ActivityManagerService启动过程-1
基于Android 6.0的源码
frameworks/base/core/java/android/app/ - ActivityThread.java - LoadedApk.java - ContextImpl.java frameworks/base/services/java/com/android/server/ - SystemServer.java frameworks/base/services/core/java/com/android/server/ - SystemServiceManager.java - ServiceThread.java - pm/Installer.java - am/ActivityManagerService.java
一、概述
本文以AMS为主线，讲述 system_server 进程中 AMS 服务的启动过程，以 startBootstrapServices()方法为起点，紧跟着 startCoreServices(), startOtherServices() 共3个方法。
二、AMS启动过程
2.1 startBootstrapServices
[-> SystemServer.java]
private void startBootstrapServices() { ... //启动AMS服务【见小节2.2】 mActivityManagerService = mSystemServiceManager.startService( ActivityManagerService.Lifecycle.class).getService(); //设置AMS的系统服务管理器 mActivityManagerService.setSystemServiceManager(mSystemServiceManager); //设置AMS的APP安装器 mActivityManagerService.setInstaller(installer); //初始化AMS相关的PMS mActivityManagerService.initPowerManagement(); ... //设置SystemServer【见小节2.3】 mActivityManagerService.setSystemProcess(); }
2.2 启动AMS服务
SystemServiceManager.startService(ActivityManagerService.Lifecycle.class) 功能主要：
(1) 创建 ActivityManagerService.Lifecycle 对象；
(2) 调用 Lifecycle.onStart() 方法。
2.1.1 AMS.Lifecycle
[-> ActivityManagerService.java]
public static final class Lifecycle extends SystemService { private final ActivityManagerService mService; public Lifecycle(Context context) { super(context); //创建ActivityManagerService【见小节2.1.2】 mService = new ActivityManagerService(context); } @Override public void onStart() { mService.start(); //【见小节2.1.3】 } public ActivityManagerService getService() { return mService; } }
该过程：创建AMS内部类的 Lifecycle，已经创建AMS对象，并调用 AMS.start();
2.1.2 AMS创建
public ActivityManagerService(Context systemContext) { mContext = systemContext; mFactoryTest = FactoryTest.getMode();//默认为 FACTORY_TEST_OFF mSystemThread = ActivityThread.currentActivityThread(); //创建名为"ActivityManager"的前台线程，并获取mHandler mHandlerThread = new ServiceThread(TAG, android.os.Process.THREAD_PRIORITY_FOREGROUND, false); mHandlerThread.start(); mHandler = new MainHandler(mHandlerThread.getLooper()); //通过UiThread类，创建名为"android.ui"的线程 mUiHandler = new UiHandler(); //前台广播接收器，在运行超过10s将放弃执行 mFgBroadcastQueue = new BroadcastQueue(this, mHandler, "foreground", BROADCAST_FG_TIMEOUT, false); //后台广播接收器，在运行超过60s将放弃执行 mBgBroadcastQueue = new BroadcastQueue(this, mHandler, "background", BROADCAST_BG_TIMEOUT, true); mBroadcastQueues[0] = mFgBroadcastQueue; mBroadcastQueues[1] = mBgBroadcastQueue; //创建ActiveServices，其中非低内存手机mMaxStartingBackground为8 mServices = new ActiveServices(this); mProviderMap = new ProviderMap(this); //创建目录/data/system File dataDir = Environment.getDataDirectory(); File systemDir = new File(dataDir, "system"); systemDir.mkdirs(); //创建服务BatteryStatsService mBatteryStatsService = new BatteryStatsService(systemDir, mHandler); mBatteryStatsService.getActiveStatistics().readLocked(); ... //创建进程统计服务，信息保存在目录 /data/system/procstats，存在，二进制的文件 ######### mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats")); mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"), mHandler); mGrantFile = new AtomicFile(new File(systemDir, "urigrants.xml")); // User 0是第一个，也是唯一的一个开机过程中运行的用户 mStartedUsers.put(UserHandle.USER_OWNER, new UserState(UserHandle.OWNER, true)); mUserLru.add(UserHandle.USER_OWNER); updateStartedUserArrayLocked(); ... //CPU使用情况的追踪器执行初始化 mProcessCpuTracker.init(); ... mRecentTasks = new RecentTasks(this); //创建ActivityStackSupervisor对象 mStackSupervisor = new ActivityStackSupervisor(this, mRecentTasks); mTaskPersister = new