[ASDisplayNode] Fix infinite layout loop (#455)

* Fix infinite layout loop

- The problem will occur if a node does either of the followings:
1. Keeps using a stale pending layout over a calculated layout
2. Doesn't update the next layout's version after calling _setNeedsLayoutFromAbove.

* Update CHANGELOG

CHANGELOG.md

@@ -4,7 +4,8 @@
 - [ASCollectionView] Add delegate bridging and index space translation for missing UICollectionViewLayout properties. [Scott Goodson](https://github.com/appleguy)
 - [ASTextNode2] Add initial implementation for link handling. [Scott Goodson](https://github.com/appleguy) [#396](https://github.com/TextureGroup/Texture/pull/396)
 - [ASTextNode2] Provide compile flag to globally enable new implementation of ASTextNode: ASTEXTNODE_EXPERIMENT_GLOBAL_ENABLE. [Scott Goodson](https://github.com/appleguy) [#396](https://github.com/TextureGroup/Texture/pull/410)
- - Add ASCollectionGalleryLayoutDelegate - an async collection layout that makes same-size collections (e.g photo galleries, pagers, etc) fast and lightweight! [Huy Nguyen](https://github.com/nguyenhuy/) [#76](https://github.com/TextureGroup/Texture/pull/76) [#451](https://github.com/TextureGroup/Texture/pull/451)
+- Add ASCollectionGalleryLayoutDelegate - an async collection layout that makes same-size collections (e.g photo galleries, pagers, etc) fast and lightweight! [Huy Nguyen](https://github.com/nguyenhuy/) [#76](https://github.com/TextureGroup/Texture/pull/76) [#451](https://github.com/TextureGroup/Texture/pull/451)
+- Fix an issue that causes infinite layout loop in ASDisplayNode after [#428](https://github.com/TextureGroup/Texture/pull/428) [Huy Nguyen](https://github.com/nguyenhuy) [#455](https://github.com/TextureGroup/Texture/pull/455) 
 
 ##2.3.5
 - Fix an issue where inserting/deleting sections could lead to inconsistent supplementary element behavior. [Adlai Holler](https://github.com/Adlai-Holler)

Source/ASDisplayNode+Layout.mm

@@ -302,10 +302,10 @@ - (void)_locked_measureNodeWithBoundsIfNecessary:(CGRect)bounds
   }
 
   CGSize boundsSizeForLayout = ASCeilSizeValues(bounds.size);
-  
+
   // Prefer _pendingDisplayNodeLayout over _calculatedDisplayNodeLayout (if exists, it's the newest)
   // If there is no _pending, check if _calculated is valid to reuse (avoiding recalculation below).
-  if (_pendingDisplayNodeLayout == nullptr) {
+  if (_pendingDisplayNodeLayout == nullptr || _pendingDisplayNodeLayout->version < _layoutVersion) {
     if (_calculatedDisplayNodeLayout->version >= _layoutVersion
         && (_calculatedDisplayNodeLayout->requestedLayoutFromAbove == YES
             || CGSizeEqualToSize(_calculatedDisplayNodeLayout->layout.size, boundsSizeForLayout))) {
@@ -352,8 +352,10 @@ - (void)_locked_measureNodeWithBoundsIfNecessary:(CGRect)bounds
     ASLayout *layout = [self calculateLayoutThatFits:constrainedSize
                                     restrictedToSize:self.style.size
                                 relativeToParentSize:boundsSizeForLayout];
-
     nextLayout = std::make_shared<ASDisplayNodeLayout>(layout, constrainedSize, boundsSizeForLayout, version);
+    // Now that the constrained size of pending layout might have been reused, the layout is useless
+    // Release it and any orphaned subnodes it retains
+    _pendingDisplayNodeLayout = nullptr;
   }
 
   if (didCreateNewContext) {
@@ -373,6 +375,9 @@ - (void)_locked_measureNodeWithBoundsIfNecessary:(CGRect)bounds
     // particular ASLayout object, and shouldn't loop asking again unless we have a different ASLayout.
     nextLayout->requestedLayoutFromAbove = YES;
     [self _setNeedsLayoutFromAbove];
+    // Update the layout's version here because _setNeedsLayoutFromAbove calls __setNeedsLayout which in turn increases _layoutVersion
+    // Failing to do this will cause the layout to be invalid immediately 
+    nextLayout->version = _layoutVersion;
   }
 
   // Prepare to transition to nextLayout
@@ -956,7 +961,7 @@ - (void)_locked_setCalculatedDisplayNodeLayout:(std::shared_ptr<ASDisplayNodeLay
     _unflattenedLayout = displayNodeLayout->layout;
     displayNodeLayout->layout = [_unflattenedLayout filteredNodeLayoutTree];
   }
-  
+
   _calculatedDisplayNodeLayout = displayNodeLayout;
 }
 

Source/ASDisplayNode.mm

@@ -920,7 +920,7 @@ - (void)__layout
     // This method will confirm that the layout is up to date (and update if needed).
     // Importantly, it will also APPLY the layout to all of our subnodes if (unless parent is transitioning).
     [self _locked_measureNodeWithBoundsIfNecessary:bounds];
-    
+
     [self _locked_layoutPlaceholderIfNecessary];
   }