[core] Render parent raster tiles when ideal tile can't be loaded

10 files changed, 100 insertions, 36 deletions

diff --git a/mapbox-gl-js b/mapbox-gl-js
-Subproject cfb4525fc9cdb5e4f9ec49f8d503cea88017d5a
+Subproject fbea8565244ad254eb9678798b4a21c88916dd8
diff --git a/platform/node/test/suite_implementation.js b/platform/node/test/suite_implementation.js
index ef97652893..a5e96f7265 100644
--- a/platform/node/test/suite_implementation.js
+++ b/platform/node/test/suite_implementation.js
@@ -17,6 +17,8 @@ module.exports = function (style, options, callback) {
             request(req.url, {encoding: null}, function (err, response, body) {
                 if (err) {
                     callback(err);
+                } else if (response.statusCode == 404) {
+                    callback();
                 } else if (response.statusCode != 200) {
                     callback(new Error(response.statusMessage));
                 } else {
diff --git a/src/mbgl/algorithm/update_renderables.hpp b/src/mbgl/algorithm/update_renderables.hpp
index fe2dc2c570..a9c348b538 100644
--- a/src/mbgl/algorithm/update_renderables.hpp
+++ b/src/mbgl/algorithm/update_renderables.hpp
@@ -43,7 +43,9 @@ void updateRenderables(GetTileFn getTile,
             retainTile(*tile, Resource::Necessity::Required);
             renderTile(idealRenderTileID, *tile);
         } else {
-            bool triedPrevious = tile->hasTriedOptional();
+            // We are now attempting to load child and parent tiles.
+            bool parentHasTriedOptional = tile->hasTriedOptional();
+            bool parentIsLoaded = tile->isLoaded();
 
             // The tile isn't loaded yet, but retain it anyway because it's an ideal tile.
             retainTile(*tile, Resource::Necessity::Required);
@@ -91,13 +93,18 @@ void updateRenderables(GetTileFn getTile,
                     }
 
                     tile = getTile(parentDataTileID);
-                    if (!tile && triedPrevious) {
+                    if (!tile && (parentHasTriedOptional || parentIsLoaded)) {
                         tile = createTile(parentDataTileID);
                     }
 
                     if (tile) {
-                        triedPrevious = tile->hasTriedOptional();
-                        retainTile(*tile, Resource::Necessity::Optional);
+                        retainTile(*tile, parentIsLoaded ? Resource::Necessity::Required
+                                                         : Resource::Necessity::Optional);
+
+                        // Save the current values, since they're the parent of the next iteration
+                        // of the parent tile ascent loop.
+                        parentHasTriedOptional = tile->hasTriedOptional();
+                        parentIsLoaded = tile->isLoaded();
 
                         if (tile->isRenderable()) {
                             renderTile(parentRenderTileID, *tile);
diff --git a/src/mbgl/tile/geometry_tile.cpp b/src/mbgl/tile/geometry_tile.cpp
index c9ed46a529..d3406e1a59 100644
--- a/src/mbgl/tile/geometry_tile.cpp
+++ b/src/mbgl/tile/geometry_tile.cpp
@@ -52,15 +52,15 @@ void GeometryTile::cancel() {
 }
 
 void GeometryTile::setError(std::exception_ptr err) {
+    loaded = true;
+    renderable = false;
     observer->onTileError(*this, err);
 }
 
 void GeometryTile::setData(std::unique_ptr<const GeometryTileData> data_) {
     // Mark the tile as pending again if it was complete before to prevent signaling a complete
     // state despite pending parse operations.
-    if (availableData == DataAvailability::All) {
-        availableData = DataAvailability::Some;
-    }
+    pending = true;
 
     ++correlationID;
     worker.invoke(&GeometryTileWorker::setData, std::move(data_), correlationID);
@@ -74,9 +74,7 @@ void GeometryTile::setPlacementConfig(const PlacementConfig& desiredConfig) {
 
