[core] TylePyramid has sorted render tiles

Thus we obviate unneeded extra sorting of render tiles at each rener layer.

src/mbgl/renderer/render_layer.cpp

@@ -43,7 +43,7 @@ RenderLayer::RenderTiles RenderLayer::filterRenderTiles(RenderTiles tiles) const
 }
 
 void RenderLayer::sortRenderTiles(const TransformState&) {
-    std::sort(renderTiles.begin(), renderTiles.end(), [](const auto& a, const auto& b) { return a.get().id < b.get().id; });
+    // no-op
 }
 
 const RenderLayerSymbolInterface* RenderLayer::getSymbolInterface() const {

src/mbgl/renderer/render_source.hpp

@@ -58,7 +58,7 @@ class RenderSource : protected TileObserver {
     virtual void startRender(PaintParameters&) = 0;
     virtual void finishRender(PaintParameters&) = 0;
 
-    // Returns an unsorted list of RenderTiles.
+    // Returns a list of RenderTiles, sorted by tile id.
     virtual std::vector<std::reference_wrapper<RenderTile>> getRenderTiles() = 0;
 
     virtual std::unordered_map<std::string, std::vector<Feature>>

src/mbgl/renderer/sources/render_geojson_source.cpp

@@ -96,11 +96,11 @@ void RenderGeoJSONSource::update(Immutable<style::Source::Impl> baseImpl_,
 
     if (data.lock() != data_) {
         data = data_;
-        tilePyramid.cache.clear();
+        tilePyramid.reduceMemoryUse();
 
         if (data_) {
             const uint8_t maxZ = impl().getZoomRange().max;
-            for (const auto& pair : tilePyramid.tiles) {
+            for (const auto& pair : tilePyramid.getTiles()) {
                 if (pair.first.canonical.z <= maxZ) {
                     static_cast<GeoJSONTile*>(pair.second.get())->updateData(data_->getTile(pair.first.canonical));
                 }
@@ -109,8 +109,7 @@ void RenderGeoJSONSource::update(Immutable<style::Source::Impl> baseImpl_,
     }
 
     if (!data_) {
-        tilePyramid.tiles.clear();
-        tilePyramid.renderTiles.clear();
+        tilePyramid.clearAll();
         return;
     }
 

src/mbgl/renderer/sources/render_raster_dem_source.cpp

@@ -38,9 +38,7 @@ void RenderRasterDEMSource::update(Immutable<style::Source::Impl> baseImpl_,
         maxzoom = tileset->zoomRange.max;
         // TODO: this removes existing buckets, and will cause flickering.
         // Should instead refresh tile data in place.
-        tilePyramid.tiles.clear();
-        tilePyramid.renderTiles.clear();
-        tilePyramid.cache.clear();
+        tilePyramid.clearAll();
     }
     // Allow clearing the tile pyramid first, before the early return in case
     //  the new tileset is not yet available or has an error in loading

src/mbgl/renderer/sources/render_raster_source.cpp

@@ -36,9 +36,7 @@ void RenderRasterSource::update(Immutable<style::Source::Impl> baseImpl_,
 
         // TODO: this removes existing buckets, and will cause flickering.
         // Should instead refresh tile data in place.
-        tilePyramid.tiles.clear();
-        tilePyramid.renderTiles.clear();
-        tilePyramid.cache.clear();
+        tilePyramid.clearAll();
     }
     // Allow clearing the tile pyramid first, before the early return in case
     //  the new tileset is not yet available or has an error in loading

src/mbgl/renderer/sources/render_vector_source.cpp

@@ -39,9 +39,7 @@ void RenderVectorSource::update(Immutable<style::Source::Impl> baseImpl_,
 