TaskPersister(systemDir, mStackSupervisor, mRecentTasks); //创建名为"CpuTracker"的线程 mProcessCpuThread = new Thread("CpuTracker") { public void run() { while (true) { synchronized(this) { final long now = SystemClock.uptimeMillis(); long nextCpuDelay = (mLastCpuTime.get()+MONITOR_CPU_MAX_TIME)-now; long nextWriteDelay = (mLastWriteTime+BATTERY_STATS_TIME)-now; if (nextWriteDelay < nextCpuDelay) { nextCpuDelay = nextWriteDelay; } if (nextCpuDelay > 0) { mProcessCpuMutexFree.set(true); this.wait(nextCpuDelay); } } updateCpuStatsNow(); //更新CPU状态 } } }; ... }
该过程共创建了3个线程，分别为”ActivityManager”，”android.ui”，”CpuTracker”。
2.1.3 AMS.start
private void start() { Process.removeAllProcessGroups(); //移除所有的进程组 mProcessCpuThread.start(); //启动CpuTracker线程 mBatteryStatsService.publish(mContext); //启动电池统计服务 mAppOpsService.publish(mContext); //创建LocalService，并添加到LocalServices ####### LocalServices.addService(ActivityManagerInternal.class, new LocalService()); }
2.3 AMS.setSystemProcess
public void setSystemProcess() { try { ServiceManager.addService(Context.ACTIVITY_SERVICE, this, true); ServiceManager.addService(ProcessStats.SERVICE_NAME, mProcessStats); ServiceManager.addService("meminfo", new MemBinder(this)); ServiceManager.addService("gfxinfo", new GraphicsBinder(this)); ServiceManager.addService("dbinfo", new DbBinder(this)); if (MONITOR_CPU_USAGE) { ServiceManager.addService("cpuinfo", new CpuBinder(this)); } ServiceManager.addService("permission", new PermissionController(this)); ServiceManager.addService("processinfo", new ProcessInfoService(this)); ApplicationInfo info = mContext.getPackageManager().getApplicationInfo( "android", STOCK_PM_FLAGS); //【见小节2.3.1】 mSystemThread.installSystemApplicationInfo(info, getClass().getClassLoader()); synchronized (this) { //创建ProcessRecord对象 ProcessRecord app = newProcessRecordLocked(info, info.processName, false, 0); app.persistent = true; //设置为persistent进程 app.pid = MY_PID; app.maxAdj = ProcessList.SYSTEM_ADJ; app.makeActive(mSystemThread.getApplicationThread(), mProcessStats); synchronized (mPidsSelfLocked) { mPidsSelfLocked.put(app.pid, app); } updateLruProcessLocked(app, false, null);//维护进程lru updateOomAdjLocked(); //更新adj } } catch (PackageManager.NameNotFoundException e) { throw new RuntimeException("", e); } }
该方法主要工作是注册各种服务。
2.3.1 AT.installSystemApplicationInfo
[-> ActivityThread.java]
public void installSystemApplicationInfo(ApplicationInfo info, ClassLoader classLoader) { synchronized (this) { getSystemContext().installSystemApplicationInfo(info, classLoader); mProfiler = new Profiler(); //创建用于性能统计的Profiler对象 } }
该方法调用 ContextImpl 的 installSystemApplicationInfo() 方法，最终调用 LoadedApk 的 installSystemApplicationInfo，加载名为 “android” 的 package
2.3.2 installSystemApplicationInfo
[-> LoadedApk.java]
void installSystemApplicationInfo(ApplicationInfo info, ClassLoader classLoader) { assert info.packageName.equals("android"); mApplicationInfo = info; //将包名为"android"的应用信息保存到mApplicationInfo mClassLoader = classLoader; }
2.4 startOtherServices
private void startOtherServices() { ... //安装系统Provider 【见小节2.4.1】 mActivityManagerService.installSystemProviders(); ... //phase480 && 500 mSystemServiceManager.startBootPhase(SystemService.PHASE_LOCK_SETTINGS_READY); mSystemServiceManager.startBootPhase(SystemService.PHASE_SYSTEM_SERVICES_READY); ... //【见小节3.1】 mActivityManagerService.systemReady(new Runnable() { public void run() { //phase550 mSystemServiceManager.startBootPhase(SystemService.PHASE_ACTIVITY_MANAGER_READY); ... //phase600 mSystemServiceManager.startBootPhase(SystemService.PHASE_THIRD_PARTY_APPS_CAN_START); ... } } }
