          path: Benchmarks/.build
          key: "swiftpm-benchmark-build-${{ runner.os }}-${{ github.event.pull_request.base.sha || github.event.after }}"
          restore-keys: "swiftpm-benchmark-build-${{ runner.os }}-"

      - name: Run benchmarks for branch ${{ github.head_ref || github.ref_name }}
        run: |
          swift package -c release --disable-sandbox \
            --package-path Benchmarks \
            benchmark baseline update \
            '${{ github.head_ref || github.ref_name }}'

      - name: Read benchmark result
        id: read-benchmark
        run: |
          set -eu

          swift package -c release --disable-sandbox \
            --package-path Benchmarks \
            benchmark baseline read \
            '${{ github.head_ref || github.ref_name }}' \
            --no-progress \
            --format markdown \
            >> result.text

          # Read the result to the output of the step
          echo 'result<<EOF' >> $GITHUB_OUTPUT
          cat result.text >> $GITHUB_OUTPUT
          echo 'EOF' >> $GITHUB_OUTPUT

      - name: Compare branch ${{ github.head_ref || github.ref_name }} against thresholds
        id: compare-benchmark
        run: |
          set -eu

          TIMESTAMP=$(date -u +"%Y-%m-%d %H:%M:%S UTC")
          ENCODED_TIMESTAMP=$(date -u +"%Y-%m-%dT%H%%3A%M%%3A%SZ")
          TIMESTAMP_LINK="https://www.timeanddate.com/worldclock/fixedtime.html?iso=$ENCODED_TIMESTAMP"
          echo "## Benchmark check running at [$TIMESTAMP]($TIMESTAMP_LINK)" >> summary.text

          # Disable 'set -e' to prevent the script from exiting on non-zero exit codes
          set +e
          swift package -c release --disable-sandbox \
            --package-path Benchmarks \
            benchmark thresholds check \
            '${{ github.head_ref || github.ref_name }}' \
            --path "$PWD/Benchmarks/Thresholds/" \
            --no-progress \
            --format markdown \
            >> summary.text
          echo "exit-status=$?" >> "${GITHUB_OUTPUT}"
          set -e

          echo 'summary<<EOF' >> $GITHUB_OUTPUT
          cat summary.text >> $GITHUB_OUTPUT
          echo 'EOF' >> $GITHUB_OUTPUT

      - name: Cache .build
        if: steps.restore-cache.outputs.cache-hit != 'true'
        uses: runs-on/cache/save@v4
        with:
          path: Benchmarks/.build
          key: "swiftpm-benchmark-build-${{ runner.os }}-${{ github.event.pull_request.base.sha || github.event.after }}"

      - name: Construct comment
        run: |
          set -eu

          EXIT_CODE='${{ steps.compare-benchmark.outputs.exit-status }}'

          echo 'PR_COMMENT<<EOF' >> "${GITHUB_ENV}"

          # The fact that the comment starts with <!-- benchmark ci tag. exit code: ' is used
          # in a other steps to find this comment again.
          # Be wary of that when changing this line.
          echo "<!-- benchmark ci tag. exit code: $EXIT_CODE -->" >> "${GITHUB_ENV}"

          echo "" >> "${GITHUB_ENV}"

          echo '## [Benchmark](https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}) Report' >> "${GITHUB_ENV}"

          case "${EXIT_CODE}" in
              0)
                  echo '**✅ Pull request has no significant performance differences ✅**' >> "${GITHUB_ENV}"
                  ;;
              1)
                  echo '**❌ Pull request has significant performance differences 📊**' >> "${GITHUB_ENV}"
                  ;;
              2)
                  echo '**❌ Pull request has significant performance regressions 📉**' >> "${GITHUB_ENV}"
                  ;;
              4)
                  echo '**❌ Pull request has significant performance improvements 📈**' >> "${GITHUB_ENV}"
                  ;;
              *)
                  echo '**❌ Benchmark comparison failed to complete properly with exit code $EXIT_CODE ❌**' >> "${GITHUB_ENV}"
                  ;;
          esac

          echo '<details>' >> "${GITHUB_ENV}"
          echo '  <summary> Click to expand comparison result </summary>' >> "${GITHUB_ENV}"
          echo '' >> "${GITHUB_ENV}"
          echo '${{ steps.compare-benchmark.outputs.summary }}' >> "${GITHUB_ENV}"
          echo '' >> "${GITHUB_ENV}"
          echo '</details>' >> "${GITHUB_ENV}"

          echo '' >> "${GITHUB_ENV}"

          echo '<details>' >> "${GITHUB_ENV}"
          echo '  <summary> Click to expand benchmark result </summary>' >> "${GITHUB_ENV}"
          echo '' >> "${GITHUB_ENV}"
          echo '${{ steps.read-benchmark.outputs.result }}' >> "${GITHUB_ENV}"
          echo '' >> "${GITHUB_ENV}"
          echo '</details>' >> "${GITHUB_ENV}"

          echo 'EOF' >> "${GITHUB_ENV}"

