// 动态注入 Fragment，避免启动期反射实例化
class MeetingNavHostFragment : NavHostFragment() {
    override fun getFragmentFactory(): FragmentFactory = object : FragmentFactory() {
        override fun instantiate(classLoader: ClassLoader, className: String): Fragment =
            when (className) {
                "com.app.meeting.ui.chat.ChatFragment" -> ChatFragment::class.java.newInstance()
                "com.app.meeting.ui.share.ShareFragment" -> ShareFragment::class.java.newInstance()
                else -> super.instantiate(classLoader, className)
            }
    }
}

<!-- 主布局仅占位 -->
<ViewStub
    android:id="@+id/vs_chat_panel"
    android:layout="@layout/layout_chat_panel"
    android:inflatedId="@+id/chat_panel_root" />

// 首次展开聊天面板时才 inflate
binding.vsChatPanel.setOnInflateListener { stub ->
    ChatPanelView.bind(stub.inflate()).also { view ->
        view.lifecycleOwner = this
        view.viewModel = chatViewModel
    }
}

// Application.onCreate() 仅初始化 Crash、网络库
class MeetingApp : Application() {
    override fun onCreate() {
        super.onCreate()
        CrashSDK.init(this)
        NetSDK.init(this)
        // 统计、推送、IM、日志均延迟
        IdleTaskScheduler.schedule(IdleTaskType.ANALYTICS) { AnalyticsSDK.init(this) }
        IdleTaskScheduler.schedule(IdleTaskType.PUSH) { PushSDK.init(this) }
    }
}

// app/build.gradle
dependencies {
    androidTestImplementation "androidx.benchmark:benchmark-macro-junit4:1.2.0"
}

// BaselineProfileGenerator.kt
@RunWith(AndroidJUnit4::class)
class BaselineProfileGenerator {
    @get:Rule
    val baselineRule = BaselineProfileRule()

    @Test
    fun generate() {
        baselineRule.collect(
            packageName = "com.app.meeting",
            profileBlock = {
                // 1. 启动到首屏
                startActivityAndWait(Intent(Intent.ACTION_MAIN).apply {
                    setPackage("com.app.meeting")
                    addCategory(Intent.CATEGORY_LAUNCHER)
                })
                // 2. 加入会议流程
                onDevice.execute("am start -n com.app.meeting/.ui.join.JoinMeetingActivity")
                // 3. 创建会议流程
                onDevice.execute("am start -n com.app.meeting/.ui.create.CreateMeetingActivity")
            }
        )
    }
}

# .github/workflows/startup-perf.yml
jobs:
  startup-benchmark:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Run Macrobenchmark
        run: ./gradlew :app:connectedBenchmarkAndroidTest -Pandroid.testInstrumentationRunnerArguments.class=com.app.meeting.perf.StartupBenchmark
      - name: Upload Report
        uses: actions/upload-artifact@v4
        with:
          name: startup-report
          path: app/build/reports/androidTests/connected/
      - name: Fail if regression
        run: |
          python scripts/check_regression.py 
            --baseline docs/perf_baseline.json 
            --current app/build/outputs/connected_android_test_additional_output/benchmarkData.json 
            --threshold 0.05  # 允许 5% 波动

graph TD
    A[Application.onCreate] --> B[Crash/Network SDK]
    A --> C[Config Pull]
    C --> D[ABTest/FeatureFlag]
    D --> E[UI Theme Init]
    B --> F[MainThread: setContentView]
    E --> F
    F --> G[Navigation Restore]
    G --> H[First Frame Draw]

// 关键任务大核绑定示例（需 root 或厂商白名单，普通应用可通过 setThreadPriority 调整 nice 值）
fun bindToBigCores(thread: Thread) {
    try {
        val cpuSet = Cpuset.getBigCoreCpuset() // 解析 /sys/devices/system/cpu/cpu*/topology/thread_siblings_list
        ThreadAffinity.setAffinity(thread.nativePeer, cpuSet)
    } catch (e: Exception) {
        thread.priority = Thread.MAX_PRIORITY // 兜底提升优先级
    }
}

// native 层创建共享内存
int fd = ashmem_create_region("meeting_config", 64 * 1024);
void* ptr = mmap(nullptr, 64*1024, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
// 主进程写入 FlatBuffers 序列化配置
// 子进程 mmap 同一 fd 直接零拷贝读取

