chg: dev: refactor out ``get_service_relation_tech_dep``

bin/compose-core

@@ -1172,11 +1172,26 @@ get_charm_tech_dep_orientation_for_relation() {
     relation_def=$(get_charm_relation_def "$charm" "$relation_name" 2>/dev/null)
     value=$(echo "$relation_def" | shyaml get-value 'tech-dep' 2>/dev/null)
     value=${value:-True}
-    echo "$value" | tee "$cache_file"
+    printf "%s" "$value" | tee "$cache_file"
 }
 export -f get_charm_tech_dep_orientation_for_relation
 
 
+get_service_relation_tech_dep() {
+    local service="$1" relation_name="$2" cache_file="$state_tmpdir/$FUNCNAME.cache.$1.$2" \
+          charm tech_dep
+    if [ -e "$cache_file" ]; then
+        # debug "$FUNCNAME: cache hit ($*)"
+        cat "$cache_file"
+        return 0
+    fi
+    charm=$(get_service_charm "$service") || return 1
+    tech_dep="$(get_charm_tech_dep_orientation_for_relation "$charm" "$relation_name")" || return 1
+    printf "%s" "$tech_dep" | tee "$cache_file"
+}
+export -f get_service_relation_tech_dep
+
+
 ##
 ## Use compose file to get deps, and relation definition in metadata.yml
 ## for tech-dep attribute.
@@ -1624,22 +1639,19 @@ _get_compose_relations_cached () {
                 (
                     case "$(echo "$relation_def" | shyaml get-type 2>/dev/null)" in
                     "str")
-                        target_service="$(echo "$relation_def" | shyaml get-value 2>/dev/null)"
-                        target_charm=$(get_service_charm "$target_service") || return 1
-                        tech_dep="$(get_charm_tech_dep_orientation_for_relation "$target_charm" "$relation_name")"
+                        target_service="$(echo "$relation_def" | shyaml get-value 2>/dev/null)" || return 1
+                        tech_dep="$(get_service_relation_tech_dep "$target_service" "$relation_name")" || return 1
                         echo -en "$relation_name\0$target_service\0\0$tech_dep\0"
                         ;;
                     "sequence")
                         while read-0 target_service; do
-                            target_charm=$(get_service_charm "$target_service") || return 1
-                            tech_dep="$(get_charm_tech_dep_orientation_for_relation "$target_charm" "$relation_name")"
+                            tech_dep="$(get_service_relation_tech_dep "$target_service" "$relation_name")" || return 1
                             echo -en "$relation_name\0$target_service\0\0$tech_dep\0"
                         done < <(echo "$relation_def" | shyaml get-values-0 2>/dev/null)
                         ;;
                     "struct")
                         while read-0 target_service relation_config; do
-                            target_charm=$(get_service_charm "$target_service") || return 1
-                            tech_dep="$(get_charm_tech_dep_orientation_for_relation "$target_charm" "$relation_name")"
+                            tech_dep="$(get_service_relation_tech_dep "$target_service" "$relation_name")" || return 1
                             echo -en "$relation_name\0$target_service\0$relation_config\0$tech_dep\0"
                         done < <(echo "$relation_def" | shyaml key-values-0 2>/dev/null)
                         ;;