python.yml

name: Python

on:
  push:
    branches: [main]
  pull_request:
    paths:
      - '.github/workflows/python.yml'
      - 'cmake/**'
      - 'python/src/**'
      - 'python/CMakeLists.txt'
      - 'python/src/CMakeLists.txt'
      - 'src/**'
      - 'CMakeLists.txt'
      - 'pyproject.toml'

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}

jobs:
  Python-Versions:
    runs-on: ubuntu-latest
    outputs:
      all: ${{ steps.matrix.outputs.all }}
      pr: ${{ steps.matrix.outputs.pr }}
    steps:
      - name: Compute supported Python versions
        id: matrix
        env:
          MIN_MINOR: 11   # our own floor; raise it manually if we ever need to
        run: |
          today=$(date +%F)
          all=$(curl -fsS https://endoflife.date/api/python.json | jq -c \
            --arg today "$today" --argjson min "$MIN_MINOR" '
              [ .[]
                | select(.cycle | startswith("3."))
                | select((.cycle | split(".")[1] | tonumber) >= $min)
                | select(.releaseDate <= $today)   # already released
                | select(.eol > $today)            # not yet EOL
                | .cycle ]
              | sort_by(split(".")[1] | tonumber)')
          # PRs: second-newest release (currently 3.14), so we don't
          # chase brand-new wheels on every PR
          pr=$(jq -c '[.[-2]]' <<< "$all")
          echo "all=$all" >> "$GITHUB_OUTPUT"
          echo "pr=$pr"   >> "$GITHUB_OUTPUT"

  Build:
    needs: Python-Versions
    name: ${{ matrix.name }} Python ${{ matrix.python-version }}
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
        python-version: ${{ github.event_name == 'pull_request' && fromJSON(needs.Python-Versions.outputs.pr) || fromJSON(needs.Python-Versions.outputs.all) }}
        include:
          - os: ubuntu-latest
            name: Linux
          - os: windows-latest
            name: Windows
          - os: macOS-latest
            name: macOS
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v6
        with:
          fetch-depth: 10

      - name: Set up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v6
        with:
          python-version: ${{ matrix.python-version }}

      - name: Install Ccache (Linux)
        if: runner.os == 'Linux'
        run: |
          sudo apt-get install ccache
          echo 'CACHE_PATH=~/.cache/ccache' >> "$GITHUB_ENV"

      - name: Install Ccache (macOS)
        if: runner.os == 'macOS'
        run: |
          brew install ccache
          echo 'CACHE_PATH=~/Library/Caches/ccache' >> "$GITHUB_ENV"

      - name: Install Ccache (Windows)
        if: runner.os == 'Windows'
        run: |
          choco install ccache
          "CACHE_PATH=${env:LOCALAPPDATA}\ccache" | Out-File -FilePath $env:GITHUB_ENV -Append

      # scikit-build-core picks the Visual Studio generator on Windows. That
      # generator ignores CMAKE_<LANG>_COMPILER_LAUNCHER, so ccache never runs,
      # and it compiles the files of each target one at a time. We use Ninja
      # instead, which needs the MSVC environment set up first.
      - name: Setup MSVC (Windows)
        if: runner.os == 'Windows'
        uses: ilammy/msvc-dev-cmd@v1
        with:
          arch: x64

      - name: Use Ninja (Windows)
        if: runner.os == 'Windows'
        run: |
          "CMAKE_GENERATOR=Ninja" | Out-File -FilePath $env:GITHUB_ENV -Append

      # On Linux, explicitly build for x86-64-v3 instead of -march=native. This
      # avoids issues with ccache restoring from a runner with a different ISA.
      - name: Check x86-64-v3 support (Linux)
        if: runner.os == 'Linux'
        run: |
          for f in avx2 bmi1 bmi2 f16c fma abm movbe xsave; do
            grep -qw "$f" /proc/cpuinfo || { echo "::error::Runner CPU lacks $f, which x86-64-v3 requires"; exit 1; }
          done
          echo "CPU: $(grep -m1 '^model name' /proc/cpuinfo | cut -d: -f2-)"

      # Cache entries are immutable, so a fixed key is saved once and never
      # updated. We give each run its own key and restore the newest one by
      # prefix instead. Only pushes to main save, and PRs restore from those.
      - name: Restore ccache
        uses: actions/cache/restore@v5
        with:
          path: ${{ env.CACHE_PATH }}
          key: ${{ runner.os }}-Python${{ matrix.python-version }}-ccache-${{ github.run_id }}
          restore-keys: ${{ runner.os }}-Python${{ matrix.python-version }}-ccache-

      - name: Prepare Ccache
        run: |
          ccache --max-size=1.0G
          ccache -V && ccache --show-config
          ccache --show-stats && ccache --zero-stats

      - name: Build and Install
        env:
          CMAKE_ARGS: ${{ runner.os == 'Linux' && '-DSIMD_CXX_FLAGS=-march=x86-64-v3' || '' }}
        run: |
          pip install --verbose . && ccache --show-stats

      - name: Save ccache
        if: ${{ !cancelled() && github.event_name == 'push' && github.ref == 'refs/heads/main' }}
        uses: actions/cache/save@v5
        with:
          path: ${{ env.CACHE_PATH }}
          key: ${{ runner.os }}-Python${{ matrix.python-version }}-ccache-${{ github.run_id }}

      - name: Tests
        run: |
          pip install -r python/tests/requirements.txt
          nose2 -v --pretty-assert -s python/tests