[core] Fix flickering caused by regression in #7586

It should be safe to invoke GeometryTileWorker::setData multiple times without invoking GeometryTileWorker::setLayers. Therefore GeometryTileWorker::redoLayout() must not consume the layers.

9 files changed, 24 insertions, 22 deletions

diff --git a/src/mbgl/geometry/feature_index.cpp b/src/mbgl/geometry/feature_index.cpp
index a04d9e0606..5019d888ca 100644
--- a/src/mbgl/geometry/feature_index.cpp
+++ b/src/mbgl/geometry/feature_index.cpp
@@ -151,8 +151,8 @@ optional<GeometryCoordinates> FeatureIndex::translateQueryGeometry(
     return translated;
 }
 
-void FeatureIndex::addBucketLayerName(const std::string& bucketName, const std::string& layerID) {
-    bucketLayerIDs[bucketName].push_back(layerID);
+void FeatureIndex::setBucketLayerIDs(const std::string& bucketName, const std::vector<std::string>& layerIDs) {
+    bucketLayerIDs[bucketName] = layerIDs;
 }
 
 } // namespace mbgl
diff --git a/src/mbgl/geometry/feature_index.hpp b/src/mbgl/geometry/feature_index.hpp
index 662e78aa2c..ca813f4b6b 100644
--- a/src/mbgl/geometry/feature_index.hpp
+++ b/src/mbgl/geometry/feature_index.hpp
@@ -52,7 +52,7 @@ public:
             const float bearing,
             const float pixelsToTileUnits);
 
-    void addBucketLayerName(const std::string& bucketName, const std::string& layerName);
+    void setBucketLayerIDs(const std::string& bucketName, const std::vector<std::string>& layerIDs);
 
 private:
     void addFeature(
diff --git a/src/mbgl/layout/symbol_layout.cpp b/src/mbgl/layout/symbol_layout.cpp
index 85e0b19609..eaa0332995 100644
--- a/src/mbgl/layout/symbol_layout.cpp
+++ b/src/mbgl/layout/symbol_layout.cpp
@@ -27,7 +27,7 @@ namespace mbgl {
 
 using namespace style;
 
-SymbolLayout::SymbolLayout(std::vector<std::unique_ptr<Layer>> layers_,
+SymbolLayout::SymbolLayout(std::vector<std::string> layerIDs_,
                            std::string sourceLayerName_,
                            uint32_t overscaling_,
                            float zoom_,
@@ -37,7 +37,7 @@ SymbolLayout::SymbolLayout(std::vector<std::unique_ptr<Layer>> layers_,
                            style::SymbolLayoutProperties::Evaluated layout_,
                            float textMaxSize_,
                            SpriteAtlas& spriteAtlas_)
-    : layers(std::move(layers_)),
+    : layerIDs(std::move(layerIDs_)),
       sourceLayerName(std::move(sourceLayerName_)),
       overscaling(overscaling_),
       zoom(zoom_),
@@ -254,7 +254,7 @@ void SymbolLayout::addFeature(const SymbolFeature& feature,
                                                   ? SymbolPlacementType::Point
                                                   : layout.get<SymbolPlacement>();
     const float textRepeatDistance = symbolSpacing / 2;
-    IndexedSubfeature indexedFeature = {feature.index, sourceLayerName, layers.at(0)->getID(), symbolInstances.size()};
+    IndexedSubfeature indexedFeature = {feature.index, sourceLayerName, layerIDs.at(0), symbolInstances.size()};
 
     auto addSymbolInstance = [&] (const GeometryCoordinates& line, Anchor& anchor) {
         // https://github.com/mapbox/vector-tile-spec/tree/master/2.1#41-layers
diff --git a/src/mbgl/layout/symbol_layout.hpp b/src/mbgl/layout/symbol_layout.hpp
index 63c0a8859d..c89b791ccc 100644
--- a/src/mbgl/layout/symbol_layout.hpp
+++ b/src/mbgl/layout/symbol_layout.hpp
@@ -28,7 +28,7 @@ struct Anchor;
 
 class SymbolLayout {
 public:
-    SymbolLayout(std::vector<std::unique_ptr<style::Layer>>,
+    SymbolLayout(std::vector<std::string> layerIDs_,
                  std::string sourceLayerName_,
                  uint32_t overscaling,
                  float zoom,
@@ -56,7 +56,7 @@ public:
 
     State state = Pending;
 
-    const std::vector<std::unique_ptr<style::Layer>> layers;
+    const std::vector<std::string> layerIDs;
     const std::string sourceLayerName;
 
 private:
diff --git a/src/mbgl/style/group_by_layout.cpp b/src/mbgl/style/group_by_layout.cpp
index 52d33827ef..b15fe1ca0d 100644
--- a/src/mbgl/style/group_by_layout.cpp
+++ b/src/mbgl/style/group_by_layout.cpp
@@ -32,16 +32,15 @@ std::string layoutKey(const Layer& layer) {
     return s.GetString();
 }
 
-std::vector<std::vector<std::unique_ptr<Layer>>> groupByLayout(std::vector<std::unique_ptr<Layer>> layers) {
-    std::unordered_map<std::string, std::vector<std::unique_ptr<Layer>>> map;
+std::vector<std::vector<const Layer*>> groupByLayout(const std::vector<std::unique_ptr<Layer>>& layers) {
+    std::unordered_map<std::string, std::vector<const Layer*>> map;
     for (auto& layer : layers) {
-        auto& vector = map[layoutKey(*layer)];
-        vector.push_back(std::move(layer));
+        map[layoutKey(*layer)].push_back(layer.get());
     }
 
