Cleanup ASTextNode and add locking

For now we use a big recursive lock. This needs to be revisited as we revisit the whole ASDK locking strategy.

AsyncDisplayKit/ASTextNode.mm

@@ -11,22 +11,19 @@
 #import "ASTextNode.h"
 #import "ASTextNode+Beta.h"
 
+#include <mutex>
+
 #import <AsyncDisplayKit/_ASDisplayLayer.h>
-#import <AsyncDisplayKit/ASAssert.h>
 #import <AsyncDisplayKit/ASDisplayNode+Subclasses.h>
 #import <AsyncDisplayKit/ASDisplayNodeInternal.h>
 #import <AsyncDisplayKit/ASHighlightOverlayLayer.h>
 #import <AsyncDisplayKit/ASDisplayNodeExtras.h>
 
 #import "ASTextKitCoreTextAdditions.h"
-#import "ASTextKitComponents.h"
-#import "ASTextKitFontSizeAdjuster.h"
-#import "ASTextKitRenderer.h"
 #import "ASTextKitRenderer+Positioning.h"
 #import "ASTextKitShadower.h"
 
 #import "ASInternalHelpers.h"
-#import "ASEqualityHelpers.h"
 #import "ASLayout.h"
 
 static const NSTimeInterval ASTextNodeHighlightFadeOutDuration = 0.15;
@@ -38,15 +35,13 @@ static NSString *ASTextNodeTruncationTokenAttributeName = @"ASTextNodeTruncation
 @interface ASTextNodeDrawParameters : NSObject
 
 @property (nonatomic, assign, readonly) CGRect bounds;
-
 @property (nonatomic, strong, readonly) UIColor *backgroundColor;
 
 @end
 
 @implementation ASTextNodeDrawParameters
 
-- (instancetype)initWithBounds:(CGRect)bounds
-               backgroundColor:(UIColor *)backgroundColor
+- (instancetype)initWithBounds:(CGRect)bounds backgroundColor:(UIColor *)backgroundColor
 {
   if (self = [super init]) {
     _bounds = bounds;
@@ -76,7 +71,7 @@ static NSString *ASTextNodeTruncationTokenAttributeName = @"ASTextNodeTruncation
   NSRange _highlightRange;
   ASHighlightOverlayLayer *_activeHighlightLayer;
 
-  ASDN::Mutex _rendererLock;
+  std::recursive_mutex _textLock;
 
   CGSize _constrainedSize;
 
@@ -160,6 +155,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (NSString *)description
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   NSString *plainString = [[_attributedText string] stringByTrimmingCharactersInSet:[NSCharacterSet newlineCharacterSet]];
   NSString *truncationString = [_composedTruncationText string];
   if (plainString.length > 50)
@@ -227,7 +224,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (ASTextKitRenderer *)_rendererWithBounds:(CGRect)bounds
 {
-  ASDN::MutexLocker l(_rendererLock);
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+
   if (_renderer == nil) {
     CGSize constrainedSize = _constrainedSize.width != -INFINITY ? _constrainedSize : bounds.size;
     _renderer = [[ASTextKitRenderer alloc] initWithTextKitAttributes:[self _rendererAttributes]
@@ -250,9 +248,28 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   };
 }
 
+- (void)_invalidateRendererIfNeeded
+{
+  [self _invalidateRendererIfNeededForBoundsSize:self.threadSafeBounds.size];
+}
+
+- (void)_invalidateRendererIfNeededForBoundsSize:(CGSize)boundsSize
+{
+  if ([self _needInvalidateRendererForBoundsSize:boundsSize]) {
+    // Our bounds of frame have changed to a size that is not identical to our constraining size,
+    // so our previous layout information is invalid, and TextKit may draw at the
+    // incorrect origin.
+    {
+      std::lock_guard<std::recursive_mutex> l(_textLock);
+      _constrainedSize = CGSizeMake(-INFINITY, -INFINITY);
+    }
+    [self _invalidateRenderer];
+  }
+}
+
 - (void)_invalidateRenderer
 {
-  ASDN::MutexLocker l(_rendererLock);
+  std::lock_guard<std::recursive_mutex> l(_textLock);
   
   if (_renderer) {
     // Destruction of the layout managers/containers/text storage is quite
@@ -267,27 +284,13 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   }
 }
 