         // TODO: this removes existing buckets, and will cause flickering.
         // Should instead refresh tile data in place.
-        tilePyramid.tiles.clear();
-        tilePyramid.renderTiles.clear();
-        tilePyramid.cache.clear();
+        tilePyramid.clearAll();
     }
     // Allow clearing the tile pyramid first, before the early return in case
     //  the new tileset is not yet available or has an error in loading

src/mbgl/renderer/tile_pyramid.cpp

@@ -53,7 +53,7 @@ void TilePyramid::finishRender(PaintParameters& parameters) {
 }
 
 std::vector<std::reference_wrapper<RenderTile>> TilePyramid::getRenderTiles() {
-    return { renderTiles.begin(), renderTiles.end() };
+    return sortedTiles;
 }
 
 Tile* TilePyramid::getTile(const OverscaledTileID& tileID){
@@ -85,7 +85,7 @@ void TilePyramid::update(const std::vector<Immutable<style::Layer::Impl>>& layer
         }
 
         tiles.clear();
-        renderTiles.clear();
+        clearRenderTiles();
 
         return;
     }
@@ -183,7 +183,7 @@ void TilePyramid::update(const std::vector<Immutable<style::Layer::Impl>>& layer
         tile.markRenderedIdeal();
     };
 
-    renderTiles.clear();
+    clearRenderTiles();
 
     if (!panTiles.empty()) {
         algorithm::updateRenderables(getTileFn, createTileFn, retainTileFn,
@@ -205,6 +205,9 @@ void TilePyramid::update(const std::vector<Immutable<style::Layer::Impl>>& layer
         }
     }
 
+    sortedTiles = std::vector<std::reference_wrapper<RenderTile>>(renderTiles.begin(), renderTiles.end());
+    std::sort(sortedTiles.begin(), sortedTiles.end(), [](const RenderTile& a, const RenderTile& b) { return a.id < b.id; });
+
     if (type != SourceType::Annotations) {
         size_t conservativeCacheSize =
             std::max((float)parameters.transformState.getSize().width / tileSize, 1.0f) *
@@ -297,13 +300,6 @@ std::unordered_map<std::string, std::vector<Feature>> TilePyramid::queryRendered
 
     mapbox::geometry::box<double> box = mapbox::geometry::envelope(queryGeometry);
 
-    std::vector<std::reference_wrapper<const RenderTile>> sortedTiles{ renderTiles.begin(),
-                                                                       renderTiles.end() };
-    std::sort(sortedTiles.begin(), sortedTiles.end(), [](const RenderTile& a, const RenderTile& b) {
-        return std::tie(a.id.canonical.z, a.id.canonical.y, a.id.wrap, a.id.canonical.x) <
-            std::tie(b.id.canonical.z, b.id.canonical.y, b.id.wrap, b.id.canonical.x);
-    });
-
     auto maxPitchScaleFactor = transformState.maxPitchScaleFactor();
 
     for (const RenderTile& renderTile : sortedTiles) {
@@ -365,4 +361,15 @@ void TilePyramid::dumpDebugLogs() const {
     }
 }
 
+void TilePyramid::clearAll() {
+    tiles.clear();
+    clearRenderTiles();
+    cache.clear();
+}
+
+void TilePyramid::clearRenderTiles() {
+    renderTiles.clear();
+    sortedTiles.clear();
+}
+
 } // namespace mbgl

src/mbgl/renderer/tile_pyramid.hpp

@@ -66,12 +66,16 @@ class TilePyramid {
     void setObserver(TileObserver*);
     void dumpDebugLogs() const;
 
-    bool enabled = false;
+    const std::map<OverscaledTileID, std::unique_ptr<Tile>>& getTiles() const { return tiles; }
+    void clearAll();
 
+private:
     std::map<OverscaledTileID, std::unique_ptr<Tile>> tiles;
     TileCache cache;
 
     std::vector<RenderTile> renderTiles;
+    std::vector<std::reference_wrapper<RenderTile>> sortedTiles;
+    void clearRenderTiles();
 
     TileObserver* observer = nullptr;