     // Mark the tile as pending again if it was complete before to prevent signaling a complete
     // state despite pending parse operations.
-    if (availableData == DataAvailability::All) {
-        availableData = DataAvailability::Some;
-    }
+    pending = true;
 
     ++correlationID;
     requestedConfig = desiredConfig;
@@ -86,9 +84,7 @@ void GeometryTile::setPlacementConfig(const PlacementConfig& desiredConfig) {
 void GeometryTile::redoLayout() {
     // Mark the tile as pending again if it was complete before to prevent signaling a complete
     // state despite pending parse operations.
-    if (availableData == DataAvailability::All) {
-        availableData = DataAvailability::Some;
-    }
+    pending = true;
 
     std::vector<std::unique_ptr<Layer>> copy;
 
@@ -111,7 +107,8 @@ void GeometryTile::redoLayout() {
 }
 
 void GeometryTile::onLayout(LayoutResult result) {
-    availableData = DataAvailability::Some;
+    loaded = true;
+    renderable = true;
     nonSymbolBuckets = std::move(result.nonSymbolBuckets);
     featureIndex = std::move(result.featureIndex);
     data = std::move(result.tileData);
@@ -120,8 +117,10 @@ void GeometryTile::onLayout(LayoutResult result) {
 }
 
 void GeometryTile::onPlacement(PlacementResult result) {
+    loaded = true;
+    renderable = true;
     if (result.correlationID == correlationID) {
-        availableData = DataAvailability::All;
+        pending = false;
     }
     symbolBuckets = std::move(result.symbolBuckets);
     collisionTile = std::move(result.collisionTile);
@@ -129,7 +128,9 @@ void GeometryTile::onPlacement(PlacementResult result) {
 }
 
 void GeometryTile::onError(std::exception_ptr err) {
-    availableData = DataAvailability::All;
+    loaded = true;
+    pending = false;
+    renderable = false;
     observer->onTileError(*this, err);
 }
     
diff --git a/src/mbgl/tile/raster_tile.cpp b/src/mbgl/tile/raster_tile.cpp
index 887ebb67b8..1e3c772200 100644
--- a/src/mbgl/tile/raster_tile.cpp
+++ b/src/mbgl/tile/raster_tile.cpp
@@ -28,6 +28,8 @@ void RasterTile::cancel() {
 }
 
 void RasterTile::setError(std::exception_ptr err) {
+    loaded = true;
+    renderable = false;
     observer->onTileError(*this, err);
 }
 
@@ -41,13 +43,15 @@ void RasterTile::setData(std::shared_ptr<const std::string> data,
 
 void RasterTile::onParsed(std::unique_ptr<Bucket> result) {
     bucket = std::move(result);
-    availableData = bucket ? DataAvailability::All : DataAvailability::None;
+    loaded = true;
+    renderable = bucket ? true : false;
     observer->onTileChanged(*this);
 }
 
 void RasterTile::onError(std::exception_ptr err) {
     bucket.reset();
-    availableData = DataAvailability::None;
+    loaded = true;
+    renderable = false;
     observer->onTileError(*this, err);
 }
 
diff --git a/src/mbgl/tile/tile.hpp b/src/mbgl/tile/tile.hpp
index a8034c40e4..b3085071c2 100644
--- a/src/mbgl/tile/tile.hpp
+++ b/src/mbgl/tile/tile.hpp
@@ -74,11 +74,23 @@ public:
     // partial state is still waiting for network resources but can also
     // be rendered, although layers will be missing.
     bool isRenderable() const {
-        return availableData != DataAvailability::None;
+        return renderable;
     }
 
