背景
当 SystemServer 启动的时候，从Zygote进程fork() 出 SystemServer进程，经过初始化后，会通过反射调用 SystemServer.java的 mian()方法，其中会启动一系列系统服务。 AMS 就是其中的一个。
一、缘起 SystemServer 进程
SystemServer 的 main():
/**
* The main entry point from zygote.
*/
public static void main(String[] args) {
new SystemServer().run();
}run()方法:
private void run() {
...
// 1 把当前线程作为主线程，绑定looper
Looper.prepareMainLooper();
Looper.getMainLooper().setSlowLogThresholdMs(
SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS);
SystemServiceRegistry.sEnableServiceNotFoundWtf = true;
// 加载android_servers.so库
System.loadLibrary("android_servers");
// 初始化系统上下文
createSystemContext();
...
// 创建系统服务的管理者
mSystemServiceManager = new SystemServiceManager(mSystemContext);
mSystemServiceManager.setStartInfo(mRuntimeRestart,
mRuntimeStartElapsedTime, mRuntimeStartUptime);
// 加载到本地服务
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
// Prepare the thread pool for init tasks that can be parallelized
SystemServerInitThreadPool.start();
...
// Start services.
//启动服务
try {
t.traceBegin("StartServices");
startBootstrapServices(t);
startCoreServices(t);
startOtherServices(t);
}
...
// 初始化VM的严格模式
StrictMode.initVmDefaults(null);
// Loop forever.
Looper.loop();
throw new RuntimeException("Main thread loop unexpectedly exited");
}- 绑定主线程 looper
- 加载 android_servers.so
- 创建系统上下文 systemContext
- 创建 SystemServerManager
- 启动一系列服务
- 开启loop循环
1.1 createSystemContext()
private void createSystemContext() {
ActivityThread activityThread = ActivityThread.systemMain();
mSystemContext = activityThread.getSystemContext();
mSystemContext.setTheme(DEFAULT_SYSTEM_THEME);
final Context systemUiContext = activityThread.getSystemUiContext();
systemUiContext.setTheme(DEFAULT_SYSTEM_THEME);
}ActivityThread.systemMain() ：
public static ActivityThread systemMain() {
// The system process on low-memory devices do not get to use hardware
// accelerated drawing, since this can add too much overhead to the
// process.
ActivityThread thread = new ActivityThread();
// 这里
thread.attach(true, 0);
return thread;
}重点看 attach() 方法 ：
private void attach(boolean system, long startSeq) {
sCurrentActivityThread = this;
mSystemThread = system;
if (!system) {
...
} else {
// Don't set application object here -- if the system crashes,
// we can't display an alert, we just want to die die die.
android.ddm.DdmHandleAppName.setAppName("system_process",
UserHandle.myUserId());
try {
mInstrumentation = new Instrumentation();
mInstrumentation.basicInit(this);
ContextImpl context = ContextImpl.createAppContext(
this, getSystemContext().mPackageInfo);
// mPackageInfo 为 LoadApk类型 ,注意第二个参数是null！
mInitialApplication = context.mPackageInfo.makeApplication(true, null);
mInitialApplication.onCreate();
} catch (Exception e) {
throw new RuntimeException(
"Unable to instantiate Application():" + e.toString(), e);
}
}- 创建
Instrumentation对象，引导类 - contextIpml.createSystemContext()创建系统上下文 systemContext。
- 根据 mPackageInfo 创建 appContext 对象
- 创建 application 对象，表示这个进程的入口
- 回调 application 的 onCreate()
1.1.1 getSystemContext()
public ContextImpl getSystemContext() {
synchronized (this) {
if (mSystemContext == null) {
mSystemContext = ContextImpl.createSystemContext(this);
}
return mSystemContext;
}
}mSystemContext 在 SystemServer 进程是单例对象。
@UnsupportedAppUsage
static ContextImpl createSystemContext(ActivityThread mainThread) {
LoadedApk packageInfo = new LoadedApk(mainThread);
ContextImpl context = new ContextImpl(null, mainThread, packageInfo, null, null, null, 0,
null, null);
context.setResources(packageInfo.getResources());
context.mResources.updateConfiguration(context.mResourcesManager.getConfiguration(),
context.mResourcesManager.getDisplayMetrics());
return context;
}-
new LoadedApk对象，传入的 systemServer 的 ActivityThread 对象，得到packageInfo,包含系统apk包的所有信息。 -
new ContextImpl对象，把packageInfo传入，得到systemContext。 - 设置资源、更新配置
1.1.2 ContextImpl.createAppContext()
static ContextImpl createAppContext(ActivityThread mainThread, LoadedApk packageInfo, // 是mSystemContext中 packageInfo： loadApk
String opPackageName) {
if (packageInfo == null) throw new IllegalArgumentException("packageInfo");
ContextImpl context = new ContextImpl(null, mainThread, packageInfo, null, null, null, 0,
null, opPackageName);
context.setResources(packageInfo.getResources());
return context;
}- 根据之前创建的
loadedApk类型的packageInfo，创建一个新的ContextImpl对象。 - 设置资源
到这里，systemServer 进程得到了两个 ContextImpl 对象。
- 一个是
systemContextsystemServer自己使用 - 一个是
appContext
1.1.3 makeApplication()
public Application makeApplication(boolean forceDefaultAppClass,
Instrumentation instrumentation) {
// 只创建一次
if (mApplication != null) {
return mApplication;
}
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "makeApplication");
Application app = null;
String appClass = mApplicationInfo.className;
// appclass如果为空，则赋值为 android.app.Application
if (forceDefaultAppClass || (appClass == null)) {
appClass = "android.app.Application";
}
try {
// 获得classloader
java.lang.ClassLoader cl = getClassLoader();
if (!mPackageName.equals("android")) {
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER,
"initializeJavaContextClassLoader");
initializeJavaContextClassLoader();
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}
// 再次创建一个contextImpl 对象，
ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this);
// 内部通过反射，创建 application 对象
app = mActivityThread.mInstrumentation.newApplication(
cl, appClass, appContext);
//
appContext.setOuterContext(app);
} catch (Exception e) {
if (!mActivityThread.mInstrumentation.onException(app, e)) {
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
throw new RuntimeException(
"Unable to instantiate application " + appClass
+ ": " + e.toString(), e);
}
}
mActivityThread.mAllApplications.add(app);
mApplication = app;
// 这里不会被调用，因为传入的是null
if (instrumentation != null) {
try {
instrumentation.callApplicationOnCreate(app);
} catch (Exception e) {
if (!instrumentation.onException(app, e)) {
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
throw new RuntimeException(
"Unable to create application " + app.getClass().getName()
+ ": " + e.toString(), e);
}
}
}
// Rewrite the R 'constants' for all library apks.
