add some output to the eviction step to measure effectiveness

.ci/compile.sh

@@ -273,6 +273,11 @@ echo "::endgroup::"
 if [[ $USE_CCACHE ]]; then
   if [[ $CCACHE_EVICTION_AGE ]]; then
     echo "::group::evict ccache files older than $CCACHE_EVICTION_AGE"
+    ccache_dir=$(ccache --get-config cache_dir)
+    mapfile -t timestamps < <(find "$ccache_dir" -name CACHEDIR.TAG -prune -o -type f -printf '%T+\n' | sort)
+    filecount=${#timestamps[@]}
+    oldest_file=${timestamps[0]}
+    echo "the oldest file before deletion is from $oldest_file out of $filecount files in $ccache_dir"
     ccache --evict-older-than "$CCACHE_EVICTION_AGE"
     echo "::endgroup::"
   fi

.github/workflows/desktop-build.yml

@@ -187,10 +187,17 @@ jobs:
       - name: Build debug and test
         if: matrix.test != 'skip'
         shell: bash
+        env:
+          package: '${{matrix.package}}'
         run: |
           source .ci/docker.sh
-          RUN --server --debug --test --ccache "$CCACHE_SIZE" \
-                  --cmake-generator "$CMAKE_GENERATOR"
+          args=()
+          if [[ $GITHUB_REF == "refs/heads/master" && $package == "skip" ]]; then
+            args+=(--evict-ccache "$CCACHE_EVICTION_AGE")
+          fi
+          args+=(--ccache "$CCACHE_SIZE")
+          args+=(--cmake-generator "$CMAKE_GENERATOR")
+          RUN --server --debug --test "${args[@]}"
 
       - name: Build release package
         id: build