CI/Caching: Fix Gradle cache retention (apache#2604)

Older versions of Gradle's setup-gradle action did not actively trigger stale cache entry cleanup, which is why there was a separate step "Trigger Gradle home cleanup" in `gradle.yml`.
Nowadays, that action triggers a "noop build" to explicitly trigger stale cache entry cleanup, but uses somewhat different defaults than [described here](https://docs.gradle.org/current/userguide/directory_layout.html#dir:gradle_user_home:configure_cache_cleanup).

This change adds an explicit configuration for Gradle cache cleanup/retention with reasonable values considering the total 10GB limit for all GitHub caches per repository.

The change described above lead to a behavioral change, which evicts all non-accessed cache entries within the current GH workflow job, which effectively evicted all cache entries from dependent jobs - in other words: the (build) cache was nearly empty, leading to full rebuilds.
This behavior could be observed in the output of the "Post Collect partial Gradle build caches"-step in the log message "Build cache (/home/runner/.gradle/caches/build-cache-1) removing files not accessed on or after ..." showing the timestamp when the setup-gradle action was started.

Author: snazy

.github/actions/ci-incr-build-cache-prepare/action.yml

@@ -32,6 +32,27 @@ inputs:
 runs:
   using: "composite"
   steps:
+    - name: Configure Gradle cache retention settings
+      # Without these settings, the Gradle Setup action will evict effectively all "restored incremental" entries,
+      # as it will remove all cache entries created before the start-time of the "Store Gradle Cache" job.
+      # The total size of GitHub caches for each repository is limited to 10GB, which means that we have to use
+      # more aggressive retention settings to keep the size of the Gradle cache stored in GitHub at an appropriate
+      # size.
+      shell: bash
+      run: |
+        mkdir -p ~/.gradle/init.d
+        cat > ~/.gradle/init.d/cache-settings.gradle.kts <<!
+        beforeSettings {
+          caches {
+            releasedWrappers.setRemoveUnusedEntriesAfterDays(5)
+            snapshotWrappers.setRemoveUnusedEntriesAfterDays(1)
+            downloadedResources.setRemoveUnusedEntriesAfterDays(2)
+            createdResources.setRemoveUnusedEntriesAfterDays(5)
+            buildCache.setRemoveUnusedEntriesAfterDays(5)
+          }
+        }
+        !
+
     - name: Prep env
       shell: bash
       run: |
@@ -71,12 +92,12 @@ runs:
         if [[ -d ~/downloaded-artifacts/ ]] ; then
           find ~/downloaded-artifacts/ -type f -name "ci-gradle-caches-*-${{ inputs.java-version }}.tar" | while read arch ; do
             echo "Adding archive content from $arch ..."
-            (cd ~/.gradle/caches/ ; tar xf $arch)
+            (cd ~/.gradle/caches/ ; tar xf $arch --atime-preserve)
           done
         else
           echo "No previous build cache artifacts downloaded."
         fi
-        
+
         date +%s > ~/caches-prepared-at-epoch
 
         echo "::endgroup::"

.github/actions/ci-incr-build-cache-save/action.yml

@@ -47,7 +47,6 @@ runs:
             -path './[0-9]*/kotlin-dsl/*' -or \
             -path './jars-*/*' -or \
             -path './modules-*/files-*/*' -or \
-            -path './modules-*/files-*/*' -or \
             -path './build-cache-*/*' \
             ')' | grep -v '[.]lock$'  > ~/ci-gradle-caches-diff || true
           echo "Identified $(wc -l < ~/ci-gradle-caches-diff) changed/added files in caches/"

.github/workflows/gradle.yml

@@ -160,9 +160,6 @@ jobs:
         uses: ./.github/actions/ci-incr-build-cache-prepare
         with:
           cache-read-only: false
-      - name: Trigger Gradle home cleanup
-        env:
-          DEVELOCITY_ACCESS_KEY: ${{ secrets.DEVELOCITY_ACCESS_KEY }}
-        run: ./gradlew --no-daemon :showVersion
 
-      # Note: the "Post Gradle invocation" archives the updated build cache.
+      # Note: the "Post Collect partial Gradle build caches"-step cleans up stale cache entries
+      # and archives the updated build cache.