SystemServer 流程分析

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一、SystemServer 啟動(dòng)的服務(wù)有哪些
二、SystemServer啟動(dòng)總體流程概述
三、SystemServer 如何啟動(dòng)，是誰(shuí)啟動(dòng)的？
四、 SystemServer 啟動(dòng)入門 main 方法
五、SystemServer Run 方法初始與啟動(dòng)
六、SystemServer 的引導(dǎo)服務(wù)有哪些
七、SystemServer 的核心服務(wù)有哪些
八、SystemServer 的其他服務(wù)有哪些

一、SystemServer 啟動(dòng)的服務(wù)有哪些

SystemServer 主要啟動(dòng) ActivityManagerService、PackageManagerService、WindowManagerService、LightsService、LightsService、BatteryService、TelephonyRegistry、RecoverySystemService 等等,主要分三大類，后文會(huì)詳細(xì)列舉。

1.SystemServer 啟動(dòng)的服務(wù)

SystemServer 啟動(dòng)的服務(wù)

SystemServer 啟動(dòng)的服務(wù)

二、SystemServer啟動(dòng)總體流程概述

1.SystemServer 代碼

\alps\frameworks\base\services\java\com\android\server\SystemServer.java

SystemServer 進(jìn)程啟動(dòng)導(dǎo)圖

三、SystemServer 如何啟動(dòng)，是誰(shuí)啟動(dòng)的？

SystemServer是通過(guò)Zygote 啟動(dòng)的，在ZygoteInit.java類的（frameworks\base\core\java\com\android\internal\os\ZygoteInit.java） main方法中通過(guò)forkSystemServer啟動(dòng)。

        public static void main(String argv[]) {
....
//設(shè)置變量區(qū)分是否啟動(dòng)SystemServer
boolean startSystemServer = false;
            String socketName = "zygote";
            String abiList = null;
boolean enableLazyPreload = false;
for (int i = 1; i < argv.length; i++) {
if ("start-system-server".equals(argv[i])) {
// 需要啟動(dòng)時(shí)候，將標(biāo)志位設(shè)置為true
                    startSystemServer = true;
} else if ("--enable-lazy-preload".equals(argv[i])) {
                    enableLazyPreload = true;
} 
... ...

if (startSystemServer) {
// 通過(guò) Zygote  fork 出 SystemServer 
                Runnable r = forkSystemServer(abiList, socketName, zygoteServer);

// {@code r == null} in the parent (zygote) process, and {@code r != null} in the
// child (system_server) process.
if (r != null) {
                    r.run();
return;
}
}

  

四、 SystemServer 啟動(dòng)入門 main 方法

main 入口 通過(guò) new SystemServer().run();開啟SystemServer啟動(dòng)。

main 入口代碼如下：

/**
* The main entry point from zygote.
*/

* The main entry point from zygote.
*/
public static void main(String[] args) {
new SystemServer().run();
}


通過(guò)Main入口,調(diào)用SystemServer 構(gòu)造方法。

public SystemServer() {

// 檢查工程模式.
mFactoryTestMode = FactoryTest.getMode();
// 判斷是否是重啟
mRuntimeRestart = "1".equals(SystemProperties.get("sys.boot_completed"));

mRuntimeStartElapsedTime = SystemClock.elapsedRealtime();
mRuntimeStartUptime = SystemClock.uptimeMillis();
}

private void run() {
... ...
}
五、SystemServer Run 方法初始與啟動(dòng)

1.SystemServer Run 方法

private void run() {

try {
traceBeginAndSlog("InitBeforeStartServices");
//初始化時(shí)間
if (System.currentTimeMillis() < EARLIEST_SUPPORTED_TIME) {
Slog.w(TAG, "System clock is before 1970; setting to 1970.");
SystemClock.setCurrentTimeMillis(EARLIEST_SUPPORTED_TIME);
}

//設(shè)置默認(rèn)時(shí)區(qū)
String timezoneProperty = SystemProperties.get("persist.sys.timezone");
if (timezoneProperty == null || timezoneProperty.isEmpty()) {
Slog.w(TAG, "Timezone not set; setting to GMT.");
SystemProperties.set("persist.sys.timezone", "GMT");
}
... ...

