From 81def94f6f83667a5b37fa5efe1572aedc0f8b73 Mon Sep 17 00:00:00 2001
From: appleguy <scottgoodson@gmail.com>
Date: Wed, 14 Jun 2017 13:55:52 -0700
Subject: [PATCH] [ASTraitCollection] Convert ASPrimitiveTraitCollection from
 lock to atomic. (#355)

* [ASTraitCollection] Convert ASPrimitiveTraitCollection from lock to atomic.

This resolves a deadlock case: https://github.com/TextureGroup/Texture/issues/353

* [ASTraitCollection] Use assignment operator instead of .store() for C++ atomic.
---
 CHANGELOG.md                                |  1 +
 Source/ASDisplayNode+Layout.mm              | 13 +++----------
 Source/Details/ASTraitCollection.h          |  2 +-
 Source/Private/ASDisplayNodeInternal.h      |  2 +-
 Source/Private/Layout/ASLayoutSpecPrivate.h |  2 +-
 5 files changed, 7 insertions(+), 13 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 978c2fc3b..42bc33956 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## master
 
 * Add your own contributions to the next release on the line below this with your name.
+- [ASTraitCollection] Convert ASPrimitiveTraitCollection from lock to atomic. [Scott Goodson](https://github.com/appleguy)
 - Add a synchronous mode to ASCollectionNode, for colletion view data source debugging. [Hannah Troisi](https://github.com/hannahmbanana)
 - [ASDisplayNode+Layout] Add check for orphaned nodes after layout transition to clean up. #336. [Scott Goodson](https://github.com/appleguy)
 - Fixed an issue where GIFs with placeholders never had their placeholders uncover the GIF. [Garrett Moon](https://github.com/garrettmoon)
diff --git a/Source/ASDisplayNode+Layout.mm b/Source/ASDisplayNode+Layout.mm
index f34628976..cd80e7f65 100644
--- a/Source/ASDisplayNode+Layout.mm
+++ b/Source/ASDisplayNode+Layout.mm
@@ -98,28 +98,21 @@ - (ASLayout *)layoutThatFits:(ASSizeRange)constrainedSize parentSize:(CGSize)par
 
 - (ASPrimitiveTraitCollection)primitiveTraitCollection
 {
-  ASDN::MutexLocker l(__instanceLock__);
-  return _primitiveTraitCollection;
+  return _primitiveTraitCollection.load();
 }
 
 - (void)setPrimitiveTraitCollection:(ASPrimitiveTraitCollection)traitCollection
 {
-  __instanceLock__.lock();
-  if (ASPrimitiveTraitCollectionIsEqualToASPrimitiveTraitCollection(traitCollection, _primitiveTraitCollection) == NO) {
+  if (ASPrimitiveTraitCollectionIsEqualToASPrimitiveTraitCollection(traitCollection, _primitiveTraitCollection.load()) == NO) {
     _primitiveTraitCollection = traitCollection;
     ASDisplayNodeLogEvent(self, @"asyncTraitCollectionDidChange: %@", NSStringFromASPrimitiveTraitCollection(traitCollection));
-    __instanceLock__.unlock();
-    
+
     [self asyncTraitCollectionDidChange];
-    return;
   }
-  
-  __instanceLock__.unlock();
 }
 
 - (ASTraitCollection *)asyncTraitCollection
 {
-  ASDN::MutexLocker l(__instanceLock__);
   return [ASTraitCollection traitCollectionWithASPrimitiveTraitCollection:self.primitiveTraitCollection];
 }
 
diff --git a/Source/Details/ASTraitCollection.h b/Source/Details/ASTraitCollection.h
index a1e9971b1..760919c0d 100644
--- a/Source/Details/ASTraitCollection.h
+++ b/Source/Details/ASTraitCollection.h
@@ -104,7 +104,7 @@ ASDISPLAYNODE_EXTERN_C_END
 #define ASPrimitiveTraitCollectionDefaults \
 - (ASPrimitiveTraitCollection)primitiveTraitCollection\
 {\
-  return _primitiveTraitCollection;\
+  return _primitiveTraitCollection.load();\
 }\
 - (void)setPrimitiveTraitCollection:(ASPrimitiveTraitCollection)traitCollection\
 {\
diff --git a/Source/Private/ASDisplayNodeInternal.h b/Source/Private/ASDisplayNodeInternal.h
index 83e2db737..7d16fb8b1 100644
--- a/Source/Private/ASDisplayNodeInternal.h
+++ b/Source/Private/ASDisplayNodeInternal.h
@@ -127,7 +127,7 @@ FOUNDATION_EXPORT NSString * const ASRenderingEngineDidDisplayNodesScheduledBefo
   NSArray<ASDisplayNode *> *_cachedSubnodes;
 
   ASLayoutElementStyle *_style;
-  ASPrimitiveTraitCollection _primitiveTraitCollection;
+  std::atomic<ASPrimitiveTraitCollection> _primitiveTraitCollection;
 
   std::atomic_uint _displaySentinel;
 
diff --git a/Source/Private/Layout/ASLayoutSpecPrivate.h b/Source/Private/Layout/ASLayoutSpecPrivate.h
index 17cf16c98..f8813afeb 100644
--- a/Source/Private/Layout/ASLayoutSpecPrivate.h
+++ b/Source/Private/Layout/ASLayoutSpecPrivate.h
@@ -28,7 +28,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface ASLayoutSpec() {
   ASDN::RecursiveMutex __instanceLock__;
-  ASPrimitiveTraitCollection _primitiveTraitCollection;
+  std::atomic <ASPrimitiveTraitCollection> _primitiveTraitCollection;
   ASLayoutElementStyle *_style;
   NSMutableArray *_childrenArray;
 }