pr-checks.yml

name: PR checks

# Per-package parallel pipeline: each codec is built, tested, and benchmarked
# independently. The matrix mirrors what CircleCI was doing — every entry
# runs concurrently, any failure fails the workflow.
#
# CodSpeed's first-class GHA integration replaces the manual codspeed-bench
# job from CircleCI: `CodSpeedHQ/action@v3` installs valgrind, sets up
# instrumentation, and uploads results in one step.

on:
  pull_request:
  push:
    # Run on every branch including main so each merge to main seeds a
    # fresh CodSpeed baseline. Without a main run, PR comments stay stuck
    # on "Congrats! CodSpeed is installed" with no before/after deltas.
    branches:
      - "**"
  # workflow_dispatch lets CodSpeed trigger a backtest run from the
  # dashboard (to seed initial perf data after the repo is connected).
  workflow_dispatch:

# Cancel in-flight runs when a new push lands on the same PR / branch.
concurrency:
  group: pr-checks-${{ github.workflow }}-${{ github.head_ref || github.ref }}
  cancel-in-progress: true

permissions:
  contents: read
  pull-requests: write  # CodSpeed action posts a sticky PR comment
  id-token: write       # OIDC token used by CodSpeedHQ/action for auth

jobs:
  detect-changes:
    # Build the matrix dynamically from the set of packages that actually
    # changed since main. Mirrors CircleCI's --since main skip logic. On a
    # PR where every README was touched (this branch) the list is the full
    # 8 packages; on a docs-only PR the build matrix is empty.
    runs-on: ubuntu-latest
    outputs:
      packages: ${{ steps.list.outputs.packages }}
      any: ${{ steps.list.outputs.any }}
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - id: list
        name: List changed packages
        env:
          EVENT_NAME: ${{ github.event_name }}
          REF: ${{ github.ref }}
        run: |
          set -e
          ALL=(charls libjpeg-turbo-8bit libjpeg-turbo-12bit openjpeg openjphjs little-endian big-endian dicom-codec)

          # Baseline runs: on a manual dispatch or any commit landing on
          # main, build/test/bench every package. The "diff vs main" trick
          # only makes sense on PR/feature branches — when HEAD === main,
          # `git diff origin/main..HEAD` is empty and would skip CodSpeed
          # entirely, leaving the dashboard with no baseline data.
          if [ "$EVENT_NAME" = "workflow_dispatch" ] || [ "$REF" = "refs/heads/main" ]; then
            json=$(printf '%s\n' "${ALL[@]}" | jq -R . | jq -s -c .)
            echo "Baseline run ($EVENT_NAME on $REF): forcing all packages"
            echo "packages=$json" >> "$GITHUB_OUTPUT"
            echo "any=true" >> "$GITHUB_OUTPUT"
            exit 0
          fi

          git fetch --no-tags --depth=50 origin main || true
          BASE=$(git merge-base origin/main HEAD || echo "origin/main")
          changed=()
          for pkg in "${ALL[@]}"; do
            if ! git diff --quiet "$BASE"..HEAD -- "packages/$pkg/"; then
              changed+=("$pkg")
            fi
          done
          if [ ${#changed[@]} -eq 0 ]; then
            echo "No packages changed since $BASE."
            echo 'packages=[]' >> "$GITHUB_OUTPUT"
            echo "any=false" >> "$GITHUB_OUTPUT"
          else
            json=$(printf '%s\n' "${changed[@]}" | jq -R . | jq -s -c .)
            echo "Changed packages: $json"
            echo "packages=$json" >> "$GITHUB_OUTPUT"
            echo "any=true" >> "$GITHUB_OUTPUT"
          fi

