⚡ Optimize DateFormatter creation in ActivityHeatmapView#65
⚡ Optimize DateFormatter creation in ActivityHeatmapView#65debugtheworldbot wants to merge 1 commit intomainfrom
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- Caches `DateFormatter` for month and tooltip formatting as lazy properties. - Caches `Calendar.current` to avoid repeated calls to the system property. - Caches `weekdaySymbols` to avoid re-generating them on every draw call. - Refactors `recalculateLayout()`, `drawMonthLabels()`, `drawWeekdayLabels()`, and `updateTooltip()` to use these cached properties. Co-authored-by: chatgpt-codex-connector[bot] <199175422+chatgpt-codex-connector[bot]@users.noreply.github.com> Co-authored-by: debugtheworldbot <62830430+debugtheworldbot@users.noreply.github.com>
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Summary of ChangesHello @debugtheworldbot, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed! This pull request significantly enhances the performance of the Highlights
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Code Review
This pull request effectively optimizes the ActivityHeatmapView by introducing lazy properties for DateFormatter and Calendar instances. This change prevents repeated, expensive object creation during drawing cycles, which is a common performance bottleneck in AppKit/UIKit applications. The approach aligns well with Apple's performance optimization guidelines and should lead to reduced CPU usage and smoother UI performance.
| private lazy var weekdaySymbols: [String] = { | ||
| let formatter = DateFormatter() | ||
| formatter.locale = Locale.current | ||
| return formatter.shortWeekdaySymbols ?? ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"] | ||
| }() |
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The weekdaySymbols lazy property currently initializes a DateFormatter solely to retrieve shortWeekdaySymbols. While this is lazy, DateFormatter is an expensive object to create. The Calendar object, which is already cached as self.calendar, provides shortWeekdaySymbols directly. Using self.calendar.shortWeekdaySymbols would be more efficient and avoid an unnecessary DateFormatter instantiation.
private lazy var weekdaySymbols: [String] = {
return calendar.shortWeekdaySymbols ?? ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]
}()
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Good catch! I've simplified weekdaySymbols to use the cached calendar object instead of creating a new DateFormatter instance. I've also pre-calculated the 3-character prefixes and converted them to String once during initialization to avoid redundant work in the draw loop.
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| private var gridWidth: CGFloat = 0 | ||
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| // MARK: - 缓存 | ||
| private lazy var calendar = Calendar.current |
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Caching Calendar.current in a lazy property captures a snapshot of calendar settings at first access, so long-running sessions can render stale weekday alignment after the user changes region/first-weekday or time zone in macOS settings. recalculateLayout() and drawWeekdayLabels() now depend on this cached value, which can misplace cells and labels until restart, whereas the previous code re-read Calendar.current on each call. Use Calendar.autoupdatingCurrent (or refresh the cache on locale/time-zone change notifications) to preserve correct rendering.
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debugtheworldbot
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This PR optimizes the
ActivityHeatmapViewby caching expensive objects likeDateFormatterandCalendarthat were previously being created repeatedly during the drawing cycle.💡 What
ActivityHeatmapViewto store:calendar(Calendar.current)monthFormatter(DateFormatter with "MMM" format)weekdaySymbols(Localized weekday strings)tooltipDateFormatter(DateFormatter with medium date style)recalculateLayout(),drawMonthLabels(),drawWeekdayLabels(), andupdateTooltip()to use these cached properties.🎯 Why
DateFormatterandCalendarinstantiation are known to be expensive operations in macOS/iOS. Creating them inside a drawing loop or frequently called UI methods can lead to:📊 Measured Improvement
Direct benchmarks could not be performed as the environment does not provide
swiftorxcodebuild. However, this change follows standard Apple performance optimization guidelines and is a net positive for any AppKit view performing frequent redraws.PR created automatically by Jules for task 13101833943979519934 started by @debugtheworldbot