SparseArray<String> packageIdentifiers = getAssets().getAssignedPackageIdentifiers();
final int N = packageIdentifiers.size();
for (int i = 0; i < N; i++) {
final int id = packageIdentifiers.keyAt(i);
if (id == 0x01 || id == 0x7f) {
continue;
}
rewriteRValues(getClassLoader(), packageIdentifiers.valueAt(i), id);
}
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
return app;
}- 内部通过反射创建出
application对象 - 调用 setOuterContext()
继续看 mInstrumentation 的 newApplication() 方法：
1.1.4 newApplication()
public Application newApplication(ClassLoader cl, String className, Context context)
throws InstantiationException, IllegalAccessException,
ClassNotFoundException {
Application app = getFactory(context.getPackageName())
.instantiateApplication(cl, className);
// 调用 aatch方法
app.attach(context);
return app;
}1.1.5 instantiateApplication()
public @NonNull Application instantiateApplication(@NonNull ClassLoader cl,
@NonNull String className)
throws InstantiationException, IllegalAccessException, ClassNotFoundException {
// classloader 加载类对象，反射创建实例对象
return (Application) cl.loadClass(className).newInstance();
}classloader 加载类对象，反射创建实例对象 Application 。
1.1.6 attach()
Application类中：
@UnsupportedAppUsage
/* package */ final void attach(Context context) {
attachBaseContext(context);
mLoadedApk = ContextImpl.getImpl(context).mPackageInfo;
}protected void attachBaseContext(Context base) {
if (mBase != null) {
throw new IllegalStateException("Base context already set");
}
mBase = base;
}至此，systemServer 进程有了三个 contextImpl 对象：
- systemContext
- appContext
- Application 中的mBase contextImpl对象
Application 是继承 contextWraaper 的。contextWraper 又是继承 context 的，因此，Application 想要能够调用 contextImpl 的方法，则必须要要通过 attachBaseContext() 外部设置一个，真正做事的是 contextImpl。
1.1.7 callApplicationOnCreate
public void callApplicationOnCreate(Application app) {
app.onCreate();
}这里会调用 application 的 onCreate 方法。
二、 创建 SystemServerManager
在 systemServer的 run 方法中：
// Create the system service manager.
//构造对象， 传入 systemContext
mSystemServiceManager = new SystemServiceManager(mSystemContext);
mSystemServiceManager.setStartInfo(mRuntimeRestart,
mRuntimeStartElapsedTime, mRuntimeStartUptime);
// 注册到本地服务
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);构造对象， 传入 systemContext。
LocalServices 功能类似于 SM，但是存入的不是Binder对象。全局存储的对象，更偏向于给本进程使用。
三、startBootstrapServices()
private void startBootstrapServices(@NonNull TimingsTraceAndSlog t) {
...
// 1 启动 Installer service 用来安装apk
Installer installer = mSystemServiceManager.startService(Installer.class);
...
// Activity manager runs the show. Activity的管理类，开始初始化
// TODO: Might need to move after migration to WM.
// 2 启动一个 ActivityTaskManagerService
ActivityTaskManagerService atm = mSystemServiceManager.startService(
ActivityTaskManagerService.Lifecycle.class).getService();
//3， 启动 AMS
mActivityManagerService = ActivityManagerService.Lifecycle.startService(
mSystemServiceManager, atm);
mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
//设置installer
mActivityManagerService.setInstaller(installer);
...
// 4 注册服务
mActivityManagerService.setSystemProcess();3.1 Installer 服务
// 继承了 SystemService
public class Installer extends SystemService继承了 SystemService。
1 启动 Installer service
Installer installer = mSystemServiceManager.startService(Installer.class);因为 Installer 是直接继承 systemService 的，因此内部通过反射直接构造对象，注册到内部 mServices 列表中。接着回调 onStart() 方法。
@Override
public void onStart() {
if (mIsolated) {
mInstalld = null;
} else {
// 开始从SM中获取已注册的服务
connect();
}
}
private void connect() {
IBinder binder = ServiceManager.getService("installd");
if (binder != null) {
try {
// 如果binder服务已存在，则注册死亡通知，再次连接
binder.linkToDeath(new DeathRecipient() {
@Override
public void binderDied() {
Slog.w(TAG, "installd died; reconnecting");
connect();
}
}, 0);
} catch (RemoteException e) {
binder = null;
}
}
if (binder != null) {
//mInstalld 转成本地代理服务对象
mInstalld = IInstalld.Stub.asInterface(binder);
try {
//
invalidateMounts();
} catch (InstallerException ignored) {
}
} else {
Slog.w(TAG, "installd not found; trying again");
BackgroundThread.getHandler().postDelayed(() -> {
connect();
}, DateUtils.SECOND_IN_MILLIS);// 如果还未注册，则每隔1s 在检测一次
}
}总结：
从 IInstalled 接口 可以看出，提供了 createAppData、clearAppData、getAppSize、dexopt、destroyUserData等等功能。 在启动其他服务之前我们需要 Installed 服务去创建关键性的目录，如 /data/user。
interface IInstalld {
21 void createUserData(@nullable @utf8InCpp String uuid, int userId, int userSerial, int flags);
22 void destroyUserData(@nullable @utf8InCpp String uuid, int userId, int flags);
23
24 long createAppData(@nullable @utf8InCpp String uuid, in @utf8InCpp String packageName,
25 int userId, int flags, int appId, in @utf8InCpp String seInfo, int targetSdkVersion);
26 void restoreconAppData(@nullable @utf8InCpp String uuid, @utf8InCpp String packageName,
27 int userId, int flags, int appId, @utf8InCpp String seInfo);
28 void migrateAppData(@nullable @utf8InCpp String uuid, @utf8InCpp String packageName,
29 int userId, int flags);
30 void clearAppData(@nullable @utf8InCpp String uuid, @utf8InCpp String packageName,
31 int userId, int flags, long ceDataInode);
32 void destroyAppData(@nullable @utf8InCpp String uuid, @utf8InCpp String packageName,
33 int userId, int flags, long ceDataInode);
34
35 void fixupAppData(@nullable @utf8InCpp String uuid, int flags);
36
37 long[] getAppSize(@nullable @utf8InCpp String uuid, in @utf8InCpp String[] packageNames,
38 int userId, int flags, int appId, in long[] ceDataInodes,
39 in @utf8InCpp String[] codePaths);
40 long[] getUserSize(@nullable @utf8InCpp String uuid, int userId, int flags, in int[] appIds);
41 long[] getExternalSize(@nullable @utf8InCpp String uuid, int userId, int flags, in int[] appIds);
42
43 void setAppQuota(@nullable @utf8InCpp String uuid, int userId, int appId, long cacheQuota);
44
45 void moveCompleteApp(@nullable @utf8InCpp String fromUuid, @nullable @utf8InCpp String toUuid,
