Change experiment gating and add tests

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -364,6 +364,7 @@
 		CC3B208C1C3F7A5400798563 /* ASWeakSet.mm in Sources */ = {isa = PBXBuildFile; fileRef = CC3B20881C3F7A5400798563 /* ASWeakSet.mm */; };
 		CC3B208E1C3F7D0A00798563 /* ASWeakSetTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CC3B208D1C3F7D0A00798563 /* ASWeakSetTests.mm */; };
 		CC3B20901C3F892D00798563 /* ASBridgedPropertiesTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CC3B208F1C3F892D00798563 /* ASBridgedPropertiesTests.mm */; };
+		CC3F59C022CAACAD002C3824 /* ASNodeContextTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CC3F59BF22CAACAD002C3824 /* ASNodeContextTests.mm */; };
 		CC4981B31D1A02BE004E13CC /* ASTableViewThrashTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CC4981B21D1A02BE004E13CC /* ASTableViewThrashTests.mm */; };
 		CC54A81C1D70079800296A24 /* ASDispatch.h in Headers */ = {isa = PBXBuildFile; fileRef = CC54A81B1D70077A00296A24 /* ASDispatch.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		CC54A81E1D7008B300296A24 /* ASDispatchTests.mm in Sources */ = {isa = PBXBuildFile; fileRef = CC54A81D1D7008B300296A24 /* ASDispatchTests.mm */; };
@@ -890,6 +891,7 @@
 		CC3B20881C3F7A5400798563 /* ASWeakSet.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASWeakSet.mm; sourceTree = "<group>"; };
 		CC3B208D1C3F7D0A00798563 /* ASWeakSetTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASWeakSetTests.mm; sourceTree = "<group>"; };
 		CC3B208F1C3F892D00798563 /* ASBridgedPropertiesTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; lineEnding = 0; path = ASBridgedPropertiesTests.mm; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objcpp; };
+		CC3F59BF22CAACAD002C3824 /* ASNodeContextTests.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = ASNodeContextTests.mm; sourceTree = "<group>"; };
 		CC4981B21D1A02BE004E13CC /* ASTableViewThrashTests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ASTableViewThrashTests.mm; sourceTree = "<group>"; };
 		CC4981BA1D1C7F65004E13CC /* NSIndexSet+ASHelpers.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "NSIndexSet+ASHelpers.h"; sourceTree = "<group>"; };
 		CC4981BB1D1C7F65004E13CC /* NSIndexSet+ASHelpers.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = "NSIndexSet+ASHelpers.mm"; sourceTree = "<group>"; };
@@ -1353,6 +1355,7 @@
 				058D0A32195D057000B7D73C /* ASMutableAttributedStringBuilderTests.mm */,
 				BB5FC3CD1F9BA688007F191E /* ASNavigationControllerTests.mm */,
 				CC11F9791DB181180024D77B /* ASNetworkImageNodeTests.mm */,
+				CC3F59BF22CAACAD002C3824 /* ASNodeContextTests.mm */,
 				ACF6ED591B178DC700DA7C62 /* ASOverlayLayoutSpecSnapshotTests.mm */,
 				AE6987C01DD04E1000B9E458 /* ASPagerNodeTests.mm */,
 				CC8B05D41D73836400F54286 /* ASPerformanceTestContext.h */,
@@ -2353,6 +2356,7 @@
 				254C6B541BF8FF2A003EC431 /* ASTextKitTests.mm in Sources */,
 				05EA6FE71AC0966E00E35788 /* ASSnapshotTestCase.mm in Sources */,
 				CC35CEC620DD87280006448D /* ASCollectionsTests.mm in Sources */,
+				CC3F59C022CAACAD002C3824 /* ASNodeContextTests.mm in Sources */,
 				ACF6ED631B178DC700DA7C62 /* ASStackLayoutSpecSnapshotTests.mm in Sources */,
 				CCE4F9BA1F0DBB5000062E4E /* ASLayoutTestNode.mm in Sources */,
 				CCAA0B82206ADECB0057B336 /* ASRecursiveUnfairLockTests.mm in Sources */,

Source/ASCollectionView.mm

@@ -1953,19 +1953,15 @@ - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAt
   }
   if (!block && !cell && _asyncDataSourceFlags.collectionNodeNodeForItem) {
     GET_COLLECTIONNODE_OR_RETURN(collectionNode, ^{ return [[ASCellNode alloc] init]; });
-    ASNodeContextPushNew();
     cell = [_asyncDataSource collectionNode:collectionNode nodeForItemAtIndexPath:indexPath];
-    ASNodeContextPop();
   }
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
  if (!block && !cell && _asyncDataSourceFlags.collectionViewNodeBlockForItem) {
     block = [_asyncDataSource collectionView:self nodeBlockForItemAtIndexPath:indexPath];
   }
   if (!block && !cell && _asyncDataSourceFlags.collectionViewNodeForItem) {
-    ASNodeContextPushNew();
     cell = [_asyncDataSource collectionView:self nodeForItemAtIndexPath:indexPath];
-    ASNodeContextPop();
   }
 #pragma clang diagnostic pop
 