-    std::vector<std::vector<std::unique_ptr<Layer>>> result;
+    std::vector<std::vector<const Layer*>> result;
     for (auto& pair : map) {
-        result.push_back(std::move(pair.second));
+        result.push_back(pair.second);
     }
 
     return result;
diff --git a/src/mbgl/style/group_by_layout.hpp b/src/mbgl/style/group_by_layout.hpp
index dd7b5d118a..3a89ac95f3 100644
--- a/src/mbgl/style/group_by_layout.hpp
+++ b/src/mbgl/style/group_by_layout.hpp
@@ -8,7 +8,7 @@ namespace style {
 
 class Layer;
 
-std::vector<std::vector<std::unique_ptr<Layer>>> groupByLayout(std::vector<std::unique_ptr<Layer>>);
+std::vector<std::vector<const Layer*>> groupByLayout(const std::vector<std::unique_ptr<Layer>>&);
 
 } // namespace style
 } // namespace mbgl
diff --git a/src/mbgl/style/layers/symbol_layer_impl.cpp b/src/mbgl/style/layers/symbol_layer_impl.cpp
index 8fb85513cf..f058598f5f 100644
--- a/src/mbgl/style/layers/symbol_layer_impl.cpp
+++ b/src/mbgl/style/layers/symbol_layer_impl.cpp
@@ -31,7 +31,7 @@ std::unique_ptr<Bucket> SymbolLayer::Impl::createBucket(BucketParameters&, const
 
 std::unique_ptr<SymbolLayout> SymbolLayer::Impl::createLayout(BucketParameters& parameters,
                                                               const GeometryTileLayer& layer,
-                                                              std::vector<std::unique_ptr<Layer>> group) const {
+                                                              std::vector<std::string> group) const {
     PropertyEvaluationParameters p(parameters.tileID.overscaledZ);
     SymbolLayoutProperties::Evaluated evaluated = layout.evaluate(p);
 
diff --git a/src/mbgl/style/layers/symbol_layer_impl.hpp b/src/mbgl/style/layers/symbol_layer_impl.hpp
index 0d9a7c07e3..db18da07e2 100644
--- a/src/mbgl/style/layers/symbol_layer_impl.hpp
+++ b/src/mbgl/style/layers/symbol_layer_impl.hpp
@@ -52,7 +52,7 @@ public:
 
     std::unique_ptr<Bucket> createBucket(BucketParameters&, const GeometryTileLayer&) const override;
     std::unique_ptr<SymbolLayout> createLayout(BucketParameters&, const GeometryTileLayer&,
-                                               std::vector<std::unique_ptr<Layer>>) const;
+                                               std::vector<std::string>) const;
 
     SymbolPropertyValues iconPropertyValues(const SymbolLayoutProperties::Evaluated&) const;
     SymbolPropertyValues textPropertyValues(const SymbolLayoutProperties::Evaluated&) const;
diff --git a/src/mbgl/tile/geometry_tile_worker.cpp b/src/mbgl/tile/geometry_tile_worker.cpp
index 169339f13f..2a86b7feda 100644
--- a/src/mbgl/tile/geometry_tile_worker.cpp
+++ b/src/mbgl/tile/geometry_tile_worker.cpp
@@ -214,7 +214,7 @@ void GeometryTileWorker::redoLayout() {
     auto featureIndex = std::make_unique<FeatureIndex>();
     BucketParameters parameters { id, obsolete, *featureIndex, mode };
 
-    std::vector<std::vector<std::unique_ptr<Layer>>> groups = groupByLayout(std::move(*layers));
+    std::vector<std::vector<const Layer*>> groups = groupByLayout(*layers);
     for (auto& group : groups) {
         if (obsolete) {
             return;
@@ -231,13 +231,16 @@ void GeometryTileWorker::redoLayout() {
             continue;
         }
 
+        std::vector<std::string> layerIDs;
         for (const auto& layer : group) {
-            featureIndex->addBucketLayerName(leader.getID(), layer->getID());
+            layerIDs.push_back(layer->getID());
         }
 
+        featureIndex->setBucketLayerIDs(leader.getID(), layerIDs);
+
         if (leader.is<SymbolLayer>()) {
             symbolLayoutMap.emplace(leader.getID(),
-                leader.as<SymbolLayer>()->impl->createLayout(parameters, *geometryLayer, std::move(group)));
+                leader.as<SymbolLayer>()->impl->createLayout(parameters, *geometryLayer, layerIDs));
         } else {
             std::shared_ptr<Bucket> bucket = leader.baseImpl->createBucket(parameters, *geometryLayer);
             if (!bucket->hasData()) {
@@ -321,8 +324,8 @@ void GeometryTileWorker::attemptPlacement() {
         }
 
         std::shared_ptr<Bucket> bucket = symbolLayout->place(*collisionTile);
-        for (const auto& layer : symbolLayout->layers) {
-            buckets.emplace(layer->getID(), bucket);
+        for (const auto& layerID : symbolLayout->layerIDs) {
+            buckets.emplace(layerID, bucket);
         }
     }