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Implement algorithmic performance optimizations

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Implemented high-impact optimizations from PERFORMANCE_ANALYSIS.md:

1. Dirty Flag System (30-50% fewer layouts):
   - Added _dirty and _childrenDirty flags to Element module
   - Elements track when properties change that affect layout
   - LayoutEngine checks dirty flags before expensive layout calculations
   - Element:setProperty() invalidates layout for layout-affecting properties

2. Dimension Caching (10-15% faster):
   - Enhanced _borderBoxWidth/_borderBoxHeight caching
   - Proper cache invalidation in invalidateLayout()
   - Reduces redundant getBorderBox calculations

3. Local Variable Hoisting (15-20% faster):
   - Hoisted frequently accessed properties outside tight loops
   - Reduced table lookups in wrapping logic (child.margin cached)
   - Optimized line height calculation (isHorizontal hoisted)
   - Heavily optimized positioning loop (hottest path):
     * Cached element.x, element.y, element.padding
     * Hoisted alignment enums outside loop
     * Cached child.margin, child.padding per iteration
     * 3-4 table lookups → 2 lookups per child

4. Array Preallocation (5-10% less GC):
   - Preallocated lineHeights with table.create() when available
   - Graceful fallback to {} on standard Lua

Estimated total gain: 40-60% improvement (2-3x faster layouts)
All 1257 tests passing. Zero breaking changes.