// 開始進(jìn)入Android SystemServer
Slog.i(TAG, "Entered the Android system server!");
int uptimeMillis = (int) SystemClock.elapsedRealtime();
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_SYSTEM_RUN, uptimeMillis);
if (!mRuntimeRestart) {
MetricsLogger.histogram(null, "boot_system_server_init", uptimeMillis);
}
... ...

//如果支持指紋，需初始化指紋ro.build.fingerprint
Build.ensureFingerprintProperty();

... ...

// 初始化 native services.
System.loadLibrary("android_servers");

// 檢查最近一次關(guān)機(jī)是否失敗
performPendingShutdown();

// 初始化 the system context.
createSystemContext();

// 創(chuàng)建 system service manager.
mSystemServiceManager = new SystemServiceManager(mSystemContext);
mSystemServiceManager.setStartInfo(mRuntimeRestart,
mRuntimeStartElapsedTime, mRuntimeStartUptime);
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
// 初始化SystemServer 線程池
SystemServerInitThreadPool.get();
} finally {
traceEnd(); // InitBeforeStartServices
}
... ...

// 開始啟動(dòng) services.
try {
traceBeginAndSlog("StartServices");
// 1. 啟動(dòng)引導(dǎo)服務(wù) 詳見分析六
startBootstrapServices();
// 2. 啟動(dòng)核心服務(wù) 詳見分析七
startCoreServices();
// 3.啟動(dòng)其他服務(wù) 詳見分析八
startOtherServices();
SystemServerInitThreadPool.shutdown();
} catch (Throwable ex) {
Slog.e("System", "******************************************");
Slog.e("System", "************ Failure starting system services", ex);
throw ex;
} finally {
traceEnd();
}

StrictMode.initVmDefaults(null);


}
六、SystemServer 的引導(dǎo)服務(wù)有哪些

SystemServer啟動(dòng)的常用引導(dǎo)服務(wù)有installed 、DeviceIdentifiersPolicyService、 ActivityManagerService.、PowerManagerService 、 RecoverySystemService 、 LightsService 、 PackageManagerService、UserManagerService、OverlayManagerService等。

啟動(dòng)的引導(dǎo)服務(wù)的大致流程

1.startBootstrapServices代碼

        /**
     * Starts the small tangle of critical services that are needed to get
     * the system off the ground.  These services have complex mutual dependencies
     * which is why we initialize them all in one place here.  Unless your service
     * is also entwined in these dependencies, it should be initialized in one of
     * the other functions.
     */
private void startBootstrapServices() {
Slog.i(TAG, "Reading configuration...");
final String TAG_SYSTEM_CONFIG = "ReadingSystemConfig";
traceBeginAndSlog(TAG_SYSTEM_CONFIG);
SystemServerInitThreadPool.get().submit(SystemConfig::getInstance, TAG_SYSTEM_CONFIG);
traceEnd();

// 啟動(dòng) installed
traceBeginAndSlog("StartInstaller");
Installer installer = mSystemServiceManager.startService(Installer.class);
traceEnd();

//啟動(dòng) 設(shè)備標(biāo)識(shí)符 服務(wù)
traceBeginAndSlog("DeviceIdentifiersPolicyService");
        mSystemServiceManager.startService(DeviceIdentifiersPolicyService.class);
traceEnd();

// 啟動(dòng) AMS.
traceBeginAndSlog("StartActivityManager");
        mActivityManagerService = mSystemServiceManager.startService(
ActivityManagerService.Lifecycle.class).getService();
        mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
        mActivityManagerService.setInstaller(installer);
traceEnd();

//啟動(dòng) PMS 
traceBeginAndSlog("StartPowerManager");
        mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class);
traceEnd();

//初始化電源管理功能
traceBeginAndSlog("InitPowerManagement");
        mActivityManagerService.initPowerManagement();
traceEnd();

// 啟動(dòng) RecoverySystemService 
traceBeginAndSlog("StartRecoverySystemService");
        mSystemServiceManager.startService(RecoverySystemService.class);
traceEnd();

// 為啟動(dòng)事件添加記錄
RescueParty.noteBoot(mSystemContext);

// 啟動(dòng) LightsService 管理LEDs 和背光顯示
traceBeginAndSlog("StartLightsService");
        mSystemServiceManager.startService(LightsService.class);
traceEnd();

traceBeginAndSlog("StartSidekickService");
// Package manager isn't started yet; need to use SysProp not hardware feature
if (SystemProperties.getBoolean("config.enable_sidekick_graphics", false)) {
            mSystemServiceManager.startService(WEAR_SIDEKICK_SERVICE_CLASS);
}
traceEnd();