Source/ASDisplayNode+Yoga.mm

@@ -109,6 +109,7 @@ - (void)_locked_insertYogaChild:(ASDisplayNode *)child atIndex:(NSUInteger)index
   if (child == nil) {
     return;
   }
+  ASDisplayNodeAssert(_nodeContext == child->_nodeContext, @"Cannot add yoga child from different node context.");
   if (_yogaChildren == nil) {
     _yogaChildren = [[NSMutableArray alloc] init];
   }

Source/ASDisplayNode.h

@@ -115,7 +115,6 @@ AS_EXTERN NSInteger const ASDefaultDrawingPriority;
  */
 - (instancetype)init NS_DESIGNATED_INITIALIZER;
 
-
 /**
  * @abstract Alternative initializer with a block to create the backing view.
  *

Source/ASDisplayNode.mm

@@ -302,13 +302,10 @@ - (void)_staticInitialize
 - (void)_initializeInstance
 {
   [self _staticInitialize];
-  if (ASNodeContext *ctx = ASNodeContextGet()) {
-    _nodeContext = ctx;
-    new (&_mutexOrPtr) AS::MutexOrPointer(&ctx->_mutex);
+  _nodeContext = ASNodeContextGet();
+  if (_nodeContext) {
+    new (&_mutexOrPtr) AS::MutexOrPointer(&_nodeContext->_mutex);
   } else {
-    ASDisplayNodeAssert(!ASActivateExperimentalFeature(ASExperimentalNodeContext), @"In node context experiment, but no"
-                        "node context. Did you forget to push one before creating your node for an ASViewController?"
-                        "Please report to the maintainers what circumstance this happened in if it seems unusual.");
     new (&_mutexOrPtr) AS::MutexOrPointer(nullptr);
     _mutexOrPtr.get().SetDebugNameWithObject(self);
   }

Source/ASExperimentalFeatures.h

@@ -31,7 +31,6 @@ typedef NS_OPTIONS(NSUInteger, ASExperimentalFeatures) {
   ASExperimentalRemoveTextKitInitialisingLock = 1 << 10,    // exp_remove_textkit_initialising_lock
   ASExperimentalDrawingGlobal = 1 << 11,                    // exp_drawing_global
   ASExperimentalOptimizeDataControllerPipeline = 1 << 12,   // exp_optimize_data_controller_pipeline
-  ASExperimentalNodeContext = 1 << 13,                      // exp_node_context
   ASExperimentalFeatureAll = 0xFFFFFFFF
 };
 

Source/ASExperimentalFeatures.mm

@@ -24,8 +24,7 @@
                                       @"exp_oom_bg_dealloc_disable",
                                       @"exp_remove_textkit_initialising_lock",
                                       @"exp_drawing_global",
-                                      @"exp_optimize_data_controller_pipeline",
-                                      @"exp_node_context"]));
+                                      @"exp_optimize_data_controller_pipeline"]));
   if (flags == ASExperimentalFeatureAll) {
     return allNames;
   }

Source/ASNodeContext.h

@@ -14,25 +14,14 @@ NS_ASSUME_NONNULL_BEGIN
 @class ASNodeContext;
 
 /**
- * Push the given context, which will apply to any nodes initialized with `init` instead of `initWithContext:`.
+ * Push the given context, which will apply to any nodes initialized until the corresponding `pop`.
  *
- * A default context is provided by the system under the following circumstances:
- * - During the execution of a node block for ASCollectionNode or ASTableNode.
- * - During the call to `nodeForItem:` & related methods for ASCollectionNode or ASTableNode.
- * - During the execution of `calculateLayoutThatFits:` or `layoutSpecThatFits:` (context of receiver is pushed.)
- *
- * @discussion Generally users will not need to call this function themselves.
+ * Generally each cell in a collection or table, and the root of an ASViewController, will be a context.
  */
 AS_EXTERN void ASNodeContextPush(unowned ASNodeContext *context);
 
 /**
- * Creates a new context and pushes it. This is useful during experimentation, so that if you aren't in the context
- * experiment, you won't create a context for no reason.
- */
-AS_EXTERN void ASNodeContextPushNew(void);
-
-/**
- * Get the current default context, if there is one.
+ * Get the current top context, if there is one.
  */
 AS_EXTERN ASNodeContext *_Nullable ASNodeContextGet(void);
 