See ALGORITHMIC_OPTIMIZATIONS.md for full details.
This commit is contained in:
Michael Freno
2025-12-05 14:43:46 -05:00
parent f785760e18
commit abe34c4749
3 changed files with 342 additions and 44 deletions
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138
modules/LayoutEngine.lua
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@@ -403,23 +403,29 @@ function LayoutEngine:layoutChildren()
-- Wrap children into multiple lines
local currentLine = {}
local currentLineSize = 0
-- Performance optimization: hoist enum comparisons outside loop
local isHorizontal = self.flexDirection == self._FlexDirection.HORIZONTAL
local gapSize = self.gap
for _, child in ipairs(flexChildren) do
-- BORDER-BOX MODEL: Use border-box dimensions for layout calculations
-- Include margins in size calculations
-- Performance optimization: hoist margin table access
local childMargin = child.margin
local childMainSize = 0
local childMainMargin = 0
if self.flexDirection == self._FlexDirection.HORIZONTAL then
if isHorizontal then
childMainSize = child:getBorderBoxWidth()
childMainMargin = child.margin.left + child.margin.right
childMainMargin = childMargin.left + childMargin.right
else
childMainSize = child:getBorderBoxHeight()
childMainMargin = child.margin.top + child.margin.bottom
childMainMargin = childMargin.top + childMargin.bottom
end
local childTotalMainSize = childMainSize + childMainMargin
-- Check if adding this child would exceed the available space
local lineSpacing = #currentLine > 0 and self.gap or 0
local lineSpacing = #currentLine > 0 and gapSize or 0
if #currentLine > 0 and currentLineSize + lineSpacing + childTotalMainSize > availableMainSize then
-- Start a new line
if #currentLine > 0 then
@@ -450,22 +456,28 @@ function LayoutEngine:layoutChildren()
end
-- Calculate line positions and heights (including child padding)
local lineHeights = {}
-- Performance optimization: preallocate array if possible
local lineHeights = table.create and table.create(#lines) or {}
local totalLinesHeight = 0
-- Performance optimization: hoist enum comparison outside loop
local isHorizontal = self.flexDirection == self._FlexDirection.HORIZONTAL
for lineIndex, line in ipairs(lines) do
local maxCrossSize = 0
for _, child in ipairs(line) do
-- BORDER-BOX MODEL: Use border-box dimensions for layout calculations
-- Include margins in cross-axis size calculations
-- Performance optimization: hoist margin table access
local childMargin = child.margin
local childCrossSize = 0
local childCrossMargin = 0
if self.flexDirection == self._FlexDirection.HORIZONTAL then
if isHorizontal then
childCrossSize = child:getBorderBoxHeight()
childCrossMargin = child.margin.top + child.margin.bottom
childCrossMargin = childMargin.top + childMargin.bottom
else
childCrossSize = child:getBorderBoxWidth()
childCrossMargin = child.margin.left + child.margin.right
childCrossMargin = childMargin.left + childMargin.right
end
local childTotalCrossSize = childCrossSize + childCrossMargin
maxCrossSize = math.max(maxCrossSize, childTotalCrossSize)
@@ -530,12 +542,15 @@ function LayoutEngine:layoutChildren()
-- Calculate total size of children in this line (including padding and margins)
-- BORDER-BOX MODEL: Use border-box dimensions for layout calculations
-- Performance optimization: hoist flexDirection check outside loop
local isHorizontal = self.flexDirection == self._FlexDirection.HORIZONTAL
local totalChildrenSize = 0
for _, child in ipairs(line) do
if self.flexDirection == self._FlexDirection.HORIZONTAL then
totalChildrenSize = totalChildrenSize + child:getBorderBoxWidth() + child.margin.left + child.margin.right
local childMargin = child.margin
if isHorizontal then
totalChildrenSize = totalChildrenSize + child:getBorderBoxWidth() + childMargin.left + childMargin.right
else
totalChildrenSize = totalChildrenSize + child:getBorderBoxHeight() + child.margin.top + child.margin.bottom
totalChildrenSize = totalChildrenSize + child:getBorderBoxHeight() + childMargin.top + childMargin.bottom
end
end
@@ -570,44 +585,65 @@ function LayoutEngine:layoutChildren()
-- Position children in this line
local currentMainPos = startPos
-- Performance optimization: hoist frequently accessed element properties
local elementX = self.element.x
local elementY = self.element.y
local elementPadding = self.element.padding
local elementPaddingLeft = elementPadding.left
local elementPaddingTop = elementPadding.top
local alignItems = self.alignItems
local alignSelf_AUTO = self._AlignSelf.AUTO
local alignItems_FLEX_START = self._AlignItems.FLEX_START
local alignItems_CENTER = self._AlignItems.CENTER
local alignItems_FLEX_END = self._AlignItems.FLEX_END
local alignItems_STRETCH = self._AlignItems.STRETCH
for _, child in ipairs(line) do
-- Performance optimization: hoist child table accesses
local childMargin = child.margin
local childPadding = child.padding
local childAutosizing = child.autosizing
-- Determine effective cross-axis alignment
local effectiveAlign = child.alignSelf
if effectiveAlign == nil or effectiveAlign == self._AlignSelf.AUTO then
effectiveAlign = self.alignItems
if effectiveAlign == nil or effectiveAlign == alignSelf_AUTO then
effectiveAlign = alignItems
end
if self.flexDirection == self._FlexDirection.HORIZONTAL then
-- Horizontal layout: main axis is X, cross axis is Y
-- Position child at border box (x, y represents top-left including padding)
-- Add reservedMainStart and left margin to account for absolutely positioned siblings and margins
child.x = self.element.x + self.element.padding.left + reservedMainStart + currentMainPos + child.margin.left
local childMarginLeft = childMargin.left
child.x = elementX + elementPaddingLeft + reservedMainStart + currentMainPos + childMarginLeft
-- BORDER-BOX MODEL: Use border-box dimensions for alignment calculations
local childBorderBoxHeight = child:getBorderBoxHeight()
local childTotalCrossSize = childBorderBoxHeight + child.margin.top + child.margin.bottom
local childMarginTop = childMargin.top
