[core] Stop download when tile limit is reached

The tile limit guard (when used) stops a download from continuing
when the tile limit is reached. This wraps the guard in a method
and employs it in both places currently necessary to ensure the
guard has a chance to function. Tests have been updated to
ensure the fix works for a less trivial tile limit scenario.

2 files changed, 20 insertions, 7 deletions

diff --git a/platform/default/mbgl/storage/offline_download.cpp b/platform/default/mbgl/storage/offline_download.cpp
index 36b6f5d502..cda00bf8df 100644
--- a/platform/default/mbgl/storage/offline_download.cpp
+++ b/platform/default/mbgl/storage/offline_download.cpp
@@ -229,12 +229,8 @@ void OfflineDownload::ensureResource(const Resource& resource, std::function<voi
 
             return;
         }
-
-        if (resource.kind == Resource::Kind::Tile
-            && util::mapbox::isMapboxURL(resource.url)
-            && offlineDatabase.offlineMapboxTileCountLimitExceeded()) {
-            observer->mapboxTileCountLimitExceeded(offlineDatabase.getOfflineMapboxTileCountLimit());
-            setState(OfflineRegionDownloadState::Inactive);
+        
+        if (checkTileCountLimit(resource)) {
             return;
         }
 
@@ -256,6 +252,10 @@ void OfflineDownload::ensureResource(const Resource& resource, std::function<voi
 
             observer->statusChanged(status);
             
+            if (checkTileCountLimit(resource)) {
+                return;
+            }
+            
             if (status.complete()) {
                 setState(OfflineRegionDownloadState::Inactive);
             }
@@ -263,4 +263,16 @@ void OfflineDownload::ensureResource(const Resource& resource, std::function<voi
     });
 }
 
+bool OfflineDownload::checkTileCountLimit(const Resource& resource) {
+    if (resource.kind == Resource::Kind::Tile
+        && util::mapbox::isMapboxURL(resource.url)
+        && offlineDatabase.offlineMapboxTileCountLimitExceeded()) {
+        observer->mapboxTileCountLimitExceeded(offlineDatabase.getOfflineMapboxTileCountLimit());
+        setState(OfflineRegionDownloadState::Inactive);
+        return true;
+    }
+    
+    return false;
+}
+
 } // namespace mbgl
diff --git a/platform/default/mbgl/storage/offline_download.hpp b/platform/default/mbgl/storage/offline_download.hpp
index d5ba801540..be8e90b251 100644
--- a/platform/default/mbgl/storage/offline_download.hpp
+++ b/platform/default/mbgl/storage/offline_download.hpp
@@ -49,7 +49,8 @@ private:
      */
     void ensureResource(const Resource&, std::function<void (Response)> = {});
     void ensureTiles(SourceType, uint16_t, const SourceInfo&);
-
+    bool checkTileCountLimit(const Resource& resource);
+    
     int64_t id;
     OfflineRegionDefinition definition;
     OfflineDatabase& offlineDatabase;