[core] invoke optional resource path change completion listener

include/mbgl/storage/default_file_source.hpp

@@ -18,6 +18,9 @@ template <typename T> class Thread;
 
 class ResourceTransform;
 
+// TODO: the callback should include a potential error info when https://github.com/mapbox/mapbox-gl-native/issues/14759 is resolved
+using PathChangeCallback = std::function<void ()>;
+
 class DefaultFileSource : public FileSource {
 public:
     /*
@@ -47,7 +50,7 @@ public:
 
     void setResourceTransform(optional<ActorRef<ResourceTransform>>&&);
 
-    void setResourceCachePath(const std::string&);
+    void setResourceCachePath(const std::string&, optional<ActorRef<PathChangeCallback>>&&);
 
     std::unique_ptr<AsyncRequest> request(const Resource&, Callback) override;
 

platform/default/src/mbgl/storage/default_file_source.cpp

@@ -46,8 +46,11 @@ public:
         onlineFileSource.setResourceTransform(std::move(transform));
     }
 
-    void setResourceCachePath(const std::string& path) {
+    void setResourceCachePath(const std::string& path, optional<ActorRef<PathChangeCallback>>&& callback) {
         offlineDatabase->changePath(path);
+        if (callback) {
+            callback->invoke(&PathChangeCallback::operator());
+        }
     }
 
     void listRegions(std::function<void (expected<OfflineRegions, std::exception_ptr>)> callback) {
@@ -252,8 +255,8 @@ void DefaultFileSource::setResourceTransform(optional<ActorRef<ResourceTransform
     impl->actor().invoke(&Impl::setResourceTransform, std::move(transform));
 }
 
-void DefaultFileSource::setResourceCachePath(const std::string& path) {
-    impl->actor().invoke(&Impl::setResourceCachePath, path);
+void DefaultFileSource::setResourceCachePath(const std::string& path, optional<ActorRef<PathChangeCallback>>&& callback) {
+    impl->actor().invoke(&Impl::setResourceCachePath, path, std::move(callback));
 }
 
 std::unique_ptr<AsyncRequest> DefaultFileSource::request(const Resource& resource, Callback callback) {

test/storage/default_file_source.test.cpp

@@ -572,6 +572,18 @@ TEST(DefaultFileSource, TEST_REQUIRES_SERVER(SetResourceTransform)) {
     loop.run();
 }
 
+TEST(DefaultFileSource, SetResourceCachePath) {
+    util::RunLoop loop;
+    DefaultFileSource fs(":memory:", ".");
+
+    Actor<PathChangeCallback> callback(loop, [&]() -> void {
+        loop.stop();
+    });
+
+    fs.setResourceCachePath("./new_offline.db", callback.self());
+    loop.run();
+}
+
 // Test that a stale cache file that has must-revalidate set will trigger a response.
 TEST(DefaultFileSource, TEST_REQUIRES_SERVER(RespondToStaleMustRevalidate)) {
     util::RunLoop loop;