ci: use host mapping volumes to improve the ccache hits

.gitlab/ci/common.yml

@@ -89,6 +89,14 @@ variables:
 
   IDF_CI_BUILD: 1
 
+  # ccache settings
+  # some settings need to set in .gitlab-ci.yml as it takes effect while start-up the job
+  # https://ccache.dev/manual/latest.html#_configuring_ccache
+
+  # host mapping volume to share ccache between runner concurrent jobs
+  CCACHE_DIR: "/cache/idf_ccache"
+  CCACHE_MAXSIZE: "20G"
+
 ################################################
 # `before_script` and `after_script` Templates #
 ################################################
@@ -187,7 +195,7 @@ variables:
 
 .show_ccache_statistics: &show_ccache_statistics |
   # Show ccache statistics if enabled globally
-  test "$CI_CCACHE_STATS" == 1 && test -n "$(which ccache)" && ccache --show-stats || true
+  test "$CI_CCACHE_STATS" == 1 && test -n "$(which ccache)" && ccache --show-stats -vv || true
 
 .upload_failed_job_log_artifacts: &upload_failed_job_log_artifacts |
   if [ $CI_JOB_STATUS = "failed" ]; then

tools/ci/configure_ci_environment.sh

@@ -33,9 +33,20 @@ if [ "$CI_CCACHE_DISABLE" = 1 ]; then
     echo "INFO: ccache disabled globally using CI_CCACHE_DISABLE=0"
 fi
 
+# https://ccache.dev/manual/latest.html#_configuring_ccache
 # Set ccache base directory to the project checkout path, to cancel out differences between runners
 export CCACHE_BASEDIR="${CI_PROJECT_DIR}"
 
+# host mapping volume to share ccache fbetween runner concurrent jobs
+export CCACHE_SLOPPINESS="time_macros"
+
+# CCACHE_RECACHE Used when invalidating the current cache.
+# could be enabled by MR label "ccache:recache"
+if [ -n "${CI_MERGE_REQUEST_LABELS}" ] && echo "${CI_MERGE_REQUEST_LABELS}" | grep -q "ccache::recache"; then
+    export CCACHE_RECACHE="1"
+    echo "INFO: ccache recache enabled"
+fi
+
 # 'CI_CCACHE_DISABLE_NOHASHDIR' variable can be used at project level to revert to hash_dir=true, in
 # case we start seeing failures due to false cache hits.
 if [ "${CI_CCACHE_DISABLE_NOHASHDIR}" != "1" ]; then