[core] Calculate GeoJSON tile geometries in a background thread

Call `mapbox::geojsonvt::GeoJSONVT::getTile()` in a background
thread, so that the rendering thread is not blocked.

6 files changed, 86 insertions, 52 deletions

diff --git a/include/mbgl/style/sources/geojson_source.hpp b/include/mbgl/style/sources/geojson_source.hpp
index 1cc104b245..9569b61df4 100644
--- a/include/mbgl/style/sources/geojson_source.hpp
+++ b/include/mbgl/style/sources/geojson_source.hpp
@@ -39,17 +39,19 @@ struct GeoJSONOptions {
 };
 class GeoJSONData {
 public:
+    using TileFeatures = mapbox::feature::feature_collection<int16_t>;
+    using Features = mapbox::feature::feature_collection<double>;
     static std::shared_ptr<GeoJSONData> create(const GeoJSON&,
                                                Immutable<GeoJSONOptions> = GeoJSONOptions::defaultOptions());
 
     virtual ~GeoJSONData() = default;
-    virtual mapbox::feature::feature_collection<int16_t> getTile(const CanonicalTileID&) = 0;
+    virtual void getTile(const CanonicalTileID&, const std::function<void(TileFeatures)>&) = 0;
 
     // SuperclusterData
-    virtual mapbox::feature::feature_collection<double> getChildren(const std::uint32_t) = 0;
-    virtual mapbox::feature::feature_collection<double> getLeaves(const std::uint32_t,
-                                                                  const std::uint32_t limit = 10u,
-                                                                  const std::uint32_t offset = 0u) = 0;
+    virtual Features getChildren(const std::uint32_t) = 0;
+    virtual Features getLeaves(const std::uint32_t,
+                               const std::uint32_t limit = 10u,
+                               const std::uint32_t offset = 0u) = 0;
     virtual std::uint8_t getClusterExpansionZoom(std::uint32_t) = 0;
 };
 
diff --git a/src/mbgl/renderer/sources/render_geojson_source.cpp b/src/mbgl/renderer/sources/render_geojson_source.cpp
index 4ed9dd9334..94d171cf18 100644
--- a/src/mbgl/renderer/sources/render_geojson_source.cpp
+++ b/src/mbgl/renderer/sources/render_geojson_source.cpp
@@ -95,8 +95,7 @@ void RenderGeoJSONSource::update(Immutable<style::Source::Impl> baseImpl_,
             const uint8_t maxZ = impl().getZoomRange().max;
             for (const auto& pair : tilePyramid.getTiles()) {
                 if (pair.first.canonical.z <= maxZ) {
-                    static_cast<GeoJSONTile*>(pair.second.get())
-                        ->updateData(data_->getTile(pair.first.canonical), needsRelayout);
+                    static_cast<GeoJSONTile*>(pair.second.get())->updateData(data_, needsRelayout);
                 }
             }
         }
@@ -112,8 +111,8 @@ void RenderGeoJSONSource::update(Immutable<style::Source::Impl> baseImpl_,
                        util::tileSize,
                        impl().getZoomRange(),
                        optional<LatLngBounds>{},
-                       [&, data_] (const OverscaledTileID& tileID) {
-                           return std::make_unique<GeoJSONTile>(tileID, impl().id, parameters, data_->getTile(tileID.canonical));
+                       [&, data_](const OverscaledTileID& tileID) {
+                           return std::make_unique<GeoJSONTile>(tileID, impl().id, parameters, data_);
                        });
 }
 
diff --git a/src/mbgl/style/sources/geojson_source_impl.cpp b/src/mbgl/style/sources/geojson_source_impl.cpp
index 962d6bd060..e4b48223f4 100644
--- a/src/mbgl/style/sources/geojson_source_impl.cpp
+++ b/src/mbgl/style/sources/geojson_source_impl.cpp
@@ -3,6 +3,7 @@
 #include <mbgl/util/constants.hpp>
 #include <mbgl/util/feature.hpp>
 #include <mbgl/util/string.hpp>
+#include <mbgl/util/thread_pool.hpp>
 
