Optimizations for ASTextNode handling of renderer allocation and deallocation.

Optimizations for ASDisplayNode handling of bridged property "contentMode", especially for layer-backed nodes.

AsyncDisplayKit/ASTextNode.mm

@@ -62,6 +62,15 @@ static NSString *ASTextNodeTruncationTokenAttributeName = @"ASTextNodeTruncation
 - (void)dealloc
 {
   CGColorRelease(_backgroundColor);
+  
+  // Destruction of the layout managers/containers/text storage is quite
+  // expensive, and can take some time, so we dispatch onto a bg queue to
+  // actually dealloc.
+  __block ASTextKitRenderer *renderer = _renderer;
+  ASPerformBlockOnBackgroundThread(^{
+    renderer = nil;
+  });
+  _renderer = nil;
 }
 
 @end
@@ -157,6 +166,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   if (_shadowColor != NULL) {
     CGColorRelease(_shadowColor);
   }
+  
+  [self _invalidateRenderer];
 
   if (_longPressGestureRecognizer) {
     _longPressGestureRecognizer.delegate = nil;
@@ -189,6 +200,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   return [[self _renderer] size];
 }
 
+// FIXME: Re-evaluate if it is still the right decision to clear the renderer at this stage.
+// This code was written before TextKit and when 512MB devices were still the overwhelming majority.
 - (void)displayDidFinish
 {
   [super displayDidFinish];
@@ -263,16 +276,17 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 - (void)_invalidateRenderer
 {
   ASDN::MutexLocker l(_rendererLock);
+  
   if (_renderer) {
     // Destruction of the layout managers/containers/text storage is quite
     // expensive, and can take some time, so we dispatch onto a bg queue to
     // actually dealloc.
     __block ASTextKitRenderer *renderer = _renderer;
-    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+    ASPerformBlockOnBackgroundThread(^{
       renderer = nil;
     });
+    _renderer = nil;
   }
-  _renderer = nil;
 }
 
 - (void)_invalidateRendererIfNeeded
@@ -320,7 +334,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 #pragma mark - Modifying User Text
 
-- (void)setAttributedString:(NSAttributedString *)attributedString {
+- (void)setAttributedString:(NSAttributedString *)attributedString
+{
   if (ASObjectIsEqual(attributedString, _attributedString)) {
     return;
   }

AsyncDisplayKit/Private/ASDisplayNode+UIViewBridge.mm

@@ -446,19 +446,27 @@
 {
   _bridge_prologue;
   if (__loaded) {
-    return ASDisplayNodeUIContentModeFromCAContentsGravity(_layer.contentsGravity);
+    if (_flags.layerBacked) {
+      return ASDisplayNodeUIContentModeFromCAContentsGravity(_layer.contentsGravity);
+    } else {
+      return _view.contentMode;
+    }
   } else {
     return self.pendingViewState.contentMode;
   }
 }
 
-- (void)setContentMode:(UIViewContentMode)mode
+- (void)setContentMode:(UIViewContentMode)contentMode
 {
   _bridge_prologue;
   if (__loaded) {
-    _layer.contentsGravity = ASDisplayNodeCAContentsGravityFromUIContentMode(mode);
+    if (_flags.layerBacked) {
+      _layer.contentsGravity = ASDisplayNodeCAContentsGravityFromUIContentMode(contentMode);
+    } else {
+      _view.contentMode = contentMode;
+    }
   } else {
-    self.pendingViewState.contentMode = mode;
+    self.pendingViewState.contentMode = contentMode;
   }
 }
 

AsyncDisplayKit/Private/ASInternalHelpers.h

@@ -18,6 +18,7 @@ ASDISPLAYNODE_EXTERN_C_BEGIN
 BOOL ASSubclassOverridesSelector(Class superclass, Class subclass, SEL selector);
 BOOL ASSubclassOverridesClassSelector(Class superclass, Class subclass, SEL selector);
 void ASPerformBlockOnMainThread(void (^block)());
+void ASPerformBlockOnBackgroundThread(void (^block)()); // DISPATCH_QUEUE_PRIORITY_DEFAULT 
 