2.4.1 AMS.installSystemProviders
public final void installSystemProviders() { List<ProviderInfo> providers; synchronized (this) { ProcessRecord app = mProcessNames.get("system", Process.SYSTEM_UID); providers = generateApplicationProvidersLocked(app); if (providers != null) { for (int i=providers.size()-1; i>=0; i--) { ProviderInfo pi = (ProviderInfo)providers.get(i); //移除非系统的provider if ((pi.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) == 0) { providers.remove(i); } } } } if (providers != null) { //安装所有的系统provider mSystemThread.installSystemProviders(providers); } // 创建核心Settings Observer，用于监控Settings的改变。 mCoreSettingsObserver = new CoreSettingsObserver(this); }
三、AMS.systemReady
AMS.systemReady()方法的参数为 Runable 类型的 goingCallback， 该方法执行简单划分以下几部分：
public void systemReady(final Runnable goingCallback) { before goingCallback; // 见小节[3.1] goingCallback.run(); // 见小节[3.2] after goingCallback; // 见小节[3.3] }
3.1 before goingCallback
synchronized(this) { if (mSystemReady) { //首次为flase，则不进入该分支 if (goingCallback != null) { goingCallback.run(); } return; } mRecentTasks.clear(); //恢复最近任务栏的task mRecentTasks.addAll(mTaskPersister.restoreTasksLocked()); mRecentTasks.cleanupLocked(UserHandle.USER_ALL); mTaskPersister.startPersisting(); if (!mDidUpdate) { if (mWaitingUpdate) { return; } final ArrayList<ComponentName> doneReceivers = new ArrayList<ComponentName>(); //处于升级过程【见小节3.1.1】 mWaitingUpdate = deliverPreBootCompleted(new Runnable() { public void run() { synchronized (ActivityManagerService.this) { mDidUpdate = true; } showBootMessage(mContext.getText( R.string.android_upgrading_complete), false); writeLastDonePreBootReceivers(doneReceivers); systemReady(goingCallback); } }, doneReceivers, UserHandle.USER_OWNER); if (mWaitingUpdate) { return; } mDidUpdate = true; } mAppOpsService.systemReady(); mSystemReady = true; } ArrayList<ProcessRecord> procsToKill = null; synchronized(mPidsSelfLocked) { for (int i=mPidsSelfLocked.size()-1; i>=0; i--) { ProcessRecord proc = mPidsSelfLocked.valueAt(i); //非persistent进程,加入procsToKill if (!isAllowedWhileBooting(proc.info)){ if (procsToKill == null) { procsToKill = new ArrayList<ProcessRecord>(); } procsToKill.add(proc); } } } synchronized(this) { if (procsToKill != null) { //杀掉procsToKill中的进程, 杀掉进程且不允许重启 for (int i=procsToKill.size()-1; i>=0; i--) { ProcessRecord proc = procsToKill.get(i); removeProcessLocked(proc, true, false, "system update done"); } } mProcessesReady = true; //process处于ready状态 } Slog.i(TAG, "System now ready"); EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_AMS_READY, SystemClock.uptimeMillis());
该阶段的主要功能：
(1) 向 PRE_BOOT_COMPLETED 的接收者发送广播；
(2) 杀掉 procsToKill 中的进程, 杀掉进程且不允许重启；
(3) 此时，系统和进程都处于ready状态；
3.1.1 deliverPreBootCompleted
private boolean deliverPreBootCompleted(final Runnable onFinishCallback, ArrayList<ComponentName> doneReceivers, int userId) { Intent intent = new Intent(Intent.ACTION_PRE_BOOT_COMPLETED); List<ResolveInfo> ris = AppGlobals.getPackageManager().queryIntentReceivers(intent, null, 0, userId); //对于FLAG_SYSTEM=false的app直接过滤掉 for (int i=ris.size()-1; i>=0; i--) { if ((ris.get(i).activityInfo.applicationInfo.flags &ApplicationInfo.FLAG_SYSTEM) == 0) { ris.remove(i); } } intent.addFlags(Intent.FLAG_RECEIVER_BOOT_UPGRADE); if (userId == UserHandle.USER_OWNER) { ArrayList<ComponentName> lastDoneReceivers = readLastDonePreBootReceivers(); for (int i=0; i<ris.size(); i++) { ActivityInfo ai = ris.get(i).activityInfo; ComponentName comp = new ComponentName(ai.packageName, ai.name); if (lastDoneReceivers.contains(comp)) { ris.remove(i); i--; doneReceivers.add(comp); } } } ... PreBootContinuation cont = new PreBootContinuation(intent, onFinishCallback, doneReceivers, ris, users); //【见小节3.1.2】 cont.go(); //【见小节3.1.3】 return true; }
