AMS系列：
1、Activity生命周期、启动模式和隐式启动总结
2、本文ActivityManagerService启动分析
3、ActivityMnagerService分析之启动一个Acitvity流程分析
本文分析代码基于Android N,ActivityManagerService简称AMS,其它类似；
“…”代表省略部分代码
整体思路
1、android启动linux内核，加载虚拟机，走到framework启动Systemserver;
2、Systemserver启动Activity Manager,Package Manager,Window Manager等等一系列系统服务；
3、分析AMS的启动；
4、本文主要分析AMS初始化干了些什么，其他细节后续再分析；
简述Android启动
简单说一下Android的启动过程：
Android基于Linux,前面和Linux大致相同
按下电源 -> BIOS自检 -> 引导程序 -> 启动kernel -> 启动Init进程(system\core\init\init.c) -> 开启虚拟机(Zygotes)
然后
Zygote会startSystemServer，而Systemserver就开始启动framework层的各种公共服务，AMS、WMS、PMS等…
Systemserver启动AMS
从Systemserver.run开始,这里开始启动各种服务
private void run() {
....
// 初始化system Context
createSystemContext();
// 创建system manager
mSystemServiceManager = new SystemServiceManager(mSystemContext);
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
...
// Start services.
try {
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartServices");
// 开始引导Services，Installer创建user/data等目录，
// 以及MessageMonitorService，AMS,PowerManagerService,LightsService,DisplayManagerService,UserManagerService等
startBootstrapServices();
// 核心Services，BatteryService，UsageStatsService，WebViewUpdateService
startCoreServices();
// 其他Services，这里启动的服务最多，TelecomLoaderService，CameraService，AccountManagerService等等一系列Service
startOtherServices();
}
...
// Loop forever.
Looper.loop();
...
}
其他服务的启动这里就不展开了，这里开始看AMS的启动
private void startBootstrapServices() {
...
// 创建AMS
mActivityManagerService = mSystemServiceManager.startService(
ActivityManagerService.Lifecycle.class).getService();
// 设置对象关联
mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
mActivityManagerService.setInstaller(installer);
...
// 初始化power manager
mActivityManagerService.initPowerManagement();
...
// 为系统进程设置应用程序实例
mActivityManagerService.setSystemProcess();
}
private void startOtherServices() {
...
// 和SettingsProvider关联
mActivityManagerService.installSystemProviders();
...
// 设置对象关联
mActivityManagerService.setWindowManager(wm);
...
// 当AMS准备好后，再启动。类似location的服务很多，在ready之前已经创建服务并添加到ServiceManager中
mActivityManagerService.systemReady(new Runnable() {
...
startSystemUi(context);
...
Watchdog.getInstance().start();
...
if (locationF != null) locationF.systemRunning();
...
...
}
}
1.创建ActivityManagerService
mActivityManagerService = mSystemServiceManager.startService(
ActivityManagerService.Lifecycle.class).getService();
实际就是返回一个new ActivityManagerService(context);
public ActivityManagerService(Context systemContext) {
// Context 和 ActvityThread
mContext = systemContext;
mFactoryTest = FactoryTest.getMode();
mSystemThread = ActivityThread.currentActivityThread();
// AMS运行的线程和Handler,还有显示相关的UiHandler
mHandlerThread = new ServiceThread(TAG,
android.os.Process.THREAD_PRIORITY_FOREGROUND, false /*allowIo*/);
mHandlerThread.start();
mHandler = new MainHandler(mHandlerThread.getLooper());
mUiHandler = new UiHandler();
/* static; one-time init here */
if (sKillHandler == null) {
sKillThread = new ServiceThread(TAG + ":kill",
android.os.Process.THREAD_PRIORITY_BACKGROUND, true /* allowIo */);
sKillThread.start();
sKillHandler = new KillHandler(sKillThread.getLooper());
}
// Broadcast管理的相关初始化
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;
// Server管理的相关初始化
mServices = new ActiveServices(this);
// Provider管理的相关初始化
mProviderMap = new ProviderMap(this);
// App错误控制
mAppErrors = new AppErrors(mContext, this);
// 创建system文件路径
File dataDir = Environment.getDataDirectory();
File systemDir = new File(dataDir, "system");
systemDir.mkdirs();
// 初始化BatteryStatsService
mBatteryStatsService = new BatteryStatsService(systemDir, mHandler);
mBatteryStatsService.getActiveStatistics().readLocked();
mBatteryStatsService.scheduleWriteToDisk();
mOnBattery = DEBUG_POWER ? true
: mBatteryStatsService.getActiveStatistics().getIsOnBattery();
mBatteryStatsService.getActiveStatistics().setCallback(this);
// ProcessStatsService进程来统计不用的app以及不好行为的app的信息
mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));
// 权限管理，安全机制
mAppOpsService = new AppOpsService(new File(systemDir, "appops.xml"), mHandler);
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);
}
}
}
});
mGrantFile = new AtomicFile(new File(systemDir, "urigrants.xml"));
// 多用户功能
mUserController = new UserController(this);
GL_ES_VERSION = SystemProperties.getInt("ro.opengles.version",
ConfigurationInfo.GL_ES_VERSION_UNDEFINED);
mTrackingAssociations = "1".equals(SystemProperties.get("debug.track-associations"));
mConfiguration.setToDefaults();
mConfiguration.setLocales(LocaleList.getDefault());
mConfigurationSeq = mConfiguration.seq = 1;
mProcessCpuTracker.init();
// 当APK所运行的设备不满足要求时，AMS会根据设置的参数以采用屏幕兼容的方式去运行它
mCompatModePackages = new CompatModePackages(this, systemDir, mHandler);
// 一些校验
mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler);
// Activity管理的相关初始化
mStackSupervisor = new ActivityStackSupervisor(this);
mActivityStarter = new ActivityStarter(this, mStackSupervisor);
// 最近任务
mRecentTasks = new RecentTasks(this, mStackSupervisor);
// 每半小时跟新CPU信息
mProcessCpuThread = new Thread("CpuTracker") {
@Override
public void run() {
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);
}
}
} catch (InterruptedException e) {
}
updateCpuStatsNow();
} catch (Exception e) {
Slog.e(TAG, "Unexpected exception collecting process stats", e);
}
}
}
};
// 看门狗
Watchdog.getInstance().addMonitor(this);
Watchdog.getInstance().addThread(mHandler);
/// M: AMEventHook event @{
AMEventHookData.EndOfAMSCtor eventData =
AMEventHookData.EndOfAMSCtor.createInstance();
mAMEventHook.hook(AMEventHook.Event.AM_EndOfAMSCtor,
eventData);
/// M: AMEventHook event @}
}
setSystemProcess
mActivityManagerService.setSystemProcess();
初始化一些服务，为系统进程设置应用程序实例,AMS得到systemserver的ProcessRecord,以便AMS管理systemserver.
