Android10 启动之SystemServer源码分析

 public static void main(String[] args) { new SystemServer().run(); } 

 private void run() { try { ... //准备主线程lopper android.os.Process.setThreadPriority( android.os.Process.THREAD_PRIORITY_FOREGROUND); android.os.Process.setCanSelfBackground(false); Looper.prepareMainLooper(); Looper.getMainLooper().setSlowLogThresholdMs( SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS); // 加载libandroid_servers.so库 System.loadLibrary("android_servers"); //检测上次关机过程是否失败，这个调用可能不会返回 performPendingShutdown(); //初始化系统上下文 createSystemContext(); //创建系统服务管理者--SystemServiceManager mSystemServiceManager = new SystemServiceManager(mSystemContext); mSystemServiceManager.setStartInfo(mRuntimeRestart, mRuntimeStartElapsedTime, mRuntimeStartUptime); //将mSystemServiceManager添加到本地服务中，至于什么是LocalServices，它有什么作用， //以后再单独开一篇文章来讲解 LocalServices.addService(SystemServiceManager.class, mSystemServiceManager); //为可以并行化的init任务准备线程池 SystemServerInitThreadPool.get(); } finally { traceEnd();  // InitBeforeStartServices } // 在这里开始启动一系列服务了 try { traceBeginAndSlog("StartServices"); // 启动引导服务 startBootstrapServices(); // 启动核心服务 startCoreServices(); // 启动其他服务 startOtherServices(); //停止init线程池 SystemServerInitThreadPool.shutdown(); } catch (Throwable ex) { Slog.e("System", "******************************************"); Slog.e("System", "************ Failure starting system services", ex); throw ex; } finally { traceEnd(); } ... // 死循环执行 Looper.loop(); throw new RuntimeException("Main thread loop unexpectedly exited"); } 

private void createSystemContext() { //创建system_server进程的上下文信息 ActivityThread activityThread = ActivityThread.systemMain(); mSystemContext = activityThread.getSystemContext(); //设置主题 mSystemContext.setTheme(DEFAULT_SYSTEM_THEME); //获取systemui上下文信息，并设置主题 final Context systemUiContext = activityThread.getSystemUiContext(); systemUiContext.setTheme(DEFAULT_SYSTEM_THEME); } 