-- (void)_invalidateRendererIfNeeded
-{
-  [self _invalidateRendererIfNeededForBoundsSize:self.threadSafeBounds.size];
-}
-
-- (void)_invalidateRendererIfNeededForBoundsSize:(CGSize)boundsSize
-{
-  if ([self _needInvalidateRendererForBoundsSize:boundsSize]) {
-    // Our bounds of frame have changed to a size that is not identical to our constraining size,
-    // so our previous layout information is invalid, and TextKit may draw at the
-    // incorrect origin.
-    _constrainedSize = CGSizeMake(-INFINITY, -INFINITY);
-    [self _invalidateRenderer];
-  }
-}
-
 #pragma mark - Layout and Sizing
 
 - (BOOL)_needInvalidateRendererForBoundsSize:(CGSize)boundsSize
 {
-  if (!_renderer) {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
+  if (_renderer == nil) {
     return YES;
   }
   
@@ -322,6 +325,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   [super calculatedLayoutDidChange];
   
   ASLayout *layout = self.calculatedLayout;
+  
+  std::lock_guard<std::recursive_mutex> l(_textLock);
   if (layout != nil) {
     _constrainedSize = layout.size;
     _renderer.constrainedSize = layout.size;
@@ -333,6 +338,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   ASDisplayNodeAssert(constrainedSize.width >= 0, @"Constrained width for text (%f) is too  narrow", constrainedSize.width);
   ASDisplayNodeAssert(constrainedSize.height >= 0, @"Constrained height for text (%f) is too short", constrainedSize.height);
   
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   _constrainedSize = constrainedSize;
   
   // Instead of invalidating the renderer, in case this is a new call with a different constrained size,
@@ -341,7 +348,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
   [self setNeedsDisplay];
   
-  CGSize size = [[self _renderer] size];
+  CGSize size = [self _renderer].size;
   if (_attributedText.length > 0) {
     CGFloat screenScale = ASScreenScale();
     self.ascender = round([[_attributedText attribute:NSFontAttributeName atIndex:0 effectiveRange:NULL] ascender] * screenScale)/screenScale;
@@ -359,6 +366,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)setAttributedText:(NSAttributedString *)attributedText
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (attributedText == nil) {
     attributedText = [[NSAttributedString alloc] initWithString:@"" attributes:nil];
   }
@@ -388,16 +397,18 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
   [self setNeedsDisplay];
   
-  self.accessibilityLabel = _attributedText.string;
   
-  // We're an accessibility element by default if there is a string.
-  self.isAccessibilityElement = _attributedText.length != 0;
+  // Accessiblity
+  self.accessibilityLabel = _attributedText.string;
+  self.isAccessibilityElement = (_attributedText.length != 0); // We're an accessibility element by default if there is a string.
 }
 
 #pragma mark - Text Layout
 
 - (void)setExclusionPaths:(NSArray *)exclusionPaths
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (ASObjectIsEqual(exclusionPaths, _exclusionPaths)) {
     return;
   }
@@ -410,6 +421,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (NSArray *)exclusionPaths
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return _exclusionPaths;
 }
 
@@ -417,6 +430,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)drawRect:(CGRect)bounds withParameters:(ASTextNodeDrawParameters *)parameters isCancelled:(asdisplaynode_iscancelled_block_t)isCancelledBlock isRasterizing:(BOOL)isRasterizing
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   CGContextRef context = UIGraphicsGetCurrentContext();
   ASDisplayNodeAssert(context, @"This is no good without a context.");
   
@@ -437,7 +452,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   }
   
   // Draw shadow
-  [[renderer shadower] setShadowInContext:context];
+  [renderer.shadower setShadowInContext:context];
   