public void setSystemProcess() {
try {
// 添加各种服务
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));
/// M: ANRManager mechanism @{
ServiceManager.addService("anrmanager", mANRManager, true);
/// @}
// 这里是获得报名为“android”的apk信息，即获得framework-res.apk
ApplicationInfo info = mContext.getPackageManager().getApplicationInfo(
"android", STOCK_PM_FLAGS | MATCH_SYSTEM_ONLY);
// 系统进程加载framework-res.apk
mSystemThread.installSystemApplicationInfo(info, getClass().getClassLoader());
// AMS得到systemserver的ProcessRecord,以便AMS管理systemserver
synchronized (this) {
// 从info里得到systemserver所在的系统进程的名字，然后封装成一个ProcessRecord，即封装系统进程的信息
ProcessRecord app = newProcessRecordLocked(info, info.processName, false, 0);
app.persistent = true;
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);
updateOomAdjLocked();
}
} catch (PackageManager.NameNotFoundException e) {
throw new RuntimeException(
"Unable to find android system package", e);
}
}
这里说下，ProcessRecord描述一个app所在进程的所有信息。因为AMS是运行在systemserver进程中的，所以这里得到的实际就是systemserver
installSystemProviders
关联管理SettingsProvider
mActivityManagerService.installSystemProviders();
public final void installSystemProviders() {
List<ProviderInfo> providers;
synchronized (this) {
// 得到名字为“system”,pid为Process.SYSTEM_UID的进程，即systemserver所在系统进程
ProcessRecord app = mProcessNames.get("system", Process.SYSTEM_UID);
// 得到运行在系统进程中的所有ContentProvider的ProviderInfo信息
providers = generateApplicationProvidersLocked(app);
if (providers != null) {
for (int i=providers.size()-1; i>=0; i--) {
ProviderInfo pi = (ProviderInfo)providers.get(i);
if ((pi.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) == 0) {
Slog.w(TAG, "Not installing system proc provider " + pi.name
+ ": not system .apk");
// 过滤掉非系统进程运行的provider
providers.remove(i);
}
}
}
}
// 上面已经过滤掉，剩下一个ContentProvider其实就是SettingsProvider
if (providers != null) {
// 安装SettingsProvider
mSystemThread.installSystemProviders(providers);
}
// 创建CoreSettingsObserver监听SettingsProvider变化
mCoreSettingsObserver = new CoreSettingsObserver(this);
mFontScaleSettingObserver = new FontScaleSettingObserver();
//mUsageStatsService.monitorPackages();
}
systemReady
mActivityManagerService.systemReady(new Runnable(){}
先看public void systemReady(final Runnable goingCallback) {}
1、校验进行systemReady
synchronized(this) {
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);
// Make sure we have the current profile info, since it is needed for security checks.
mUserController.onSystemReady();
mRecentTasks.onSystemReadyLocked();
mAppOpsService.systemReady();
mSystemReady = true;
}
2.杀死之前系统进程启动的进程，除过persistent常驻进程
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);
}
}
}
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);
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.
mProcessesReady = true;
}
3.启动传入的Runable
if (goingCallback != null) goingCallback.run();
4.启动launcher,即HomeActivity
startHomeActivityLocked(currentUserId, "systemReady");
5.发送启动广播
try {
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, AppOpsManager.OP_NONE,
null, false, false, MY_PID, Process.SYSTEM_UID,
currentUserId);
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}, AppOpsManager.OP_NONE,
null, true, false, MY_PID, Process.SYSTEM_UID, UserHandle.USER_ALL);
}
再看一下Runnable中做了什么
1、启动carash监听
try {
mActivityManagerService.startObservingNativeCrashes();
}
2、WebView设置
if (!mOnlyCore) {
Slog.i(TAG, "WebViewFactory preparation");
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "WebViewFactoryPreparation");
mWebViewUpdateService.prepareWebViewInSystemServer();
Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
}
3、启动systemUI
try {
startSystemUi(context);
}
4、在systemReady后，各种类开始设置自己的参数
if (networkScoreF != null) networkScoreF.systemReady();
if (networkManagementF != null) networkManagementF.systemReady();
if (networkStatsF != null) networkStatsF.systemReady();
if (locationF != null) locationF.systemRunning();
...//等等，很多类似方法
总结
AMS启动简要概括：
1、new AMS 准备Handler、初始化四大组件相关、权限、多用户、看门狗
2、setSystemProcess 加载framework-res.apk,和systemserver进程建立关系
3、installSystemProviders 配置ContentProvider即SettingsProvider
4、systemReady 最后工作，启动launcher,systemUI,发送启动广播，其他各类组件准备好
Read the fucking sources code!