 CGFloat ASScreenScale();
 

AsyncDisplayKit/Private/ASInternalHelpers.mm

@@ -57,6 +57,18 @@ void ASPerformBlockOnMainThread(void (^block)())
   }
 }
 
+void ASPerformBlockOnBackgroundThread(void (^block)())
+{
+  if ([NSThread isMainThread]) {
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+      block();
+    });
+  } else {
+    block();
+  }
+}
+
+
 CGFloat ASScreenScale()
 {
   static CGFloat _scale;

AsyncDisplayKit/Private/_ASCoreAnimationExtras.mm

@@ -119,11 +119,31 @@ NSString *const ASDisplayNodeCAContentsGravityFromUIContentMode(UIViewContentMod
   return nil;
 }
 
+#define ContentModeCacheSize 10
 UIViewContentMode ASDisplayNodeUIContentModeFromCAContentsGravity(NSString *const contentsGravity)
 {
-  for (int i=0; i < ARRAY_COUNT(UIContentModeCAGravityLUT); i++) {
+  static int currentCacheIndex = 0;
+  static NSMutableArray *cachedStrings = [NSMutableArray arrayWithCapacity:ContentModeCacheSize];
+  static UIViewContentMode cachedModes[ContentModeCacheSize] = {};
+  
+  NSInteger foundCacheIndex = [cachedStrings indexOfObjectIdenticalTo:contentsGravity];
+  if (foundCacheIndex != NSNotFound && foundCacheIndex < ContentModeCacheSize) {
+    return cachedModes[foundCacheIndex];
+  }
+  
+  for (int i = 0; i < ARRAY_COUNT(UIContentModeCAGravityLUT); i++) {
     if (ASObjectIsEqual(UIContentModeCAGravityLUT[i].string, contentsGravity)) {
-      return UIContentModeCAGravityLUT[i].contentMode;
+      UIViewContentMode foundContentMode = UIContentModeCAGravityLUT[i].contentMode;
+      
+      if (currentCacheIndex < ContentModeCacheSize) {
+        // Cache the input value.  This is almost always a different pointer than in our LUT and will frequently
+        // be the same value for an overwhelming majority of inputs.
+        [cachedStrings addObject:contentsGravity];
+        cachedModes[currentCacheIndex] = foundContentMode;
+        currentCacheIndex++;
+      }
+      
+      return foundContentMode;
     }
   }
 

AsyncDisplayKit/TextKit/ASTextKitRenderer.mm

@@ -32,7 +32,9 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 
 @implementation ASTextKitRenderer {
   CGSize _calculatedSize;
+  BOOL _sizeIsCalculated;
 }
+@synthesize attributes = _attributes, context = _context, shadower = _shadower, truncater = _truncater;
 
 #pragma mark - Initialization
 
@@ -42,30 +44,50 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
   if (self = [super init]) {
     _constrainedSize = constrainedSize;
     _attributes = attributes;
+    _sizeIsCalculated = NO;
+  }
+  return self;
+}
 
+- (ASTextKitShadower *)shadower
+{
+  if (!_shadower) {
+    ASTextKitAttributes attributes = _attributes;
     _shadower = [[ASTextKitShadower alloc] initWithShadowOffset:attributes.shadowOffset
                                                     shadowColor:attributes.shadowColor
                                                   shadowOpacity:attributes.shadowOpacity
                                                    shadowRadius:attributes.shadowRadius];
+  }
+  return _shadower;
+}
 
