Android重启流程(一)

framework/base/services/core/java/com/android/server/power/PowerManagerServer.java framework/base/services/core/java/com/android/server/power/ShutdownThread.java

public void reboot(String reason) {     try {         //【见小节2.2】         mService.reboot(false, reason, true);     } catch (RemoteException e) {     } }

private final class BinderService extends IPowerManager.Stub {     public void reboot(boolean confirm, String reason, boolean wait) {         //权限检查         mContext.enforceCallingOrSelfPermission(android.Manifest.permission.REBOOT, null);         if (PowerManager.REBOOT_RECOVERY.equals(reason)) {             mContext.enforceCallingOrSelfPermission(android.Manifest.permission.RECOVERY, null);         }          final long ident = Binder.clearCallingIdentity();         try {             //【见小节2.3】             shutdownOrRebootInternal(false, confirm, reason, wait);         } finally {             Binder.restoreCallingIdentity(ident);         }     } }

private void shutdownOrRebootInternal(final boolean shutdown, final boolean confirm,         final String reason, boolean wait) {     ...     Runnable runnable = new Runnable() {         @Override         public void run() {             synchronized (this) {                 if (shutdown) {                     ShutdownThread.shutdown(mContext, reason, confirm);                 } else {                     //重启则进入该分支【见小节2.4】                     ShutdownThread.reboot(mContext, reason, confirm);                 }             }         }     };      // ShutdownThread必须运行在一个展现UI的looper     Message msg = Message.obtain(mHandler, runnable);     msg.setAsynchronous(true);     mHandler.sendMessage(msg);       if (wait) {         //等待ShutdownThread执行完毕         synchronized (runnable) {             while (true) {                 try {                     runnable.wait();                 } catch (InterruptedException e) {                 }             }         }     } }

public static void reboot(final Context context, String reason, boolean confirm) {     mReboot = true;     mRebootSafeMode = false;     mRebootUpdate = false;     mReason = reason;     //【见小节2.5】     shutdownInner(context, confirm); }

static void shutdownInner(final Context context, boolean confirm) {     //确保只有唯一的线程执行shutdown/reboot操作     synchronized (sIsStartedGuard) {         if (sIsStarted) {             return;         }     }      final int longPressBehavior = context.getResources().getInteger(                     com.android.internal.R.integer.config_longPressOnPowerBehavior);     final int resourceId = mRebootSafeMode             ? com.android.internal.R.string.reboot_safemode_confirm             : (longPressBehavior == 2                     ? com.android.internal.R.string.shutdown_confirm_question                     : com.android.internal.R.string.shutdown_confirm);      Log.d(TAG, "Notifying thread to start shutdown longPressBehavior=" + longPressBehavior);      if (confirm) {         //这里是走弹出关机/重启提示框         ...     } else {         //本次confirm=false进入该分支【见小节2.6】         beginShutdownSequence(context);     } }