46 @utf8InCpp String packageName, @utf8InCpp String dataAppName, int appId,
47 @utf8InCpp String seInfo, int targetSdkVersion);
48
49 void dexopt(@utf8InCpp String apkPath, int uid, @nullable @utf8InCpp String packageName,
50 @utf8InCpp String instructionSet, int dexoptNeeded,
51 @nullable @utf8InCpp String outputPath, int dexFlags,
52 @utf8InCpp String compilerFilter, @nullable @utf8InCpp String uuid,
53 @nullable @utf8InCpp String sharedLibraries,
54 @nullable @utf8InCpp String seInfo, boolean downgrade, int targetSdkVersion,
55 @nullable @utf8InCpp String profileName,
56 @nullable @utf8InCpp String dexMetadataPath,
57 @nullable @utf8InCpp String compilationReason);
58 boolean compileLayouts(@utf8InCpp String apkPath, @utf8InCpp String packageName,
59 @utf8InCpp String outDexFile, int uid);
60
61 void rmdex(@utf8InCpp String codePath, @utf8InCpp String instructionSet);
62
63 boolean mergeProfiles(int uid, @utf8InCpp String packageName, @utf8InCpp String profileName);
64 boolean dumpProfiles(int uid, @utf8InCpp String packageName, @utf8InCpp String profileName,
65 @utf8InCpp String codePath);
66 boolean copySystemProfile(@utf8InCpp String systemProfile, int uid,
67 @utf8InCpp String packageName, @utf8InCpp String profileName);
68 void clearAppProfiles(@utf8InCpp String packageName, @utf8InCpp String profileName);
69 void destroyAppProfiles(@utf8InCpp String packageName);
70
71 boolean createProfileSnapshot(int appId, @utf8InCpp String packageName,
72 @utf8InCpp String profileName, @utf8InCpp String classpath);
73 void destroyProfileSnapshot(@utf8InCpp String packageName, @utf8InCpp String profileName);
74
75 void idmap(@utf8InCpp String targetApkPath, @utf8InCpp String overlayApkPath, int uid);
76 void removeIdmap(@utf8InCpp String overlayApkPath);
77 void rmPackageDir(@utf8InCpp String packageDir);
78 void markBootComplete(@utf8InCpp String instructionSet);
79 void freeCache(@nullable @utf8InCpp String uuid, long targetFreeBytes,
80 long cacheReservedBytes, int flags);
81 void linkNativeLibraryDirectory(@nullable @utf8InCpp String uuid,
82 @utf8InCpp String packageName, @utf8InCpp String nativeLibPath32, int userId);
83 void createOatDir(@utf8InCpp String oatDir, @utf8InCpp String instructionSet);
84 void linkFile(@utf8InCpp String relativePath, @utf8InCpp String fromBase,
85 @utf8InCpp String toBase);
86 void moveAb(@utf8InCpp String apkPath, @utf8InCpp String instructionSet,
87 @utf8InCpp String outputPath);
88 void deleteOdex(@utf8InCpp String apkPath, @utf8InCpp String instructionSet,
89 @nullable @utf8InCpp String outputPath);
90 void installApkVerity(@utf8InCpp String filePath, in FileDescriptor verityInput,
91 int contentSize);
92 void assertFsverityRootHashMatches(@utf8InCpp String filePath, in byte[] expectedHash);
93
94 boolean reconcileSecondaryDexFile(@utf8InCpp String dexPath, @utf8InCpp String pkgName,
95 int uid, in @utf8InCpp String[] isas, @nullable @utf8InCpp String volume_uuid,
96 int storage_flag);
97
98 byte[] hashSecondaryDexFile(@utf8InCpp String dexPath, @utf8InCpp String pkgName,
99 int uid, @nullable @utf8InCpp String volumeUuid, int storageFlag);
100
101 void invalidateMounts();
102 boolean isQuotaSupported(@nullable @utf8InCpp String uuid);
103
104 boolean prepareAppProfile(@utf8InCpp String packageName,
105 int userId, int appId, @utf8InCpp String profileName, @utf8InCpp String codePath,
106 @nullable @utf8InCpp String dexMetadata);
107
108 long snapshotAppData(@nullable @utf8InCpp String uuid, in @utf8InCpp String packageName,
109 int userId, int snapshotId, int storageFlags);
110 void restoreAppDataSnapshot(@nullable @utf8InCpp String uuid, in @utf8InCpp String packageName,
111 int appId, @utf8InCpp String seInfo, int user, int snapshotId, int storageflags);
112 void destroyAppDataSnapshot(@nullable @utf8InCpp String uuid, @utf8InCpp String packageName,
113 int userId, long ceSnapshotInode, int snapshotId, int storageFlags);
114
115 void migrateLegacyObbData();
116
117 const int FLAG_STORAGE_DE = 0x1;
118 const int FLAG_STORAGE_CE = 0x2;
119 const int FLAG_STORAGE_EXTERNAL = 0x4;
120
121 const int FLAG_CLEAR_CACHE_ONLY = 0x10;
122 const int FLAG_CLEAR_CODE_CACHE_ONLY = 0x20;
123
124 const int FLAG_FREE_CACHE_V2 = 0x100;
125 const int FLAG_FREE_CACHE_V2_DEFY_QUOTA = 0x200;
126 const int FLAG_FREE_CACHE_NOOP = 0x400;
127
128 const int FLAG_USE_QUOTA = 0x1000;
129 const int FLAG_FORCE = 0x2000;
130 }
1313.2 ActivityTaskManagerService
Android 10 把 activities管理、启动相关的逻辑拆解到了 atm 中。
ActivityTaskManagerService atm = mSystemServiceManager.startService(
ActivityTaskManagerService.Lifecycle.class).getService();内部通过静态内部类 LifeCycle(继承了systemServer) 来管理 atm的生命周期。
3.2.1 atm 构造方法
public ActivityTaskManagerService(Context context) {
mContext = context;
mFactoryTest = FactoryTest.getMode();
mSystemThread = ActivityThread.currentActivityThread(); //获取当前进程的ActivityThread对象
mUiContext = mSystemThread.getSystemUiContext(); // systemUiContext，包含资源
mLifecycleManager = new ClientLifecycleManager();// 重点：生命周期管理类。activity 就是在这里被管理的
mInternal = new LocalService(); //是atm的内部类，继承ActivityTaskManagerInternal类，类似于本地服务。
GL_ES_VERSION = SystemProperties.getInt("ro.opengles.version", GL_ES_VERSION_UNDEFINED);
}- 创建了
UIContext对象 systemServer 进程有四个contextImpl - 创建
ClientLifecycleManager对象，管理activities生命周期 - 创建
mInternallocalService对象，后续的启动 homeActivity就调用了 mInternal的方法。
3.2.2 atm 的 onStart()
Lifecycle 类：
@Override
public void onStart() {
// 往SM中注册 服务
publishBinderService(Context.ACTIVITY_TASK_SERVICE, mService);
// 往本地注册 服务
mService.start();
}protected final void publishBinderService(String name, IBinder service,
235 boolean allowIsolated, int dumpPriority) {
236 ServiceManager.addService(name, service, allowIsolated, dumpPriority);
237 }
238往 SM 中注册 binder 服务。
private void start() {
