冷启动首帧耗时采集框架

完整的冷启动首帧耗时采集框架，既支持：

• 日常埋点（轻量、主流程）；
• 调试分析（高精度、开发模式）；
• 自动化集成（无侵入、支持主进程判断、多 Activity 兼容）。

目标

封装一个类 LaunchTimeTracer，具备以下功能：

最终结构概览

object LaunchTimeTracer {
    fun init(application: Application)
    fun onFirstFrameDrawn()
}

实现代码（基础版 + 可选高精度监听）

1. LaunchTimeTracer.kt

object LaunchTimeTracer {

    private var isColdStart = true
    private var hasReported = false
    private var startTime = 0L
    private var reportBlock: ((duration: Long) -> Unit)? = null

    fun init(application: Application, report: ((Long) -> Unit)? = null) {
        reportBlock = report
        if (!isMainProcess(application)) return

        application.registerActivityLifecycleCallbacks(object : Application.ActivityLifecycleCallbacks {
            override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
                if (isColdStart) {
                    startTime = SystemClock.elapsedRealtime()
                }
            }

            override fun onActivityResumed(activity: Activity) {
                if (isColdStart && !hasReported) {
                    activity.window.decorView.post {
                        Choreographer.getInstance().postFrameCallback {
                            val duration = SystemClock.elapsedRealtime() - startTime
                            hasReported = true
                            isColdStart = false
                            reportBlock?.invoke(duration)
                            Log.d("LaunchTimeTracer", "首帧耗时: ${duration}ms")
                        }
                    }
                }
            }

            override fun onActivityDestroyed(activity: Activity) {}
            override fun onActivityPaused(activity: Activity) {}
            override fun onActivityStarted(activity: Activity) {}
            override fun onActivityStopped(activity: Activity) {}
            override fun onActivitySaveInstanceState(activity: Activity, outState: Bundle) {}
        })
    }

    private fun isMainProcess(application: Application): Boolean {
        val pid = Process.myPid()
        val currentProcess = application.getSystemService(ActivityManager::class.java)
            ?.runningAppProcesses?.firstOrNull { it.pid == pid }
        return application.packageName == currentProcess?.processName
    }
}

使用方式

在你的 Application 中初始化：

class MyApp : Application() {
    override fun attachBaseContext(base: Context) {
        super.attachBaseContext(base)

        LaunchTimeTracer.init(this) { cost ->
            // 在这里做日志记录、埋点上报等
            uploadLaunchDuration(cost)
        }
    }
}

可选：高精度帧耗时监听（开发调试用）

添加这段代码，可捕捉每一帧渲染的真实耗时：

@TargetApi(Build.VERSION_CODES.N)
fun Activity.traceFrameMetrics() {
    window.addOnFrameMetricsAvailableListener({ _, metrics, _ ->
        val total = metrics.getMetric(FrameMetrics.TOTAL_DURATION)
        val draw = metrics.getMetric(FrameMetrics.DRAW_DURATION)
        Log.d("FrameMetrics", "Total: ${total / 1_000_000}ms, Draw: ${draw / 1_000_000}ms")
    }, Handler(Looper.getMainLooper()))
}

你可以在 onResume 中调试时调用：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
    traceFrameMetrics()
}

总结

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