3.1.2 PreBootContinuation
[-> ActivityManagerService.java ::PreBootContinuation]
final class PreBootContinuation extends IIntentReceiver.Stub { PreBootContinuation(Intent _intent, Runnable _onFinishCallback, ArrayList<ComponentName> _doneReceivers, List<ResolveInfo> _ris, int[] _users) { intent = _intent; onFinishCallback = _onFinishCallback; doneReceivers = _doneReceivers; ris = _ris; users = _users; } }
3.1.3 PreBootContinuation.go
void go() { if (lastRi != curRi) { ActivityInfo ai = ris.get(curRi).activityInfo; ComponentName comp = new ComponentName(ai.packageName, ai.name); intent.setComponent(comp); doneReceivers.add(comp); lastRi = curRi; CharSequence label = ai.loadLabel(mContext.getPackageManager()); showBootMessage(mContext.getString(R.string.android_preparing_apk, label), false); } //发送广播 broadcastIntentLocked(null, null, intent, null, this, 0, null, null, null, AppOpsManager.OP_NONE, null, true, false, MY_PID, Process.SYSTEM_UID, users[curUser]); }
3.2 goingCallback.run()
此处的goingCallback,便是在startOtherServices()过程中传递进来的参数
private void startOtherServices() { ... mActivityManagerService.systemReady(new Runnable() { public void run() { //phase550 mSystemServiceManager.startBootPhase( SystemService.PHASE_ACTIVITY_MANAGER_READY); mActivityManagerService.startObservingNativeCrashes(); //启动WebView WebViewFactory.prepareWebViewInSystemServer(); //启动系统UI【见小节3.2.1】 startSystemUi(context); // 执行一系列服务的systemReady方法 networkScoreF.systemReady(); networkManagementF.systemReady(); networkStatsF.systemReady(); networkPolicyF.systemReady(); connectivityF.systemReady(); audioServiceF.systemReady(); Watchdog.getInstance().start(); //Watchdog开始工作 //phase600 mSystemServiceManager.startBootPhase( SystemService.PHASE_THIRD_PARTY_APPS_CAN_START); //执行一系列服务的systemRunning方法 wallpaper.systemRunning(); inputMethodManager.systemRunning(statusBarF); location.systemRunning(); countryDetector.systemRunning(); networkTimeUpdater.systemRunning(); commonTimeMgmtService.systemRunning(); textServiceManagerService.systemRunning(); assetAtlasService.systemRunning(); inputManager.systemRunning(); telephonyRegistry.systemRunning(); mediaRouter.systemRunning(); mmsService.systemRunning(); } }); }
该过程启动各种进程：
(1) 启动阶段550，回调相应onBootPhase()方法；
(2) 启动WebView，并且会创建进程，这是zygote正式创建的第一个进程；
(3) 启动systemui服务；
...
3.2.1 startSystemUi
static final void startSystemUi(Context context) { Intent intent = new Intent(); intent.setComponent(new ComponentName("com.android.systemui", "com.android.systemui.SystemUIService")); context.startServiceAsUser(intent, UserHandle.OWNER); }
启动服务”com.android.systemui/.SystemUIService”
3.3 after goingCallback
//启动【见小节3.3.1】 mSystemServiceManager.startUser(mCurrentUserId); synchronized (this) { if (mFactoryTest != FactoryTest.FACTORY_TEST_LOW_LEVEL) { //通过pms获取所有的persistent进程 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")) { //启动persistent进程 addAppLocked(info, false, null); } } } } mBooting = true; // 启动桌面Activity 【见小节3.3.2】 startHomeActivityLocked(mCurrentUserId, "systemReady"); ... long ident = Binder.clearCallingIdentity(); try { //system发送广播USER_STARTED Intent intent = new Intent(Intent.ACTION_USER_STARTED); intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY | Intent.FLAG_RECEIVER_FOREGROUND); intent.putExtra(Intent.EXTRA_USER_HANDLE, mCurrentUserId); broadcastIntentLocked(...); //system发送广播USER_STARTING intent = new Intent(Intent.ACTION_USER_STARTING); intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY); intent.putExtra(Intent.EXTRA_USER_HANDLE, mCurrentUserId); broadcastIntentLocked(...); } finally { Binder.restoreCallingIdentity(ident); } mStackSupervisor.resumeTopActivitiesLocked(); sendUserSwitchBroadcastsLocked(-1, mCurrentUserId); }
