[core] Synchronize state of CollisionIndex and FeatureIndexes.

Fixes issue #10778, in which mismatch between FeatureIndex and CollisionIndex could lead to inconsistent results or even invalid array access.

2 files changed, 14 insertions, 0 deletions

diff --git a/src/mbgl/renderer/renderer_impl.cpp b/src/mbgl/renderer/renderer_impl.cpp
index 9fe421fa14..8e5968d4c2 100644
--- a/src/mbgl/renderer/renderer_impl.cpp
+++ b/src/mbgl/renderer/renderer_impl.cpp
@@ -389,6 +389,10 @@ void Renderer::Impl::render(const UpdateParameters& updateParameters) {
         }
 
         placementChanged = newPlacement->commit(*placement, parameters.timePoint);
+        // commitFeatureIndexes depends on the assumption that no new FeatureIndex has been loaded since placement
+        // started. If we violate this assumption, then we need to either make CollisionIndex completely independendent of
+        // FeatureIndex, or find a way for its entries to point to multiple FeatureIndexes.
+        commitFeatureIndexes();
         if (placementChanged || symbolBucketsChanged) {
             placement = std::move(newPlacement);
         }
@@ -768,6 +772,15 @@ bool Renderer::Impl::hasTransitions(TimePoint timePoint) const {
     return false;
 }
 
+void Renderer::Impl::commitFeatureIndexes() {
+    for (auto& source : renderSources) {
+        for (auto& renderTile : source.second->getRenderTiles()) {
+            Tile& tile = renderTile.get().tile;
+            tile.commitFeatureIndex();
+        }
+    }
+}
+
 void Renderer::Impl::updateFadingTiles() {
     fadingTiles = false;
     for (auto& source : renderSources) {
diff --git a/src/mbgl/renderer/renderer_impl.hpp b/src/mbgl/renderer/renderer_impl.hpp
index 5d0200a5df..4f45d514a5 100644
--- a/src/mbgl/renderer/renderer_impl.hpp
+++ b/src/mbgl/renderer/renderer_impl.hpp
@@ -74,6 +74,7 @@ private:
     void onTileChanged(RenderSource&, const OverscaledTileID&) override;
     void onTileError(RenderSource&, const OverscaledTileID&, std::exception_ptr) override;
 
+    void commitFeatureIndexes();
     void updateFadingTiles();
 
     friend class Renderer;