SystemServer进程的创建及Launcher启动

贺祥 | 发表于 | 分类于

SystemServer进程的创建及Launcher启动

1.SystemServer进程的创建

ZygoteInit.main方法中里fork出个SystemServer进程

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/* Hardcoded command line to start the system server */
       String args[] = {
           "--setuid=1000",
           "--setgid=1000",
           "--setgroups=1001,1002,1003,1004,1005,1006,1007,1008,1009,1010,1018,1021,1023,1024,1032,1065,3001,3002,3003,3006,3007,3009,3010",
           "--capabilities=" + capabilities + "," + capabilities,
           "--nice-name=system_server",
           "--runtime-args",
           "--target-sdk-version=" + VMRuntime.SDK_VERSION_CUR_DEVELOPMENT,
           "com.android.server.SystemServer",
       };
       ZygoteConnection.Arguments parsedArgs = null;

       int pid;

       try {
           parsedArgs = new ZygoteConnection.Arguments(args);
           ZygoteConnection.applyDebuggerSystemProperty(parsedArgs);
           ZygoteConnection.applyInvokeWithSystemProperty(parsedArgs);

           boolean profileSystemServer = SystemProperties.getBoolean(
                   "dalvik.vm.profilesystemserver", false);
           if (profileSystemServer) {
               parsedArgs.runtimeFlags |= Zygote.PROFILE_SYSTEM_SERVER;
           }

           /* Request to fork the system server process */
           pid = Zygote.forkSystemServer(
                   parsedArgs.uid, parsedArgs.gid,
                   parsedArgs.gids,
                   parsedArgs.runtimeFlags,
                   null,
                   parsedArgs.permittedCapabilities,
                   parsedArgs.effectiveCapabilities);
       } catch (IllegalArgumentException ex) {
           throw new RuntimeException(ex);
       }

2.SystemServer.main方法

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

run方法

2.1. 创建loop对象
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// Prepare the main looper thread (this thread).
Looper.prepareMainLooper();
2.2 创建了系统上下文
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// Initialize the system context.
createSystemContext();

创建AcitivityThread
这里创建的ActivityThread 和ActivityThread.main()中创建的不是同一个

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private void createSystemContext() {
	// systemMain()中创建activityThread 调用activityThread .attach(true, 0); 会创建Application,Instrumentation ,并调用applicition.onCreate()
    ActivityThread activityThread = ActivityThread.systemMain();
    //创建context,创建LoadedApk
    mSystemContext = activityThread.getSystemContext();
    mSystemContext.setTheme(DEFAULT_SYSTEM_THEME);

    final Context systemUiContext = activityThread.getSystemUiContext();
    systemUiContext.setTheme(DEFAULT_SYSTEM_THEME);
}

2.3启动SystemServiceManager
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// Create the system service manager.
         mSystemServiceManager = new SystemServiceManager(mSystemContext);
         mSystemServiceManager.setStartInfo(mRuntimeRestart,
                 mRuntimeStartElapsedTime, mRuntimeStartUptime);
         LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
         // Prepare the thread pool for init tasks that can be parallelized
         SystemServerInitThreadPool.get();
2.4 启动相关服务
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// Start services.
 try {
     traceBeginAndSlog("StartServices");
     startBootstrapServices();
     startCoreServices();
     startOtherServices();
     SystemServerInitThreadPool.shutdown();
 } catch (Throwable ex) {
     Slog.e("System", "******************************************");
     Slog.e("System", "************ Failure starting system services", ex);
     throw ex;
 } finally {
     traceEnd();
 }

2.4.1startBootstrapServices()启动了ActivityManagerService ,PowerManagerService,PackageManagerService …等

2.4.2
startCoreServices()启动了BatteryService,UsageStatsService,WebViewUpdateService

2.4.3 startOtherServices()启动了AlarmManagerService,BluetoothService,NotificationManagerService …等

mActivityManagerService.systemReady 启动launcher

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// We now tell the activity manager it is okay to run third party
      // code.  It will call back into us once it has gotten to the state
      // where third party code can really run (but before it has actually
      // started launching the initial applications), for us to complete our
      // initialization.
      mActivityManagerService.systemReady(...)

systemReady 方法中调用 mActivityManagerService.startHomeActivityLocked启动launcher

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startHomeActivityLocked(currentUserId, "systemReady");

下面代码1处调用ActivityStarter中的 startActivityMayWait 或者startActivity ,又开始走Activity启动流程

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void startHomeActivity(Intent intent, ActivityInfo aInfo, String reason) {
        mSupervisor.moveHomeStackTaskToTop(reason);
		//代码1
        mLastHomeActivityStartResult = obtainStarter(intent, "startHomeActivity: " + reason)
                .setOutActivity(tmpOutRecord)
                .setCallingUid(0)
                .setActivityInfo(aInfo)
                .execute();
        mLastHomeActivityStartRecord = tmpOutRecord[0];
        if (mSupervisor.inResumeTopActivity) {
            // If we are in resume section already, home activity will be initialized, but not
            // resumed (to avoid recursive resume) and will stay that way until something pokes it
            // again. We need to schedule another resume.
            mSupervisor.scheduleResumeTopActivities();
        }
    }

2.5进入消息循环
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// Loop forever.
Looper.loop();