该阶段主要功能：
(1) 回调所有 SystemService 的 onStartUser() 方法；
(2) 启动 persistent 进程；
(3) 启动 home Activity;
(4) 发送广播 USER_STARTED 和 USER_STARTING；
(5) 恢复栈顶 Activity;
(6) 发送广播 USER_SWITCHED；
3.3.1 SSM.startUser
[-> SystemServiceManager.java]
public void startUser(final int userHandle) { final int serviceLen = mServices.size(); for (int i = 0; i < serviceLen; i++) { final SystemService service = mServices.get(i); try { //回调所有SystemService的onStartUser()方法 service.onStartUser(userHandle); } catch (Exception ex) { ... } } }
3.3.2 AMS.startHomeActivityLocked
boolean startHomeActivityLocked(int userId, String reason) { //home intent有CATEGORY_HOME Intent intent = getHomeIntent(); ActivityInfo aInfo = resolveActivityInfo(intent, STOCK_PM_FLAGS, userId); if (aInfo != null) { intent.setComponent(new ComponentName(aInfo.applicationInfo.packageName, aInfo.name)); aInfo = new ActivityInfo(aInfo); aInfo.applicationInfo = getAppInfoForUser(aInfo.applicationInfo, userId); ProcessRecord app = getProcessRecordLocked(aInfo.processName, aInfo.applicationInfo.uid, true); if (app == null || app.instrumentationClass == null) { intent.setFlags(intent.getFlags() | Intent.FLAG_ACTIVITY_NEW_TASK); //启动桌面Activity mStackSupervisor.startHomeActivity(intent, aInfo, reason); } } return true; }
四. 总结
1. 创建AMS实例对象，创建 Andoid Runtime，ActivityThread 和 Context 对象；
2. setSystemProcess：注册AMS、meminfo、cpuinfo 等服务到 ServiceManager；
3. installSystemProviderss，加载 SettingsProvider；
4. 启动 SystemUIService，再调用一系列服务的 systemReady()方法；
4.1 发布Binder服务
[小节2.3]的 AMS.setSystemProcess() 过程向 servicemanager 注册了如下这个binder服务
| 服务名 | 类名 | 功能 |
|---|---|---|
| activity | ActivityManagerService | AMS |
| procstats | ProcessStatsService | 进程统计 |
| meminfo | MemBinder | 内存 |
| gfxinfo | GraphicsBinder | 图像信息 |
| dbinfo | DbBinder | 数据库 |
| cpuinfo | CpuBinder | CPU |
| permission | PermissionController | 权限 |
| processinfo | ProcessInfoService | 进程服务 |
| usagestats | UsageStatsService | 应用的使用情况 |
想要查看这些服务的信息，可通过dumpsys <服务名>命令。比如查看CPU信息命令dumpsys cpuinfo。
4.2 AMS.systemReady
另外，AMS.systemReady()的大致过程如下:
public final class ActivityManagerService{ public void systemReady(final Runnable goingCallback) { ...//更新操作 mSystemReady = true; //系统处于ready状态 removeProcessLocked(proc, true, false, "system update done"); //杀掉所有非persistent进程 mProcessesReady = true; //进程处于ready状态 goingCallback.run(); //这里有可能启动进程 addAppLocked(info, false, null); //启动所有的persistent进程 mBooting = true; //正在启动中 startHomeActivityLocked(mCurrentUserId, "systemReady"); //启动桌面 mStackSupervisor.resumeTopActivitiesLocked(); //恢复栈顶的Activity } }
再说一说 mProcessesReady：
startProcessLocked()过程对于非 persistent 进程必须等待 mProcessesReady = true 才会真正创建进程，否则进程放入 mProcessesOnHold 队列。 当然以下情况不会判断 mProcessesReady：
(1) addAppLocked()启动persistent进程; //但此时已经mProcessesReady；
(2) finishBooting()启动on-hold进程; //但此时已经mProcessesReady；
(3) cleanUpApplicationRecordLock() //启动需要restart进程，前提是进程已创建；
(4) attachApplicationLocked() //绑定Bind死亡通告失败，前台同样是进程要已创建。
还有一个特殊情况，可以创建进程：processNextBroadcast()过程对于flag为 FLAG_RECEIVER_BOOT_UPGRADE 的广播拉进程 ，只在小节3.1.1的升级过程会出现。
由此可见，mProcessesReady 在没有ready前，则基本没有应用进程。
参考：
ActivityManagerService启动过程：http://gityuan.com/2016/02/21/activity-manager-service/
posted on 2023-08-14 22:57 Hello-World3 阅读(55) 评论(0) 编辑 收藏 举报