 #include <mapbox/geojsonvt.hpp>
 #include <supercluster.hpp>
@@ -18,18 +19,16 @@ public:
         : impl(geoJSON, options) {
     }
 
-    mapbox::feature::feature_collection<int16_t> getTile(const CanonicalTileID& tileID) final {
-        return impl.getTile(tileID.z, tileID.x, tileID.y).features;
+    void getTile(const CanonicalTileID& id, const std::function<void(TileFeatures)>& fn) final {
+        assert(fn);
+        // It's safe to pass `this` as scheduler will die earlier.
+        scheduler.scheduleAndReplyValue(
+            [id, this]() -> TileFeatures { return impl.getTile(id.z, id.x, id.y).features; }, fn);
     }
 
-    mapbox::feature::feature_collection<double> getChildren(const std::uint32_t) final {
-        return {};
-    }
+    Features getChildren(const std::uint32_t) final { return {}; }
 
-    mapbox::feature::feature_collection<double>
-    getLeaves(const std::uint32_t, const std::uint32_t, const std::uint32_t) final {
-        return {};
-    }
+    Features getLeaves(const std::uint32_t, const std::uint32_t, const std::uint32_t) final { return {}; }
 
     std::uint8_t getClusterExpansionZoom(std::uint32_t) final {
         return 0;
@@ -37,26 +36,22 @@ public:
 
 private:
     mapbox::geojsonvt::GeoJSONVT impl;
+    SequencedScheduler scheduler;
 };
 
 class SuperclusterData : public GeoJSONData {
 public:
-    SuperclusterData(const mapbox::feature::feature_collection<double>& features,
-                     const mapbox::supercluster::Options& options)
-        : impl(features, options) {
-    }
+    SuperclusterData(const Features& features, const mapbox::supercluster::Options& options)
+        : impl(features, options) {}
 
-    mapbox::feature::feature_collection<int16_t> getTile(const CanonicalTileID& tileID) final {
-        return impl.getTile(tileID.z, tileID.x, tileID.y);
+    void getTile(const CanonicalTileID& id, const std::function<void(TileFeatures)>& fn) final {
+        assert(fn);
+        fn(impl.getTile(id.z, id.x, id.y));
     }
 
-    mapbox::feature::feature_collection<double> getChildren(const std::uint32_t cluster_id) final {
-        return impl.getChildren(cluster_id);
-    }
+    Features getChildren(const std::uint32_t cluster_id) final { return impl.getChildren(cluster_id); }
 
-    mapbox::feature::feature_collection<double> getLeaves(const std::uint32_t cluster_id,
-                                                          const std::uint32_t limit,
-                                                          const std::uint32_t offset) final {
+    Features getLeaves(const std::uint32_t cluster_id, const std::uint32_t limit, const std::uint32_t offset) final {
         return impl.getLeaves(cluster_id, limit, offset);
     }
 
@@ -85,8 +80,7 @@ T evaluateFeature(const mapbox::feature::feature<double>& f,
 // static
 std::shared_ptr<GeoJSONData> GeoJSONData::create(const GeoJSON& geoJSON, Immutable<GeoJSONOptions> options) {
     constexpr double scale = util::EXTENT / util::tileSize;
-    if (options->cluster && geoJSON.is<mapbox::feature::feature_collection<double>>() &&
-        !geoJSON.get<mapbox::feature::feature_collection<double>>().empty()) {
+    if (options->cluster && geoJSON.is<Features>() && !geoJSON.get<Features>().empty()) {
         mapbox::supercluster::Options clusterOptions;
         clusterOptions.maxZoom = options->clusterMaxZoom;
         clusterOptions.extent = util::EXTENT;
@@ -111,8 +105,7 @@ std::shared_ptr<GeoJSONData> GeoJSONData::create(const GeoJSON& geoJSON, Immutab
                 toReturn[p.first] = evaluateFeature<Value>(*feature, p.second.second, accumulated);
             }
         };
-        return std::make_shared<SuperclusterData>(geoJSON.get<mapbox::feature::feature_collection<double>>(),
-                                                  clusterOptions);
+        return std::make_shared<SuperclusterData>(geoJSON.get<Features>(), clusterOptions);
     }
 
