Native AOT 与裁剪

<!-- 启用 Native AOT 的项目配置 -->
<PropertyGroup>
  <OutputType>Exe</OutputType>
  <TargetFramework>net8.0</TargetFramework>
  <PublishAot>true</PublishAot>
  <InvariantGlobalization>true</InvariantGlobalization>
  <StripSymbols>true</StripSymbols>
  <IlcOptimizationPreference>Speed</IlcOptimizationPreference>
</PropertyGroup>

# 发布
dotnet publish -c Release -r linux-x64

# 产物：单个可执行文件
ls -lh bin/Release/net8.0/linux-x64/publish/app

// 用特性告诉裁剪器：这个类型的方法会被反射使用
public static object Create(
    [DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicConstructors)]
    Type type)
{
    return Activator.CreateInstance(type)!;
}

// 明确声明此方法不兼容裁剪
[RequiresUnreferencedCode("使用反射解析类型，裁剪后可能失败")]
public static object Resolve(string typeName)
{
    var t = Type.GetType(typeName)!;
    return Activator.CreateInstance(t)!;
}

// 显式保留某个成员
[DynamicDependency(DynamicallyAccessedMemberTypes.PublicMethods, typeof(Plugin))]
public static void RegisterPlugins() { }

<!-- ILLink.Descriptors.xml：根描述符 -->
<linker>
  <assembly fullname="MyApp">
    <type fullname="MyApp.Plugins.*" preserve="all" />
  </assembly>
</linker>

// 源生成 JSON 上下文
[JsonSourceGenerationOptions(
    PropertyNamingPolicy = JsonKnownNamingPolicy.CamelCase,
    WriteIndented = false)]
[JsonSerializable(typeof(OrderDto))]
[JsonSerializable(typeof(List<OrderDto>))]
[JsonSerializable(typeof(ApiResponse<OrderDto>))]
public partial class ApiJsonContext : JsonSerializerContext { }

// 使用：零反射
var json = JsonSerializer.Serialize(dto, ApiJsonContext.Default.OrderDto);

// Minimal API 中配置 AOT 友好的 JSON
builder.Services.ConfigureHttpJsonOptions(options =>
{
    options.SerializerOptions.TypeInfoResolverChain.Insert(0, ApiJsonContext.Default);
});

// 路由处理器必须用强类型，避免反射绑定
app.MapPost("/orders", (OrderDto dto) => Results.Ok(dto));

// 源生成 DI：编译期生成注册
[ServiceProviderModule]
public static class ServiceModule
{
    public static IServiceCollection AddAppServices(this IServiceCollection services)
    {
        services.AddSingleton<IClock, SystemClock>();
        services.AddScoped<IOrderService, OrderService>();
        return services;
    }
}

# 对比体积
dotnet publish -c Release -r linux-x64 --self-contained        # 自包含
dotnet publish -c Release -r linux-x64 -p:PublishAot=true      # AOT

# 对比启动时间
hyperfine './app --urls http://localhost:5000'

<!-- 进一步压缩体积的开关 -->
<PropertyGroup>
  <InvariantGlobalization>true</InvariantGlobalization>   <!-- 去掉 ICU -->
  <UseSystemResourceKeys>true</UseSystemResourceKeys>     <!-- 精简异常消息 -->
  <IlcGenerateStackTraceData>false</IlcGenerateStackTraceData>
  <EventSourceSupport>false</EventSourceSupport>
  <MetadataUpdaterSupport>false</MetadataUpdaterSupport>
</PropertyGroup>

<PropertyGroup>
  <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
  <EnableAotAnalyzer>true</EnableAotAnalyzer>
  <EnableSingleFileAnalyzer>true</EnableSingleFileAnalyzer>
  <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
  <IsAotCompatible>true</IsAotCompatible>
</PropertyGroup>

# 定位警告来源
dotnet publish -c Release -r linux-x64 -p:PublishAot=true /warnaserror

# 查看保留的成员（诊断裁剪结果）
dotnet publish -c Release -r linux-x64 -p:PublishAot=true \
  -p:IlcGenerateMapFile=true

// 运行期排错：捕获 AOT 特有的异常
try
{
    var obj = JsonSerializer.Deserialize<Order>(json);
}
catch (NotSupportedException ex)
{
    // AOT 下常见：未配置源生成上下文
    logger.LogError(ex, "序列化失败，检查 JsonSerializerContext 配置");
}

// 场景一：CLI 工具——AOT 的完美用例
// 启动 5ms vs 300ms，用户感知明显
app.MapGet("/", () => "ok");

// 场景二：Serverless 函数——冷启动直接决定成本
// AOT 后冷启动从秒级降到毫秒级

// 场景三：容器化微服务——镜像更小，扩缩容更快
// FROM scratch 直接跑 AOT 二进制

# AOT 产物可以直接跑在 scratch 镜像上
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY . .
RUN dotnet publish -c Release -r linux-x64 -p:PublishAot=true -o /app

FROM mcr.microsoft.com/dotnet/runtime-deps:8.0-noble-chiseled
WORKDIR /app
COPY --from=build /app .
USER $APP_UID
ENTRYPOINT ["./MyApp"]

<!-- 第一步：只分析，不改行为 -->
<PropertyGroup>
  <EnableTrimAnalyzer>true</EnableTrimAnalyzer>
  <EnableAotAnalyzer>true</EnableAotAnalyzer>
  <IsAotCompatible>true</IsAotCompatible>
  <!-- 暂不开启 -->
  <PublishAot>false</PublishAot>
  <PublishTrimmed>false</PublishTrimmed>
</PropertyGroup>

// 用条件编译隔离不兼容代码
#if !AOT
    // 反射回退路径，仅 JIT 构建使用
    var plugin = Assembly.LoadFrom(path);
#else
    throw new PlatformNotSupportedException("AOT 构建不支持插件热加载");
#endif