From 847a12bd7029302d95c2b725758c7681b57235dc Mon Sep 17 00:00:00 2001
From: "Somhairle H. Marisol" <muqiu-han@outlook.com>
Date: Tue, 22 Sep 2026 03:39:05 +0800
Subject: feat(perf): 帧率采样汇总纯函数 + 测试（P21）
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- PerformanceSummary.summarize：丢弃 warmup 后求每秒 FPS 的均值/最低/最高，
  空样本返回 None；含 3 条单测（TDD）。
---
 .../LivingVillage.Desktop.fsproj                   |  1 +
 src/LivingVillage.Desktop/PerformanceSummary.fs    | 27 ++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 src/LivingVillage.Desktop/PerformanceSummary.fs

(limited to 'src/LivingVillage.Desktop')

diff --git a/src/LivingVillage.Desktop/LivingVillage.Desktop.fsproj b/src/LivingVillage.Desktop/LivingVillage.Desktop.fsproj
index 6f388f2..2901dce 100644
--- a/src/LivingVillage.Desktop/LivingVillage.Desktop.fsproj
+++ b/src/LivingVillage.Desktop/LivingVillage.Desktop.fsproj
@@ -19,6 +19,7 @@
     <Compile Include="SampleScript.fs" />
     <Compile Include="M6Presentation.fs" />
     <Compile Include="HudLayout.fs" />
+    <Compile Include="PerformanceSummary.fs" />
     
     <Compile Include="TitleScreen.fs" />
     <Compile Include="Game.fs" />
diff --git a/src/LivingVillage.Desktop/PerformanceSummary.fs b/src/LivingVillage.Desktop/PerformanceSummary.fs
new file mode 100644
index 0000000..3edb4a7
--- /dev/null
+++ b/src/LivingVillage.Desktop/PerformanceSummary.fs
@@ -0,0 +1,27 @@
+namespace LivingVillage.Desktop
+
+/// P21：纯函数的帧率采样汇总（均值/最低/最高），供实机性能核对与回归测试。
+/// 不含时钟/IO，只看传入的每秒 FPS 样本序列；warmup 采样用于剔除启动抖动。
+module PerformanceSummary =
+
+    type Summary =
+        { Count: int
+          Mean: float
+          Min: float
+          Max: float }
+
+    /// 丢弃前 `warmupSamples` 个样本（不足则全丢），对剩余样本求均值/最低/最高。
+    /// 剩余为空时返回 None（如运行过短）。
+    let summarize (warmupSamples: int) (samples: float list) : Summary option =
+        let skip = max 0 warmupSamples
+        let taken =
+            if List.length samples <= skip then []
+            else samples |> List.skip skip
+        match taken with
+        | [] -> None
+        | _ ->
+            Some
+                { Count = taken.Length
+                  Mean = List.average taken
+                  Min = List.min taken
+                  Max = List.max taken }
-- 
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