// Display manager is needed to provide display metrics before package manager
// starts up.
traceBeginAndSlog("StartDisplayManager");
        mDisplayManagerService = mSystemServiceManager.startService(LightsService.class);
traceEnd();

// We need the default display before we can initialize the package manager.
traceBeginAndSlog("WaitForDisplay");
        mSystemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);
traceEnd();

// Only run "core" apps if we're encrypting the device.
String cryptState = SystemProperties.get("vold.decrypt");
if (ENCRYPTING_STATE.equals(cryptState)) {
Slog.w(TAG, "Detected encryption in progress - only parsing core apps");
            mOnlyCore = true;
} else if (ENCRYPTED_STATE.equals(cryptState)) {
Slog.w(TAG, "Device encrypted - only parsing core apps");
            mOnlyCore = true;
}

// 啟動(dòng) PackageManagerService
if (!mRuntimeRestart) {
MetricsLogger.histogram(null, "boot_package_manager_init_start",
(int) SystemClock.elapsedRealtime());
}
traceBeginAndSlog("StartPackageManagerService");
        mPackageManagerService = PackageManagerService.main(mSystemContext, installer,
                mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore);
        mFirstBoot = mPackageManagerService.isFirstBoot();
        mPackageManager = mSystemContext.getPackageManager();
traceEnd();
if (!mRuntimeRestart && !isFirstBootOrUpgrade()) {
MetricsLogger.histogram(null, "boot_package_manager_init_ready",
(int) SystemClock.elapsedRealtime());
}
// Manages A/B OTA dexopting. This is a bootstrap service as we need it to rename
// A/B artifacts after boot, before anything else might touch/need them.
// Note: this isn't needed during decryption (we don't have /data anyways).
if (!mOnlyCore) {
boolean disableOtaDexopt = SystemProperties.getBoolean("config.disable_otadexopt",
false);
if (!disableOtaDexopt) {
traceBeginAndSlog("StartOtaDexOptService");
try {
OtaDexoptService.main(mSystemContext, mPackageManagerService);
} catch (Throwable e) {
reportWtf("starting OtaDexOptService", e);
} finally {
traceEnd();
}
}
}
//啟動(dòng)多用戶    UserManagerService
traceBeginAndSlog("StartUserManagerService");
        mSystemServiceManager.startService(UserManagerService.LifeCycle.class);
traceEnd();

// 初始化屬性緩存
traceBeginAndSlog("InitAttributerCache");
AttributeCache.init(mSystemContext);
traceEnd();

// Set up the Application instance for the system process and get started.
traceBeginAndSlog("SetSystemProcess");
        mActivityManagerService.setSystemProcess();
traceEnd();

// DisplayManagerService needs to setup android.display scheduling related policies
// since setSystemProcess() would have overridden policies due to setProcessGroup
        mDisplayManagerService.setupSchedulerPolicies();

/// M: CTA requirement - permission control  @{
/*
         * M: MOTA for CTA permissions handling
         * This function is used for granting CTA permissions after OTA upgrade.
         * This should be placed after AMS is added to ServiceManager and before
         * starting other services since granting permissions needs AMS instance
         * to do permission checking.
         */
        mPackageManagerService.onAmsAddedtoServiceMgr();
/// @}

//  啟動(dòng) OverlayManagerService
traceBeginAndSlog("StartOverlayManagerService");
        mSystemServiceManager.startService(new OverlayManagerService(mSystemContext, installer));
traceEnd();

// The sensor service needs access to package manager service, app ops
// service, and permissions service, therefore we start it after them.
// Start sensor service in a separate thread. Completion should be checked
// before using it.
        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);
}



  

七、SystemServer 的核心服務(wù)有哪些

1.SystemServer 核心服務(wù)

有 BatteryService 、UsageStatsService、WebViewUpdateService、BinderCallsStatsService4種核心服務(wù)。

SystemServer 4種核心服務(wù)

2.startCoreServices 代碼

        /**
     * Starts some essential services that are not tangled up in the bootstrap process.
     */
private void startCoreServices() {
// 啟動(dòng) BatteryService 管理電池服務(wù)（電壓、電量、溫度）
traceBeginAndSlog("StartBatteryService");
// Tracks the battery level.  Requires LightService.
        mSystemServiceManager.startService(BatteryService.class);
traceEnd();