private static void beginShutdownSequence(Context context) {     synchronized (sIsStartedGuard) {         if (sIsStarted) {             return; //shutdown操作正在执行，则直接返回         }         sIsStarted = true;     }     //创建进度显示对话框     ProgressDialog pd = new ProgressDialog(context);      //当重启原因为"recovery"     if (PowerManager.REBOOT_RECOVERY.equals(mReason)) {         mRebootUpdate = new File(UNCRYPT_PACKAGE_FILE).exists();         if (mRebootUpdate) {             pd.setTitle(context.getText(com.android.internal.R.string.reboot_to_update_title));             pd.setMessage(context.getText(                     com.android.internal.R.string.reboot_to_update_prepare));             pd.setMax(100);             pd.setProgressNumberFormat(null);             pd.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);             pd.setProgress(0);             pd.setIndeterminate(false);         } else {             pd.setTitle(context.getText(com.android.internal.R.string.reboot_to_reset_title));             pd.setMessage(context.getText(                     com.android.internal.R.string.reboot_to_reset_message));             pd.setIndeterminate(true);         }     } else {         //重启/关机则进入该分支         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();      sInstance.mProgressDialog = pd;     sInstance.mContext = context;     sInstance.mPowerManager = (PowerManager)context.getSystemService(Context.POWER_SERVICE);      //确保系统不会进入休眠状态     sInstance.mCpuWakeLock = null;     try {         sInstance.mCpuWakeLock = sInstance.mPowerManager.newWakeLock(                 PowerManager.PARTIAL_WAKE_LOCK, TAG + "-cpu");         sInstance.mCpuWakeLock.setReferenceCounted(false);         sInstance.mCpuWakeLock.acquire();     } catch (SecurityException e) {         sInstance.mCpuWakeLock = null;     }      //当处理亮屏状态，则获取亮屏锁，提供用户体验     sInstance.mScreenWakeLock = null;     if (sInstance.mPowerManager.isScreenOn()) {         try {             sInstance.mScreenWakeLock = sInstance.mPowerManager.newWakeLock(                     PowerManager.FULL_WAKE_LOCK, TAG + "-screen");             sInstance.mScreenWakeLock.setReferenceCounted(false);             sInstance.mScreenWakeLock.acquire();         } catch (SecurityException e) {             sInstance.mScreenWakeLock = null;         }     }      sInstance.mHandler = new Handler() {};     //启动线程来执行shutdown初始化【见小节2.7】     sInstance.start(); }

public final class ShutdownThread extends Thread {     public void run() {         BroadcastReceiver br = new BroadcastReceiver() {             public void onReceive(Context context, Intent intent) {                 actionDone();             }         };          String reason = (mReboot ? "1" : "0") + (mReason != null ? mReason : "");         //设置"sys.shutdown.requested"属性值         SystemProperties.set(SHUTDOWN_ACTION_PROPERTY, reason);          if (mRebootSafeMode) {             //如果需要重启进入安全模式，则设置"persist.sys.safemode"=1             SystemProperties.set(REBOOT_SAFEMODE_PROPERTY, "1");         }          //1. 发送关机广播         mActionDone = false;         Intent intent = new Intent(Intent.ACTION_SHUTDOWN);         intent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);         mContext.sendOrderedBroadcastAsUser(intent,                 UserHandle.ALL, null, br, mHandler, 0, null, null);         //其中MAX_BROADCAST_TIME=10s         final long endTime = SystemClock.elapsedRealtime() + MAX_BROADCAST_TIME;         synchronized (mActionDoneSync) {             while (!mActionDone) {                 long delay = endTime - SystemClock.elapsedRealtime();                 if (delay <= 0) {                     break; //关机广播超时                 } else if (mRebootUpdate) {                     int status = (int)((MAX_BROADCAST_TIME - delay) * 1.0 *                             BROADCAST_STOP_PERCENT / MAX_BROADCAST_TIME);                     sInstance.setRebootProgress(status, null);                 }                 try {                     //最长等待时间为500ms                     mActionDoneSync.wait(Math.min(delay, PHONE_STATE_POLL_SLEEP_MSEC));                 } catch (InterruptedException e) {                 }             }         }         if (mRebootUpdate) {             sInstance.setRebootProgress(BROADCAST_STOP_PERCENT, null);         }          //2. 关闭AMS         final IActivityManager am =             ActivityManagerNative.asInterface(ServiceManager.checkService("activity"));         if (am != null) {             try {                 am.shutdown(MAX_BROADCAST_TIME);             } catch (RemoteException e) {             }         }         if (mRebootUpdate) {             sInstance.setRebootProgress(ACTIVITY_MANAGER_STOP_PERCENT, null);         }          //3. 关闭PMS         final PackageManagerService pm = (PackageManagerService)             ServiceManager.getService("package");         if (pm != null) {             pm.shutdown();         }         if (mRebootUpdate) {             sInstance.setRebootProgress(PACKAGE_MANAGER_STOP_PERCENT, null);         }          //4. 关闭radios.         shutdownRadios(MAX_RADIO_WAIT_TIME);         if (mRebootUpdate) {             sInstance.setRebootProgress(RADIO_STOP_PERCENT, null);         }          //5. 关闭MountService         IMountShutdownObserver observer = new IMountShutdownObserver.Stub() {             public void onShutDownComplete(int statusCode) throws RemoteException {                 actionDone();             }         };          mActionDone = false;         //其中MAX_SHUTDOWN_WAIT_TIME=20s         final long endShutTime = SystemClock.elapsedRealtime() + MAX_SHUTDOWN_WAIT_TIME;         synchronized (mActionDoneSync) {             try {                 final IMountService mount = IMountService.Stub.asInterface(                         ServiceManager.checkService("mount"));                 if (mount != null) {                     mount.shutdown(observer);                 }             } catch (Exception e) {                 Log.e(TAG, "Exception during MountService shutdown", e);             }             while (!mActionDone) {                 long delay = endShutTime - SystemClock.elapsedRealtime();                 if (delay <= 0) {                     break; // Mount观察者广播超时                 } else if (mRebootUpdate) {                     int status = (int)((MAX_SHUTDOWN_WAIT_TIME - delay) * 1.0 *                             (MOUNT_SERVICE_STOP_PERCENT - RADIO_STOP_PERCENT) /                             MAX_SHUTDOWN_WAIT_TIME);                     status += RADIO_STOP_PERCENT;                     sInstance.setRebootProgress(status, null);                 }                 try {                     //当收到mActionDoneSync.notifyAll()，则继续往下执行程序                     mActionDoneSync.wait(Math.min(delay, PHONE_STATE_POLL_SLEEP_MSEC));                 } catch (InterruptedException e) {                 }             }         }         ...         //【2.8】         rebootOrShutdown(mContext, mReboot, mReason);     } }

