name: Cache Keepalive

# The shared Linux target caches (rust-test / packages / fmt-clippy, ~2-3 GB
# each) are only saved from main runs. When the changes filter skips those
# jobs for a few days, the entries go idle and GitHub's 10 GB LRU quota
# evicts them, forcing fully cold builds for every PR (including fork PRs
# that cannot access the S3 sccache backend). This workflow periodically
# refreshes the main-saved caches on schedule.

on:
  schedule:
    # Every Tuesday 01:30 UTC, ahead of typical PR activity hours.
    - cron: "30 1 * * 2"
  workflow_dispatch:

permissions:
  actions: write
  contents: read

concurrency:
  group: cache-keepalive
  cancel-in-progress: false

env:
  RUSTFLAGS: -C debuginfo=line-tables-only

jobs:
  rust-test-keepalive:
    runs-on: ubuntu-24.04
    timeout-minutes: 60
    env:
      # sccache cannot reuse Cargo incremental artifacts, so avoid generating them in CI.
      CARGO_INCREMENTAL: "0"
      # Deep async export tests exceed the Rust test harness's default thread stack on Linux.
      RUST_MIN_STACK: 8388608
      RUSTC_WRAPPER: sccache
      # "workspace" matches the full-coverage matrix group used on main pushes.
      RUST_TEST_GROUP: workspace
      RUST_FEATURE_MODE: full
    steps:
      - uses: actions/checkout@v7

      - name: Install system dependencies
        run: |
          sudo timeout --kill-after=30s 10m apt-get \
            -o Acquire::Retries=3 \
            -o Acquire::http::Timeout=30 \
            -o Acquire::https::Timeout=30 \
            update
          sudo timeout --kill-after=30s 10m apt-get \
            -o Acquire::Retries=3 \
            -o Acquire::http::Timeout=30 \
            -o Acquire::https::Timeout=30 \
            install -y libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf libssl-dev libsecret-1-dev

      # Pin mold because runner image updates can change bundled C++ links.
      # See the ci.yml rust-test note for the pinned upstream build.
      - name: Install mold linker
        run: |
          curl -fsSL https://github.com/rui314/mold/releases/download/v2.42.1/mold-2.42.1-x86_64-linux.tar.gz \
            | sudo tar -C /usr/local --strip-components=1 -xz
          mold --version

      - name: Setup Rust
        uses: dtolnay/rust-toolchain@1.97.1

      - name: Setup sccache
        uses: mozilla-actions/sccache-action@fc920bf0ec8de6ee65d409111f7ec508035751ba # v0.0.11
        with:
          version: "v0.16.0"

      # Mirrors the ci.yml rust-test configuration: S3 when secrets are
      # available (they are on schedule runs), otherwise no cross-run caching.
      - name: Configure sccache
        shell: bash
        env:
          CACHE_BUCKET: ${{ secrets.SCCACHE_S3_BUCKET }}
          CACHE_ENDPOINT: ${{ secrets.SCCACHE_S3_ENDPOINT }}
          CACHE_REGION: ${{ secrets.SCCACHE_S3_REGION }}
          CACHE_KEY_PREFIX: ${{ secrets.SCCACHE_S3_KEY_PREFIX }}
          CACHE_ACCESS_KEY_ID: ${{ secrets.SCCACHE_S3_ACCESS_KEY_ID }}
          CACHE_SECRET_ACCESS_KEY: ${{ secrets.SCCACHE_S3_SECRET_ACCESS_KEY }}
        run: |
          {
            if [[ -n "$CACHE_BUCKET" ]]; then
              echo "SCCACHE_BUCKET=${CACHE_BUCKET}"
              echo "SCCACHE_ENDPOINT=${CACHE_ENDPOINT}"
              echo "SCCACHE_REGION=${CACHE_REGION}"
              echo "SCCACHE_S3_KEY_PREFIX=${CACHE_KEY_PREFIX}"
              echo "SCCACHE_S3_USE_SSL=true"
              echo "AWS_ACCESS_KEY_ID=${CACHE_ACCESS_KEY_ID}"
              echo "AWS_SECRET_ACCESS_KEY=${CACHE_SECRET_ACCESS_KEY}"
            fi
            # Keep the server alive through post-compile test/lint phases so
            # "Show sccache stats" reflects the real counters.
            echo "SCCACHE_IDLE_TIMEOUT=0"
            # Also cache the C/C++ compilation of -sys crates. These jobs are
            # native Linux builds, so plain CC/CXX select the target compiler.
            echo "CC=${SCCACHE_PATH} cc"
            echo "CXX=${SCCACHE_PATH} c++"
          } >> "$GITHUB_ENV"

