Change StyleBucket::source to indirect reference

This eliminates a reference loop: VectorTileData holds StyleLayers which
hold StyleBuckets which held Sources which hold VectorTileDatas. This
breaks the StyleBucket -> Source link in favor of manually resolving the
reference where necessary.

src/mbgl/map/map_context.cpp

@@ -139,13 +139,7 @@ void MapContext::updateAnnotationTiles(const std::unordered_set<TileID, TileID::
 
     // grab existing, single shape annotations source
     const auto& shapeID = AnnotationManager::ShapeLayerID;
-
-    const auto source_it = std::find_if(style->sources.begin(), style->sources.end(),
-        [&shapeID](util::ptr<Source> source) {
-        return (source->info.source_id == shapeID);
-    });
-    assert(source_it != style->sources.end());
-    source_it->get()->enabled = true;
+    style->getSource(shapeID)->enabled = true;
 
     // create (if necessary) layers and buckets for each shape
     for (const auto &shapeAnnotationID : data.annotationManager.getOrderedShapeAnnotations()) {
@@ -202,8 +196,8 @@ void MapContext::updateAnnotationTiles(const std::unordered_set<TileID, TileID::
             // create shape bucket & connect to source
             util::ptr<StyleBucket> shapeBucket = std::make_shared<StyleBucket>(shapeLayer->type);
             shapeBucket->name = shapeLayer->id;
+            shapeBucket->source = shapeID;
             shapeBucket->source_layer = shapeLayer->id;
-            shapeBucket->source = *source_it;
 
             // apply line layout properties to bucket
             if (shapeStyle.is<LineProperties>()) {

src/mbgl/renderer/painter.cpp

@@ -323,7 +323,8 @@ std::vector<RenderItem> Painter::determineRenderOrder(const Style& style) {
             continue;
         }
 
-        if (!layer.bucket->source) {
+        util::ptr<Source> source = style.getSource(layer.bucket->source);
+        if (!source) {
             Log::Warning(Event::Render, "can't find source for layer '%s'", layer.id.c_str());
             continue;
         }
@@ -345,7 +346,7 @@ std::vector<RenderItem> Painter::determineRenderOrder(const Style& style) {
         // Determine what render passes we need for this layer.
         const RenderPass passes = determineRenderPasses(layer);
 
-        const auto& tiles = layer.bucket->source->getTiles();
+        const auto& tiles = source->getTiles();
         for (auto tile : tiles) {
             assert(tile);
             if (!tile->data && !tile->data->isReady()) {

src/mbgl/style/style.cpp

@@ -110,12 +110,27 @@ void Style::recalculate(float z, TimePoint now) {
 
     for (const auto& layer : layers) {
         layer->updateProperties(z, now, zoomHistory);
-        if (layer->bucket && layer->bucket->source) {
-            layer->bucket->source->enabled = true;
+        if (!layer->bucket) {
+            continue;
         }
+
+        util::ptr<Source> source = getSource(layer->bucket->source);
+        if (!source) {
+            continue;
+        }
+
+        source->enabled = true;
     }
 }
 
+util::ptr<Source> Style::getSource(const std::string& id) const {
+    const auto it = std::find_if(sources.begin(), sources.end(), [&](util::ptr<Source> source) {
+        return source->info.source_id == id;
+    });
+
+    return it != sources.end() ? *it : nullptr;
+}
+
 void Style::setDefaultTransitionDuration(Duration duration) {
     defaultTransition.duration = duration;
 }

src/mbgl/style/style.hpp

@@ -63,6 +63,8 @@ public:
         return lastError;
     }
 
+    util::ptr<Source> getSource(const std::string& id) const;
+
     std::unique_ptr<GlyphStore> glyphStore;
     std::unique_ptr<GlyphAtlas> glyphAtlas;
     util::ptr<Sprite> sprite;

src/mbgl/style/style_bucket.hpp

@@ -10,8 +10,6 @@
 
 namespace mbgl {
 
-class Source;
-
 class StyleBucket : public util::noncopyable {
 public:
     typedef util::ptr<StyleBucket> Ptr;
@@ -20,7 +18,7 @@ public:
 
     const StyleLayerType type;
     std::string name;
-    util::ptr<Source> source;
+    std::string source;
     std::string source_layer;
     FilterExpression filter;
     ClassProperties layout;

src/mbgl/style/style_parser.cpp

@@ -57,6 +57,7 @@ void StyleParser::parse(JSVal document) {
         // create point annotations symbol bucket
         util::ptr<StyleBucket> pointBucket = std::make_shared<StyleBucket>(pointAnnotationsLayer->type);
         pointBucket->name = pointAnnotationsLayer->id;
+        pointBucket->source = pointID;
         pointBucket->source_layer = pointAnnotationsLayer->id;
 
         // build up point annotations style
@@ -74,7 +75,6 @@ void StyleParser::parse(JSVal document) {
         sources.emplace_back(pointAnnotationsSource);
         pointAnnotationsSource->info.type = SourceType::Annotations;
         pointAnnotationsSource->info.source_id = pointID;
-        pointBucket->source = pointAnnotationsSource;
         pointAnnotationsLayer->bucket = pointBucket;
     }
 
@@ -231,6 +231,7 @@ void StyleParser::parseSources(JSVal value) {
             parseRenderProperty<SourceTypeClass>(itr->value, source->info.type, "type");
             parseRenderProperty(itr->value, source->info.url, "url");
             parseRenderProperty(itr->value, source->info.tile_size, "tileSize");
+            source->info.source_id = name;
             source->info.parseTileJSONProperties(itr->value);
             sources.emplace_back(source);
             sourcesMap.emplace(name, source);
@@ -947,12 +948,10 @@ void StyleParser::parseBucket(JSVal value, util::ptr<StyleLayer> &layer) {
     if (value.HasMember("source")) {
         JSVal value_source = replaceConstant(value["source"]);
         if (value_source.IsString()) {
-            const std::string source_name = { value_source.GetString(), value_source.GetStringLength() };
-            auto source_it = sourcesMap.find(source_name);
-            if (source_it != sourcesMap.end()) {
-                bucket->source = source_it->second;
-            } else {
-                Log::Warning(Event::ParseStyle, "can't find source '%s' required for layer '%s'", source_name.c_str(), layer->id.c_str());
+            bucket->source = { value_source.GetString(), value_source.GetStringLength() };
+            auto source_it = sourcesMap.find(bucket->source);
+            if (source_it == sourcesMap.end()) {
+                Log::Warning(Event::ParseStyle, "can't find source '%s' required for layer '%s'", bucket->source.c_str(), layer->id.c_str());
             }
         } else {
             Log::Warning(Event::ParseStyle, "source of layer '%s' must be a string", layer->id.c_str());