ogc: linux-unstable: GCC ccache restore-only, cleanup, prune master seeds

.github/workflows/cleanup-pr-caches.yml

@@ -0,0 +1,51 @@
+# Drop Actions caches scoped to a PR merge ref when the PR closes.
+# Those entries cannot seed other PRs or master, but they still count
+# against the repository 10GB cache quota.
+
+name: Cleanup PR Actions caches
+
+on:
+  pull_request:
+    types: [closed]
+  workflow_dispatch:
+    inputs:
+      pr_number:
+        description: "PR number whose refs/pull/N/merge caches to delete (empty = skip)"
+        required: false
+        type: string
+
+permissions:
+  actions: write
+  contents: read
+
+jobs:
+  cleanup:
+    name: Delete PR-scoped caches
+    runs-on: ubuntu-latest
+    steps:
+      - name: Delete caches for the PR merge ref
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          PR_NUMBER: ${{ github.event.pull_request.number || inputs.pr_number }}
+        run: |
+          set -euo pipefail
+          if [ -z "${PR_NUMBER}" ]; then
+            echo "No PR number; nothing to delete."
+            exit 0
+          fi
+          BRANCH="refs/pull/${PR_NUMBER}/merge"
+          echo "Listing caches for ${BRANCH}..."
+          # gh cache list --ref filters by the ref that created the cache.
+          mapfile -t IDS < <(gh cache list --ref "${BRANCH}" --limit 100 --json id --jq '.[].id')
+          if [ "${#IDS[@]}" -eq 0 ]; then
+            echo "No caches found for ${BRANCH}."
+            exit 0
+          fi
+          echo "Deleting ${#IDS[@]} cache(s)..."
+          set +e
+          for id in "${IDS[@]}"; do
+            echo "  gh cache delete ${id}"
+            gh cache delete "${id}"
+          done
+          echo "Done."

.github/workflows/test-pr.yml

@@ -121,12 +121,16 @@ jobs:
         with:
           fetch-depth: 1
 
+      # Restore-only: warm-ccache-master.yml is the sole writer of the shared
+      # GCC seed on master. Saving per-PR caches fills the 10GB Actions quota
+      # and those entries are invisible to other PRs anyway.
       - name: Restore compiler cache
-        uses: actions/cache@v6
+        uses: actions/cache/restore@v6
         with:
           path: /ccache
-          key: ccache-pr-gcc-${{ github.sha }}
+          key: ccache-pr-gcc-master-${{ github.sha }}
           restore-keys: |
+            ccache-pr-gcc-master-
             ccache-pr-gcc-
 
       - name: Assemble test config (same as the Arch release build)

.github/workflows/warm-ccache-master.yml

@@ -2,8 +2,10 @@
 #
 # GitHub Actions scopes caches by branch: entries created on a PR merge ref
 # are invisible to other PRs. Entries created on master are visible to every
-# PR. This workflow rebuilds with the same GCC + Arch/OGC config recipe as
-# test-pr.yml and saves under the shared ccache-pr-gcc- prefix.
+# PR. This workflow is the sole writer of the shared GCC seed
+# (ccache-pr-gcc-master-*); test-pr.yml restores it but does not save.
+# After a successful save it deletes older ccache-pr-gcc-master-* entries
+# so the ~10GB Actions quota is not filled with stale seeds.
 #
 # Triggers on every push to master so both human PR merges and the daily
 # linux-next sync (force-push) refresh the cache against the current tree.
@@ -17,6 +19,7 @@ on:
 
 permissions:
   contents: read
+  actions: write
 
 concurrency:
   group: warm-ccache-master
@@ -117,4 +120,38 @@ jobs:
             echo "- Cache key: \`ccache-pr-gcc-master-${{ github.sha }}\`"
             echo "- Shared with PR builds via restore-keys prefix \`ccache-pr-gcc-\`"
             echo "- Config: same as test-pr.yml GCC job (Arch headers + OGC fragments, Rust off)"
+            echo "- Older \`ccache-pr-gcc-master-*\` seeds are pruned after this job succeeds"
           } >> "$GITHUB_STEP_SUMMARY"
+
+  # actions/cache saves in a post step after all job steps finish. A dependent
+  # job therefore runs only once the new seed is already uploaded.
+  prune-old-seeds:
+    name: Prune older master GCC ccache seeds
+    needs: warm
+    if: success()
+    runs-on: ubuntu-latest
+    steps:
+      - name: Delete older ccache-pr-gcc-master-* entries
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GH_REPO: ${{ github.repository }}
+          KEEP_KEY: ccache-pr-gcc-master-${{ github.sha }}
+        run: |
+          set -euo pipefail
+          echo "Keeping ${KEEP_KEY}"
+          mapfile -t IDS < <(
+            gh cache list --key ccache-pr-gcc-master- --limit 100 \
+              --json id,key --jq \
+              '.[] | select(.key != env.KEEP_KEY) | .id'
+          )
+          if [ "${#IDS[@]}" -eq 0 ]; then
+            echo "No older master GCC seeds to delete."
+            exit 0
+          fi
+          echo "Deleting ${#IDS[@]} older seed(s)..."
+          set +e
+          for id in "${IDS[@]}"; do
+            echo "  gh cache delete ${id}"
+            gh cache delete "${id}"
+          done
+          echo "Done."