      - name: Output the comment as job summary
        run: echo '${{ env.PR_COMMENT }}' >> "${GITHUB_STEP_SUMMARY}"

      # There is a '<!-- benchmark ci tag. exit code: {some_number} -->' comment at the beginning of the benchamrk report comment.
      # The number in that comment is the exit code of the last benchmark run.
      - name: Find existing comment ID
        if: github.event_name == 'pull_request'
        id: existing-comment
        run: |
          set -eu

          # Known limitation: This only fetches the first 100 comments. This should not
          # matter much because a benchmark comment should have been sent early in the PR.
          curl -sL \
            -X GET \
            -H 'Accept: application/vnd.github+json' \
            -H 'Authorization: BEARER ${{ secrets.GITHUB_TOKEN }}' \
            -H 'X-GitHub-Api-Version: 2022-11-28' \
            -o result.json \
            'https://api.github.com/repos/${{ github.repository }}/issues/${{ github.event.number }}/comments?per_page=100'

          # Get the last comment that has a body that starts with '<!-- benchmark ci tag. exit code: '.
          # If available, we can just update this comment instead of creating new ones.
          EXISTING_COMMENT=$(
            cat result.json |
              jq '
                [
                  .[] |
                    select(.body | startswith("<!-- benchmark ci tag. exit code: "))
                ][-1]
              '
          )

          # Check if EXISTING_COMMENT is empty or null
          if [ "$EXISTING_COMMENT" = "null" ] || [ -z "$EXISTING_COMMENT" ]; then
            ID=""
            BODY=""
            PARSED_EXIT_CODE=""
          else
            ID="$(echo "$EXISTING_COMMENT" | jq '.id')"
            BODY="$(echo "$EXISTING_COMMENT" | jq -r '.body')"
            PARSED_EXIT_CODE="$(echo "$BODY" | head -n 1 | grep -o 'exit code: [0-9]\+' | grep -o '[0-9]\+')"

            if [ "$ID" = "null" ]; then
              echo "Comment ID was null? something is wrong"
              echo "Comment: $EXISTING_COMMENT"
              exit 111
            fi
          fi

          # Output the results to GITHUB_OUTPUT
          {
            echo "id=$ID"
            echo "exit-code=$PARSED_EXIT_CODE"
            echo "body<<EOF"
            echo "$BODY"
            echo "EOF"
          } >> "$GITHUB_OUTPUT"

      - name: Comment in PR
        if: github.event_name == 'pull_request'
        run: |
          set -eu

          EXISTING_COMMENT_ID="${{ steps.existing-comment.outputs.id }}"
          # Need to provide the argument in a way that anything in the comment itself is not evaluated.
          BODY_JSON="$(jq -n -c --arg COMMENT "$(echo '${{ env.PR_COMMENT }}')" '{"body": $COMMENT}')"

          if [ -n "$EXISTING_COMMENT_ID" ]; then
            echo "Will update a comment: $EXISTING_COMMENT_ID"
            ENDPOINT="https://api.github.com/repos/${{ github.repository }}/issues/comments/$EXISTING_COMMENT_ID"
          else
            echo "Will create a new comment"
            ENDPOINT="https://api.github.com/repos/${{ github.repository }}/issues/${{ github.event.number }}/comments"
          fi

          curl -sL \
            -X POST \
            -H "Accept: application/vnd.github+json" \
            -H "Authorization: BEARER ${{ secrets.GITHUB_TOKEN }}" \
            -H "X-GitHub-Api-Version: 2022-11-28" \
            -d "$BODY_JSON" \
            "$ENDPOINT"

      - name: Exit with correct status
        run: |
          EXIT_CODE='${{ steps.compare-benchmark.outputs.exit-status }}'
          echo "Previous exit code was: $EXIT_CODE"
          exit $EXIT_CODE