   // Draw text
   bounds.origin = textOrigin;
@@ -470,6 +485,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
    inAdditionalTruncationMessage:(out BOOL *)inAdditionalTruncationMessageOut
                  forHighlighting:(BOOL)highlighting
 {
+  ASDisplayNodeAssertMainThread();
+  
   ASTextKitRenderer *renderer = [self _renderer];
   NSRange visibleRange = renderer.firstVisibleRange;
   NSAttributedString *attributedString = _attributedText;
@@ -562,6 +579,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
 {
+  ASDisplayNodeAssertMainThread();
+  
   if (gestureRecognizer == _longPressGestureRecognizer) {
     // Don't allow long press on truncation message
     if ([self _pendingTruncationTap]) {
@@ -593,6 +612,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (NSRange)highlightRange
 {
+  ASDisplayNodeAssertMainThread();
+  
   return _highlightRange;
 }
 
@@ -603,6 +624,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)setHighlightRange:(NSRange)highlightRange animated:(BOOL)animated
 {
+  ASDisplayNodeAssertMainThread();
+  
   [self _setHighlightRange:highlightRange forAttributeName:nil value:nil animated:animated];
 }
 
@@ -672,7 +695,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
         NSMutableArray *converted = [NSMutableArray arrayWithCapacity:highlightRects.count];
         for (NSValue *rectValue in highlightRects) {
           UIEdgeInsets shadowPadding = _renderer.shadower.shadowPadding;
-          CGRect rendererRect = [[self class] _adjustRendererRect:rectValue.CGRectValue forShadowPadding:shadowPadding];
+          CGRect rendererRect = ASTextNodeAdjustRenderRectForShadowPadding(rectValue.CGRectValue, shadowPadding);
           CGRect highlightedRect = [self.layer convertRect:rendererRect toLayer:highlightTargetLayer];
 
           // We set our overlay layer's frame to the bounds of the highlight target layer.
@@ -709,6 +732,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)_clearHighlightIfNecessary
 {
+  ASDisplayNodeAssertMainThread();
+  
   if ([self _pendingLinkTap] || [self _pendingTruncationTap]) {
     [self setHighlightRange:NSMakeRange(0, 0) animated:YES];
   }
@@ -726,29 +751,12 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 #pragma mark - Text rects
 
-+ (CGRect)_adjustRendererRect:(CGRect)rendererRect forShadowPadding:(UIEdgeInsets)shadowPadding
-{
+static CGRect ASTextNodeAdjustRenderRectForShadowPadding(CGRect rendererRect, UIEdgeInsets shadowPadding) {
   rendererRect.origin.x -= shadowPadding.left;
   rendererRect.origin.y -= shadowPadding.top;
   return rendererRect;
 }
 
-- (NSArray *)_rectsForTextRange:(NSRange)textRange measureOption:(ASTextKitRendererMeasureOption)measureOption
-{
-  NSArray *rects = [[self _renderer] rectsForTextRange:textRange measureOption:measureOption];
-  NSMutableArray *adjustedRects = [NSMutableArray array];
-
-  for (NSValue *rectValue in rects) {
-    CGRect rect = [rectValue CGRectValue];
-    rect = [self.class _adjustRendererRect:rect forShadowPadding:self.shadowPadding];
-
-    NSValue *adjustedRectValue = [NSValue valueWithCGRect:rect];
-    [adjustedRects addObject:adjustedRectValue];
-  }
-
-  return adjustedRects;
-}
-
 - (NSArray *)rectsForTextRange:(NSRange)textRange
 {
   return [self _rectsForTextRange:textRange measureOption:ASTextKitRendererMeasureOptionCapHeight];
@@ -759,22 +767,46 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   return [self _rectsForTextRange:textRange measureOption:ASTextKitRendererMeasureOptionBlock];
 }
 
+- (NSArray *)_rectsForTextRange:(NSRange)textRange measureOption:(ASTextKitRendererMeasureOption)measureOption
+{
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
+  NSArray *rects = [[self _renderer] rectsForTextRange:textRange measureOption:measureOption];
+  NSMutableArray *adjustedRects = [NSMutableArray array];
+
+  for (NSValue *rectValue in rects) {
+    CGRect rect = [rectValue CGRectValue];
+    rect = ASTextNodeAdjustRenderRectForShadowPadding(rect, self.shadowPadding);
+
+    NSValue *adjustedRectValue = [NSValue valueWithCGRect:rect];
+    [adjustedRects addObject:adjustedRectValue];
+  }
+
+  return adjustedRects;
+}
+
 - (CGRect)trailingRect
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   CGRect rect = [[self _renderer] trailingRect];
-  return [self.class _adjustRendererRect:rect forShadowPadding:self.shadowPadding];
+  return ASTextNodeAdjustRenderRectForShadowPadding(rect, self.shadowPadding);
 }
 
