[core] add support for stale responses

We're now returning stale responses from cache. Those responses will have the `stale` flag set to true. Currently, all requesters in the core code discard stale responses, and cancel the request immediately after they got a non-stale response.

1 files changed, 4 insertions, 0 deletions

diff --git a/include/mbgl/storage/response.hpp b/include/mbgl/storage/response.hpp
index e665f177fc..b232cd06f4 100644
--- a/include/mbgl/storage/response.hpp
+++ b/include/mbgl/storage/response.hpp
@@ -7,9 +7,13 @@ namespace mbgl {
 
 class Response {
 public:
+    bool isExpired() const;
+
+public:
     enum Status { Error, Successful, NotFound };
 
     Status status = Error;
+    bool stale = false;
     std::string message;
     int64_t modified = 0;
     int64_t expires = 0;