Android系统启动进程

int main(){
　　　　 ……       for(;;){              execute_one_command();              restart_processes();              for (i = 0; i < fd_count; i++) {            if (ufds[i].revents == POLLIN) {                if (ufds[i].fd == get_property_set_fd())                    handle_property_set_fd();                else if (ufds[i].fd == get_keychord_fd())                    handle_keychord();                else if (ufds[i].fd == get_signal_fd())                    handle_signal();            }        }       }}

service servicemanager /system/bin/servicemanager　　class core　　user system　　group system　　critical　　onrestart restart zygote　　onrestart restart media　　onrestart restart surfaceflinger　　onrestart restart drm

service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-server　　class main　　socket zygote stream 666　　onrestart write /sys/android_power/request_state wake　　onrestart write /sys/power/state on　　onrestart restart media　　onrestart restart netd参数：--zygote --start-system-server

int main( ){       AppRuntime runtime;       if (zygote) {              runtime.start("com.android.internal.os.ZygoteInit",                startSystemServer ? "start-system-server" : "");       }}class AppRuntime : public AndroidRuntime{}；

void start(const char* className, const char* options){       // start the virtual machine Java在虚拟机中运行的       JNIEnv* env;       if (startVm(&mJavaVM, &env) != 0) {              return;       }       //向刚刚新建的虚拟机注册JNI本地接口       if (startReg(env) < 0) {              return;       }　　　　// jni 调用 java 方法，获取对应类的静态main方法　　　　jmethodID startMeth = env->GetStaticMethodID(startClass,       　　"main","([Ljava/lang/String;)V");       // jni调用 java方法，调用到ZygoteInit类的main函数       jclass startClass = env->FindClass(className);       env->CallStaticVoidMethod(startClass, startMeth, strArray);}

public static void main(String argv[]) {       //Registers a server socket for zygote command connections       registerZygoteSocket();       //Loads and initializes commonly used classes and       //used resources that can be shared across processes       preload();       // Do an initial gc to clean up after startup       gc();       if (argv[1].equals("start-system-server")) {              startSystemServer();       }
/**       * Runs the zygote process's select loop. Accepts new connections as       * they happen, and reads commands from connections one spawn-request's       * worth at a time.       */       runSelectLoopMode();    //loop中       /**       * Close and clean up zygote sockets. Called on shutdown and on the       * child's exit path.       */       closeServerSocket();}

private static boolean startSystemServer(){       /* Request to fork the system server process 孵化新的进程 */　　　　ZygoteConnection.Arguments parsedArgs = null;       pid = Zygote.forkSystemServer(              parsedArgs.uid, parsedArgs.gid,              parsedArgs.gids,              parsedArgs.debugFlags,              null,              parsedArgs.permittedCapabilities,              parsedArgs.effectiveCapabilities);               /* For child process 对新的子进程设置 */       if (pid == 0) {              handleSystemServerProcess(parsedArgs);       }}void handleSystemServerProcess(parsedArgs){       closeServerSocket();       //"system_server"       Process.setArgV0(parsedArgs.niceName);       //Pass the remaining arguments to SystemServer.　　　　RuntimeInit.zygoteInit(parsedArgs.targetSdkVersion,　　　　　　parsedArgs.remainingArgs);       /* should never reach here */}

//The main function called when started through the zygote process.void zygoteInit(int targetSdkVersion, String[] argv){        applicationInit(targetSdkVersion, argv);}void applicationInit(int targetSdkVersion, String[] argv){    // Remaining arguments are passed to the start class's static main    invokeStaticMain(args.startClass, args.startArgs);}
void invokeStaticMain(String className, String[] argv){    Class<?> cl;    cl = Class.forName(className);     //获取SystemServer的main方法，抛出MethodAndArgsCaller异常    Method m;    m = cl.getMethod("main", new Class[] { String[].class });    int modifiers = m.getModifiers();    throw new ZygoteInit.MethodAndArgsCaller(m, argv);}

public static void main(String argv[]) {       try {              ……              if (argv[1].equals("start-system-server")) {                  startSystemServer();       //这里如果抛出异常，跳过下面流程              }          　　　　　　　　runSelectLoopMode();    //loop中              ……       } catch (MethodAndArgsCaller caller) {              caller.run();        //处理的异常       }}

