上一集：SystemServer启动分析
系统服务启动AMS
SystemServer.startBootstrapServices
private void startBootstrapServices() {
Installer installer = mSystemServiceManager.startService(Installer.class);
// 启动 AMS
mActivityManagerService = mSystemServiceManager.startService(ActivityManagerService.Lifecycle.class).getService();
// AMS设置 系统服务管理器
mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
// AMS设置 APP安装器
mActivityManagerService.setInstaller(installer);
// 启动电源管理器，AMS对其进行初始化
mPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class);
mActivityManagerService.initPowerManagement();
// 设置系统进程及相关
mActivityManagerService.setSystemProcess();
}
AMS构建和启动
ActivityManagerService构造函数
- 初始化一些对象属性，包括 Context、ActivityThread、ServiceThread、MainHandler、ActivityManagerConstants 等对象
- 创建和管理四大组件相关的类对象，包括 BroadcastQueue、ActiveServices、ProviderMap、ActivityStackSupervisor、RecentTasks 和 ActivityStarter 等对象
- 创建一个 CPU 监控线程 mProcessCpuThread
public static final class Lifecycle extends SystemService{
private final ActivityManagerService mService;
// ServiceManager反射调用构造方法构造
public Lifecycle(Context context) {
super(context);
mService = new ActivityManagerService(context);
}
@Override
public void onStart() {
mService.start(); // AMS 启动
}
}
public ActivityManagerService(Context systemContext) {
mContext = systemContext; // 赋值 SystemServer的context
mFactoryTest = FactoryTest.getMode();
// 赋值 SystemServer 的ActivityThread
mSystemThread = ActivityThread.currentActivityThread();
// 创建带Handler的前台线程和MainHandler，AMS内部通信用
mHandlerThread = new ServiceThread(TAG,
android.os.Process.THREAD_PRIORITY_FOREGROUND, false);
mHandlerThread.start();
mHandler = new MainHandler(mHandlerThread.getLooper());
// 创建UIHandler，AMS所需要的界面交互用
mUiHandler = new UiHandler();
// 创建前台广播接受队列 和 后台广播接受队列
mFgBroadcastQueue = new BroadcastQueue(this, mHandler,
"foreground", BROADCAST_FG_TIMEOUT, false);
mBgBroadcastQueue = new BroadcastQueue(this, mHandler,
"background", BROADCAST_BG_TIMEOUT, true);
mBroadcastQueues[0] = mFgBroadcastQueue;
mBroadcastQueues[1] = mBgBroadcastQueue;
// 创建Service 和Provider 容器
mServices = new ActiveServices(this);
mProviderMap = new ProviderMap(this);
// 创建 /data/system 目录
File dataDir = Environment.getDataDirectory();
File systemDir = new File(dataDir, "system");
systemDir.mkdirs();
// 创建 电量统计服务
mBatteryStatsService = new BatteryStatsService(systemDir, mHandler);
mBatteryStatsService.getActiveStatistics().readLocked();
mBatteryStatsService.scheduleWriteToDisk();
mOnBattery = DEBUG_POWER ? true
: mBatteryStatsService.getActiveStatistics().getIsOnBattery();
mBatteryStatsService.getActiveStatistics().setCallback(this);
// 创建 进程统计服务
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 is the first and only user that runs at boot.
mStartedUsers.put(UserHandle.USER_OWNER, new UserState(UserHandle.OWNER, true));
mUserLru.add(UserHandle.USER_OWNER);
updateStartedUserArrayLocked();
...
// CPU 追踪器初始化
mProcessCpuTracker.init();
// 创建Activity相关对象
mRecentTasks = new RecentTasks(this);
mStackSupervisor = new ActivityStackSupervisor(this, mRecentTasks);
mTaskPersister = new TaskPersister(systemDir, mStackSupervisor, mRecentTasks);
// 创建‘CpuTracker’的现场
mProcessCpuThread = new Thread("CpuTracker") {
@Override
public void run() {
while (true) {
synchronized(this) {
... // 更新cpu状态
updateCpuStatsNow();
}
}
}
};
...
