Add partial tile parsing

This change will add a new state to the tile called "partial" which
is a state where the tile can be rendered but some information might
be missing.

For now we skip the SymbolBucket if the Sprites are not loaded (will
also do the same for the glyphs in the future). When the Sprites are
finally loaded, we trigger another update, this time the Tile will
get completely re-rendered and change the state to "parsed".

1 files changed, 13 insertions, 4 deletions

diff --git a/src/mbgl/map/vector_tile_data.hpp b/src/mbgl/map/vector_tile_data.hpp
index 10eaf9c184..146bc93229 100644
--- a/src/mbgl/map/vector_tile_data.hpp
+++ b/src/mbgl/map/vector_tile_data.hpp
@@ -10,6 +10,7 @@
 
 #include <iosfwd>
 #include <memory>
+#include <mutex>
 #include <unordered_map>
 
 namespace mbgl {
@@ -42,6 +43,8 @@ public:
     void parse() override;
     virtual Bucket* getBucket(StyleLayer const &layer_desc) override;
 
+    void setBucket(StyleLayer const &layer_desc, std::unique_ptr<Bucket> bucket);
+
 protected:
     // Holds the actual geometries in this tile.
     FillVertexBuffer fillVertexBuffer;
@@ -50,16 +53,22 @@ protected:
     TriangleElementsBuffer triangleElementsBuffer;
     LineElementsBuffer lineElementsBuffer;
 
-    // Holds the buckets of this tile.
-    // They contain the location offsets in the buffers stored above
-    std::unordered_map<std::string, std::unique_ptr<Bucket>> buckets;
-
     GlyphAtlas& glyphAtlas;
     GlyphStore& glyphStore;
     SpriteAtlas& spriteAtlas;
     util::ptr<Sprite> sprite;
     Style& style;
 
+private:
+    // Contains all the Bucket objects for the tile. Buckets are render
+    // objects and they get added to this std::map<> by the workers doing
+    // the actual tile parsing as they get processed. Tiles partially
+    // parsed can get new buckets at any moment but are also fit for
+    // rendering. That said, access to this list needs locking unless
+    // the tile is completely parsed.
+    std::unordered_map<std::string, std::unique_ptr<Bucket>> buckets;
+    mutable std::mutex bucketsMutex;
+
 public:
     const float depth;
 };