public static void main(String[] args) {       　　System.loadLibrary("android_servers");           　　/*       　　* This method is called from Zygote to initialize the system.       　　* This will cause the native services (SurfaceFlinger, AudioFlinger, etc..)       　　* to be started. After that it will call back       　　* up into init2() to start the Android services.      　　 */      　　 init1(args);    //native 完了回调init2( )　　}//init1:　　frameworks/base/services/jni/com_android_server_SystemServer.cpp:: android_server_SystemServer_init1( ) 
　　中调用：system_initextern "C" status_t system_init(){       sp<ProcessState> proc(ProcessState::self());       sp<IServiceManager> sm = defaultServiceManager();       //启动SurfaceFlinger 和传感器       property_get("system_init.startsurfaceflinger", propBuf, "1");       SurfaceFlinger::instantiate();       property_get("system_init.startsensorservice", propBuf, "1");       SensorService::instantiate();       // And now start the Android runtime.  We have to do this bit       // of nastiness because the Android runtime initialization requires       // some of the core system services to already be started.　　　　// All other servers should just start the Android runtime at       // the beginning of their processes's main(), before calling       // the init function.       AndroidRuntime* runtime = AndroidRuntime::getRuntime();       //回调 com.android.server.SystemServer init2 方法             JNIEnv* env = runtime->getJNIEnv();       jclass clazz = env->FindClass("com/android/server/SystemServer");       jmethodID methodId = env->GetStaticMethodID(clazz, "init2", "()V");       env->CallStaticVoidMethod(clazz, methodId);           //启动线程池 做为binder 服务       ProcessState::self()->startThreadPool();       IPCThreadState::self()->joinThreadPool();       return NO_ERROR;}

public static final void init2() {   　　　　//建立线程来处理       Thread thr = new ServerThread();             thr.setName("android.server.ServerThread");       thr.start();}//看看线程ServerThread里面都做了什么事情？public void run() {    addBootEvent(new String("Android:SysServerInit_START"));    Looper.prepare();    android.os.Process.setThreadPriority(    android.os.Process.THREAD_PRIORITY_FOREGROUND);    //初始化服务，创建各种服务实例，如：电源、网络、Wifi、蓝牙，USB等，　　//初始化完成以后加入到 ServiceManager中，    //事我们用 Context.getSystemService (String name) 才获取到相应的服务    PowerManagerService power = null;    NetworkManagementService networkManagement = null;    WifiP2pService wifiP2p = null;    WindowManagerService wm = null;    BluetoothService bluetooth = null;    UsbService usb = null;    NotificationManagerService notification = null;    StatusBarManagerService statusBar = null;    ……
    power = new PowerManagerService();    ServiceManager.addService(Context.POWER_SERVICE, power);    ……    // ActivityManagerService作为ApplicationFramework最重要的服务    ActivityManagerService.setSystemProcess();    ActivityManagerService.installSystemProviders();    ActivityManagerService.self().setWindowManager(wm);   　　// 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.　　//系统服务初始化准备就绪，通知各个模块    ActivityManagerService.self().systemReady(new Runnable() {           public void run() {                  startSystemUi(contextF);                  batteryF.systemReady();                  networkManagementF.systemReady();                  usbF.systemReady();                  ……                  // It is now okay to let the various system services start their                  // third party code...                  appWidgetF.systemReady(safeMode);                  wallpaperF.systemReady();           }    });    //    //BOOTPROF    addBootEvent(new String("Android:SysServerInit_END"));    Looper.loop();}

 public void systemReady(final Runnable goingCallback) {　　　　……　　　　//ready callback       if (goingCallback != null)              goingCallback.run();
synchronized (this) {              // Start up initial activity.              // ActivityStack mMainStack;              mMainStack.resumeTopActivityLocked(null);       }……}final boolean resumeTopActivityLocked(ActivityRecord prev) {　　// Find the first activity that is not finishing.　　ActivityRecord next = topRunningActivityLocked(null);　　if (next == null) {　　　　// There are no more activities!  Let's just start up the　　　　// Launcher...　　　　if (mMainStack) {　　　　　　//ActivityManagerService mService;　　　　　　return mService.startHomeActivityLocked();　　　　}　　}　　……}