[core] Added GeometryTileWorker-owned image correlation ID

4 files changed, 29 insertions, 9 deletions

diff --git a/src/mbgl/tile/geometry_tile.cpp b/src/mbgl/tile/geometry_tile.cpp
index a3ccd86479..017861884b 100644
--- a/src/mbgl/tile/geometry_tile.cpp
+++ b/src/mbgl/tile/geometry_tile.cpp
@@ -28,6 +28,22 @@ namespace mbgl {
 
 using namespace style;
 
+/*
+   Correlation between GeometryTile and GeometryTileWorker is safeguarded by two
+   correlation schemes:
+
+   GeometryTile's 'correlationID' is used for ensuring the tile will be flagged
+   as non-pending only when the placement coming from the last operation (as in
+   'setData', 'setLayers',  'setPlacementConfig') occurs. This is important for
+   still mode rendering as we want to render only when all layout and placement
+   operations are completed.
+
+   GeometryTileWorker's 'imageCorrelationID' is used for checking whether an
+   image request reply coming from `GeometryTile` is valid. Previous image
+   request replies are ignored as they result in incomplete placement attempts
+   that could flag the tile as non-pending too early.
+ */
+
 GeometryTile::GeometryTile(const OverscaledTileID& id_,
                            std::string sourceID_,
                            const TileParameters& parameters)
@@ -170,12 +186,12 @@ void GeometryTile::getGlyphs(GlyphDependencies glyphDependencies) {
     glyphManager.getGlyphs(*this, std::move(glyphDependencies));
 }
 
-void GeometryTile::onImagesAvailable(ImageMap images) {
-    worker.invoke(&GeometryTileWorker::onImagesAvailable, std::move(images));
+void GeometryTile::onImagesAvailable(ImageMap images, uint64_t imageCorrelationID) {
+    worker.invoke(&GeometryTileWorker::onImagesAvailable, std::move(images), imageCorrelationID);
 }
 
-void GeometryTile::getImages(ImageDependencies imageDependencies) {
-    imageManager.getImages(*this, std::move(imageDependencies));
+void GeometryTile::getImages(ImageRequestPair pair) {
+    imageManager.getImages(*this, std::move(pair));
 }
 
 void GeometryTile::upload(gl::Context& context) {
diff --git a/src/mbgl/tile/geometry_tile.hpp b/src/mbgl/tile/geometry_tile.hpp
index 7d70e1cb9a..ebad0f5410 100644
--- a/src/mbgl/tile/geometry_tile.hpp
+++ b/src/mbgl/tile/geometry_tile.hpp
@@ -40,10 +40,10 @@ public:
     void setLayers(const std::vector<Immutable<style::Layer::Impl>>&) override;
     
     void onGlyphsAvailable(GlyphMap) override;
-    void onImagesAvailable(ImageMap) override;
+    void onImagesAvailable(ImageMap, uint64_t imageCorrelationID) override;
     
     void getGlyphs(GlyphDependencies);
-    void getImages(ImageDependencies);
+    void getImages(ImageRequestPair);
 
     void upload(gl::Context&) override;
     Bucket* getBucket(const style::Layer::Impl&) const override;
diff --git a/src/mbgl/tile/geometry_tile_worker.cpp b/src/mbgl/tile/geometry_tile_worker.cpp
index c622d82e31..4af35e2326 100644
--- a/src/mbgl/tile/geometry_tile_worker.cpp
+++ b/src/mbgl/tile/geometry_tile_worker.cpp
@@ -216,7 +216,10 @@ void GeometryTileWorker::onGlyphsAvailable(GlyphMap newGlyphMap) {
     symbolDependenciesChanged();
 }
 
-void GeometryTileWorker::onImagesAvailable(ImageMap newImageMap) {
+void GeometryTileWorker::onImagesAvailable(ImageMap newImageMap, uint64_t imageCorrelationID_) {
+    if (imageCorrelationID != imageCorrelationID_) {
+        return; // Ignore outdated image request replies.
+    }
     imageMap = std::move(newImageMap);
     pendingImageDependencies.clear();
     symbolDependenciesChanged();
@@ -239,7 +242,7 @@ void GeometryTileWorker::requestNewGlyphs(const GlyphDependencies& glyphDependen
 void GeometryTileWorker::requestNewImages(const ImageDependencies& imageDependencies) {
     pendingImageDependencies = imageDependencies;
     if (!pendingImageDependencies.empty()) {
-        parent.invoke(&GeometryTile::getImages, pendingImageDependencies);
+        parent.invoke(&GeometryTile::getImages, std::make_pair(pendingImageDependencies, ++imageCorrelationID));
     }
 }
 
diff --git a/src/mbgl/tile/geometry_tile_worker.hpp b/src/mbgl/tile/geometry_tile_worker.hpp
index 7f80c3b4f7..1425daa7a1 100644
--- a/src/mbgl/tile/geometry_tile_worker.hpp
+++ b/src/mbgl/tile/geometry_tile_worker.hpp
@@ -38,7 +38,7 @@ public:
     void setPlacementConfig(PlacementConfig, uint64_t correlationID);
     
     void onGlyphsAvailable(GlyphMap glyphs);
-    void onImagesAvailable(ImageMap images);
+    void onImagesAvailable(ImageMap images, uint64_t imageCorrelationID);
 
 private:
     void coalesced();
@@ -70,6 +70,7 @@ private:
 
     State state = Idle;
     uint64_t correlationID = 0;
+    uint64_t imageCorrelationID = 0;
 
     // Outer optional indicates whether we've received it or not.
     optional<std::vector<Immutable<style::Layer::Impl>>> layers;