Move the Collision object from TileParser to VectorTileData

We keep the Collision object alive longer because we need it
for the SymbolBuckets yet to be created in case more data
resources arrive. When the tile is no longer needed or if it
is completely parsed or obsolete (i.e. in a immutable state)
we throw the Collision object away.

src/mbgl/map/tile_parser.cpp

@@ -8,7 +8,6 @@
 #include <mbgl/renderer/line_bucket.hpp>
 #include <mbgl/renderer/symbol_bucket.hpp>
 #include <mbgl/util/constants.hpp>
-#include <mbgl/text/collision.hpp>
 #include <mbgl/util/std.hpp>
 #include <mbgl/style/style.hpp>
 
@@ -35,10 +34,8 @@ TileParser::TileParser(const GeometryTile& geometryTile_,
       glyphStore(glyphStore_),
       spriteAtlas(spriteAtlas_),
       sprite(sprite_),
-      collision(util::make_unique<Collision>(tile.id.z, 4096, tile.source.tile_size, tile.depth)),
       partialParse(false) {
     assert(sprite);
-    assert(collision);
 }
 
 bool TileParser::obsolete() const {
@@ -196,7 +193,7 @@ std::unique_ptr<Bucket> TileParser::createSymbolBucket(const GeometryTileLayer&
         return nullptr;
     }
 
-    auto bucket = util::make_unique<SymbolBucket>(*collision);
+    auto bucket = util::make_unique<SymbolBucket>(*tile.getCollision());
 
     const float z = tile.id.z;
     auto& layout = bucket->layout;

src/mbgl/map/tile_parser.hpp

@@ -29,7 +29,6 @@ class StyleLayoutRaster;
 class StyleLayoutLine;
 class StyleLayoutSymbol;
 class VectorTileData;
-class Collision;
 
 class TileParser : private util::noncopyable {
 public:
@@ -69,7 +68,6 @@ private:
     SpriteAtlas& spriteAtlas;
     util::ptr<Sprite> sprite;
 
-    std::unique_ptr<Collision> collision;
     bool partialParse;
 };
 

src/mbgl/map/vector_tile_data.cpp

@@ -6,6 +6,7 @@
 #include <mbgl/map/source.hpp>
 #include <mbgl/geometry/glyph_atlas.hpp>
 #include <mbgl/platform/log.hpp>
+#include <mbgl/text/collision.hpp>
 #include <mbgl/util/pbf.hpp>
 
 using namespace mbgl;
@@ -19,12 +20,13 @@ VectorTileData::VectorTileData(const TileID& id_,
                                util::ptr<Sprite> sprite_,
                                const SourceInfo& source_)
     : TileData(id_, source_),
+      depth(id_.z >= source_.max_zoom ? mapMaxZoom - id_.z : 1),
       glyphAtlas(glyphAtlas_),
       glyphStore(glyphStore_),
       spriteAtlas(spriteAtlas_),
       sprite(sprite_),
       style(style_),
-      depth(id.z >= source.max_zoom ? mapMaxZoom - id.z : 1) {
+      collision(util::make_unique<Collision>(id_.z, 4096, source_.tile_size, depth)) {
 }
 
 VectorTileData::~VectorTileData() {
@@ -91,3 +93,11 @@ void VectorTileData::setBucket(StyleLayer const& layer, std::unique_ptr<Bucket>
 
     buckets[layer.bucket->name] = std::move(bucket);
 }
+
+void VectorTileData::setState(const State& state_) {
+    TileData::setState(state_);
+
+    if (isImmutable()) {
+        collision.reset();
+    }
+}

src/mbgl/map/vector_tile_data.hpp

@@ -16,6 +16,7 @@
 namespace mbgl {
 
 class Bucket;
+class Collision;
 class Painter;
 class SourceInfo;
 class StyleLayer;
@@ -45,6 +46,14 @@ public:
 
     void setBucket(StyleLayer const &layer_desc, std::unique_ptr<Bucket> bucket);
 
+    void setState(const State& state) override;
+
+    inline Collision* getCollision() const {
+        return collision.get();
+    }
+
+    const float depth;
+
 protected:
     // Holds the actual geometries in this tile.
     FillVertexBuffer fillVertexBuffer;
@@ -69,8 +78,7 @@ private:
     std::unordered_map<std::string, std::unique_ptr<Bucket>> buckets;
     mutable std::mutex bucketsMutex;
 
-public:
-    const float depth;
+    std::unique_ptr<Collision> collision;
 };
 
 }