//class类型， mInternal： localService。
LocalServices.addService(ActivityTaskManagerInternal.class, mInternal);
}LocalServices： 类似于SM的功能。不过这里注册的不是Binder对象，并且只能在同一个进程中使用。
3.2.3 atm 的 initialize()
后续 AMS 的构造方法中会调用：
public void initialize(IntentFirewall intentFirewall, PendingIntentController intentController,
Looper looper) {
// looper : DisplayThread的loop
mH = new H(looper);
// 创建uihandle ，会创建 UiThread 线程，绑定loop
mUiHandler = new UiHandler();
mIntentFirewall = intentFirewall;
final File systemDir = SystemServiceManager.ensureSystemDir();
mAppWarnings = new AppWarnings(this, mUiContext, mH, mUiHandler, systemDir);
mCompatModePackages = new CompatModePackages(this, systemDir, mH);
mPendingIntentController = intentController;
mTempConfig.setToDefaults();
mTempConfig.setLocales(LocaleList.getDefault());
mConfigurationSeq = mTempConfig.seq = 1;
// 1 创建 ActivityStackSupervisor 对象 ,Activity栈的超级管理
mStackSupervisor = createStackSupervisor();
//暂时过渡的类，目的是与RootWindowContainer.java 关联起来
mRootActivityContainer = new RootActivityContainer(this);
mRootActivityContainer.onConfigurationChanged(mTempConfig);
mTaskChangeNotificationController =
new TaskChangeNotificationController(mGlobalLock, mStackSupervisor, mH);
mLockTaskController = new LockTaskController(mContext, mStackSupervisor, mH);
mActivityStartController = new ActivityStartController(this);
mRecentTasks = createRecentTasks();
//2 设置最近的任务栈
mStackSupervisor.setRecentTasks(mRecentTasks);
mVrController = new VrController(mGlobalLock);
mKeyguardController = mStackSupervisor.getKeyguardController();
}- 创建了
UIThread线程 - 创建了
ActivityStackSupervisor: Activity栈的管理类
ActivityStackSupervisor:
protected ActivityStackSupervisor createStackSupervisor() {
final ActivityStackSupervisor supervisor = new ActivityStackSupervisor(this, mH.getLooper());
supervisor.initialize();
return supervisor;
}前期准备工作基本完成，现在可以真正启动 AMS 了。
四、创建 AMS
mActivityManagerService = ActivityManagerService.Lifecycle.startService(
mSystemServiceManager, atm);
mActivityManagerService.setSystemServiceManager(mSystemServiceManager); //设置
installer mActivityManagerService.setInstaller(installer); ... // 4 注册服务
mActivityManagerService.setSystemProcess();内部会通过 LifeCycle 静态内部类来完成生命周期管理。
4.1 AMS.LifeCycle
public static final class Lifecycle extends SystemService {
private final ActivityTaskManagerService mService;
public Lifecycle(Context context) {
super(context);
mService = new ActivityTaskManagerService(context);
}
@Override
public void onStart() {
publishBinderService(Context.ACTIVITY_TASK_SERVICE, mService);
mService.start();
}
@Override
public void onUnlockUser(int userId) {
synchronized (mService.getGlobalLock()) {
mService.mStackSupervisor.onUserUnlocked(userId);
}
}
@Override
public void onCleanupUser(int userId) {
synchronized (mService.getGlobalLock()) {
mService.mStackSupervisor.mLaunchParamsPersister.onCleanupUser(userId);
}
}
public ActivityTaskManagerService getService() {
return mService;
}
}- 通过反射构造 LifeCycle 对象。构造方法中再
创建 AMS对象。 - 回调
onStart()方法
4.2 AMS 构造方法
public ActivityManagerService(Context systemContext, ActivityTaskManagerService atm) {
LockGuard.installLock(this, LockGuard.INDEX_ACTIVITY);
mInjector = new Injector();
mContext = systemContext;
mFactoryTest = FactoryTest.getMode();
mSystemThread = ActivityThread.currentActivityThread();
mUiContext = mSystemThread.getSystemUiContext();
Slog.i(TAG, "Memory class: " + ActivityManager.staticGetMemoryClass());
// 创建一个前台线程 ,作为主线程
mHandlerThread = new ServiceThread(TAG,
THREAD_PRIORITY_FOREGROUND, false /*allowIo*/);
mHandlerThread.start();
mHandler = new MainHandler(mHandlerThread.getLooper());
//mUiHandler 用来通知activities的生命周期
mUiHandler = mInjector.getUiHandler(this);
// 新建一个前台线程 procStart
mProcStartHandlerThread = new ServiceThread(TAG + ":procStart",
THREAD_PRIORITY_FOREGROUND, false /* allowIo */);
mProcStartHandlerThread.start();
mProcStartHandler = new Handler(mProcStartHandlerThread.getLooper());
mConstants = new ActivityManagerConstants(mContext, this, mHandler);
final ActiveUids activeUids = new ActiveUids(this, true /* postChangesToAtm */);
mProcessList.init(this, activeUids);
mLowMemDetector = new LowMemDetector(this);
mOomAdjuster = new OomAdjuster(this, mProcessList, activeUids);
// Broadcast policy parameters
final BroadcastConstants foreConstants = new BroadcastConstants(
Settings.Global.BROADCAST_FG_CONSTANTS);
foreConstants.TIMEOUT = BROADCAST_FG_TIMEOUT; //10s
final BroadcastConstants backConstants = new BroadcastConstants(
Settings.Global.BROADCAST_BG_CONSTANTS);
backConstants.TIMEOUT = BROADCAST_BG_TIMEOUT; //60s超时
final BroadcastConstants offloadConstants = new BroadcastConstants(
Settings.Global.BROADCAST_OFFLOAD_CONSTANTS);
offloadConstants.TIMEOUT = BROADCAST_BG_TIMEOUT; //60s超时
// by default, no "slow" policy in this queue
offloadConstants.SLOW_TIME = Integer.MAX_VALUE;
mEnableOffloadQueue = SystemProperties.getBoolean(
"persist.device_config.activity_manager_native_boot.offload_queue_enabled", false);
//前台广播队列 处理超时时长是 10s
mFgBroadcastQueue = new BroadcastQueue(this, mHandler,
"foreground", foreConstants, false);
//后台广播队列 处理超时时长是 60s
mBgBroadcastQueue = new BroadcastQueue(this, mHandler,
"background", backConstants, true);
//分流广播队列 处理超时时长是 60s
mOffloadBroadcastQueue = new BroadcastQueue(this, mHandler,
"offload", offloadConstants, true);
mBroadcastQueues[0] = mFgBroadcastQueue;
mBroadcastQueues[1] = mBgBroadcastQueue;
mBroadcastQueues[2] = mOffloadBroadcastQueue;
// 四大组件的 service，管理 ServiceRecord
mServices = new ActiveServices(this);
// 四大组件 管理 ContentProviderRecord 对象
mProviderMap = new ProviderMap(this);
mPackageWatchdog = PackageWatchdog.getInstance(mUiContext);
mAppErrors = new AppErrors(mUiContext, this, mPackageWatchdog);
final File systemDir = SystemServiceManager.ensureSystemDir();
// TODO: Move creation of battery stats service outside of activity manager service.