 - (CGRect)frameForTextRange:(NSRange)textRange
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   CGRect frame = [[self _renderer] frameForTextRange:textRange];
-  return [self.class _adjustRendererRect:frame forShadowPadding:self.shadowPadding];
+  return ASTextNodeAdjustRenderRectForShadowPadding(frame, self.shadowPadding);
 }
 
 #pragma mark - Placeholders
 
 - (void)setPlaceholderColor:(UIColor *)placeholderColor
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   _placeholderColor = placeholderColor;
 
   // prevent placeholders if we don't have a color
@@ -790,6 +822,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
     return nil;
   }
   
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   UIGraphicsBeginImageContext(size);
   [self.placeholderColor setFill];
 
@@ -816,8 +850,10 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 #pragma mark - Touch Handling
 
--(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
+- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
 {
+  ASDisplayNodeAssertMainThread();
+  
   if (!_passthroughNonlinkTouches) {
     return [super pointInside:point withEvent:event];
   }
@@ -846,9 +882,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
 {
-  [super touchesBegan:touches withEvent:event];
-
   ASDisplayNodeAssertMainThread();
+  [super touchesBegan:touches withEvent:event];
 
   CGPoint point = [[touches anyObject] locationInView:self.view];
 
@@ -878,6 +913,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
 {
+  ASDisplayNodeAssertMainThread();
   [super touchesCancelled:touches withEvent:event];
   
   [self _clearHighlightIfNecessary];
@@ -885,6 +921,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
 {
+  ASDisplayNodeAssertMainThread();
   [super touchesEnded:touches withEvent:event];
   
   if ([self _pendingLinkTap] && [_delegate respondsToSelector:@selector(textNode:tappedLinkAttribute:value:atPoint:textRange:)]) {
@@ -903,6 +940,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
 {
+  ASDisplayNodeAssertMainThread();
   [super touchesMoved:touches withEvent:event];
 
   UITouch *touch = [touches anyObject];
@@ -928,6 +966,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (void)_handleLongPress:(UILongPressGestureRecognizer *)longPressRecognizer
 {
+  ASDisplayNodeAssertMainThread();
+  
   // Respond to long-press when it begins, not when it ends.
   if (longPressRecognizer.state == UIGestureRecognizerStateBegan) {
     if ([self.delegate respondsToSelector:@selector(textNode:longPressedLinkAttribute:value:atPoint:textRange:)]) {
@@ -939,11 +979,15 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (BOOL)_pendingLinkTap
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return (_highlightedLinkAttributeValue != nil && ![self _pendingTruncationTap]) && _delegate != nil;
 }
 
 - (BOOL)_pendingTruncationTap
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return [_highlightedLinkAttributeName isEqualToString:ASTextNodeTruncationTokenAttributeName];
 }
 
@@ -951,11 +995,15 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (CGColorRef)shadowColor
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return _shadowColor;
 }
 
 - (void)setShadowColor:(CGColorRef)shadowColor
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (_shadowColor != shadowColor) {
     if (shadowColor != NULL) {
       CGColorRetain(shadowColor);
@@ -968,11 +1016,15 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (CGSize)shadowOffset
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return _shadowOffset;
 }
 
 - (void)setShadowOffset:(CGSize)shadowOffset
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (!CGSizeEqualToSize(_shadowOffset, shadowOffset)) {
     _shadowOffset = shadowOffset;
     [self _invalidateRenderer];
@@ -982,11 +1034,15 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (CGFloat)shadowOpacity
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return _shadowOpacity;
 }
 