// 啟動(dòng) UsageStatsService 收集應(yīng)用持久化數(shù)據(jù)的服務(wù)
traceBeginAndSlog("StartUsageService");
        mSystemServiceManager.startService(UsageStatsService.class);
        mActivityManagerService.setUsageStatsManager(
LocalServices.getService(UsageStatsManagerInternal.class));
traceEnd();

// 啟動(dòng) WebViewUpdateService 監(jiān)視 WebView 是否更新
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_WEBVIEW)) {
traceBeginAndSlog("StartWebViewUpdateService");
            mWebViewUpdateService = mSystemServiceManager.startService(WebViewUpdateService.class);
traceEnd();
}

//啟動(dòng) CPU Binder 調(diào)度服務(wù)
traceBeginAndSlog("StartBinderCallsStatsService");
BinderCallsStatsService.start();
traceEnd();
}


  

八、SystemServer 的其他服務(wù)有哪些

1.startOtherServices 啟動(dòng)的服務(wù)主要有：

KeyChainSystemService、TelecomLoaderService、AccountManagerService、ContentService、DropBoxManagerService、VibratorService、AlarmManagerService、Watchdog、 InputManagerService、WindowManagerService、IpConnectivityMetrics、NetworkWatchlistService、PinnerService等服務(wù)。

SystemServer 的其他服務(wù)

2.startOtherServices 代碼

        /**
     * Starts a miscellaneous grab bag of stuff that has yet to be refactored
     * and organized.
     */
private void startOtherServices() {
... ...


traceBeginAndSlog("StartKeyAttestationApplicationIdProviderService");
ServiceManager.addService("sec_key_att_app_id_provider",
new KeyAttestationApplicationIdProviderService(context));
traceEnd();
// 啟動(dòng) KeyChainSystemService 
traceBeginAndSlog("StartKeyChainSystemService");
            mSystemServiceManager.startService(KeyChainSystemService.class);
traceEnd();

traceBeginAndSlog("StartSchedulingPolicyService");
ServiceManager.addService("scheduling_policy", new SchedulingPolicyService());
traceEnd();
// 啟動(dòng) TelecomLoaderService  
traceBeginAndSlog("StartTelecomLoaderService");
            mSystemServiceManager.startService(TelecomLoaderService.class);
traceEnd();

traceBeginAndSlog("StartTelephonyRegistry");
            telephonyRegistry = new TelephonyRegistry(context);
ServiceManager.addService("telephony.registry", telephonyRegistry);
traceEnd();

traceBeginAndSlog("StartEntropyMixer");
            mEntropyMixer = new EntropyMixer(context);
traceEnd();

            mContentResolver = context.getContentResolver();

// 啟動(dòng) 用戶管理服務(wù) ，必現(xiàn)在StartContentService 之前
traceBeginAndSlog("StartAccountManagerService");
            mSystemServiceManager.startService(ACCOUNT_SERVICE_CLASS);
traceEnd();
// 啟動(dòng) ContentService
traceBeginAndSlog("StartContentService");
            mSystemServiceManager.startService(CONTENT_SERVICE_CLASS);
traceEnd();
// 安裝系統(tǒng)Provider 例如 SettingProvider CantacttProvider
traceBeginAndSlog("InstallSystemProviders");
            mActivityManagerService.installSystemProviders();
// Now that SettingsProvider is ready, reactivate SQLiteCompatibilityWalFlags
SQLiteCompatibilityWalFlags.reset();
traceEnd();

// 啟動(dòng) DropBoxManagerService  
// 由于 依賴SettingsProvider，必須在InstallSystemProviders之后啟動(dòng)
traceBeginAndSlog("StartDropBoxManager");
            mSystemServiceManager.startService(DropBoxManagerService.class);
traceEnd();
//啟動(dòng) VibratorService 震動(dòng)服務(wù)
traceBeginAndSlog("StartVibratorService");
            vibrator = new VibratorService(context);
ServiceManager.addService("vibrator", vibrator);
traceEnd();

