Make yoga & layout specs faster by eliminating some copies (#1128)

CHANGELOG.md

@@ -46,6 +46,7 @@
 - Unlock before cleanup and calling out to subclass hooks for animated images. [Michael Schneider](https://github.com/maicki) [#1087](https://github.com/TextureGroup/Texture/pull/1087)
 - [ASDisplayNode] Fix interface state update for layer backed nodes when layer thrashes (interface coaleascing case).[Max Wang](https://github.com/wsdwsd0829). [#1111](https://github.com/TextureGroup/Texture/pull/1111)
 - [ASPINRemoteImageManager] Add a new API for setting a preconfigured PINRemoteImageManager. [Ernest Ma](https://github.com/ernestmama) [#1124](https://github.com/TextureGroup/Texture/pull/1124)
+- Small optimization to the layout spec & yoga layout systems by eliminating array copies. [Adlai Holler](https://github.com/Adlai-Holler)
 
 ## 2.7
 - Fix pager node for interface coalescing. [Max Wang](https://github.com/wsdwsd0829) [#877](https://github.com/TextureGroup/Texture/pull/877)

Source/ASDisplayNode+Yoga.mm

@@ -13,6 +13,7 @@
 
 #import <AsyncDisplayKit/_ASDisplayViewAccessiblity.h>
 #import <AsyncDisplayKit/ASYogaUtilities.h>
+#import <AsyncDisplayKit/ASCollections.h>
 #import <AsyncDisplayKit/ASDisplayNode+Beta.h>
 #import <AsyncDisplayKit/ASDisplayNode+FrameworkPrivate.h>
 #import <AsyncDisplayKit/ASDisplayNode+Subclasses.h>
@@ -155,10 +156,12 @@
   ASDisplayNodeAssert(childCount == self.yogaChildren.count,
                       @"Yoga tree should always be in sync with .yogaNodes array! %@", self.yogaChildren);
 
-  NSMutableArray *sublayouts = [NSMutableArray arrayWithCapacity:childCount];
+  ASLayout *rawSublayouts[childCount];
+  int i = 0;
   for (ASDisplayNode *subnode in self.yogaChildren) {
-    [sublayouts addObject:[subnode layoutForYogaNode]];
+    rawSublayouts[i++] = [subnode layoutForYogaNode];
   }
+  let sublayouts = [NSArray<ASLayout *> arrayByTransferring:rawSublayouts count:childCount];
 
   // The layout for self should have position CGPointNull, but include the calculated size.
   CGSize size = CGSizeMake(YGNodeLayoutGetWidth(yogaNode), YGNodeLayoutGetHeight(yogaNode));

Source/Layout/ASAbsoluteLayoutSpec.mm

@@ -9,6 +9,7 @@
 
 #import <AsyncDisplayKit/ASAbsoluteLayoutSpec.h>
 
+#import <AsyncDisplayKit/ASCollections.h>
 #import <AsyncDisplayKit/ASLayout.h>
 #import <AsyncDisplayKit/ASLayoutSpec+Subclasses.h>
 #import <AsyncDisplayKit/ASLayoutSpecUtilities.h>
@@ -64,7 +65,8 @@
   };
   
   NSArray *children = self.children;
-  NSMutableArray *sublayouts = [NSMutableArray arrayWithCapacity:children.count];
+  ASLayout *rawSublayouts[children.count];
+  int i = 0;
 
   for (id<ASLayoutElement> child in children) {
     CGPoint layoutPosition = child.style.layoutPosition;
@@ -77,13 +79,14 @@
     
     ASLayout *sublayout = [child layoutThatFits:childConstraint parentSize:size];
     sublayout.position = layoutPosition;
-    [sublayouts addObject:sublayout];
+    rawSublayouts[i++] = sublayout;
   }
-  
+  let sublayouts = [NSArray<ASLayout *> arrayByTransferring:rawSublayouts count:i];
+
   if (_sizing == ASAbsoluteLayoutSpecSizingSizeToFit || isnan(size.width)) {
     size.width = constrainedSize.min.width;
     for (ASLayout *sublayout in sublayouts) {
-      size.width  = MAX(size.width,  sublayout.position.x + sublayout.size.width);
+      size.width = MAX(size.width,  sublayout.position.x + sublayout.size.width);
     }
   }
   

Source/Layout/ASBackgroundLayoutSpec.mm

@@ -12,6 +12,7 @@
 #import <AsyncDisplayKit/ASLayoutSpec+Subclasses.h>
 
 #import <AsyncDisplayKit/ASAssert.h>
+#import <AsyncDisplayKit/ASCollections.h>
 
 static NSUInteger const kForegroundChildIndex = 0;
 static NSUInteger const kBackgroundChildIndex = 1;
@@ -48,17 +49,19 @@ static NSUInteger const kBackgroundChildIndex = 1;
 {
   ASLayout *contentsLayout = [self.child layoutThatFits:constrainedSize parentSize:parentSize];
 
