From 4bb3a9c58ca3beb8ab695ae66456cf9c4d9847d4 Mon Sep 17 00:00:00 2001
From: Jesse Crocker <jesse@gaiagps.com>
Date: Mon, 6 Mar 2017 09:59:00 -0700
Subject: Fix crash when source is dealloced

---
 platform/darwin/src/MGLComputedShapeSource.mm   | 30 +++++++++++++++++--------
 src/mbgl/style/sources/custom_vector_source.cpp | 16 ++++---------
 2 files changed, 25 insertions(+), 21 deletions(-)

diff --git a/platform/darwin/src/MGLComputedShapeSource.mm b/platform/darwin/src/MGLComputedShapeSource.mm
index b4e4a6c54a..7eeea58f6c 100644
--- a/platform/darwin/src/MGLComputedShapeSource.mm
+++ b/platform/darwin/src/MGLComputedShapeSource.mm
@@ -29,7 +29,10 @@
 @property (nonatomic, readonly) uint8_t z;
 @property (nonatomic, readonly) uint32_t x;
 @property (nonatomic, readonly) uint32_t y;
-@property (nonatomic, readonly, weak) MGLComputedShapeSource *source;
+@property (nonatomic, assign) BOOL dataSourceImplementsFeaturesForTile;
+@property (nonatomic, assign) BOOL dataSourceImplementsFeaturesForBounds;
+@property (nonatomic, weak, nullable) id<MGLComputedShapeSourceDataSource> dataSource;
+@property (nonatomic, nullable) mbgl::style::CustomVectorSource *rawSource;
 
 - (instancetype)initForSource:(MGLComputedShapeSource*)source z:(uint8_t)z x:(uint32_t)x y:(uint32_t)y;
 
@@ -43,7 +46,11 @@
     _x = x;
     _y = y;
     _z = z;
-    _source = source;
+    _dataSourceImplementsFeaturesForTile = source.dataSourceImplementsFeaturesForTile;
+    _dataSourceImplementsFeaturesForBounds = source.dataSourceImplementsFeaturesForBounds;
+    _dataSource = source.dataSource;
+    mbgl::style::CustomVectorSource *rawSource = (mbgl::style::CustomVectorSource *)source.rawSource;
+    _rawSource = rawSource;
     return self;
 }
 
@@ -53,16 +60,16 @@
     }
 
     NSArray<MGLShape <MGLFeature> *> *data;
-    if(!self.source.dataSource) {
+    if(!self.dataSource) {
         data = nil;
-    } else if(self.source.dataSourceImplementsFeaturesForTile) {
-        data = [self.source.dataSource featuresInTileAtX:self.x
+    } else if(self.dataSourceImplementsFeaturesForTile) {
+        data = [self.dataSource featuresInTileAtX:self.x
                                                 y:self.y
                                         zoomLevel:self.z];
     } else {
         mbgl::CanonicalTileID tileID = mbgl::CanonicalTileID(self.z, self.x, self.y);
         mbgl::LatLngBounds tileBounds = mbgl::LatLngBounds(tileID);
-        data = [self.source.dataSource featuresInCoordinateBounds:MGLCoordinateBoundsFromLatLngBounds(tileBounds)
+        data = [self.dataSource featuresInCoordinateBounds:MGLCoordinateBoundsFromLatLngBounds(tileBounds)
                                                  zoomLevel:self.z];
     }
     
@@ -74,14 +81,19 @@
             featureCollection.push_back(geoJsonObject);
         }
         const auto geojson = mbgl::GeoJSON{featureCollection};
-        dispatch_async(dispatch_get_main_queue(), ^{
-            if(![self isCancelled] && self.source.rawSource) {
-                self.source.rawSource->setTileData(self.z, self.x, self.y, geojson);
+        dispatch_sync(dispatch_get_main_queue(), ^{
+            if(![self isCancelled] && self.rawSource) {
+                self.rawSource->setTileData(self.z, self.x, self.y, geojson);
             }
         });
     }
 }
 
+- (void)cancel {
+    [super cancel];
+    self.rawSource = NULL;
+}
+
 @end
 
 @implementation MGLComputedShapeSource
diff --git a/src/mbgl/style/sources/custom_vector_source.cpp b/src/mbgl/style/sources/custom_vector_source.cpp
index 3a12c08f5e..55e7974a83 100644
--- a/src/mbgl/style/sources/custom_vector_source.cpp
+++ b/src/mbgl/style/sources/custom_vector_source.cpp
@@ -10,27 +10,19 @@ CustomVectorSource::CustomVectorSource(std::string id, GeoJSONOptions options, s
 }
       
 void CustomVectorSource::setTileData(uint8_t z, uint32_t x, uint32_t y, const mapbox::geojson::geojson& geoJSON) {
-    if(impl != nullptr) {
-        impl->setTileData(z, x, y, geoJSON);
-    }
+    impl->setTileData(z, x, y, geoJSON);
 }
 
 void CustomVectorSource::reloadRegion(mbgl::LatLngBounds bounds, uint8_t z) {
-    if(impl != nullptr) {
-        impl->reloadRegion(bounds, z);
-    }
+    impl->reloadRegion(bounds, z);
 }
   
 void CustomVectorSource::updateTile(uint8_t z, uint32_t x, uint32_t y) {
-    if(impl != nullptr) {
-        impl->updateTile(z, x, y);
-    }
+    impl->updateTile(z, x, y);
 }
   
 void CustomVectorSource::reload() {
-    if(impl != nullptr) {
-        impl->reload();
-    }
+    impl->reload();
 }
 
 } // namespace style
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