      # Same key recipe as ci.yml rust-test so the restored/saved entry is the
      # one PR jobs look up. save-if is satisfied: scheduled runs are on main.
      - name: Rust cache
        env:
          RUST_FEATURE_MODE: ""
          RUST_TEST_GROUP: ""
        uses: swatinem/rust-cache@v2
        with:
          prefix-key: v1-rust-complete
          workspaces: "./ -> target"
          shared-key: ci-rust-test-v2-x86_64-unknown-linux-gnu
          # Test linking dominates this job and sccache cannot cache those crate types.
          cache-workspace-crates: true
          cache-on-failure: false
          save-if: ${{ github.ref == 'refs/heads/main' }}

      - name: Install nextest
        uses: taiki-e/install-action@a3324fb0eb94b8230ec968c3389c1b7929fc2f3b # v2.68.13
        with:
          tool: cargo-nextest@0.9.137

      # mold -run wraps the whole process tree (see the ci.yml rust-test note).
      - name: Nextest
        run: |-
          mold -run node .github/scripts/ci-rust.mjs test "$RUST_TEST_GROUP" "$RUST_FEATURE_MODE"

      - name: Rust doc tests
        run: |-
          mold -run node .github/scripts/ci-rust.mjs doctest "$RUST_TEST_GROUP" "$RUST_FEATURE_MODE"

      - name: Show sccache stats
        if: always()
        continue-on-error: true
        run: ${SCCACHE_PATH} --show-stats

  prune-sccache-entries:
    runs-on: ubuntu-24.04
    timeout-minutes: 15
    steps:
      - name: Prune stale sccache GHA cache entries
        shell: bash
        env:
          GH_TOKEN: ${{ github.token }}
        run: |
          set -euo pipefail
          # The Windows jobs only enable the GHA sccache backend when S3
          # secrets are absent, but release workflows can still accumulate
          # thousands of small sccache/* entries that crowd the 10 GB quota.
          # The GHA backend keys on content hash, so entries nobody touched
          # for a week can be dropped without losing reachable warm caches.
          cutoff_days=7
          cutoff=$(date -u -d "-${cutoff_days} days" +%s)
          page=1
          ids=()
          while :; do
            resp=$(gh api "repos/${GITHUB_REPOSITORY}/actions/caches?key=sccache&per_page=100&page=${page}")
            count=$(printf '%s' "$resp" | jq '.actions_caches | length')
            [[ "$count" -eq 0 ]] && break
            while read -r id accessed; do
              [[ "$(date -u -d "$accessed" +%s)" -lt "$cutoff" ]] || continue
              ids+=("$id")
            done < <(printf '%s' "$resp" | jq -r '.actions_caches[] | "\(.id) \(.last_accessed_at)"')
            page=$((page + 1))
          done
          # Collect first, delete after: removing entries mid-pagination would
          # shift later pages and skip candidates.
          pruned=0
          for id in "${ids[@]}"; do
            if gh api -X DELETE "repos/${GITHUB_REPOSITORY}/actions/caches/${id}"; then
              pruned=$((pruned + 1))
            fi
          done
          echo "Pruned ${pruned} sccache cache entries idle for over ${cutoff_days} days."