[core] Include prior values of caching headers in Resource

This allows the FileSource interface itself to support revalidation. We could (and probably should) now rewrite HTTPContextBase implementations as FileSource implementations.

2 files changed, 15 insertions, 14 deletions

diff --git a/include/mbgl/storage/resource.hpp b/include/mbgl/storage/resource.hpp
index 1bbd90ea37..8a61702183 100644
--- a/include/mbgl/storage/resource.hpp
+++ b/include/mbgl/storage/resource.hpp
@@ -1,12 +1,15 @@
 #ifndef MBGL_STORAGE_RESOURCE
 #define MBGL_STORAGE_RESOURCE
 
+#include <mbgl/storage/response.hpp>
+#include <mbgl/util/optional.hpp>
+
 #include <string>
-#include <functional>
 
 namespace mbgl {
 
-struct Resource {
+class Resource {
+public:
     enum Kind : uint8_t {
         Unknown = 0,
         Style,
@@ -17,19 +20,17 @@ struct Resource {
         SpriteJSON
     };
 
-    const Kind kind;
-    const std::string url;
-
-    inline bool operator==(const Resource &res) const {
-        return kind == res.kind && url == res.url;
+    Resource(Kind kind_, const std::string& url_)
+        : kind(kind_),
+          url(url_) {
     }
 
-    struct Hash {
-        std::size_t operator()(Resource const& r) const {
-            return std::hash<std::string>()(r.url) ^ (std::hash<uint8_t>()(r.kind) << 1);
-        }
-    };
+    const Kind kind;
+    const std::string url;
 
+    optional<SystemTimePoint> priorModified;
+    optional<SystemTimePoint> priorExpires;
+    optional<std::string> priorEtag;
 };
 
 } // namespace mbgl
diff --git a/include/mbgl/storage/response.hpp b/include/mbgl/storage/response.hpp
index e81af710f7..29af5281fe 100644
--- a/include/mbgl/storage/response.hpp
+++ b/include/mbgl/storage/response.hpp
@@ -23,7 +23,7 @@ public:
     // This is set to true for 304 Not Modified responses.
     bool notModified = false;
 
-    // The actual data of the response. This is guaranteed to never be empty.
+    // The actual data of the response. This is null if notModified is true.
     std::shared_ptr<const std::string> data;
 
     optional<SystemTimePoint> modified;
@@ -34,7 +34,7 @@ public:
 class Response::Error {
 public:
     enum class Reason : uint8_t {
-        // Success = 1, // Reserve 1 for Success.
+        Success = 1,
         NotFound = 2,
         Server = 3,
         Connection = 4,