}
private void start() {
// 启动 CPU 监控线程，在启动 CPU 监控线程之前，首先将进程复位
// 注册电池状态服务和权限管理服务
Process.removeAllProcessGroups(); //移除所有的进程组
mProcessCpuThread.start(); //启动CpuTracker线程
//启动电池统计服务
mBatteryStatsService.publish(mContext);
mAppOpsService.publish(mContext);
//创建LocalService，并添加到LocalServices
LocalServices.addService(ActivityManagerInternal.class, new LocalService());
}
SystemServer调用AMS注册各种服务
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);
//创建用于性能统计的Profiler对象
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);
}
}
系统服务Ready-AMS
SystemServer.startOtherServices
private void startOtherServices() {
...
//安装系统Provider
mActivityManagerService.installSystemProviders();
...
//调用AMS systemReady , 传递了 一个Runnable对象
mActivityManagerService.systemReady(new Runnable() {
public void run() {
... // AMS的systemReady方法会执行该Runnable
}
}
}
AMS.systemReady
- task清理和恢复、是否更新广播、进程清理等systemReady前任务执行
- 系统准备好后,回调runnable，启动webView、系统UI、一系列服务ready和systemRunning
- 启动persistent进程，启动HomeActivity，发送系统广播等
public void systemReady(final Runnable goingCallback) {
// before goingCallback执行
// goingCallback执行
// after goingCallback执行
}
public void systemReady(final Runnable goingCallback) {
// before goingCallback执行
// 同步执行 待 systemReady ok
synchronized(this) {
if (mSystemReady) {
if (goingCallback != null) {
goingCallback.run();
}
return;
}
mLocalDeviceIdleController
= LocalServices.getService(DeviceIdleController.LocalService.class);
updateCurrentProfileIdsLocked();
// 清理最近task，把需要恢复的task添加上
mRecentTasks.clear();
mRecentTasks.addAll(mTaskPersister.restoreTasksLocked());
mRecentTasks.cleanupLocked(UserHandle.USER_ALL);
mTaskPersister.startPersisting();
// 检查是否需要更新
if (!mDidUpdate) {
if (mWaitingUpdate) {
return;
}
final ArrayList<ComponentName> doneReceivers = new ArrayList<ComponentName>();
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;
}
// 将非persistent进程，添加到procsToKill
ArrayList<ProcessRecord> procsToKill = null;
synchronized(mPidsSelfLocked) {
for (int i=mPidsSelfLocked.size()-1; i>=0; i--) {
ProcessRecord proc = mPidsSelfLocked.valueAt(i);
if (!isAllowedWhileBooting(proc.info)){
if (procsToKill == null) {
procsToKill = new ArrayList<ProcessRecord>();
}
procsToKill.add(proc);
}
}
}
// 杀掉进程
synchronized(this) {
if (procsToKill != null) {
for (int i=procsToKill.size()-1; i>=0; i--) {
ProcessRecord proc = procsToKill.get(i);
removeProcessLocked(proc, true, false, "system update done");
}
}
// 进程 ready
mProcessesReady = true;
}
// system 现在进入ready 状态
Slog.i(TAG, "System now ready");
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_AMS_READY,
SystemClock.uptimeMillis());
retrieveSettings();
loadResourcesOnSystemReady();
synchronized (this) {
readGrantedUriPermissionsLocked(); // 权限检查
}
...
// goingCallback 执行
if (goingCallback != null) goingCallback.run();
}
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
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();
}
});
}
public void systemReady(final Runnable goingCallback) {
... // before goingCallback执行
... // goingCallback执行
// after goingCallback执行
...
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
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);
}
// 恢复栈顶Activity
mStackSupervisor.resumeTopActivitiesLocked();
sendUserSwitchBroadcastsLocked(-1, mCurrentUserId);
}
下一集：Launcher启动分析
推荐阅读：图形系统总结
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