Binder IPC on the main thread: ANR risks and fixes

// ❌ BAD: blocking Binder calls on Main
class StartupFragment : Fragment() {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        // All of these are synchronous Binder calls to system services:
        val packages = requireContext().packageManager.getInstalledPackages(0)   // 200–500 ms
        val wifi     = Settings.Global.getInt(requireContext().contentResolver, Settings.Global.WIFI_ON, 0)
        val contacts = requireContext().contentResolver.query(ContactsContract.Contacts.CONTENT_URI, null, null, null, null)
    }
}

// ✅ CORRECT: move Binder calls to Dispatchers.IO
class StartupViewModel(private val pm: PackageManager) : ViewModel() {
    fun loadInstalledPackages() {
        viewModelScope.launch {
            val packages = withContext(Dispatchers.IO) { pm.getInstalledPackages(0) }
            _packageList.value = packages
        }
    }
}

if (BuildConfig.DEBUG) {
    StrictMode.setThreadPolicy(
        StrictMode.ThreadPolicy.Builder()
            .detectAll()
            .penaltyLog()        // Logcat in dev
            // .penaltyDeath()   // Use in CI to hard-fail on any violation
            .build()
    )
}

// ❌ BAD: synchronous SDK init in a ContentProvider (runs on Main at process start)
class MySdkInitProvider : ContentProvider() {
    override fun onCreate(): Boolean {
        HeavySdk.init(context!!)  // 300ms of reflection + I/O on Main at cold start
        return true
    }
}

// ✅ CORRECT option A: remove ContentProvider; init in Application.onCreate on background thread
class MyApp : Application() {
    @ApplicationScope @Inject lateinit var appScope: CoroutineScope

    override fun onCreate() {
        super.onCreate()
        appScope.launch(Dispatchers.IO) { HeavySdk.init(applicationContext) }
    }
}

// ✅ CORRECT option B: Jetpack App Startup with async initializer
class MySdkInitializer : Initializer<Unit> {
    override fun create(context: Context) {
        // Runs synchronously but you can chain dependencies explicitly
        // For async init: store a Deferred and await it lazily when first needed
    }
    override fun dependencies(): List<Class<out Initializer<*>>> = emptyList()
}

// ❌ BAD: querying multiple system services sequentially on startup
class StartupActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        // Each call below is a Binder round-trip to system_server.
        // Under load, any one of them can block for hundreds of ms or seconds.
        val pm   = packageManager.getInstalledPackages(0)          // Binder → PMS
        val accs = getSystemService(AccountManager::class.java)
                     .getAccountsByType("com.google")              // Binder → AMS
        val crs  = contentResolver.query(CONTACTS_URI, ...)        // Binder → ContentProvider
    }
}

// ✅ CORRECT: batch and defer all system service calls off the main thread
class StartupViewModel : ViewModel() {
    val startupData = viewModelScope.async(Dispatchers.IO) {
        val pm    = appContext.packageManager.getInstalledPackages(0)
        val accts = accountManager.getAccountsByType("com.google")
        StartupData(pm, accts)
    }
}

at com.android.internal.os.BinderProxy.transact

# App was frozen at screen-off:
OemPowerManager : freeze uid: 10182 package: com.example.myapp reason: LcdOff

# Back key dispatched to the frozen app — no response for 5s → ANR
WindowManager: Input event dispatching timed out sending to com.example.myapp

# System unfreezes app only *after* ANR is triggered:
OemPowerManager : unfreeze uid: 10182 package: com.example.myapp reason: Signal