@@ -41,6 +30,18 @@ AS_EXTERN ASNodeContext *_Nullable ASNodeContextGet(void);
  */
 AS_EXTERN void ASNodeContextPop(void);
 
+/**
+ * A convenience to perform the given block with the provided context active.
+ */
+AS_EXTERN id ASNodeContextPerform(unowned ASNodeContext *ctx, id (^NS_NOESCAPE body)(void));
+
+/**
+ * Node contexts can have extensions attached to them. For instance, if your application wants to do custom logging
+ * on a per-context basis, you can define an extension identifier (pick an arbitrary uint32_t that won't collide)
+ * and the logger can be stored & retrieved from the node context.
+ */
+typedef uint32_t ASNodeContextExtensionIdentifier NS_TYPED_EXTENSIBLE_ENUM;
+
 /**
  * A node context is an object that is shared by, and uniquely identifies, an "embedding" of nodes. For example,
  * each cell in a collection view has its own context. Each ASViewController's node has its own context. You can
@@ -51,12 +52,15 @@ AS_EXTERN void ASNodeContextPop(void);
  *
  * Nodes may not be moved from one context to another. For instance, you may not detach a subnode of a cell node,
  * and reattach it to a subtree of another cell node in the same or another collection view.
- *
- * Node contexts are established in the `-initWithContext:` method and do not change. For ease of use, a default
- * context will be used from the `-init` method if available.
  */
 AS_SUBCLASSING_RESTRICTED
-@interface ASNodeContext : NSObject
+@interface ASNodeContext : NSObject <ASLocking>
+
+#pragma mark - Extension
+
+- (nullable id)extensionWithIdentifier:(ASNodeContextExtensionIdentifier)extensionIdentifier;
+
+- (void)setExtension:(nullable id)extension forIdentifier:(ASNodeContextExtensionIdentifier)extensionIdentifier;
 
 @end
 

Source/ASNodeContext.mm

@@ -9,13 +9,14 @@
 
 #import <AsyncDisplayKit/ASAssert.h>
 
-#if AS_TLS_AVAILABLE
-
 #import <stack>
+#import <unordered_map>
+
+#if AS_TLS_AVAILABLE
 
 static thread_local std::stack<ASNodeContext *> gContexts;
 
-void _ASNodeContextPushNoCheck(unowned ASNodeContext *context) {
+void ASNodeContextPush(unowned ASNodeContext *context) {
   gContexts.push(context);
 }
 
@@ -24,10 +25,11 @@ void _ASNodeContextPushNoCheck(unowned ASNodeContext *context) {
 }
 
 void ASNodeContextPop() {
-  if (ASActivateExperimentalFeature(ASExperimentalNodeContext)) {
-    ASDisplayNodeCAssertFalse(gContexts.empty());
-    gContexts.pop();
+  if (DISPATCH_EXPECT(gContexts.empty(), false)) {
+    ASDisplayNodeCFailAssert(@"Attempt to pop empty context stack.");
+    return;
   }
+  gContexts.pop();
 }
 
 #else   // !AS_TLS_AVAILABLE
@@ -37,7 +39,7 @@ void ASNodeContextPop() {
 // Points to a NSMutableArray<ASNodeContext *>.
 static constexpr NSString *ASNodeContextStackKey = @"org.TextureGroup.Texture.nodeContexts";
 
-void _ASNodeContextPushNoCheck(unowned ASNodeContext *context) {
+void ASNodeContextPush(unowned ASNodeContext *context) {
   unowned NSMutableDictionary *td = NSThread.currentThread.threadDictionary;
   unowned NSMutableArray<ASNodeContext *> *stack = td[ASNodeContextStackKey];
   if (!stack) {
@@ -59,18 +61,53 @@ void ASNodeContextPop() {
 
 #endif  // !AS_TLS_AVAILABLE
 
-void ASNodeContextPush(unowned ASNodeContext *context) {
-  if (ASActivateExperimentalFeature(ASExperimentalNodeContext)) {
-    _ASNodeContextPushNoCheck(context);
+id ASNodeContextPerform(unowned ASNodeContext *ctx, id(^ NS_NOESCAPE body)(void))
+{
+  ASNodeContextPush(ctx);
+  id result = body();
+  ASNodeContextPop();
+  return result;
+}
+
+@implementation ASNodeContext {
+  std::unordered_map<uint32_t, id> _extensions;
+}
+
+- (id)createObject:(id(^ NS_NOESCAPE)())body
+{
+  ASNodeContextPush(self);
+  id result = body();
+  ASNodeContextPop();
+  return result;
+}
+
+- (instancetype)init
+{
+  if (self = [super init]) {
+    _mutex.SetDebugNameWithObject(self);
   }
+  return self;
 }
 