mBatteryStatsService = new BatteryStatsService(systemContext, systemDir,
BackgroundThread.get().getHandler());
mBatteryStatsService.getActiveStatistics().readLocked();
mBatteryStatsService.scheduleWriteToDisk();
mOnBattery = DEBUG_POWER ? true
: mBatteryStatsService.getActiveStatistics().getIsOnBattery();
mBatteryStatsService.getActiveStatistics().setCallback(this);
mOomAdjProfiler.batteryPowerChanged(mOnBattery);
// 系统所有进程统计信息
mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));
mAppOpsService = mInjector.getAppOpsService(new File(systemDir, "appops.xml"), mHandler);
mUgmInternal = LocalServices.getService(UriGrantsManagerInternal.class);
mUserController = new UserController(this);
mPendingIntentController = new PendingIntentController(
mHandlerThread.getLooper(), mUserController);
if (SystemProperties.getInt("sys.use_fifo_ui", 0) != 0) {
mUseFifoUiScheduling = true;
}
mTrackingAssociations = "1".equals(SystemProperties.get("debug.track-associations"));
mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler);
mActivityTaskManager = atm;
// 调用initialize ，内部创建UIthread、stackSuperVisor等
mActivityTaskManager.initialize(mIntentFirewall, mPendingIntentController,
DisplayThread.get().getLooper());
mAtmInternal = LocalServices.getService(ActivityTaskManagerInternal.class);
// cpu使用runtime 收集线程
mProcessCpuThread = new Thread("CpuTracker") {
@Override
public void run() {
synchronized (mProcessCpuTracker) {
mProcessCpuInitLatch.countDown();
mProcessCpuTracker.init();
}
while (true) {
try {
try {
synchronized(this) {
final long now = SystemClock.uptimeMillis();
long nextCpuDelay = (mLastCpuTime.get()+MONITOR_CPU_MAX_TIME)-now;
long nextWriteDelay = (mLastWriteTime+BATTERY_STATS_TIME)-now;
//Slog.i(TAG, "Cpu delay=" + nextCpuDelay
// + ", write delay=" + nextWriteDelay);
if (nextWriteDelay < nextCpuDelay) {
nextCpuDelay = nextWriteDelay;
}
if (nextCpuDelay > 0) {
mProcessCpuMutexFree.set(true);
this.wait(nextCpuDelay); //释放CPU
}
}
} catch (InterruptedException e) {
}
updateCpuStatsNow();
} catch (Exception e) {
Slog.e(TAG, "Unexpected exception collecting process stats", e);
}
}
}
};
mHiddenApiBlacklist = new HiddenApiSettings(mHandler, mContext);
Watchdog.getInstance().addMonitor(this);
Watchdog.getInstance().addThread(mHandler);
// bind background threads to little cores
// this is expected to fail inside of framework tests because apps can't touch cpusets directly
// make sure we've already adjusted system_server's internal view of itself first
updateOomAdjLocked(OomAdjuster.OOM_ADJ_REASON_NONE);
try {
Process.setThreadGroupAndCpuset(BackgroundThread.get().getThreadId(),
Process.THREAD_GROUP_SYSTEM);
Process.setThreadGroupAndCpuset(
mOomAdjuster.mAppCompact.mCompactionThread.getThreadId(),
Process.THREAD_GROUP_SYSTEM);
} catch (Exception e) {
Slog.w(TAG, "Setting background thread cpuset failed");
}
}-
activities管理基本交给了atm。 -
service、contentProvider、broadcast则在 AMS 内部进行管理。 - 此外还会检测
CPU的使用情况、统计系统中所以进程的占用信息。
4.3 AMS start()
private void start() {
// 移除所有进程组
removeAllProcessGroups();
// 开启CPU使用 监控线程
mProcessCpuThread.start();
// 注册 电池服务到SM 和 localServices
mBatteryStatsService.publish();
mAppOpsService.publish(mContext);
Slog.d("AppOps", "AppOpsService published");
// 通知atm ActivityManagerInternal已加
LocalServices.addService(ActivityManagerInternal.class, new LocalService());
mActivityTaskManager.onActivityManagerInternalAdded();
mUgmInternal.onActivityManagerInternalAdded();
mPendingIntentController.onActivityManagerInternalAdded();
// Wait for the synchronized block started in mProcessCpuThread,
// so that any other access to mProcessCpuTracker from main thread
// will be blocked during mProcessCpuTracker initialization.
try {
mProcessCpuInitLatch.await();
} catch (InterruptedException e) {
Slog.wtf(TAG, "Interrupted wait during start", e);
Thread.currentThread().interrupt();
throw new IllegalStateException("Interrupted wait during start");
}
}- 开启CPU使用 监控线程
4.4 setSystemProcess()
在 startOtherServices()方法中会 调用 AMS 的setSystemProcess():
private void startOtherServices() {
...
Set up the Application instance for the system process and get started.
mActivityManagerService.setSystemProcess();
...
}为system 进程初始化appclication 对象。
public void setSystemProcess() {
try {
// 注册AMS
ServiceManager.addService(Context.ACTIVITY_SERVICE, this, /* allowIsolated= */ true,
DUMP_FLAG_PRIORITY_CRITICAL | DUMP_FLAG_PRIORITY_NORMAL | DUMP_FLAG_PROTO);
// 注册 ProcessStats 进程统计服务 IProcessStats
ServiceManager.addService(ProcessStats.SERVICE_NAME, mProcessStats);
// 注册 内存信息服务
ServiceManager.addService("meminfo", new MemBinder(this), /* allowIsolated= */ false,
DUMP_FLAG_PRIORITY_HIGH);
// 注册 图形相关服务
ServiceManager.addService("gfxinfo", new GraphicsBinder(this));
// 数据库服务
ServiceManager.addService("dbinfo", new DbBinder(this));
if (MONITOR_CPU_USAGE) {
ServiceManager.addService("cpuinfo", new CpuBinder(this),
/* allowIsolated= */ false, DUMP_FLAG_PRIORITY_CRITICAL);
}
// 注册 权限服务
ServiceManager.addService("permission", new PermissionController(this));
// 注册 processinfo 进程信息服务 IProcessInfoService
ServiceManager.addService("processinfo", new ProcessInfoService(this));
// systemServer进程的 application
ApplicationInfo info = mContext.getPackageManager().getApplicationInfo(
"android", STOCK_PM_FLAGS | MATCH_SYSTEM_ONLY);
mSystemThread.installSystemApplicationInfo(info, getClass().getClassLoader());
synchronized (this) {
ProcessRecord app = mProcessList.newProcessRecordLocked(info, info.processName,
false,
0,
new HostingRecord("system"));
app.setPersistent(true);
app.pid = MY_PID;
app.getWindowProcessController().setPid(MY_PID);
app.maxAdj = ProcessList.SYSTEM_ADJ;
app.makeActive(mSystemThread.getApplicationThread(), mProcessStats);
mPidsSelfLocked.put(app);
mProcessList.updateLruProcessLocked(app, false, null);
updateOomAdjLocked(OomAdjuster.OOM_ADJ_REASON_NONE);
}
} catch (PackageManager.NameNotFoundException e) {
throw new RuntimeException(
"Unable to find android system package", e);
}
// Start watching app ops after we and the package manager are up and running.
mAppOpsService.startWatchingMode(AppOpsManager.OP_RUN_IN_BACKGROUND, null,
new IAppOpsCallback.Stub() {
@Override public void opChanged(int op, int uid, String packageName) {
if (op == AppOpsManager.OP_RUN_IN_BACKGROUND && packageName != null) {
if (mAppOpsService.checkOperation(op, uid, packageName)
!= AppOpsManager.MODE_ALLOWED) {
runInBackgroundDisabled(uid);
}
}
}
});
}- 注册各种Binder服务：
ams、meminfo、 gfxinfo等 - 通过解析
framework-res.apk里的AndroidManifest.xml获得ApplicationInfo - 为ActivityThread 安装system appInfo信息。最终把
ApplicationInfo安装到loadedApk中的mApplicationInfo。 - 新建
systemServer的进程对象processRecord,用来维护进程信息 - 开始监管
app的操作
4.4 AMS systemReady()
在 systemServer 的 startOtherServices()的最后，会调用 AMS 的 systemReady()。表示Android系统已准备好了。内部主要做了三个阶段的工作：
- 杀掉在AMS启动前的非常驻进程
- 执行goingcallback
- 启动homeActivity
4.4.1 阶段一
public void systemReady(final Runnable goingCallback, TimingsTraceLog traceLog) {
traceLog.traceBegin("PhaseActivityManagerReady");
synchronized(this) {
//1 如果已经ready，则直接运行goingcallback
if (mSystemReady) {
// If we're done calling all the receivers, run the next "boot phase" passed in
// by the SystemServer
if (goingCallback != null) {
goingCallback.run();
}
return;
}
mLocalDeviceIdleController
= LocalServices.getService(DeviceIdleController.LocalService.class);
//2 调用一系列服务的 onSystemReady()
mActivityTaskManager.onSystemReady();
// Make sure we have the current profile info, since it is needed for security checks.
