ActivityManagerService启动过程

我就是我 2022-10-01 10:42 182阅读 0赞

frameworks/base/services/core/java/com/android/server/
      - am/ActivityManagerService.java
      - SystemServiceManager.java
    frameworks/base/services/java/com/android/server/
      - SystemServer.java
    复制代码

# 1 创建ActivityManagerService对象，并注册 #

在分析phone进程开启过程中提到了ActivityManagerService，ActivityManagerService又是如何开启的？system\_server进程启动后，进入SystemServer的main方法,调用startBootstrapServices。

1、在SystemServiceManager的startService中创建ActivityManagerService对象，并回调Lifecycle的onStart。

2、并在ActivityManagerService的setSystemProcess中往ServiceManager中注册"activity"服务。

frameworks/base/services/java/com/android/server/SystemServer.java
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public static void main(String[] args) {
            new SystemServer().run();
    }
    private void run() {
            // Start services.
            try {
                startBootstrapServices();
                startCoreServices();
                startOtherServices();
            }
    }
    private void startBootstrapServices() {
            mActivityManagerService = mSystemServiceManager.startService(
            ActivityManagerService.Lifecycle.class).getService();
            mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
            mActivityManagerService.setInstaller(installer);
            ...
            // Set up the Application instance for the system process and get started.
            mActivityManagerService.setSystemProcess();
    }
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frameworks/base/services/core/java/com/android/server/SystemServiceManager.java
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public <T extends SystemService> T startService(Class<T> serviceClass) {
        Constructor<T> constructor = serviceClass.getConstructor(Context.class);
        service = constructor.newInstance(mContext);
        service.onStart();
    }
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frameworks/base/services/core/java/com/android/server/ActivityManagerService.java
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private void start() {
            Process.removeAllProcessGroups();
            mProcessCpuThread.start();
    
            mBatteryStatsService.publish(mContext);
            mAppOpsService.publish(mContext);
            Slog.d("AppOps", "AppOpsService published");
            LocalServices.addService(ActivityManagerInternal.class, new LocalService());
        }
        
        public static final class Lifecycle extends SystemService {
            private final ActivityManagerService mService;
    
            public Lifecycle(Context context) {
                super(context);
                mService = new ActivityManagerService(context);//创建ActivityManagerService对象
            }
    
            @Override
            public void onStart() {
                mService.start();
            }
    
            public ActivityManagerService getService() {
                return mService;
            }
        }
    
    public void setSystemProcess() {
        ServiceManager.addService(Context.ACTIVITY_SERVICE, this, true);//注册”activity“服务
    }
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# 2 启动persistent进程、启动桌面 #

通过startOtherServices方法启动persistent进程、启动桌面

frameworks/base/services/java/com/android/server/SystemServer.java
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private void startOtherServices() {
         mActivityManagerService.systemReady(new Runnable() {
                @Override
                public void run() {
                }
        }
    }
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frameworks/base/services/core/java/com/android/server/ActivityManagerService.java
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public void systemReady(final Runnable goingCallback) {
             synchronized (this) {
                if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) {
                    try {
                        List apps = AppGlobals.getPackageManager().
                            getPersistentApplications(STOCK_PM_FLAGS);
                        if (apps != null) {
                            int N = apps.size();
                            int i;
                            for (i=0; i<N; i++) {
                                ApplicationInfo info
                                    = (ApplicationInfo)apps.get(i);
                                if (info != null &&
                                        !info.packageName.equals("android")) {
                                    addAppLocked(info, false, null /* ABI override */);
                                }
                            }
                        }
                    } catch (RemoteException ex) {
                        // pm is in same process, this will never happen.
                    }
                }
    
                // Start up initial activity.
                mBooting = true;
                startHomeActivityLocked(mCurrentUserId, "systemReady");
     }
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# 3 创建app进程函数 #

//app进程的创建全部走这个函数
    private final void startProcessLocked(ProcessRecord app, String hostingType,
               String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs) {
        if (entryPoint == null) entryPoint = "android.app.ActivityThread";
               Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "Start proc: " +
                       app.processName);
               checkTime(startTime, "startProcess: asking zygote to start proc");
               Process.ProcessStartResult startResult = Process.start(entryPoint,
                       app.processName, uid, uid, gids, debugFlags, mountExternal,
                       app.info.targetSdkVersion, app.info.seinfo, requiredAbi, instructionSet,
                       app.info.dataDir, entryPointArgs);
               checkTime(startTime, "startProcess: returned from zygote!");
               }
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# 总结 #

ActivityManagerService提供了启动launcher、启动persistent进程、通过startActivity\\startService等方式创建应用进程的方法startProcessLocked。

[Launcher启动过程][Launcher]

转载于:https://juejin.im/post/5c78c23bf265da2daf79ba59

[Launcher]: https://juejin.im/post/5c78c19d5188256fe061fbbe