android L 关机流程图_pmic halt

下面是简单的流程图，从java到kernel层。

ShutdownThread.java文件

stop playing music，因为后面可能要playing shutdown music.

代码如下：

private static void beginShutdownSequence(Context context) {
  ....
        //acquire audio focus to make the other apps to stop playing muisc
        mAudioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        mAudioManager.requestAudioFocus(null,
                AudioManager.STREAM_MUSIC, AudioManager.AUDIOFOCUS_GAIN);

show system dialog to indicate phone is shutting down，如果没有关机动画的话，要show一个关机提示出来。

代码如下：

        if (!checkAnimationFileExist()) {
            // throw up an indeterminate system dialog to indicate radio is
            // shutting down.
            ProgressDialog pd = new ProgressDialog(context);
            pd.setTitle(context.getText(com.android.internal.R.string.power_off));
            pd.setMessage(context.getText(com.android.internal.R.string.shutdown_progress));
            pd.setIndeterminate(true);
            pd.setCancelable(false);
            pd.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
 
            pd.show();
        }

Hold the wakelock,make sure we never fall asleep again，抓锁防止机器关机过程中休眠

代码如下：

            sInstance.mCpuWakeLock = sInstance.mPowerManager.newWakeLock(
                    PowerManager.PARTIAL_WAKE_LOCK, TAG + "-cpu");//这个只是锁住cpu不进入休眠，但screen是off的，需full锁来保证screen常亮
            sInstance.mCpuWakeLock.setReferenceCounted(false);
            sInstance.mCpuWakeLock.acquire();

make sure the screen stays on,再抓一个full锁，防止屏幕半暗

代码如下：

                sInstance.mScreenWakeLock = sInstance.mPowerManager.newWakeLock(
                        PowerManager.FULL_WAKE_LOCK, TAG + "-screen");//保持srceen常亮
                sInstance.mScreenWakeLock.setReferenceCounted(false);
                sInstance.mScreenWakeLock.acquire();

起一下新进程

sending shutdown broadcast，发出广播，通知各app该保存数据赶紧的，我要关机了

代码如下：

        Intent intent = new Intent(Intent.ACTION_SHUTDOWN);
        intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
        mContext.sendOrderedBroadcastAsUser(intent,//发广播
                UserHandle.ALL, null, br, mHandler, 0, null, null);

shutdown activity manager，关闭activity manager，即关闭AppOpsService，UsageStatsService，BatteryStatsService

注意：android L 与KK在关闭UsageStatsService上有所区别

代码如下：

[ActivityManagerService.java]

final IActivityManager am =
            ActivityManagerNative.asInterface(ServiceManager.checkService("activity"));
        if (am != null) {
            try {
                am.shutdown(MAX_BROADCAST_TIME);
            } catch (RemoteException e) {
            }
        }

shutdown package manager，保存app使用时间到 disk里，这是android L新增的功能。

代码如下：

[PackageManagerService.java]

        final PackageManagerService pm = (PackageManagerService)
            ServiceManager.getService("package");
        if (pm != null) {
            pm.shutdown();