pebrel/.github/actions/rust-cache/action.yml

name: Cargo downloads and compiled targets
description: Share downloads across jobs without duplicating them in every target cache

inputs:
  key:
    description: Compiled workload (core, product, release or legacy)
    required: true
  target:
    description: Compiled profile directories to retain, relative to the repository
    required: true
  legacy-key:
    description: Previous combined cache key, restored only during migration
    default: ""
  extra-key:
    description: Additional inputs for native build tools stored with this target
    default: ""

outputs:
  cache-key:
    description: Key to use when saving compiled targets
    value: ${{ steps.identity.outputs.key }}
  cache-hit:
    description: Whether the compiled target cache matched exactly
    value: ${{ steps.target.outputs.cache-hit }}

runs:
  using: composite
  steps:
    - name: Identify compiler and build environment
      id: identity
      shell: bash
      env:
        CACHE_OS: ${{ runner.os }}
        CACHE_ARCH: ${{ runner.arch }}
        CACHE_WORKLOAD: ${{ inputs.key }}
        CACHE_REVISION: ${{ github.sha }}
        CACHE_MANIFESTS: ${{ hashFiles('Cargo.lock', '**/Cargo.toml', 'rust-toolchain.toml', '**/.cargo/config.toml', '.github/ci-profile.toml') }}${{ inputs.extra-key }}
      run: |
        python - <<'PY'
        import hashlib
        import json
        import os
        from pathlib import Path
        import subprocess
        facts = {"rustc": subprocess.check_output(["rustc", "-vV"], text=True)}
        prefixes = ("CARGO_PROFILE_", "CFLAGS", "CXXFLAGS", "RUSTFLAGS")
        names = {"CARGO_BUILD_TARGET", "CARGO_ENCODED_RUSTFLAGS", "RUSTC_WRAPPER",
                 "CC", "CXX", "ImageOS", "MACOSX_DEPLOYMENT_TARGET", "SDKROOT", "DEVELOPER_DIR"}
        normalize = str.upper if os.name == "nt" else str
        names = {normalize(name) for name in names}
        facts["environment"] = {normalize(key): value for key, value in os.environ.items()
                                if normalize(key) in names or normalize(key).startswith(prefixes)}
        if os.environ["CACHE_OS"] == "macOS":
            facts["sdk"] = subprocess.check_output(["xcrun", "--sdk", "macosx", "--show-sdk-version"], text=True)
        fingerprint = hashlib.sha256(json.dumps(facts, sort_keys=True).encode()).hexdigest()[:16]
        prefix = "cargo-targets-v1-" + "-".join(os.environ[name] for name in
                                              ("CACHE_OS", "CACHE_ARCH", "CACHE_WORKLOAD"))
        prefix += "-" + fingerprint + "-"
        with open(os.environ["GITHUB_OUTPUT"], "a", encoding="utf-8") as output:
            # Immutable caches need a new entry after a source change, including
            # when the prior revision failed before it compiled every profile.
            output.write("key=" + prefix + os.environ["CACHE_MANIFESTS"] + "-" + os.environ["CACHE_REVISION"] + "\n")
            output.write("manifest-key=" + prefix + os.environ["CACHE_MANIFESTS"] + "\n")
            output.write("restore-key=" + prefix + "\n")
            # Recover the preceding Windows cache, which omitted ImageOS because
            # Python uppercases environment names there. Cargo revalidates it.
            if os.name == "nt":
                facts["environment"].pop("IMAGEOS", None)
                previous = hashlib.sha256(json.dumps(facts, sort_keys=True).encode()).hexdigest()[:16]
                output.write("migration-key=" + prefix.replace(fingerprint, previous) + "\n")
            output.write("cargo-home=" + (os.environ.get("CARGO_HOME") or str(Path.home() / ".cargo")) + "\n")
        PY
    - name: Restore shared Cargo downloads
      id: downloads
      uses: actions/cache/restore@v4
      with:
        # Preserve Git source checkouts with their mtimes. Recreating them from
        # git/db can make timestamp-based dependency fingerprints dirty even
        # after compiled targets were restored. Registry crates remain immutable
        # archives: Cargo can recreate their extracted sources without this risk.
        path: |
          ${{ steps.identity.outputs.cargo-home }}/registry/index
          ${{ steps.identity.outputs.cargo-home }}/registry/cache
          ${{ steps.identity.outputs.cargo-home }}/git/db
          ${{ steps.identity.outputs.cargo-home }}/git/checkouts
        key: cargo-downloads-v2-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('Cargo.lock', '**/Cargo.toml') }}
        restore-keys: cargo-downloads-v2-${{ runner.os }}-${{ runner.arch }}-
    - name: Restore compiled targets
      id: target
      uses: actions/cache/restore@v4
      with:
        path: ${{ inputs.target }}
        key: ${{ steps.identity.outputs.key }}
        restore-keys: |
          ${{ steps.identity.outputs.manifest-key }}
          ${{ steps.identity.outputs.restore-key }}
          ${{ steps.identity.outputs.migration-key }}
    - name: Recover an existing combined cache during migration
      if: steps.target.outputs.cache-matched-key == '' && inputs.legacy-key != ''
      uses: Swatinem/rust-cache@v2
      with:
        shared-key: ${{ inputs.legacy-key }}
        workspaces: . -> target
        cache-bin: false
        cache-on-failure: true
        save-if: false
    - name: Populate complete downloads before sharing the cache
      if: steps.downloads.outputs.cache-hit != 'true'
      shell: bash
      run: |
        host_target="$(rustc -vV | sed -n 's/^host: //p')"
        test -n "$host_target"
        cargo fetch --locked --target "$host_target"
    - name: Save complete shared Cargo downloads
      if: steps.downloads.outputs.cache-hit != 'true'
      uses: actions/cache/save@v4
      with:
        path: |
          ${{ steps.identity.outputs.cargo-home }}/registry/index
          ${{ steps.identity.outputs.cargo-home }}/registry/cache
          ${{ steps.identity.outputs.cargo-home }}/git/db
          ${{ steps.identity.outputs.cargo-home }}/git/checkouts
        key: ${{ steps.downloads.outputs.cache-primary-key }}