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[Performance] Convert ASLayoutElementSize to atomic #trivial #331

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merged 3 commits into from
Jun 13, 2017
Merged

[Performance] Convert ASLayoutElementSize to atomic #trivial #331

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a9196c1
[Performance] Convert ASLayoutElementSize to atomic
hannahmbanana Jun 6, 2017
4b52515
[ASLayoutElementStyle] Put locks around setter methods.
hannahmbanana Jun 10, 2017
e8c2131
Also add lock to setSize: internal method.
hannahmbanana Jun 10, 2017
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122 changes: 63 additions & 59 deletions Source/Layout/ASLayoutElement.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -124,9 +124,9 @@ void ASLayoutElementClearCurrentContext()

@implementation ASLayoutElementStyle {
ASDN::RecursiveMutex __instanceLock__;
ASLayoutElementSize _size;
ASLayoutElementStyleExtensions _extensions;

std::atomic<ASLayoutElementSize> _size;
std::atomic<CGFloat> _spacingBefore;
std::atomic<CGFloat> _spacingAfter;
std::atomic<CGFloat> _flexGrow;
Expand Down Expand Up @@ -180,93 +180,91 @@ - (instancetype)init

- (ASLayoutElementSize)size
{
ASDN::MutexLocker l(__instanceLock__);
return _size;
return _size.load();
}

- (void)setSize:(ASLayoutElementSize)size
{
ASDN::MutexLocker l(__instanceLock__);
_size = size;
_size.store(size);
}

#pragma mark - ASLayoutElementStyleSizeForwarding

- (ASDimension)width
{
ASDN::MutexLocker l(__instanceLock__);
return _size.width;
return _size.load().width;
}

- (void)setWidth:(ASDimension)width
{
ASDN::MutexLocker l(__instanceLock__);
_size.width = width;
ASLayoutElementSize newSize = _size.load();
newSize.width = width;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleWidthProperty);
}

- (ASDimension)height
{
ASDN::MutexLocker l(__instanceLock__);
return _size.height;
return _size.load().height;
}

- (void)setHeight:(ASDimension)height
{
ASDN::MutexLocker l(__instanceLock__);
_size.height = height;
ASLayoutElementSize newSize = _size.load();
newSize.height = height;
_size.store(newSize);
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Unfortunately this breaks atomicity =/ Imagine:

Thread 1: read size A
Thread 2: read size A
Thread 1: write size { A, height = x }
Thread 2: write size { A, width = y }

So we end up with size { A, width = y }, thread 2 overwrote thread 1's change. We should have ended up with size { A, height = x, width = y }.

We have to do the read-update-write all in one operation.

ASLayoutElementStyleCallDelegate(ASLayoutElementStyleHeightProperty);
}

- (ASDimension)minWidth
{
ASDN::MutexLocker l(__instanceLock__);
return _size.minWidth;
return _size.load().minWidth;
}

- (void)setMinWidth:(ASDimension)minWidth
{
ASDN::MutexLocker l(__instanceLock__);
_size.minWidth = minWidth;
ASLayoutElementSize newSize = _size.load();
newSize.minWidth = minWidth;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMinWidthProperty);
}

- (ASDimension)maxWidth
{
ASDN::MutexLocker l(__instanceLock__);
return _size.maxWidth;
return _size.load().maxWidth;
}

- (void)setMaxWidth:(ASDimension)maxWidth
{
ASDN::MutexLocker l(__instanceLock__);
_size.maxWidth = maxWidth;
ASLayoutElementSize newSize = _size.load();
newSize.maxWidth = maxWidth;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMaxWidthProperty);
}

- (ASDimension)minHeight
{
ASDN::MutexLocker l(__instanceLock__);
return _size.minHeight;
return _size.load().minHeight;
}

- (void)setMinHeight:(ASDimension)minHeight
{
ASDN::MutexLocker l(__instanceLock__);
_size.minHeight = minHeight;
ASLayoutElementSize newSize = _size.load();
newSize.minHeight = minHeight;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMinHeightProperty);
}

- (ASDimension)maxHeight
{
ASDN::MutexLocker l(__instanceLock__);
return _size.maxHeight;
return _size.load().maxHeight;
}

- (void)setMaxHeight:(ASDimension)maxHeight
{
ASDN::MutexLocker l(__instanceLock__);
_size.maxHeight = maxHeight;
ASLayoutElementSize newSize = _size.load();
newSize.maxHeight = maxHeight;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMaxHeightProperty);
}

Expand All @@ -277,88 +275,94 @@ - (void)setMaxHeight:(ASDimension)maxHeight

- (void)setPreferredSize:(CGSize)preferredSize
{
ASDN::MutexLocker l(__instanceLock__);
_size.width = ASDimensionMakeWithPoints(preferredSize.width);
_size.height = ASDimensionMakeWithPoints(preferredSize.height);
ASLayoutElementSize newSize = _size.load();
newSize.width = ASDimensionMakeWithPoints(preferredSize.width);
newSize.height = ASDimensionMakeWithPoints(preferredSize.height);
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleWidthProperty);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleHeightProperty);
}