     mapbox::geojsonvt::Options vtOptions;
diff --git a/src/mbgl/tile/geojson_tile.cpp b/src/mbgl/tile/geojson_tile.cpp
index 0782f74d5d..a4c48fb809 100644
--- a/src/mbgl/tile/geojson_tile.cpp
+++ b/src/mbgl/tile/geojson_tile.cpp
@@ -1,20 +1,29 @@
-#include <mbgl/tile/geojson_tile.hpp>
-#include <mbgl/tile/geojson_tile_data.hpp>
 #include <mbgl/renderer/query.hpp>
 #include <mbgl/renderer/tile_parameters.hpp>
-
+#include <mbgl/style/sources/geojson_source.hpp>
+#include <mbgl/tile/geojson_tile.hpp>
+#include <mbgl/tile/geojson_tile_data.hpp>
 namespace mbgl {
 
 GeoJSONTile::GeoJSONTile(const OverscaledTileID& overscaledTileID,
                          std::string sourceID_,
                          const TileParameters& parameters,
-                         mapbox::feature::feature_collection<int16_t> features)
+                         std::shared_ptr<style::GeoJSONData> data_)
     : GeometryTile(overscaledTileID, sourceID_, parameters) {
-    updateData(std::move(features));
+    updateData(std::move(data_));
 }
 
-void GeoJSONTile::updateData(mapbox::feature::feature_collection<int16_t> features, bool resetLayers) {
-    setData(std::make_unique<GeoJSONTileData>(std::move(features)), resetLayers);
+void GeoJSONTile::updateData(std::shared_ptr<style::GeoJSONData> data_, bool resetLayers) {
+    assert(data_);
+    data = std::move(data_);
+    data->getTile(id.canonical,
+                  [this, self = weakFactory.makeWeakPtr(), capturedData = data.get(), resetLayers](
+                      style::GeoJSONData::TileFeatures features) {
+                      if (!self) return;
+                      if (data.get() != capturedData) return;
+                      auto tileData = std::make_unique<GeoJSONTileData>(std::move(features));
+                      setData(std::move(tileData), resetLayers);
+                  });
 }
 
 void GeoJSONTile::querySourceFeatures(
diff --git a/src/mbgl/tile/geojson_tile.hpp b/src/mbgl/tile/geojson_tile.hpp
index 9161e33f0c..26dc300bdc 100644
--- a/src/mbgl/tile/geojson_tile.hpp
+++ b/src/mbgl/tile/geojson_tile.hpp
@@ -4,6 +4,9 @@
 #include <mbgl/util/feature.hpp>
 
 namespace mbgl {
+namespace style {
+class GeoJSONData;
+} // namespace style
 
 class TileParameters;
 
@@ -12,13 +15,17 @@ public:
     GeoJSONTile(const OverscaledTileID&,
                 std::string sourceID,
                 const TileParameters&,
-                mapbox::feature::feature_collection<int16_t>);
+                std::shared_ptr<style::GeoJSONData>);
 
-    void updateData(mapbox::feature::feature_collection<int16_t>, bool resetLayers = false);
+    void updateData(std::shared_ptr<style::GeoJSONData> data, bool resetLayers = false);
 
     void querySourceFeatures(
         std::vector<Feature>& result,
         const SourceQueryOptions&) override;
+
+private:
+    std::shared_ptr<style::GeoJSONData> data;
+    mapbox::base::WeakPtrFactory<GeoJSONTile> weakFactory{this};
 };
 