public boolean shutdown(int timeout) {     //权限检测     if (checkCallingPermission(android.Manifest.permission.SHUTDOWN)             != PackageManager.PERMISSION_GRANTED) {         throw new SecurityException("Requires permission "                 + android.Manifest.permission.SHUTDOWN);     }      boolean timedout = false;      synchronized(this) {         mShuttingDown = true;         //禁止WMS继续处理Event         updateEventDispatchingLocked();         timedout = mStackSupervisor.shutdownLocked(timeout);     }      mAppOpsService.shutdown();     if (mUsageStatsService != null) {         mUsageStatsService.prepareShutdown();     }     mBatteryStatsService.shutdown();     synchronized (this) {         mProcessStats.shutdownLocked();         notifyTaskPersisterLocked(null, true);     }      return timedout; }

public void shutdown() {     mPackageUsage.write(true); }

private class PackageUsage {     void write(boolean force) {         if (force) {             writeInternal();             return;         }         ...     } }

private class PackageUsage {     private void writeInternal() {         synchronized (mPackages) {             synchronized (mFileLock) {                 //file是指/data/system/package-usage.list                 AtomicFile file = getFile();                 FileOutputStream f = null;                 try {                     //将原来的文件记录到package-usage.list.bak                     f = file.startWrite();                     BufferedOutputStream out = new BufferedOutputStream(f);                     FileUtils.setPermissions(file.getBaseFile().getPath(), 0640, SYSTEM_UID, PACKAGE_INFO_GID);                     StringBuilder sb = new StringBuilder();                     for (PackageParser.Package pkg : mPackages.values()) {                         if (pkg.mLastPackageUsageTimeInMills == 0) {                             continue;                         }                         sb.setLength(0);                         sb.append(pkg.packageName);                         sb.append(' ');                         sb.append((long)pkg.mLastPackageUsageTimeInMills);                         sb.append('/n');                         out.write(sb.toString().getBytes(StandardCharsets.US_ASCII));                     }                     out.flush();                     //将文件内容同步到磁盘，并删除.bak文件                     file.finishWrite(f);                 } catch (IOException e) {                     if (f != null) {                         file.failWrite(f);                     }                     Log.e(TAG, "Failed to write package usage times", e);                 }             }         }         mLastWritten.set(SystemClock.elapsedRealtime());     } }