-  NSMutableArray *sublayouts = [NSMutableArray arrayWithCapacity:2];
+  ASLayout *rawSublayouts[2];
+  int i = 0;
   if (self.background) {
     // Size background to exactly the same size.
     ASLayout *backgroundLayout = [self.background layoutThatFits:ASSizeRangeMake(contentsLayout.size)
                                                       parentSize:parentSize];
     backgroundLayout.position = CGPointZero;
-    [sublayouts addObject:backgroundLayout];
+    rawSublayouts[i++] = backgroundLayout;
   }
   contentsLayout.position = CGPointZero;
-  [sublayouts addObject:contentsLayout];
+  rawSublayouts[i++] = contentsLayout;
 
+  let sublayouts = [NSArray<ASLayout *> arrayByTransferring:rawSublayouts count:i];
   return [ASLayout layoutWithLayoutElement:self size:contentsLayout.size sublayouts:sublayouts];
 }
 

Source/Layout/ASLayoutSpec.mm

@@ -113,14 +113,12 @@ ASLayoutElementLayoutCalculationDefaults
 {
   ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
 
-  [_childrenArray removeAllObjects];
+#if ASDISPLAYNODE_ASSERTIONS_ENABLED
-  
-  NSUInteger i = 0;
   for (id<ASLayoutElement> child in children) {
     ASDisplayNodeAssert([child conformsToProtocol:NSProtocolFromString(@"ASLayoutElement")], @"Child %@ of spec %@ is not an ASLayoutElement!", child, self);
-    _childrenArray[i] = child;
-    i += 1;
   }
+#endif
+  [_childrenArray setArray:children];
 }
 
 - (nullable NSArray<id<ASLayoutElement>> *)children
@@ -291,7 +289,9 @@ ASSynthesizeLockingMethodsWithMutex(__instanceLock__)
 - (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
 {
   NSArray *children = self.children;
-  NSMutableArray *sublayouts = [NSMutableArray arrayWithCapacity:children.count];
+  let count = children.count;
+  ASLayout *rawSublayouts[count];
+  int i = 0;
   
   CGSize size = constrainedSize.min;
   for (id<ASLayoutElement> child in children) {
@@ -301,9 +301,9 @@ ASSynthesizeLockingMethodsWithMutex(__instanceLock__)
     size.width = MAX(size.width,  sublayout.size.width);
     size.height = MAX(size.height, sublayout.size.height);
     
-    [sublayouts addObject:sublayout];
+    rawSublayouts[i++] = sublayout;
   }
-  
+  let sublayouts = [NSArray<ASLayout *> arrayByTransferring:rawSublayouts count:i];
   return [ASLayout layoutWithLayoutElement:self size:size sublayouts:sublayouts];
 }
 

Source/Layout/ASOverlayLayoutSpec.mm

@@ -10,6 +10,7 @@
 #import <AsyncDisplayKit/ASOverlayLayoutSpec.h>
 #import <AsyncDisplayKit/ASLayoutSpec+Subclasses.h>
 #import <AsyncDisplayKit/ASAssert.h>
+#import <AsyncDisplayKit/ASCollections.h>
 
 static NSUInteger const kUnderlayChildIndex = 0;
 static NSUInteger const kOverlayChildIndex = 1;
@@ -70,14 +71,17 @@ static NSUInteger const kOverlayChildIndex = 1;
 {
   ASLayout *contentsLayout = [self.child layoutThatFits:constrainedSize parentSize:parentSize];
   contentsLayout.position = CGPointZero;
-  NSMutableArray *sublayouts = [NSMutableArray arrayWithObject:contentsLayout];
+  ASLayout *rawSublayouts[2];
+  int i = 0;
+  rawSublayouts[i++] = contentsLayout;
   if (self.overlay) {
     ASLayout *overlayLayout = [self.overlay layoutThatFits:ASSizeRangeMake(contentsLayout.size)
                                                 parentSize:contentsLayout.size];
     overlayLayout.position = CGPointZero;
-    [sublayouts addObject:overlayLayout];
+    rawSublayouts[i++] = overlayLayout;
   }
   
+  let sublayouts = [NSArray<ASLayout *> arrayByTransferring:rawSublayouts count:i];
   return [ASLayout layoutWithLayoutElement:self size:contentsLayout.size sublayouts:sublayouts];
 }
 

Source/Layout/ASStackLayoutSpec.mm

@@ -12,6 +12,7 @@
 #import <numeric>
 #import <vector>
 
+#import <AsyncDisplayKit/ASCollections.h>
 #import <AsyncDisplayKit/ASDimension.h>
 #import <AsyncDisplayKit/ASLayout.h>
 #import <AsyncDisplayKit/ASLayoutElement.h>
@@ -151,12 +152,14 @@
     self.style.ascender = stackChildren.front().style.ascender;
     self.style.descender = stackChildren.back().style.descender;
   }
-  
+
-  const auto sublayouts = [[NSMutableArray<ASLayout *> alloc] init];
+  ASLayout *rawSublayouts[positionedLayout.items.size()];
+  int i = 0;
   for (const auto &item : positionedLayout.items) {
-    [sublayouts addObject:item.layout];
+    rawSublayouts[i++] = item.layout;
   }
 
+  let sublayouts = [NSArray<ASLayout *> arrayByTransferring:rawSublayouts count:i];
   return [ASLayout layoutWithLayoutElement:self size:positionedLayout.size sublayouts:sublayouts];
 }