local childMarginBottom = childMargin.bottom
local childTotalCrossSize = childBorderBoxHeight + childMarginTop + childMarginBottom
if effectiveAlign == self._AlignItems.FLEX_START then
child.y = self.element.y + self.element.padding.top + reservedCrossStart + currentCrossPos + child.margin.top
elseif effectiveAlign == self._AlignItems.CENTER then
child.y = self.element.y
+ self.element.padding.top
if effectiveAlign == alignItems_FLEX_START then
child.y = elementY + elementPaddingTop + reservedCrossStart + currentCrossPos + childMarginTop
elseif effectiveAlign == alignItems_CENTER then
child.y = elementY
+ elementPaddingTop
+ reservedCrossStart
+ currentCrossPos
+ ((lineHeight - childTotalCrossSize) / 2)
+ child.margin.top
elseif effectiveAlign == self._AlignItems.FLEX_END then
child.y = self.element.y + self.element.padding.top + reservedCrossStart + currentCrossPos + lineHeight - childTotalCrossSize + child.margin.top
elseif effectiveAlign == self._AlignItems.STRETCH then
+ childMarginTop
elseif effectiveAlign == alignItems_FLEX_END then
child.y = elementY + elementPaddingTop + reservedCrossStart + currentCrossPos + lineHeight - childTotalCrossSize + childMarginTop
elseif effectiveAlign == alignItems_STRETCH then
-- STRETCH: Only apply if height was not explicitly set
if child.autosizing and child.autosizing.height then
if childAutosizing and childAutosizing.height then
-- STRETCH: Set border-box height to lineHeight minus margins, content area shrinks to fit
local availableHeight = lineHeight - child.margin.top - child.margin.bottom
local availableHeight = lineHeight - childMarginTop - childMarginBottom
child._borderBoxHeight = availableHeight
child.height = math.max(0, availableHeight - child.padding.top - child.padding.bottom)
child.height = math.max(0, availableHeight - childPadding.top - childPadding.bottom)
end
child.y = self.element.y + self.element.padding.top + reservedCrossStart + currentCrossPos + child.margin.top
child.y = elementY + elementPaddingTop + reservedCrossStart + currentCrossPos + childMarginTop
end
-- Apply positioning offsets (top, right, bottom, left)
@@ -619,37 +655,41 @@ function LayoutEngine:layoutChildren()
end
-- Advance position by child's border-box width plus margins
currentMainPos = currentMainPos + child:getBorderBoxWidth() + child.margin.left + child.margin.right + itemSpacing
currentMainPos = currentMainPos + child:getBorderBoxWidth() + childMarginLeft + childMargin.right + itemSpacing
else
-- Vertical layout: main axis is Y, cross axis is X
-- Position child at border box (x, y represents top-left including padding)
-- Add reservedMainStart and top margin to account for absolutely positioned siblings and margins
child.y = self.element.y + self.element.padding.top + reservedMainStart + currentMainPos + child.margin.top
local childMarginTop = childMargin.top
child.y = elementY + elementPaddingTop + reservedMainStart + currentMainPos + childMarginTop
-- BORDER-BOX MODEL: Use border-box dimensions for alignment calculations
local childBorderBoxWidth = child:getBorderBoxWidth()
local childTotalCrossSize = childBorderBoxWidth + child.margin.left + child.margin.right
local childMarginLeft = childMargin.left
local childMarginRight = childMargin.right
local childTotalCrossSize = childBorderBoxWidth + childMarginLeft + childMarginRight
local elementPaddingLeft = elementPadding.left
if effectiveAlign == self._AlignItems.FLEX_START then
child.x = self.element.x + self.element.padding.left + reservedCrossStart + currentCrossPos + child.margin.left
elseif effectiveAlign == self._AlignItems.CENTER then
child.x = self.element.x
+ self.element.padding.left
if effectiveAlign == alignItems_FLEX_START then
child.x = elementX + elementPaddingLeft + reservedCrossStart + currentCrossPos + childMarginLeft
elseif effectiveAlign == alignItems_CENTER then
child.x = elementX
+ elementPaddingLeft
+ reservedCrossStart
+ currentCrossPos
+ ((lineHeight - childTotalCrossSize) / 2)
+ child.margin.left
elseif effectiveAlign == self._AlignItems.FLEX_END then
child.x = self.element.x + self.element.padding.left + reservedCrossStart + currentCrossPos + lineHeight - childTotalCrossSize + child.margin.left
elseif effectiveAlign == self._AlignItems.STRETCH then
+ childMarginLeft
elseif effectiveAlign == alignItems_FLEX_END then
child.x = elementX + elementPaddingLeft + reservedCrossStart + currentCrossPos + lineHeight - childTotalCrossSize + childMarginLeft
elseif effectiveAlign == alignItems_STRETCH then
-- STRETCH: Only apply if width was not explicitly set
if child.autosizing and child.autosizing.width then
if childAutosizing and childAutosizing.width then
-- STRETCH: Set border-box width to lineHeight minus margins, content area shrinks to fit
local availableWidth = lineHeight - child.margin.left - child.margin.right
local availableWidth = lineHeight - childMarginLeft - childMarginRight
child._borderBoxWidth = availableWidth
child.width = math.max(0, availableWidth - child.padding.left - child.padding.right)
child.width = math.max(0, availableWidth - childPadding.left - childPadding.right)
end
child.x = self.element.x + self.element.padding.left + reservedCrossStart + currentCrossPos + child.margin.left
child.x = elementX + elementPaddingLeft + reservedCrossStart + currentCrossPos + childMarginLeft
end
-- Apply positioning offsets (top, right, bottom, left)
@@ -1224,6 +1264,16 @@ function LayoutEngine:_canSkipLayout()
return false
end
-- Performance optimization: Check dirty flags first (fastest check)
-- If element or children are marked dirty, we must recalculate
if self.element._dirty or self.element._childrenDirty then
-- Clear dirty flags after acknowledging them
self.element._dirty = false
self.element._childrenDirty = false
return false
end
-- If not dirty, check if layout inputs have actually changed (secondary check)
local childrenCount = #self.element.children
local containerWidth = self.element.width
local containerHeight = self.element.height