Android System Server

System Server

Android 系统服务进程 system_server，运行着各种服务，比如 PMS, AMS, WMS 等等。 该进程是启动时，由 Zygote 启动。

frameworks/base/core/java/com/android/internal/os/ZygoteInit.java

private static Runnable forkSystemServer(String abiList, string socketName,
        ZygoteServer zygoteServer) {
    ......
    String args[] = {
        ......
        "com.android.server.SystemServer"
    };
    ......
    pid = Zygote.forkSystemServer(...)
    if (pid == 0) {
        ......
        zygoteServer.closeServerSocket();
        return handleSystemServerProcess(parsedArgs);
    }
    return null;
}

frameworks/base/services/java/com/android/server/SystemServer.java

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

private void run() {
    ......
    // Initialize native services.
    System.loadLibrary("android_servers");

    // Check whether we failed to shut down last time.
    performPendingShutdown();

    // Initialize the system context
    createSystemContext();

    // Create the system service manager.
    mSystemServiceManager = new SystemServiceManager(mSystemContext);
    mSystemServiceManager.setStartInfo(...);
    LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
    // prepare the thread pool for init tasks that can be parallelized
    SystemServerInitThreadPool.get();

    // Start services.
    try {
        traceBeginAndSlog("StartServices");
        startBootstrapServices();
        startCoreServices();
        startOtherServices();
        SystemServerInitThreadPool.shutdown();
    } catch (Throwable ex) {
        ...
    } finally {
        traceEnd();
    }

    // Loop forever.
    Looper.loop();
    throw new RuntimeException("Main thread loop unexpectedly exited");
}

private void startBootstrapService() {
    Installer installer = mSystemServiceManager.startService(Installer.class);

    mSystemServiceManager.startService(DevicesIdentifiersPolicyService.class);

    mActivityManagerService = mSystemServiceManager.startService(ActivityManagerService.Lifecycle.class).getService();
    mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
    mActivityManagerService.setInstaller(installer);

    mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class);

    mActivityManagerService.initPowerManagement();

    mSystemServiceManager.startService(RecoverySystemService.class);

    mSystemServiceManager.startService(LisghtService.class);

    mDisplayManagerService = mSystemServiceManager.startService(DisplayManagerService.class);

    mSYstemServiceManager.startBootPhase(SystemService.PHASE_WAIT_FOR_DEFAULT_DISPLAY);

    mPackageManagerService = PackageManagerService.main(...);

    mSystemServiceManager.startService(UserManagerService.LifeCycle.class);
    ......
}

private void startCoreService() {
    mSystemServiceManager.startService(BatterService.class);
    mSystemServiceManager.startService(UsageStatsService.class);
    mWebViewUpdateService = mSystemServiceManager.startService(WebViewUpdateService.class);
}

private void startOtherServices() {
    //
    VibrateService
    IStorageManager
    NewWorkManagementService
    IpSecService
    NetworkStatsService
    NetworkPolicyManagerService
    ConnectivityService
    NsdService
    WindowManagerService
    SerialService
    NetworkTimeUpdateService
    CommonTimeManagementService
    InputManagerService
    TelephonyRegistry
    ConsumerIrService
    MmsServiceBroker
    HardwarePropertiesManagerService
}