+    // A tile is "Loaded" when we have received a response from a FileSource, and have attempted to
+    // parse the tile (if applicable). Tile implementations should set this to true when a load
+    // error occurred, or after the tile was parsed successfully.
+    bool isLoaded() const {
+        return loaded;
+    }
+
+    // "Completion" of a tile means that we have attempted to load it, and parsed it completely,
+    // i.e. no parsing or placement operations are pending for that tile.
+    // Completeness doesn't mean that the tile can be rendered, but merely that we have exhausted
+    // all options to get this tile to a renderable state. Some tiles may not be renderable, but
+    // complete, e.g. when a raster tile couldn't be loaded, or parsing failed.
     bool isComplete() const {
-        return availableData == DataAvailability::All;
+        return loaded && !pending;
     }
 
     void dumpDebugLogs() const;
@@ -92,21 +104,9 @@ public:
 
 protected:
     bool triedOptional = false;
-
-    enum class DataAvailability : uint8_t {
-        // Still waiting for data to load or parse.
-        None,
-
-        // Tile is partially parsed, some buckets are still waiting for dependencies
-        // to arrive, but it is good for rendering. Partial tiles can also be re-parsed,
-        // but might remain in the same state if dependencies are still missing.
-        Some,
-
-        // Tile is fully parsed, and all buckets are available if they exist.
-        All,
-    };
-
-    DataAvailability availableData = DataAvailability::None;
+    bool renderable = false;
+    bool pending = false;
+    bool loaded = false;
 
     TileObserver* observer = nullptr;
 };
diff --git a/test/algorithm/mock.hpp b/test/algorithm/mock.hpp
index efa76f238e..d87f55343b 100644
--- a/test/algorithm/mock.hpp
+++ b/test/algorithm/mock.hpp
@@ -34,8 +34,13 @@ struct MockTileData {
         return renderable;
     }
 
+    bool isLoaded() const {
+        return loaded;
+    }
+
     bool renderable = false;
     bool triedOptional = false;
+    bool loaded = false;
     const mbgl::OverscaledTileID tileID;
 };
 
diff --git a/test/algorithm/update_renderables.test.cpp b/test/algorithm/update_renderables.test.cpp
index c284c37475..af90d262de 100644
--- a/test/algorithm/update_renderables.test.cpp
+++ b/test/algorithm/update_renderables.test.cpp
@@ -1226,3 +1226,36 @@ TEST(UpdateRenderables, RepeatedRenderWithMissingOptionals) {
               }),
               log);
 }
+
+TEST(UpdateRenderables, LoadRequiredIfIdealTileCantBeFound) {
+    ActionLog log;
+    MockSource source;
+    auto getTileData = getTileDataFn(log, source.dataTiles);
+    auto createTileData = createTileDataFn(log, source.dataTiles);
+    auto retainTileData = retainTileDataFn(log);
+    auto renderTile = renderTileFn(log);
+
+    source.zoomRange.max = 6;
+    source.idealTiles.emplace(UnwrappedTileID{ 6, 0, 0 });
+
+    auto tile_6_6_0_0 = source.createTileData(OverscaledTileID{ 6, { 6, 0, 0 } });
+    tile_6_6_0_0->triedOptional = true;
+    tile_6_6_0_0->loaded = true;
+
+    algorithm::updateRenderables(getTileData, createTileData, retainTileData, renderTile,
+                                 source.idealTiles, source.zoomRange, 6);
+    EXPECT_EQ(ActionLog({
+                  GetTileDataAction{ { 6, { 6, 0, 0 } }, Found }, // ideal tile, not found
+                  RetainTileDataAction{ { 6, { 6, 0, 0 } }, Resource::Necessity::Required }, //
+                  GetTileDataAction{ { 7, { 6, 0, 0 } }, NotFound }, // overzoomed child
+                  GetTileDataAction{ { 5, { 5, 0, 0 } }, NotFound }, // ascent
+                  CreateTileDataAction{ { 5, { 5, 0, 0 } } },
+                  RetainTileDataAction{ { 5, { 5, 0, 0 } }, Resource::Necessity::Required },
+                  GetTileDataAction{ { 4, { 4, 0, 0 } }, NotFound }, // ...
+                  GetTileDataAction{ { 3, { 3, 0, 0 } }, NotFound }, // ...
+                  GetTileDataAction{ { 2, { 2, 0, 0 } }, NotFound }, // ...
+                  GetTileDataAction{ { 1, { 1, 0, 0 } }, NotFound }, // ...
+                  GetTileDataAction{ { 0, { 0, 0, 0 } }, NotFound }, // ...
+              }),
+              log);
+}
diff --git a/test/tile/raster_tile.test.cpp b/test/tile/raster_tile.test.cpp
index 5cfc274be0..d0252555ac 100644
--- a/test/tile/raster_tile.test.cpp
+++ b/test/tile/raster_tile.test.cpp
@@ -40,6 +40,8 @@ TEST(RasterTile, setError) {
     RasterTile tile(OverscaledTileID(0, 0, 0), test.updateParameters, test.tileset);
     tile.setError(std::make_exception_ptr(std::runtime_error("test")));
     EXPECT_FALSE(tile.isRenderable());
+    EXPECT_TRUE(tile.isLoaded());
+    EXPECT_TRUE(tile.isComplete());
 }
 