- (CGSize)preferredSize
{
ASDN::MutexLocker l(__instanceLock__);
if (_size.width.unit == ASDimensionUnitFraction) {
NSCAssert(NO, @"Cannot get preferredSize of element with fractional width. Width: %@.", NSStringFromASDimension(_size.width));
ASLayoutElementSize size = _size.load();
if (size.width.unit == ASDimensionUnitFraction) {
NSCAssert(NO, @"Cannot get preferredSize of element with fractional width. Width: %@.", NSStringFromASDimension(size.width));
return CGSizeZero;
}

if (_size.height.unit == ASDimensionUnitFraction) {
NSCAssert(NO, @"Cannot get preferredSize of element with fractional height. Height: %@.", NSStringFromASDimension(_size.height));
if (size.height.unit == ASDimensionUnitFraction) {
NSCAssert(NO, @"Cannot get preferredSize of element with fractional height. Height: %@.", NSStringFromASDimension(size.height));
return CGSizeZero;
}

return CGSizeMake(_size.width.value, _size.height.value);
return CGSizeMake(size.width.value, size.height.value);
}

- (void)setMinSize:(CGSize)minSize
{
ASDN::MutexLocker l(__instanceLock__);
_size.minWidth = ASDimensionMakeWithPoints(minSize.width);
_size.minHeight = ASDimensionMakeWithPoints(minSize.height);
ASLayoutElementSize newSize = _size.load();
newSize.minWidth = ASDimensionMakeWithPoints(minSize.width);
newSize.minHeight = ASDimensionMakeWithPoints(minSize.height);
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMinWidthProperty);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMinHeightProperty);
}

- (void)setMaxSize:(CGSize)maxSize
{
ASDN::MutexLocker l(__instanceLock__);
_size.maxWidth = ASDimensionMakeWithPoints(maxSize.width);
_size.maxHeight = ASDimensionMakeWithPoints(maxSize.height);
ASLayoutElementSize newSize = _size.load();
newSize.maxWidth = ASDimensionMakeWithPoints(maxSize.width);
newSize.maxHeight = ASDimensionMakeWithPoints(maxSize.height);
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMaxWidthProperty);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMaxHeightProperty);
}

- (ASLayoutSize)preferredLayoutSize
{
ASDN::MutexLocker l(__instanceLock__);
return ASLayoutSizeMake(_size.width, _size.height);
ASLayoutElementSize size = _size.load();
return ASLayoutSizeMake(size.width, size.height);
}

- (void)setPreferredLayoutSize:(ASLayoutSize)preferredLayoutSize
{
ASDN::MutexLocker l(__instanceLock__);
_size.width = preferredLayoutSize.width;
_size.height = preferredLayoutSize.height;
ASLayoutElementSize newSize = _size.load();
newSize.width = preferredLayoutSize.width;
newSize.height = preferredLayoutSize.height;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleWidthProperty);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleHeightProperty);
}

- (ASLayoutSize)minLayoutSize
{
ASDN::MutexLocker l(__instanceLock__);
return ASLayoutSizeMake(_size.minWidth, _size.minHeight);
ASLayoutElementSize size = _size.load();
return ASLayoutSizeMake(size.minWidth, size.minHeight);
}

- (void)setMinLayoutSize:(ASLayoutSize)minLayoutSize
{
ASDN::MutexLocker l(__instanceLock__);
_size.minWidth = minLayoutSize.width;
_size.minHeight = minLayoutSize.height;
ASLayoutElementSize newSize = _size.load();
newSize.minWidth = minLayoutSize.width;
newSize.minHeight = minLayoutSize.height;
_size.store(newSize);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMinWidthProperty);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMinHeightProperty);
}

- (ASLayoutSize)maxLayoutSize
{
ASDN::MutexLocker l(__instanceLock__);
return ASLayoutSizeMake(_size.maxWidth, _size.maxHeight);
ASLayoutElementSize size = _size.load();
return ASLayoutSizeMake(size.maxWidth, size.maxHeight);
}

- (void)setMaxLayoutSize:(ASLayoutSize)maxLayoutSize
{
ASDN::MutexLocker l(__instanceLock__);
_size.maxWidth = maxLayoutSize.width;
_size.maxHeight = maxLayoutSize.height;
ASLayoutElementSize newSize = _size.load();
newSize.maxWidth = maxLayoutSize.width;
newSize.maxHeight = maxLayoutSize.height;
_size.store(newSize);
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What if _size is changed after it's loaded here but before the new size is stored?

ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMaxWidthProperty);
ASLayoutElementStyleCallDelegate(ASLayoutElementStyleMaxHeightProperty);
}
Expand Down