  build:
    needs: detect-changes
    if: needs.detect-changes.outputs.any == 'true'
    strategy:
      fail-fast: false
      matrix:
        package: ${{ fromJson(needs.detect-changes.outputs.packages) }}
    runs-on: ubuntu-latest
    container:
      image: emscripten/emsdk:3.1.74
    steps:
      - name: Install yarn + cmake + C++ build deps
        run: |
          npm install --global yarn@1.22.22
          apt-get update
          apt-get -y install build-essential git
          wget -qO- "https://cmake.org/files/v3.17/cmake-3.17.4-Linux-x86_64.tar.gz" \
            | tar --strip-components=1 -xz -C /usr/local
          apt-get autoremove -y
          apt-get clean -y
          rm -rf /var/lib/apt/lists/*
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0
      - name: Allow git to operate on the workspace
        # The container runs as root but the workspace is owned by the
        # checkout action's user, which makes git complain about
        # `dubious ownership`. Mark it safe.
        run: git config --global --add safe.directory "$GITHUB_WORKSPACE"
      - name: Init submodules for this package
        run: |
          if [ -d "packages/${{ matrix.package }}/extern" ]; then
            git submodule update --init --recursive "packages/${{ matrix.package }}/extern"
          else
            echo "No extern/ submodule for ${{ matrix.package }}; skipping."
          fi
      - name: Restore yarn cache
        uses: actions/cache@v4
        with:
          path: ~/.cache/yarn
          key: yarn-${{ hashFiles('yarn.lock') }}
          restore-keys: yarn-
      - name: Install dependencies
        run: yarn install --frozen-lockfile
      - name: Build
        run: cd "packages/${{ matrix.package }}" && yarn run build:ci
      - name: Ensure dist exists (no-op packages still need a placeholder)
        run: mkdir -p "packages/${{ matrix.package }}/dist"
      - name: Upload dist
        uses: actions/upload-artifact@v4
        with:
          name: dist-${{ matrix.package }}
          path: packages/${{ matrix.package }}/dist
          if-no-files-found: ignore
          retention-days: 7

  test:
    needs: [detect-changes, build]
    if: needs.detect-changes.outputs.any == 'true'
    strategy:
      fail-fast: false
      matrix:
        package: ${{ fromJson(needs.detect-changes.outputs.packages) }}
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '22'
      - name: Download all built dists
        uses: actions/download-artifact@v4
        with:
          pattern: dist-*
          path: tmp/
      - name: Replay dists into packages/<pkg>/dist
        # actions/download-artifact lands each artifact in tmp/<name>/.
        # Move each into its proper packages/<pkg>/dist location so vitest
        # finds them, mirroring how CircleCI workspace persist worked.
        run: |
          set -e
          for d in tmp/dist-*; do
            [ -d "$d" ] || continue
            pkg=$(basename "$d" | sed 's/^dist-//')
            mkdir -p "packages/$pkg/dist"
            shopt -s dotglob nullglob
            cp -r "$d"/* "packages/$pkg/dist/" 2>/dev/null || true
          done
          ls packages/*/dist 2>/dev/null | head
      - name: Restore yarn cache
        uses: actions/cache@v4
        with:
          path: ~/.cache/yarn
          key: yarn-${{ hashFiles('yarn.lock') }}
          restore-keys: yarn-
      - name: Install dependencies
        run: yarn install --frozen-lockfile
      - name: Test
        run: cd "packages/${{ matrix.package }}" && yarn run test:ci

  codspeed-bench:
    needs: [detect-changes, build]
    if: needs.detect-changes.outputs.any == 'true'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '22'
      - name: Download all built dists
        uses: actions/download-artifact@v4
        with:
          pattern: dist-*
          path: tmp/
      - name: Replay dists into packages/<pkg>/dist
        run: |
          set -e
          for d in tmp/dist-*; do
            [ -d "$d" ] || continue
            pkg=$(basename "$d" | sed 's/^dist-//')
            mkdir -p "packages/$pkg/dist"
            shopt -s dotglob nullglob
            cp -r "$d"/* "packages/$pkg/dist/" 2>/dev/null || true
          done
      - name: Restore yarn cache
        uses: actions/cache@v4
        with:
          path: ~/.cache/yarn
          key: yarn-${{ hashFiles('yarn.lock') }}
          restore-keys: yarn-
      - name: Install dependencies
        run: yarn install --frozen-lockfile
      - name: Run CodSpeed benchmarks
        # CodSpeedHQ/action@v4 sets up CPU simulation (Cachegrind-based
        # instruction counting on a modeled CPU + cache hierarchy), runs
        # the inner command under valgrind, uploads to codspeed.io, and
        # posts/updates a sticky PR comment with the per-bench deltas.
        # Authenticates via GitHub OIDC (id-token: write above) so no
        # CODSPEED_TOKEN secret is needed.
        #
        # mode: simulation (vs walltime) — we chose simulation because:
        #   - deterministic: <1% run-to-run drift (verified across 3
        #     runs of identical source)
        #   - free CI minutes (walltime needs CodSpeed macro-runners)
        #   - regression-detection signal is strong even though the
        #     headline numbers are MODELED instruction-time, not real
        #     wall-clock (JS-loop benches inflate 30-100x vs production
        #     V8 due to no JIT under Cachegrind; wasm decode kernels
        #     inflate ~5-15x; pure native ~1x)
        # See BENCHMARKING.md at the repo root for the full measurement
        # model, how to read the cold/warm bench split, and what the
        # CodSpeed dashboard warnings mean.
        uses: CodSpeedHQ/action@v4
        with:
          mode: simulation
          run: yarn run bench