+- (ASTextKitTailTruncater *)truncater
+{
+  if (!_truncater) {
+    ASTextKitAttributes attributes = _attributes;
     // We must inset the constrained size by the size of the shadower.
-    CGSize shadowConstrainedSize = [_shadower insetSizeWithConstrainedSize:_constrainedSize];
+    CGSize shadowConstrainedSize = [[self shadower] insetSizeWithConstrainedSize:_constrainedSize];
+    _truncater = [[ASTextKitTailTruncater alloc] initWithContext:[self context]
+                                      truncationAttributedString:attributes.truncationAttributedString
+                                          avoidTailTruncationSet:attributes.avoidTailTruncationSet ?: _defaultAvoidTruncationCharacterSet()
+                                                 constrainedSize:shadowConstrainedSize];
+  }
+  return _truncater;
+}
 
+- (ASTextKitContext *)context
+{
+  if (!_context) {
+    ASTextKitAttributes attributes = _attributes;
+    CGSize shadowConstrainedSize = [[self shadower] insetSizeWithConstrainedSize:_constrainedSize];
     _context = [[ASTextKitContext alloc] initWithAttributedString:attributes.attributedString
                                                     lineBreakMode:attributes.lineBreakMode
                                              maximumNumberOfLines:attributes.maximumNumberOfLines
                                                    exclusionPaths:attributes.exclusionPaths
                                                   constrainedSize:shadowConstrainedSize
                                              layoutManagerFactory:attributes.layoutManagerFactory];
-
-    _truncater = [[ASTextKitTailTruncater alloc] initWithContext:_context
-                                      truncationAttributedString:attributes.truncationAttributedString
-                                          avoidTailTruncationSet:attributes.avoidTailTruncationSet ?: _defaultAvoidTruncationCharacterSet()
-                                                 constrainedSize:shadowConstrainedSize];
-
-    [self _calculateSize];
   }
-  return self;
+  return _context;
 }
 
 #pragma mark - Sizing
@@ -74,14 +96,14 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 {
   // Force glyph generation and layout, which may not have happened yet (and isn't triggered by
   // -usedRectForTextContainer:).
-  [_context performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
+  [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
     [layoutManager ensureLayoutForTextContainer:textContainer];
   }];
 
 
   CGRect constrainedRect = {CGPointZero, _constrainedSize};
   __block CGRect boundingRect;
-  [_context performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
+  [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
     boundingRect = [layoutManager usedRectForTextContainer:textContainer];
   }];
 
@@ -94,6 +116,10 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 
 - (CGSize)size
 {
+  if (!_sizeIsCalculated) {
+    [self _calculateSize];
+    _sizeIsCalculated = YES;
+  }
   return _calculatedSize;
 }
 
@@ -104,13 +130,13 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
   // We add an assertion so we can track the rare conditions where a graphics context is not present
   ASDisplayNodeAssertNotNil(context, @"This is no good without a context.");
 
-  CGRect shadowInsetBounds = [_shadower insetRectWithConstrainedRect:bounds];
+  CGRect shadowInsetBounds = [[self shadower] insetRectWithConstrainedRect:bounds];
 
   CGContextSaveGState(context);
-  [_shadower setShadowInContext:context];
+  [[self shadower] setShadowInContext:context];
   UIGraphicsPushContext(context);
 
-  [_context performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
+  [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
     NSRange glyphRange = [layoutManager glyphRangeForTextContainer:textContainer];
     [layoutManager drawBackgroundForGlyphRange:glyphRange atPoint:shadowInsetBounds.origin];
     [layoutManager drawGlyphsForGlyphRange:glyphRange atPoint:shadowInsetBounds.origin];
@@ -125,7 +151,7 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 - (NSUInteger)lineCount
 {
   __block NSUInteger lineCount = 0;
-  [_context performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
+  [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
     for (NSRange lineRange = { 0, 0 }; NSMaxRange(lineRange) < [layoutManager numberOfGlyphs]; lineCount++) {
       [layoutManager lineFragmentRectForGlyphAtIndex:NSMaxRange(lineRange) effectiveRange:&lineRange];
     }
@@ -135,7 +161,7 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 
 - (std::vector<NSRange>)visibleRanges
 {
-  return _truncater.visibleRanges;
+  return [self truncater].visibleRanges;
 }
 
 @end