 TEST(RasterTile, onError) {
@@ -47,6 +49,8 @@ TEST(RasterTile, onError) {
     RasterTile tile(OverscaledTileID(0, 0, 0), test.updateParameters, test.tileset);
     tile.onError(std::make_exception_ptr(std::runtime_error("test")));
     EXPECT_FALSE(tile.isRenderable());
+    EXPECT_TRUE(tile.isLoaded());
+    EXPECT_TRUE(tile.isComplete());
 }
 
 TEST(RasterTile, onParsed) {
@@ -54,6 +58,8 @@ TEST(RasterTile, onParsed) {
     RasterTile tile(OverscaledTileID(0, 0, 0), test.updateParameters, test.tileset);
     tile.onParsed(std::make_unique<RasterBucket>(UnassociatedImage{}));
     EXPECT_TRUE(tile.isRenderable());
+    EXPECT_TRUE(tile.isLoaded());
+    EXPECT_TRUE(tile.isComplete());
 }
 
 TEST(RasterTile, onParsedEmpty) {
@@ -61,4 +67,6 @@ TEST(RasterTile, onParsedEmpty) {
     RasterTile tile(OverscaledTileID(0, 0, 0), test.updateParameters, test.tileset);
     tile.onParsed(nullptr);
     EXPECT_FALSE(tile.isRenderable());
+    EXPECT_TRUE(tile.isLoaded());
+    EXPECT_TRUE(tile.isComplete());
 }
diff --git a/test/tile/vector_tile.test.cpp b/test/tile/vector_tile.test.cpp
index a388e8937e..0f43645d49 100644
--- a/test/tile/vector_tile.test.cpp
+++ b/test/tile/vector_tile.test.cpp
@@ -46,13 +46,17 @@ TEST(VectorTile, setError) {
     VectorTile tile(OverscaledTileID(0, 0, 0), "source", test.updateParameters, test.tileset);
     tile.setError(std::make_exception_ptr(std::runtime_error("test")));
     EXPECT_FALSE(tile.isRenderable());
+    EXPECT_TRUE(tile.isLoaded());
+    EXPECT_TRUE(tile.isComplete());
 }
 
 TEST(VectorTile, onError) {
     VectorTileTest test;
     VectorTile tile(OverscaledTileID(0, 0, 0), "source", test.updateParameters, test.tileset);
     tile.onError(std::make_exception_ptr(std::runtime_error("test")));
-    EXPECT_TRUE(tile.isRenderable());
+    EXPECT_FALSE(tile.isRenderable());
+    EXPECT_TRUE(tile.isLoaded());
+    EXPECT_TRUE(tile.isComplete());
 }
 
 TEST(VectorTile, Issue7615) {