mUserController.onSystemReady();
mAppOpsService.systemReady();
mSystemReady = true; // 修改ready状态
}
try {
sTheRealBuildSerial = IDeviceIdentifiersPolicyService.Stub.asInterface(
ServiceManager.getService(Context.DEVICE_IDENTIFIERS_SERVICE))
.getSerial();
} catch (RemoteException e) {}
ArrayList<ProcessRecord> procsToKill = null; // 准备要杀死的进程列表
synchronized(mPidsSelfLocked) {
//3 mPidsSelfLocked 保存了所以运行中的进程
for (int i=mPidsSelfLocked.size()-1; i>=0; i--) {
ProcessRecord proc = mPidsSelfLocked.valueAt(i);
// 在AMS启动完成前，且info.flag!=FLAG_PERSISTENT, 则加入到被杀的列表中
if (!isAllowedWhileBooting(proc.info)){
if (procsToKill == null) {
procsToKill = new ArrayList<ProcessRecord>();
}
procsToKill.add(proc);
}
}
}
// 杀掉列表中的进程
synchronized(this) {
if (procsToKill != null) {
for (int i=procsToKill.size()-1; i>=0; i--) {
ProcessRecord proc = procsToKill.get(i);
Slog.i(TAG, "Removing system update proc: " + proc);
mProcessList.removeProcessLocked(proc, true, false, "system update done");
}
}
// Now that we have cleaned up any update processes, we
// are ready to start launching real processes and know that
// we won't trample on them any more.
// 至此，system 进程启动完毕
mProcessesReady = true;
}
Slog.i(TAG, "System now ready");
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_AMS_READY, SystemClock.uptimeMillis());
mAtmInternal.updateTopComponentForFactoryTest();
mAtmInternal.getLaunchObserverRegistry().registerLaunchObserver(mActivityLaunchObserver);
watchDeviceProvisioning(mContext);
retrieveSettings();
mUgmInternal.onSystemReady();
final PowerManagerInternal pmi = LocalServices.getService(PowerManagerInternal.class);
if (pmi != null) {
pmi.registerLowPowerModeObserver(ServiceType.FORCE_BACKGROUND_CHECK,
state -> updateForceBackgroundCheck(state.batterySaverEnabled));
updateForceBackgroundCheck(
pmi.getLowPowerState(ServiceType.FORCE_BACKGROUND_CHECK).batterySaverEnabled);
} else {
Slog.wtf(TAG, "PowerManagerInternal not found.");
}
//阶段二: 运行 systemServer传递过来的 callback。用来通知外部服务systemReady 工作，并启动服务或者应用进程。
if (goingCallback != null) goingCallback.run();
//... 阶段三
}- 调用一系列服务的
onSystemReady() - 杀掉 AMS 前启动的非常驻进程 ，设置 mProcessesReady = true;
4.4.2 阶段二
执行 goingCallback.run()：
// We now tell the activity manager it is okay to run third party
// code. It will call back into us once it has gotten to the state
// where third party code can really run (but before it has actually
// started launching the initial applications), for us to complete our
// initialization.
mActivityManagerService.systemReady(() -> {
Slog.i(TAG, "Making services ready");
traceBeginAndSlog("StartActivityManagerReadyPhase");
// 设置bootphase阶段 为 PHASE_ACTIVITY_MANAGER_READY=550
// 该阶段后 系统服务可以发送广播了
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
traceEnd();
traceBeginAndSlog("StartObservingNativeCrashes");
try {
// 开始监控 native 奔溃
mActivityManagerService.startObservingNativeCrashes();
} catch (Throwable e) {
reportWtf("observing native crashes", e);
}
traceEnd();
// No dependency on Webview preparation in system server. But this should
// be completed before allowing 3rd party
final String WEBVIEW_PREPARATION = "WebViewFactoryPreparation";
Future<?> webviewPrep = null;
// 启动 webview
if (!mOnlyCore && mWebViewUpdateService != null) {
webviewPrep = SystemServerInitThreadPool.get().submit(() -> {
Slog.i(TAG, WEBVIEW_PREPARATION);
TimingsTraceLog traceLog = new TimingsTraceLog(
SYSTEM_SERVER_TIMING_ASYNC_TAG, Trace.TRACE_TAG_SYSTEM_SERVER);
traceLog.traceBegin(WEBVIEW_PREPARATION);
ConcurrentUtils.waitForFutureNoInterrupt(mZygotePreload, "Zygote preload");
mZygotePreload = null;
mWebViewUpdateService.prepareWebViewInSystemServer();
traceLog.traceEnd();
}, WEBVIEW_PREPARATION);
}
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTOMOTIVE)) {
traceBeginAndSlog("StartCarServiceHelperService");
mSystemServiceManager.startService(CAR_SERVICE_HELPER_SERVICE_CLASS);
traceEnd();
}
traceBeginAndSlog("StartSystemUI");
try {
// 开始系统ui界面，通过启动一个服务service
startSystemUi(context, windowManagerF);
} catch (Throwable e) {
reportWtf("starting System UI", e);
}
traceEnd();
// Enable airplane mode in safe mode. setAirplaneMode() cannot be called
// earlier as it sends broadcasts to other services.
// TODO: This may actually be too late if radio firmware already started leaking
// RF before the respective services start. However, fixing this requires changes
// to radio firmware and interfaces.
if (safeMode) {
traceBeginAndSlog("EnableAirplaneModeInSafeMode");
try {
connectivityF.setAirplaneMode(true);
} catch (Throwable e) {
reportWtf("enabling Airplane Mode during Safe Mode bootup", e);
}
traceEnd();
}
traceBeginAndSlog("MakeNetworkManagementServiceReady");
try {
if (networkManagementF != null) {
networkManagementF.systemReady();
}
} catch (Throwable e) {
reportWtf("making Network Managment Service ready", e);
}
CountDownLatch networkPolicyInitReadySignal = null;
if (networkPolicyF != null) {
networkPolicyInitReadySignal = networkPolicyF
.networkScoreAndNetworkManagementServiceReady();
}
// 一系列的 systemReady() 通知
traceEnd();
traceBeginAndSlog("MakeIpSecServiceReady");
try {
if (ipSecServiceF != null) {
ipSecServiceF.systemReady();
}
} catch (Throwable e) {
reportWtf("making IpSec Service ready", e);
}
traceEnd();
traceBeginAndSlog("MakeNetworkStatsServiceReady");
try {
if (networkStatsF != null) {
networkStatsF.systemReady();
}
} catch (Throwable e) {
reportWtf("making Network Stats Service ready", e);
}
traceEnd();
traceBeginAndSlog("MakeConnectivityServiceReady");
try {
if (connectivityF != null) {
connectivityF.systemReady();
}
} catch (Throwable e) {
reportWtf("making Connectivity Service ready", e);
}
traceEnd();
traceBeginAndSlog("MakeNetworkPolicyServiceReady");
try {
if (networkPolicyF != null) {
networkPolicyF.systemReady(networkPolicyInitReadySignal);
}
} catch (Throwable e) {
reportWtf("making Network Policy Service ready", e);
}
traceEnd();
// Wait for all packages to be prepared
mPackageManagerService.waitForAppDataPrepared();
// It is now okay to let the various system services start their
// third party code...
