[core] move retry logic to DefaultFileSource

2 files changed, 33 insertions, 6 deletions

diff --git a/include/mbgl/storage/file_cache.hpp b/include/mbgl/storage/file_cache.hpp
index a9071b1b67..b32bdf67e6 100644
--- a/include/mbgl/storage/file_cache.hpp
+++ b/include/mbgl/storage/file_cache.hpp
@@ -16,7 +16,7 @@ class FileCache : private util::noncopyable {
 public:
     virtual ~FileCache() = default;
 
-    enum class Hint : uint8_t { Full, Refresh, No };
+    enum class Hint : bool { Full, Refresh };
     using Callback = std::function<void(std::unique_ptr<Response>)>;
 
     virtual std::unique_ptr<WorkRequest> get(const Resource &resource, Callback callback) = 0;
diff --git a/include/mbgl/storage/response.hpp b/include/mbgl/storage/response.hpp
index b5973457b5..8ab6170ba2 100644
--- a/include/mbgl/storage/response.hpp
+++ b/include/mbgl/storage/response.hpp
@@ -8,20 +8,47 @@ namespace mbgl {
 
 class Response {
 public:
+    Response() = default;
+    Response(const Response&);
+    Response& operator=(const Response&);
+
     bool isExpired() const;
 
 public:
-    enum Status { Error, Successful, NotFound };
+    class Error;
+    // When this object is empty, the response was successful.
+    std::unique_ptr<const Error> error;
 
-    Status status = Error;
+    // Stale responses are fetched from cache and are expired.
     bool stale = false;
-    std::string message;
+
+    // The actual data of the response. This is guaranteed to never be empty.
+    std::shared_ptr<const std::string> data;
+
     int64_t modified = 0;
     int64_t expires = 0;
     std::string etag;
-    std::shared_ptr<const std::string> data;
 };
 
-}
+class Response::Error {
+public:
+    enum class Reason : uint8_t {
+        // Success = 1, // Reserve 1 for Success.
+        NotFound = 2,
+        Server = 3,
+        Connection = 4,
+        Canceled = 5,
+        Other = 6,
+    } reason = Reason::Other;
+
+    // An error message from the request handler, e.g. a server message or a system message
+    // informing the user about the reason for the failure.
+    std::string message;
+
+public:
+    Error(Reason, const std::string& = "");
+};
+
+} // namespace mbgl
 
 #endif