private void shutdownRadios(final int timeout) {     final long endTime = SystemClock.elapsedRealtime() + timeout;     Thread t = new Thread() {         public void run() {             boolean nfcOff;             boolean bluetoothOff;             boolean radioOff;              final INfcAdapter nfc =                     INfcAdapter.Stub.asInterface(ServiceManager.checkService("nfc"));             final ITelephony phone =                     ITelephony.Stub.asInterface(ServiceManager.checkService("phone"));             final IBluetoothManager bluetooth =                     IBluetoothManager.Stub.asInterface(ServiceManager.checkService(                             BluetoothAdapter.BLUETOOTH_MANAGER_SERVICE));              nfcOff = nfc == null || nfc.getState() == NfcAdapter.STATE_OFF;             if (!nfcOff) {                 nfc.disable(false);//关闭NFC             }              bluetoothOff = bluetooth == null || !bluetooth.isEnabled();             if (!bluetoothOff) {                 bluetooth.disable(false);  //关闭Bluetooth             }              radioOff = phone == null || !phone.needMobileRadioShutdown();             if (!radioOff) {                 phone.shutdownMobileRadios(); //关闭cellular radios             }             ...              //等待NFC, Bluetooth, Radio             long delay = endTime - SystemClock.elapsedRealtime();             while (delay > 0) {                 ...                 if (radioOff && bluetoothOff && nfcOff) {                     Log.i(TAG, "NFC, Radio and Bluetooth shutdown complete.");                     break;                 }                 //每间隔500ms，check一次，直到nfc、bluetooth、radio全部关闭或者超时才会退出循环                 SystemClock.sleep(PHONE_STATE_POLL_SLEEP_MSEC);                 delay = endTime - SystemClock.elapsedRealtime();             }         }     };      t.start();     try {         t.join(timeout);     } catch (InterruptedException ex) {     } }

class MountServiceHandler extends Handler {     public void handleMessage(Message msg) {         switch (msg.what) {             case H_SHUTDOWN: {                 final IMountShutdownObserver obs = (IMountShutdownObserver) msg.obj;                 boolean success = false;                 try {                     //向vold发送shutdown命令                     success = mConnector.execute("volume", "shutdown").isClassOk();                 } catch (NativeDaemonConnectorException ignored) {                 }                 if (obs != null) {                     try {                         //回调方法，告知关闭工作已完成                         obs.onShutDownComplete(success ? 0 : -1);                     } catch (RemoteException ignored) {                     }                 }                 break;             }             ...         }     } }

void actionDone() {     synchronized (mActionDoneSync) {         mActionDone = true;         mActionDoneSync.notifyAll();     } }

public static void rebootOrShutdown(final Context context, boolean reboot, String reason) {     if (reboot) {         Log.i(TAG, "Rebooting, reason: " + reason);         //【见小节2.9】         PowerManagerService.lowLevelReboot(reason);         Log.e(TAG, "Reboot failed, will attempt shutdown instead");         reason = null;     } else if (SHUTDOWN_VIBRATE_MS > 0 && context != null) {         ...     }      // Shutdown power     Log.i(TAG, "Performing low-level shutdown...");     PowerManagerService.lowLevelShutdown(reason); }

public static void lowLevelReboot(String reason) {     if (reason == null) {         reason = "";     }     if (reason.equals(PowerManager.REBOOT_RECOVERY)) {         SystemProperties.set("ctl.start", "pre-recovery");     } else {         SystemProperties.set("sys.powerctl", "reboot," + reason);     }     try {         Thread.sleep(20 * 1000L);     } catch (InterruptedException e) {         Thread.currentThread().interrupt();     }     Slog.wtf(TAG, "Unexpected return from lowLevelReboot!"); }

adb shell setprop sys.powerctl reboot