-void ASNodeContextPushNew() {
-  if (ASActivateExperimentalFeature(ASExperimentalNodeContext)) {
-    _ASNodeContextPushNoCheck([[ASNodeContext alloc] init]);
+- (id)extensionWithIdentifier:(ASNodeContextExtensionIdentifier)extensionIdentifier
+{
+  AS::MutexLocker l(_mutex);
+  auto it = _extensions.find(extensionIdentifier);
+  return it != _extensions.end() ? it->second : nil;
+}
+
+- (void)setExtension:(id)extension forIdentifier:(ASNodeContextExtensionIdentifier)extensionIdentifier
+{
+  AS::MutexLocker l(_mutex);
+  if (extension) {
+    _extensions.emplace(extensionIdentifier, extension);
+  } else {
+    _extensions.erase(extensionIdentifier);
   }
 }
 
-@implementation ASNodeContext
+#pragma mark ASLocking
+
+ASSynthesizeLockingMethodsWithMutex(_mutex);
 
 @end

Source/ASNodeController+Beta.mm

@@ -25,9 +25,9 @@ @implementation ASNodeController
 - (instancetype)init
 {
   if (self = [super init]) {
-    if (ASNodeContext *ctx = ASNodeContextGet()) {
-      _nodeContext = ctx;
-      new (&_mutexOrPtr) AS::MutexOrPointer(&ctx->_mutex);
+    _nodeContext = ASNodeContextGet();
+    if (_nodeContext) {
+      new (&_mutexOrPtr) AS::MutexOrPointer(&_nodeContext->_mutex);
     } else {
       new (&_mutexOrPtr) AS::MutexOrPointer(nullptr);
       _mutexOrPtr.get().SetDebugNameWithObject(self);

Source/ASTableView.mm

@@ -1744,9 +1744,7 @@ - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAt
   } else if (_asyncDataSourceFlags.tableNodeNodeForRow) {
     ASCellNode *node = nil;
     if (ASTableNode *tableNode = self.tableNode) {
-      ASNodeContextPushNew();
     	node = [_asyncDataSource tableNode:tableNode nodeForRowAtIndexPath:indexPath];
-      ASNodeContextPop();
     }
     if ([node isKindOfClass:[ASCellNode class]]) {
       block = ^{
@@ -1760,9 +1758,7 @@ - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAt
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
     block = [_asyncDataSource tableView:self nodeBlockForRowAtIndexPath:indexPath];
   } else if (_asyncDataSourceFlags.tableViewNodeForRow) {
-    ASNodeContextPushNew();
     ASCellNode *node = [_asyncDataSource tableView:self nodeForRowAtIndexPath:indexPath];
-    ASNodeContextPop();
 #pragma clang diagnostic pop
     if ([node isKindOfClass:[ASCellNode class]]) {
       block = ^{

Source/Details/ASDataController.mm

@@ -166,13 +166,11 @@ - (void)_allocateNodesFromElements:(NSArray<ASCollectionElement *> *)elements
 
       unowned ASCollectionElement *element = elements[i];
 
-      ASNodeContextPushNew();
       NSMutableDictionary *dict = [[NSThread currentThread] threadDictionary];
       dict[ASThreadDictMaxConstraintSizeKey] =
           [NSValue valueWithCGSize:element.constrainedSize.max];
       unowned ASCellNode *node = element.node;
       [dict removeObjectForKey:ASThreadDictMaxConstraintSizeKey];
-      ASNodeContextPop();
 
       // Layout the node if the size range is valid.
       ASSizeRange sizeRange = element.constrainedSize;

Tests/ASConfigurationTests.mm

@@ -30,8 +30,7 @@
   ASExperimentalOOMBackgroundDeallocDisable,
   ASExperimentalRemoveTextKitInitialisingLock,
   ASExperimentalDrawingGlobal,
-  ASExperimentalOptimizeDataControllerPipeline,
-  ASExperimentalNodeContext
+  ASExperimentalOptimizeDataControllerPipeline
 };
 
 @interface ASConfigurationTests : ASTestCase <ASConfigurationDelegate>
@@ -57,7 +56,6 @@ + (NSArray *)names {
     @"exp_remove_textkit_initialising_lock",
     @"exp_drawing_global",
     @"exp_optimize_data_controller_pipeline",
-    @"exp_node_context"
   ];
 }