// build.gradle.kts
tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
    kotlinOptions {
        freeCompilerArgs += listOf(
            "-Xopt-in=kotlin.RequiresOptIn",
            "-P plugin:androidx.compose.compiler.plugins.kotlin:forceInline=true",
            "-P plugin:androidx.compose.compiler.plugins.kotlin:recordsToDataClasses=true"
        )
    }
}

// Compose 专项采集
baselineRule.collect(
    packageName = "com.app.meeting",
    profileBlock = {
        startActivityAndWait<MainActivity>()
        // 触发关键 Composable 重组
        composeTestRule.onNodeWithTag("join_btn").performClick()
        composeTestRule.waitForIdle()
        // 滚动列表触发 LazyColumn 布局/测量代码编译
        composeTestRule.onNodeWithTag("recent_list").performScrollTo()
    }
)

// Application 启动期预热 Compose 运行时
ComposeView(context).apply {
    setViewCompositionStrategy(ViewCompositionStrategy.DisposeOnDetachedFromWindow)
    setContent {
        // 预渲染首屏核心组件树，触发类加载、槽表分配、字体缓存
        MeetingTheme { MeetingHomeScreen(onJoinClick = {}, onCreateClick = {}) }
    }
    // 手动 attach/detach 触发初次组合
    onAttachedToWindow()
    onDetachedFromWindow()
}

object StartupDispatcher : ExecutorCoroutineDispatcher() {
    private val executor = ThreadPoolExecutor(
        corePoolSize = 2,
        maximumPoolSize = 4,
        keepAliveTime = 10, TimeUnit.SECONDS,
        SynchronousQueue(),
        ThreadFactoryBuilder().setNameFormat("Startup-%d").build()
    ).also { bindToBigCores(it.threads.first()) } // 绑定大核

    override fun dispatch(context: CoroutineContext, block: Runnable) = executor.execute(block)
    override fun close() = executor.shutdown()
}

suspend fun initializeCriticalPath(): Result<Unit> = coroutineScope {
    val config = async(StartupDispatcher) { configRepo.fetch() }
    val auth = async(StartupDispatcher) { authRepo.refreshToken() }
    val abTest = async(StartupDispatcher) { abTestRepo.pull() }

    // 关键路径超时 300 ms 熔断，降级使用本地缓存
    withTimeoutOrNull(300) {
        config.await()
        auth.await()
        abTest.await()
    } ?: runCatching { loadLocalFallback() }
}

class StartupCircuitBreaker {
    private val failureCount = AtomicInteger(0)
    private val lastFailureTime = AtomicLong(0)

    fun recordFailure() {
        failureCount.incrementAndGet()
        lastFailureTime.set(SystemClock.uptimeMillis())
    }

    fun isOpen(): Boolean = failureCount.get() >= 3 && 
        (SystemClock.uptimeMillis() - lastFailureTime.get() < 30_000)

    fun reset() { failureCount.set(0) }
}

// 使用
if (circuitBreaker.isOpen()) {
    // 直接走极简启动路径：仅加载本地缓存、离线 UI
    launchMinimalStartup()
} else {
    launchFullStartup()
}

// 无侵入 AOP 埋点（基于 ASM/Transform API）
@Aspect
class StartupTraceAspect {
    @Around("execution(* android.app.Application.onCreate(..))")
    fun aroundAppOnCreate(pjp: ProceedingJoinPoint) {
        StartupTracer.mark("App_onCreate_start")
        pjp.proceed()
        StartupTracer.mark("App_onCreate_end")
    }

    @Around("execution(* androidx.activity.ComponentActivity.onCreate(..))")
    fun aroundActivityOnCreate(pjp: ProceedingJoinPoint) {
        StartupTracer.mark("Activity_onCreate_start")
        pjp.proceed()
        StartupTracer.mark("First_Frame_Draw", Choreographer.getInstance().frameCallbackTimestamp)
    }
}

# 伪代码：发布决策引擎
def evaluate_release(candidate_version, baseline_version):
    metrics = fetch_metrics(candidate_version, last_2h)
    baseline = fetch_metrics(baseline_version, last_2h)
    
    # 核心指标无回归
    if metrics.ttid_p99 > baseline.ttid_p99 * 1.05: return "BLOCK"
    if metrics.anr_rate > baseline.anr_rate * 1.2: return "BLOCK"
    if metrics.crash_rate > 0.1: return "BLOCK"
    
    # 关键机型专项校验
    for device in KEY_DEVICES:
        if device_ttid_p99(device) > DEVICE_THRESHOLD[device]: return "BLOCK"
    
    return "PASS"