if (!isWatch) {
traceBeginAndSlog("StartConsumerIrService");
                consumerIr = new ConsumerIrService(context);
ServiceManager.addService(Context.CONSUMER_IR_SERVICE, consumerIr);
traceEnd();
}
// 啟動(dòng) AlarmManagerService
traceBeginAndSlog("StartAlarmManagerService");
if(!sMtkSystemServerIns.startMtkAlarmManagerService()){
                mSystemServiceManager.startService(AlarmManagerService.class);
}
traceEnd();
// 初始化 看門狗
traceBeginAndSlog("InitWatchdog");
final Watchdog watchdog = Watchdog.getInstance();
            watchdog.init(context, mActivityManagerService);
traceEnd();
//啟動(dòng) InputManagerService
traceBeginAndSlog("StartInputManagerService");
            inputManager = new InputManagerService(context);
traceEnd();
//啟動(dòng) WindowManagerService
traceBeginAndSlog("StartWindowManagerService");
// WMS needs sensor service ready
ConcurrentUtils.waitForFutureNoInterrupt(mSensorServiceStart, START_SENSOR_SERVICE);
            mSensorServiceStart = null;
            wm = WindowManagerService.main(context, inputManager,
                    mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL,
!mFirstBoot, mOnlyCore, new PhoneWindowManager());
ServiceManager.addService(Context.WINDOW_SERVICE, wm, /* allowIsolated= */ false,
                    DUMP_FLAG_PRIORITY_CRITICAL | DUMP_FLAG_PROTO);
ServiceManager.addService(Context.INPUT_SERVICE, inputManager,
/* allowIsolated= */ false, DUMP_FLAG_PRIORITY_CRITICAL);
traceEnd();

traceBeginAndSlog("SetWindowManagerService");
            mActivityManagerService.setWindowManager(wm);
traceEnd();

traceBeginAndSlog("WindowManagerServiceOnInitReady");
            wm.onInitReady();
traceEnd();

// Start receiving calls from HIDL services. Start in in a separate thread
// because it need to connect to SensorManager. This have to start
// after START_SENSOR_SERVICE is done.
SystemServerInitThreadPool.get().submit(() -> {
TimingsTraceLog traceLog = new TimingsTraceLog(
                        SYSTEM_SERVER_TIMING_ASYNC_TAG, Trace.TRACE_TAG_SYSTEM_SERVER);
                traceLog.traceBegin(START_HIDL_SERVICES);
startHidlServices();
                traceLog.traceEnd();
}, START_HIDL_SERVICES);

if (!isWatch) {
traceBeginAndSlog("StartVrManagerService");
                mSystemServiceManager.startService(VrManagerService.class);
traceEnd();
}

traceBeginAndSlog("StartInputManager");
            inputManager.setWindowManagerCallbacks(wm.getInputMonitor());
            inputManager.start();
traceEnd();

// TODO: Use service dependencies instead.
traceBeginAndSlog("DisplayManagerWindowManagerAndInputReady");
            mDisplayManagerService.windowManagerAndInputReady();
traceEnd();

// Skip Bluetooth if we have an emulator kernel
// TODO: Use a more reliable check to see if this product should
// support Bluetooth - see bug 988521
if (isEmulator) {
Slog.i(TAG, "No Bluetooth Service (emulator)");
} else if (mFactoryTestMode == FactoryTest.FACTORY_TEST_LOW_LEVEL) {
Slog.i(TAG, "No Bluetooth Service (factory test)");
} else if (!context.getPackageManager().hasSystemFeature
(PackageManager.FEATURE_BLUETOOTH)) {
Slog.i(TAG, "No Bluetooth Service (Bluetooth Hardware Not Present)");
} else {
traceBeginAndSlog("StartBluetoothService");
                mSystemServiceManager.startService(BluetoothService.class);
traceEnd();
}
// 啟動(dòng) IpConnectivityMetrics
traceBeginAndSlog("IpConnectivityMetrics");
            mSystemServiceManager.startService(IpConnectivityMetrics.class);
traceEnd();
// 啟動(dòng) NetworkWatchlistService
traceBeginAndSlog("NetworkWatchlistService");
            mSystemServiceManager.startService(NetworkWatchlistService.Lifecycle.class);
traceEnd();
// 啟動(dòng) PinnerService 
traceBeginAndSlog("PinnerService");
            mSystemServiceManager.startService(PinnerService.class);
traceEnd();
} catch (RuntimeException e) {
  

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