 } // namespace mbgl
diff --git a/test/tile/geojson_tile.test.cpp b/test/tile/geojson_tile.test.cpp
index cc2dbfced8..d4bf1e0752 100644
--- a/test/tile/geojson_tile.test.cpp
+++ b/test/tile/geojson_tile.test.cpp
@@ -4,15 +4,16 @@
 #include <mbgl/tile/geojson_tile.hpp>
 #include <mbgl/tile/tile_loader_impl.hpp>
 
-#include <mbgl/util/run_loop.hpp>
+#include <mbgl/annotation/annotation_manager.hpp>
 #include <mbgl/map/transform.hpp>
+#include <mbgl/renderer/image_manager.hpp>
 #include <mbgl/renderer/tile_parameters.hpp>
-#include <mbgl/style/style.hpp>
 #include <mbgl/style/layers/circle_layer.hpp>
 #include <mbgl/style/layers/circle_layer_impl.hpp>
-#include <mbgl/annotation/annotation_manager.hpp>
-#include <mbgl/renderer/image_manager.hpp>
+#include <mbgl/style/sources/geojson_source.hpp>
+#include <mbgl/style/style.hpp>
 #include <mbgl/text/glyph_manager.hpp>
+#include <mbgl/util/run_loop.hpp>
 
 #include <memory>
 
@@ -43,6 +44,29 @@ public:
     };
 };
 
+namespace {
+
+class FakeGeoJSONData : public GeoJSONData {
+public:
+    FakeGeoJSONData(TileFeatures features_) : features(std::move(features_)) {}
+
+    void getTile(const CanonicalTileID&, const std::function<void(TileFeatures)>& fn) final {
+        assert(fn);
+        fn(features);
+    }
+
+    Features getChildren(const std::uint32_t) final { return {}; }
+
+    Features getLeaves(const std::uint32_t, const std::uint32_t, const std::uint32_t) final { return {}; }
+
+    std::uint8_t getClusterExpansionZoom(std::uint32_t) final { return 0; }
+
+private:
+    TileFeatures features;
+};
+
+} // namespace
+
 TEST(GeoJSONTile, Issue7648) {
     GeoJSONTileTest test;
 
@@ -50,8 +74,8 @@ TEST(GeoJSONTile, Issue7648) {
 
     mapbox::feature::feature_collection<int16_t> features;
     features.push_back(mapbox::feature::feature<int16_t> { mapbox::geometry::point<int16_t>(0, 0) });
-
-    GeoJSONTile tile(OverscaledTileID(0, 0, 0), "source", test.tileParameters, features);
+    auto data = std::make_shared<FakeGeoJSONData>(std::move(features));
+    GeoJSONTile tile(OverscaledTileID(0, 0, 0), "source", test.tileParameters, data);
     Immutable<LayerProperties> layerProperties = makeMutable<CircleLayerProperties>(staticImmutableCast<CircleLayer::Impl>(layer.baseImpl));
     StubTileObserver observer;
     observer.tileChanged = [&] (const Tile&) {
@@ -68,7 +92,7 @@ TEST(GeoJSONTile, Issue7648) {
         test.loop.runOnce();
     }
 
-    tile.updateData(features);
+    tile.updateData(data);
     while (!tile.isComplete()) {
         test.loop.runOnce();
     }
@@ -83,8 +107,8 @@ TEST(GeoJSONTile, Issue9927) {
 
     mapbox::feature::feature_collection<int16_t> features;
     features.push_back(mapbox::feature::feature<int16_t> { mapbox::geometry::point<int16_t>(0, 0) });
-
-    GeoJSONTile tile(OverscaledTileID(0, 0, 0), "source", test.tileParameters, features);
+    auto data = std::make_shared<FakeGeoJSONData>(std::move(features));
+    GeoJSONTile tile(OverscaledTileID(0, 0, 0), "source", test.tileParameters, data);
 
     Immutable<LayerProperties> layerProperties = makeMutable<CircleLayerProperties>(staticImmutableCast<CircleLayer::Impl>(layer.baseImpl));
     std::vector<Immutable<LayerProperties>> layers { layerProperties };