traceBeginAndSlog("PhaseThirdPartyAppsCanStart");
// confirm webview completion before starting 3rd party
if (webviewPrep != null) {
ConcurrentUtils.waitForFutureNoInterrupt(webviewPrep, WEBVIEW_PREPARATION);
}
// 阶段600 在此阶段后，系统服务可以去启动/绑定第三方的 app了。
//同时 app 也可以发起binder调用了
mSystemServiceManager.startBootPhase(
SystemService.PHASE_THIRD_PARTY_APPS_CAN_START);
traceEnd();
traceBeginAndSlog("StartNetworkStack");
try {
// Note : the network stack is creating on-demand objects that need to send
// broadcasts, which means it currently depends on being started after
// ActivityManagerService.mSystemReady and ActivityManagerService.mProcessesReady
// are set to true. Be careful if moving this to a different place in the
// startup sequence.
NetworkStackClient.getInstance().start(context);
} catch (Throwable e) {
reportWtf("starting Network Stack", e);
}
traceEnd();
traceBeginAndSlog("MakeLocationServiceReady");
try {
if (locationF != null) {
locationF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying Location Service running", e);
}
traceEnd();
traceBeginAndSlog("MakeCountryDetectionServiceReady");
try {
if (countryDetectorF != null) {
countryDetectorF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying CountryDetectorService running", e);
}
traceEnd();
traceBeginAndSlog("MakeNetworkTimeUpdateReady");
try {
if (networkTimeUpdaterF != null) {
networkTimeUpdaterF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying NetworkTimeService running", e);
}
traceEnd();
traceBeginAndSlog("MakeInputManagerServiceReady");
try {
// TODO(BT) Pass parameter to input manager
if (inputManagerF != null) {
inputManagerF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying InputManagerService running", e);
}
traceEnd();
traceBeginAndSlog("MakeTelephonyRegistryReady");
try {
if (telephonyRegistryF != null) {
telephonyRegistryF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying TelephonyRegistry running", e);
}
traceEnd();
traceBeginAndSlog("MakeMediaRouterServiceReady");
try {
if (mediaRouterF != null) {
mediaRouterF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying MediaRouterService running", e);
}
traceEnd();
traceBeginAndSlog("MakeMmsServiceReady");
try {
if (mmsServiceF != null) {
mmsServiceF.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying MmsService running", e);
}
traceEnd();
traceBeginAndSlog("IncidentDaemonReady");
try {
// TODO: Switch from checkService to getService once it's always
// in the build and should reliably be there.
final IIncidentManager incident = IIncidentManager.Stub.asInterface(
ServiceManager.getService(Context.INCIDENT_SERVICE));
if (incident != null) {
incident.systemRunning();
}
} catch (Throwable e) {
reportWtf("Notifying incident daemon running", e);
}
traceEnd();
}, BOOT_TIMINGS_TRACE_LOG);- 设置
bootphase阶段 为PHASE_ACTIVITY_MANAGER_READY=550。该阶段后 系统服务可以发送广播了 - 开始监控 native 奔溃
- 启动 webview
- 启动系统UI的服务service
- 一系列的 systemReady() 通知
-
阶段600在此阶段后，系统服务可以去启动/绑定第三方的 app了。 更重要的是 app 可以发起binder调用了 - 一些服务
systemRunning()回调
4.4.3 阶段三
public void systemReady(final Runnable goingCallback, TimingsTraceLog traceLog) {
//...
// Check the current user here as a user can be started inside goingCallback.run() from
// other system services.
final int currentUserId = mUserController.getCurrentUserId();
Slog.i(TAG, "Current user:" + currentUserId);
if (currentUserId != UserHandle.USER_SYSTEM && !mUserController.isSystemUserStarted()) {
// User other than system user has started. Make sure that system user is already
// started before switching user.
throw new RuntimeException("System user not started while current user is:"
+ currentUserId);
}
traceLog.traceBegin("ActivityManagerStartApps");
mBatteryStatsService.noteEvent(BatteryStats.HistoryItem.EVENT_USER_RUNNING_START,
Integer.toString(currentUserId), currentUserId);
mBatteryStatsService.noteEvent(BatteryStats.HistoryItem.EVENT_USER_FOREGROUND_START,
Integer.toString(currentUserId), currentUserId);
//调用所有系统服务的onStartUser接口
mSystemServiceManager.startUser(currentUserId);
synchronized (this) {
// Only start up encryption-aware persistent apps; once user is
// unlocked we'll come back around and start unaware apps
//启动persistent为1的application所在的进程
startPersistentApps(PackageManager.MATCH_DIRECT_BOOT_AWARE);
// Start up initial activity.
mBooting = true;
// Enable home activity for system user, so that the system can always boot. We don't
// do this when the system user is not setup since the setup wizard should be the one
// to handle home activity in this case.
