[core] make forcing cache/network only more explicit

Previously, we used the existence of a `prior*` field in the Resource object as an indication for whether we should consult the cache or not. However, this is prone to error, since a failed cache lookup won't set any prior fields. Therefore, we manually set `priorExpires` to 0. This in turn triggered another bug where generated wrong expiration timestamps when the server response we got was expired (or expired between sending and receiving).

This commit changes the flags so that we can now explicitly request CacheOnly/NetworkOnly (or All) loading methods, rather than the implicit Optional/Required naming scheme.

1 files changed, 5 insertions, 7 deletions

diff --git a/src/mbgl/tile/tile_loader.hpp b/src/mbgl/tile/tile_loader.hpp
index bc408ebaf6..92ca74330f 100644
--- a/src/mbgl/tile/tile_loader.hpp
+++ b/src/mbgl/tile/tile_loader.hpp
@@ -21,12 +21,10 @@ public:
                const Tileset&);
     ~TileLoader();
 
-    using Necessity = Resource::Necessity;
-
-    void setNecessity(Necessity newNecessity) {
+    void setNecessity(TileNecessity newNecessity) {
         if (newNecessity != necessity) {
             necessity = newNecessity;
-            if (necessity == Necessity::Required) {
+            if (necessity == TileNecessity::Required) {
                 makeRequired();
             } else {
                 makeOptional();
@@ -45,12 +43,12 @@ private:
     // an up-to-date version or load new data
     void makeOptional();
 
-    void loadOptional();
+    void loadFromCache();
     void loadedData(const Response&);
-    void loadRequired();
+    void loadFromNetwork();
 
     T& tile;
-    Necessity necessity;
+    TileNecessity necessity;
     Resource resource;
     FileSource& fileSource;
     std::unique_ptr<AsyncRequest> request;