 private void startBootstrapServices() { // 尽早启动看门狗，这样我们在早期启动陷入死锁时就可以使system server崩溃重启。 final Watchdog watchdog = Watchdog.getInstance(); watchdog.start(); //启动Installer Service，这个Service 通过binder与installd进程通讯，负责apk安装相关的工作 Installer installer = mSystemServiceManager.startService(Installer.class); //设备标识符策略服务 mSystemServiceManager.startService(DeviceIdentifiersPolicyService.class); // 管理uri授权 mSystemServiceManager.startService(UriGrantsManagerService.Lifecycle.class); //启动ActivityTaskManagerService和ActivityManagerService ActivityTaskManagerService atm = mSystemServiceManager.startService( ActivityTaskManagerService.Lifecycle.class).getService(); mActivityManagerService = ActivityManagerService.Lifecycle.startService( mSystemServiceManager, atm); mActivityManagerService.setSystemServiceManager(mSystemServiceManager); mActivityManagerService.setInstaller(installer); mWindowManagerGlobalLock = atm.getGlobalLock(); //电源管理器需要尽早启动，因为其他服务需要它。 mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class); //启动热缓解服务，目的是在手机开始过热时进行有效的热缓解 mSystemServiceManager.startService(ThermalManagerService.class); // Now that the power manager has been started, let the activity manager // initialize power management features. mActivityManagerService.initPowerManagement(); //启动系统恢复服务，负责协调设备上与恢复有关的功能。 mSystemServiceManager.startService(RecoverySystemService.class); //到这里为止，系统启动的必须服务已经加载完毕 RescueParty.noteBoot(mSystemContext); //管理LED和屏幕背光，我们需要它来显示 mSystemServiceManager.startService(LightsService.class); //管理显示设备 //在package manager 启动之前，需要启动display manager 提供display metrics mDisplayManagerService = mSystemServiceManager.startService(DisplayManagerService.class); //只有DisplayManagerService会对PHASE_WAIT_FOR_DEFAULT_DISPLAY做处理 //目的是在初始化包管理器之前，首先需要获取一个默认的显示设备 mSystemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY); // 启动 package manager. if (!mRuntimeRestart) { MetricsLogger.histogram(null, "boot_package_manager_init_start", (int) SystemClock.elapsedRealtime()); } try { Watchdog.getInstance().pauseWatchingCurrentThread("packagemanagermain"); mPackageManagerService = PackageManagerService.main(mSystemContext, installer, mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore); } finally { Watchdog.getInstance().resumeWatchingCurrentThread("packagemanagermain"); } mFirstBoot = mPackageManagerService.isFirstBoot(); mPackageManager = mSystemContext.getPackageManager(); //启动UserManager Service mSystemServiceManager.startService(UserManagerService.LifeCycle.class); //为系统进程设置应用程序实例并启动 mActivityManagerService.setSystemProcess(); //使用ActivityManager实例完成看门狗设置并监听是否重启 watchdog.init(mSystemContext, mActivityManagerService); // DisplayManagerService needs to setup android.display scheduling related policies // since setSystemProcess() would have overridden policies due to setProcessGroup mDisplayManagerService.setupSchedulerPolicies(); //负责动态资源overlay mSystemServiceManager.startService(new OverlayManagerService(mSystemContext, installer)); mSystemServiceManager.startService(new SensorPrivacyService(mSystemContext)); if (SystemProperties.getInt("persist.sys.displayinset.top", 0) > 0) { // DisplayManager needs the overlay immediately. mActivityManagerService.updateSystemUiContext(); LocalServices.getService(DisplayManagerInternal.class).onOverlayChanged(); } //传感器服务需要访问包管理器服务、app ops服务和权限服务， //因此我们在它们之后启动它。 //在单独的线程中启动传感器服务。在使用它之前应该检查完成情况。 mSensorServiceStart = SystemServerInitThreadPool.get().submit(() -> { TimingsTraceLog traceLog = new TimingsTraceLog( SYSTEM_SERVER_TIMING_ASYNC_TAG, Trace.TRACE_TAG_SYSTEM_SERVER); traceLog.traceBegin(START_SENSOR_SERVICE); startSensorService(); traceLog.traceEnd(); }, START_SENSOR_SERVICE); } 

 private void startCoreServices() { // 追踪电池充电状态和电量。需要LightService mSystemServiceManager.startService(BatteryService.class); //跟踪应用程序使用状态 mSystemServiceManager.startService(UsageStatsService.class); mActivityManagerService.setUsageStatsManager( LocalServices.getService(UsageStatsManagerInternal.class)); // 跟踪可更新的WebView是否处于就绪状态，并监视更新安装。 if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_WEBVIEW)) { traceBeginAndSlog("StartWebViewUpdateService"); mWebViewUpdateService = mSystemServiceManager.startService(WebViewUpdateService.class); traceEnd(); } //跟踪并缓存设备状态。 mSystemServiceManager.startService(CachedDeviceStateService.class); // 跟踪在Binder调用中花费的cpu时间 mSystemServiceManager.startService(BinderCallsStatsService.LifeCycle.class); // 跟踪handlers中处理messages所花费的时间。 mSystemServiceManager.startService(LooperStatsService.Lifecycle.class); //管理apk回滚 mSystemServiceManager.startService(RollbackManagerService.class); // 用于捕获bugreport,adb bugreport 命令调用的就是这个服务 mSystemServiceManager.startService(BugreportManagerService.class); // 管理Gpu和Gpu驱动的服务 mSystemServiceManager.startService(GpuService.class); } 

 mAtmInternal.startHomeOnAllDisplays(currentUserId, "systemReady"); 

Intent getHomeIntent() { Intent intent = new Intent(mTopAction, mTopData != null ? Uri.parse(mTopData) : null); intent.setComponent(mTopComponent); intent.addFlags(Intent.FLAG_DEBUG_TRIAGED_MISSING); if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) { intent.addCategory(Intent.CATEGORY_HOME); } return intent; }