if (UserManager.isSplitSystemUser() &&
Settings.Secure.getInt(mContext.getContentResolver(),
Settings.Secure.USER_SETUP_COMPLETE, 0) != 0) {
ComponentName cName = new ComponentName(mContext, SystemUserHomeActivity.class);
try {
AppGlobals.getPackageManager().setComponentEnabledSetting(cName,
PackageManager.COMPONENT_ENABLED_STATE_ENABLED, 0,
UserHandle.USER_SYSTEM);
} catch (RemoteException e) {
throw e.rethrowAsRuntimeException();
}
}
//启动Home Activity
mAtmInternal.startHomeOnAllDisplays(currentUserId, "systemReady");
mAtmInternal.showSystemReadyErrorDialogsIfNeeded();
final int callingUid = Binder.getCallingUid();
final int callingPid = Binder.getCallingPid();
long ident = Binder.clearCallingIdentity();
try {
// system发送广播 ACTION_USER_STARTED = "android.intent.action.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, currentUserId);
broadcastIntentLocked(null, null, intent,
null, null, 0, null, null, null, OP_NONE,
null, false, false, MY_PID, SYSTEM_UID, callingUid, callingPid,
currentUserId);
// 发送广播 ACTION_USER_STARTING
intent = new Intent(Intent.ACTION_USER_STARTING);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
intent.putExtra(Intent.EXTRA_USER_HANDLE, currentUserId);
broadcastIntentLocked(null, null, intent,
null, new IIntentReceiver.Stub() {
@Override
public void performReceive(Intent intent, int resultCode, String data,
Bundle extras, boolean ordered, boolean sticky, int sendingUser)
throws RemoteException {
}
}, 0, null, null,
new String[] {INTERACT_ACROSS_USERS}, OP_NONE,
null, true, false, MY_PID, SYSTEM_UID, callingUid, callingPid,
UserHandle.USER_ALL);
} catch (Throwable t) {
Slog.wtf(TAG, "Failed sending first user broadcasts", t);
} finally {
Binder.restoreCallingIdentity(ident);
}
// resumeTopActivity
mAtmInternal.resumeTopActivities(false /* scheduleIdle */);
mUserController.sendUserSwitchBroadcasts(-1, currentUserId);
BinderInternal.nSetBinderProxyCountWatermarks(BINDER_PROXY_HIGH_WATERMARK,
BINDER_PROXY_LOW_WATERMARK);
BinderInternal.nSetBinderProxyCountEnabled(true);
BinderInternal.setBinderProxyCountCallback(
new BinderInternal.BinderProxyLimitListener() {
@Override
public void onLimitReached(int uid) {
Slog.wtf(TAG, "Uid " + uid + " sent too many Binders to uid "
+ Process.myUid());
BinderProxy.dumpProxyDebugInfo();
if (uid == Process.SYSTEM_UID) {
Slog.i(TAG, "Skipping kill (uid is SYSTEM)");
} else {
killUid(UserHandle.getAppId(uid), UserHandle.getUserId(uid),
"Too many Binders sent to SYSTEM");
}
}
}, mHandler);
traceLog.traceEnd(); // ActivityManagerStartApps
traceLog.traceEnd(); // PhaseActivityManagerReady
}- 调用所有系统服务的onStartUser接口
- 启动persistent为1的
application所在的进程 - 启动Home Activity：
startHomeOnAllDisplays - 发送广播
ACTION_USER_STARTED = "android.intent.action.USER_STARTED"; - 发送广播
ACTION_USER_STARTING resumeTopActivities()
4.4.3.1 startHomeOnAllDisplays()
mAtmInternal.startHomeOnAllDisplays(currentUserId, "systemReady");mAtmInternal 是 ActivityTaskManagerInternal 类型，会调用到它的子类 LocalService。
怎么获取 mAtmInternal 呢？ ：
ActivityManagerService.java
mAtmInternal = LocalServices.getService(ActivityTaskManagerInternal.class);什么时候注册呢？
在 atm 的start()方法中：
ActivityTaskManagerService.java
//atm 构造方法中
mInternal = new LocalService();
private void start() {
LocalServices.addService(ActivityTaskManagerInternal.class, mInternal);
}因此，我们直接看 LocalService(是ActivityTaskManagerService的静态内部类) 的 startHomeOnAllDisplays():
@Override
public boolean startHomeOnAllDisplays(int userId, String reason) {
synchronized (mGlobalLock) {
return mRootActivityContainer.startHomeOnAllDisplays(userId, reason);
}
}RootActivityContainer.java
boolean startHomeOnAllDisplays(int userId, String reason) {
boolean homeStarted = false;
for (int i = mActivityDisplays.size() - 1; i >= 0; i--) {
final int displayId = mActivityDisplays.get(i).mDisplayId;
homeStarted |= startHomeOnDisplay(userId, reason, displayId);
}
return homeStarted;
}boolean startHomeOnDisplay(int userId, String reason, int displayId) {
return startHomeOnDisplay(userId, reason, displayId, false /* allowInstrumenting */,
false /* fromHomeKey */);
}boolean startHomeOnDisplay(int userId, String reason, int displayId, boolean allowInstrumenting,
boolean fromHomeKey) {
// Fallback to top focused display if the displayId is invalid.
if (displayId == INVALID_DISPLAY) {
displayId = getTopDisplayFocusedStack().mDisplayId;
}
Intent homeIntent = null;
ActivityInfo aInfo = null;
if (displayId == DEFAULT_DISPLAY) {
// category: 为 CATEGORY_HOME
homeIntent = mService.getHomeIntent();
//解析得到 ActivityInfo
aInfo = resolveHomeActivity(userId, homeIntent);
} else if (shouldPlaceSecondaryHomeOnDisplay(displayId)) {
Pair<ActivityInfo, Intent> info = resolveSecondaryHomeActivity(userId, displayId);
aInfo = info.first;
homeIntent = info.second;
}
if (aInfo == null || homeIntent == null) {
return false;
}
if (!canStartHomeOnDisplay(aInfo, displayId, allowInstrumenting)) {
return false;
}
// Updates the home component of the intent.
homeIntent.setComponent(new ComponentName(aInfo.applicationInfo.packageName, aInfo.name));
homeIntent.setFlags(homeIntent.getFlags() | FLAG_ACTIVITY_NEW_TASK);
// Updates the extra information of the intent.
if (fromHomeKey) {
homeIntent.putExtra(WindowManagerPolicy.EXTRA_FROM_HOME_KEY, true);
}
// Update the reason for ANR debugging to verify if the user activity is the one that
// actually launched.
final String myReason = reason + ":" + userId + ":" + UserHandle.getUserId(
aInfo.applicationInfo.uid) + ":" + displayId;
mService.getActivityStartController().startHomeActivity(homeIntent, aInfo, myReason,
displayId);
return true;
}最终，通过 startHomeActivity() 来启动 launch 进程。
五、总结
AMS 主要做了如下工作：
- 为 system 创建环境：
systemContext - 创建 AMS 对象，注册一系列的服务，如：管理四大组件、内存、CPU使用监控等
- 为 system 进程创建
processRecord，加入到AMS的进程管理中 - 启动
homeActivity，拉起launch进程
文末福利
如果想要成为架构师或想突破20~30K薪资范畴，那就不要局限在编码，业务，要会选型、扩展，提升编程思维。此外，良好的职业规划也很重要，学习的习惯很重要，但是最重要的还是要能持之以恒，任何不能坚持落实的计划都是空谈。
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一、架构师筑基必备技能
1、深入理解Java泛型
2、注解深入浅出
3、并发编程
4、数据传输与序列化
5、Java虚拟机原理
6、高效IO
……
二、Android百大框架源码解析
1.Retrofit 2.0源码解析
2.Okhttp3源码解析
3.ButterKnife源码解析
4.MPAndroidChart 源码解析
5.Glide源码解析
6.Leakcanary 源码解析
7.Universal-lmage-Loader源码解析
8.EventBus 3.0源码解析
9.zxing源码分析
10.Picasso源码解析
11.LottieAndroid使用详解及源码解析
12.Fresco 源码分析——图片加载流程
三、Android性能优化实战解析
- 腾讯Bugly:对字符串匹配算法的一点理解
- 爱奇艺：安卓APP崩溃捕获方案——xCrash
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- …
四、高级kotlin强化实战
1、Kotlin入门教程
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3、项目实战《Kotlin Jetpack 实战》
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五、Android高级UI开源框架进阶解密
1.SmartRefreshLayout的使用
2.Android之PullToRefresh控件源码解析
3.Android-PullToRefresh下拉刷新库基本用法
4.LoadSir-高效易用的加载反馈页管理框架
5.Android通用LoadingView加载框架详解
6.MPAndroidChart实现LineChart（折线图）
7.hellocharts-android使用指南
8.SmartTable使用指南
9.开源项目android-uitableview介绍
10.ExcelPanel 使用指南
11.Android开源项目SlidingMenu深切解析
12.MaterialDrawer使用指南
六、NDK模块开发
1、NDK 模块开发
2、JNI 模块
3、Native 开发工具
4、Linux 编程
5、底层图片处理
6、音视频开发
7、机器学习
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1、Flutter跨平台开发概述
2、Windows中Flutter开发环境搭建
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标签：String,int,流程,utf8InCpp,void,new,Android,null,AMS From： https://blog.51cto.com/u_16163480/6534901