 - (void)setShadowOpacity:(CGFloat)shadowOpacity
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (_shadowOpacity != shadowOpacity) {
     _shadowOpacity = shadowOpacity;
     [self _invalidateRenderer];
@@ -996,11 +1052,15 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (CGFloat)shadowRadius
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return _shadowRadius;
 }
 
 - (void)setShadowRadius:(CGFloat)shadowRadius
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (_shadowRadius != shadowRadius) {
     _shadowRadius = shadowRadius;
     [self _invalidateRenderer];
@@ -1015,6 +1075,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 - (UIEdgeInsets)shadowPaddingWithRenderer:(ASTextKitRenderer *)renderer
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return renderer.shadower.shadowPadding;
 }
 
@@ -1032,6 +1094,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (void)setTruncationAttributedText:(NSAttributedString *)truncationAttributedText
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (ASObjectIsEqual(_truncationAttributedText, truncationAttributedText)) {
     return;
   }
@@ -1042,6 +1106,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (void)setAdditionalTruncationMessage:(NSAttributedString *)additionalTruncationMessage
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (ASObjectIsEqual(_additionalTruncationMessage, additionalTruncationMessage)) {
     return;
   }
@@ -1052,6 +1118,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (void)setTruncationMode:(NSLineBreakMode)truncationMode
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (_truncationMode != truncationMode) {
     _truncationMode = truncationMode;
     [self _invalidateRenderer];
@@ -1061,12 +1129,16 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (BOOL)isTruncated
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   ASTextKitRenderer *renderer = [self _renderer];
   return renderer.firstVisibleRange.length < _attributedText.length;
 }
 
 - (void)setPointSizeScaleFactors:(NSArray *)pointSizeScaleFactors
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if ([_pointSizeScaleFactors isEqualToArray:pointSizeScaleFactors] == NO) {
     _pointSizeScaleFactors = pointSizeScaleFactors;
     [self _invalidateRenderer];
@@ -1075,6 +1147,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (void)setMaximumNumberOfLines:(NSUInteger)maximumNumberOfLines
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   if (_maximumNumberOfLines != maximumNumberOfLines) {
     _maximumNumberOfLines = maximumNumberOfLines;
     [self _invalidateRenderer];
@@ -1084,6 +1158,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (NSUInteger)lineCount
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   return [[self _renderer] lineCount];
 }
 
@@ -1091,6 +1167,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
 
 - (void)_updateComposedTruncationText
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   _composedTruncationText = [self _prepareTruncationStringForDrawing:[self _composedTruncationText]];
 }
 
@@ -1107,6 +1185,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
  */
 - (NSRange)_additionalTruncationMessageRangeWithVisibleRange:(NSRange)visibleRange
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   // Check if we even have an additional truncation message.
   if (!_additionalTruncationMessage) {
     return NSMakeRange(NSNotFound, 0);
@@ -1118,8 +1198,7 @@ static NSAttributedString *DefaultTruncationAttributedString()
   NSUInteger additionalTruncationMessageLength = _additionalTruncationMessage.length;
   // We get the location of the truncation token, then add the length of the
   // truncation attributed string +1 for the space between.
-  NSRange range = NSMakeRange(truncationTokenIndex + _truncationAttributedText.length + 1, additionalTruncationMessageLength);
-  return range;
+  return NSMakeRange(truncationTokenIndex + _truncationAttributedText.length + 1, additionalTruncationMessageLength);
 }
 
 /**
@@ -1129,6 +1208,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
  */
 - (NSAttributedString *)_composedTruncationText
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   //If we have neither return the default
   if (!_additionalTruncationMessage && !_truncationAttributedText) {
     return _composedTruncationText;
@@ -1157,6 +1238,8 @@ static NSAttributedString *DefaultTruncationAttributedString()
  */
 - (NSAttributedString *)_prepareTruncationStringForDrawing:(NSAttributedString *)truncationString
 {
+  std::lock_guard<std::recursive_mutex> l(_textLock);
+  
   truncationString = ASCleanseAttributedStringOfCoreTextAttributes(truncationString);
   NSMutableAttributedString *truncationMutableString = [truncationString mutableCopy];
   // Grab the attributes from the full string