AMS系列：
1、Activity生命周期、啟動模式和隱式啟動總結
2、本文ActivityManagerService啟動分析
3、ActivityMnagerService分析之啟動一個Acitvity流程分析
本文分析代碼基于Android N,ActivityManagerService簡稱AMS,其它類似；
“...”代表省略部分代碼
整體思路
1、android啟動linux內核，加載虛擬機，走到framework啟動Systemserver;
2、Systemserver啟動Activity Manager,Package Manager,Window Manager等等一系列系統服務；
3、分析AMS的啟動；
4、本文主要分析AMS初始化干了些什么，其他細節后續再分析；
簡述Android啟動
簡單說一下Android的啟動過程：
Android基于Linux,前面和Linux大致相同
按下電源 -> BIOS自檢 -> 引導程序 -> 啟動kernel -> 啟動Init進程(system\core\init\init.c) -> 開啟虛擬機(Zygotes)
然后
Zygote會startSystemServer，而Systemserver就開始啟動framework層的各種公共服務，AMS、WMS、PMS等...
Systemserver啟動AMS
從Systemserver.run開始,這里開始啟動各種服務
private void run() {
....
// 初始化system Context
createSystemContext();
// 創建system manager
mSystemServiceManager = new SystemServiceManager(mSystemContext);
LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
...
// Start services.
try {
Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "StartServices");
// 開始引導Services，Installer創建user/data等目錄，
// 以及MessageMonitorService，AMS,PowerManagerService,LightsService,DisplayManagerService,UserManagerService等
startBootstrapServices();
// 核心Services，BatteryService，UsageStatsService，WebViewUpdateService
startCoreServices();
// 其他Services，這里啟動的服務最多，TelecomLoaderService，CameraService，AccountManagerService等等一系列Service
startOtherServices();
}
...
// Loop forever.
Looper.loop();
...
}
其他服務的啟動這里就不展開了，這里開始看AMS的啟動
private void startBootstrapServices() {
...
// 創建AMS
mActivityManagerService = mSystemServiceManager.startService(
ActivityManagerService.Lifecycle.class).getService();
// 設置對象關聯
mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
mActivityManagerService.setInstaller(installer);
...
// 初始化power manager
mActivityManagerService.initPowerManagement();
...
// 為系統進程設置應用程序實例
mActivityManagerService.setSystemProcess();
}
private void startOtherServices() {
...
// 和SettingsProvider關聯
mActivityManagerService.installSystemProviders();
...
// 設置對象關聯
mActivityManagerService.setWindowManager(wm);
...
// 當AMS準備好后，再啟動。類似location的服務很多，在ready之前已經創建服務并添加到ServiceManager中
mActivityManagerService.systemReady(new Runnable() {
...
startSystemUi(context);
...
Watchdog.getInstance().start();
...
if (locationF != null) locationF.systemRunning();
...
...
}
}
1.創建ActivityManagerService
mActivityManagerService = mSystemServiceManager.startService(
ActivityManagerService.Lifecycle.class).getService();
實際就是返回一個new ActivityManagerService(context);
public ActivityManagerService(Context systemContext) {
// Context 和 ActvityThread
mContext = systemContext;
mFactoryTest = FactoryTest.getMode();
mSystemThread = ActivityThread.currentActivityThread();
// AMS運行的線程和Handler,還有顯示相關的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管理的相關初始化
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管理的相關初始化
mServices = new ActiveServices(this);
// Provider管理的相關初始化
mProviderMap = new ProviderMap(this);
// App錯誤控制
mAppErrors = new AppErrors(mContext, this);
// 創建system文件路徑
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進程來統計不用的app以及不好行為的app的信息
mProcessStats = new ProcessStatsService(this, new File(systemDir, "procstats"));
// 權限管理，安全機制
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"));
// 多用戶功能
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();
// 當APK所運行的設備不滿足要求時，AMS會根據設置的參數以采用屏幕兼容的方式去運行它
mCompatModePackages = new CompatModePackages(this, systemDir, mHandler);
// 一些校驗
mIntentFirewall = new IntentFirewall(new IntentFirewallInterface(), mHandler);
// Activity管理的相關初始化
mStackSupervisor = new ActivityStackSupervisor(this);
mActivityStarter = new ActivityStarter(this, mStackSupervisor);
// 最近任務
mRecentTasks = new RecentTasks(this, mStackSupervisor);
// 每半小時跟新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);
}
}
}
};
// 看門狗
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();
初始化一些服務，為系統進程設置應用程序實例,AMS得到systemserver的ProcessRecord,以便AMS管理systemserver.
public void setSystemProcess() {
try {
// 添加各種服務
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);
/// @}
// 這里是獲得報名為“android”的apk信息，即獲得framework-res.apk
ApplicationInfo info = mContext.getPackageManager().getApplicationInfo(
"android", STOCK_PM_FLAGS | MATCH_SYSTEM_ONLY);
// 系統進程加載framework-res.apk
mSystemThread.installSystemApplicationInfo(info, getClass().getClassLoader());
// AMS得到systemserver的ProcessRecord,以便AMS管理systemserver
synchronized (this) {
// 從info里得到systemserver所在的系統進程的名字，然后封裝成一個ProcessRecord，即封裝系統進程的信息
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);
}
}
這里說下，ProcessRecord描述一個app所在進程的所有信息。因為AMS是運行在systemserver進程中的，所以這里得到的實際就是systemserver
installSystemProviders
關聯管理SettingsProvider
mActivityManagerService.installSystemProviders();
public final void installSystemProviders() {
List<ProviderInfo> providers;
synchronized (this) {
// 得到名字為“system”,pid為Process.SYSTEM_UID的進程，即systemserver所在系統進程
ProcessRecord app = mProcessNames.get("system", Process.SYSTEM_UID);
// 得到運行在系統進程中的所有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");
// 過濾掉非系統進程運行的provider
providers.remove(i);
}
}
}
}
// 上面已經過濾掉，剩下一個ContentProvider其實就是SettingsProvider
if (providers != null) {
// 安裝SettingsProvider
mSystemThread.installSystemProviders(providers);
}
// 創建CoreSettingsObserver監聽SettingsProvider變化
mCoreSettingsObserver = new CoreSettingsObserver(this);
mFontScaleSettingObserver = new FontScaleSettingObserver();
//mUsageStatsService.monitorPackages();
}
systemReady
mActivityManagerService.systemReady(new Runnable(){}
先看public void systemReady(final Runnable goingCallback) {}
1、校驗進行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.殺死之前系統進程啟動的進程，除過persistent常駐進程
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.啟動傳入的Runable
if (goingCallback != null) goingCallback.run();
4.啟動launcher,即HomeActivity
startHomeActivityLocked(currentUserId, "systemReady");
5.發送啟動廣播
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、啟動carash監聽
try {
mActivityManagerService.startObservingNativeCrashes();
}
2、WebView設置
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、啟動systemUI
try {
startSystemUi(context);
}
4、在systemReady后，各種類開始設置自己的參數
if (networkScoreF != null) networkScoreF.systemReady();
if (networkManagementF != null) networkManagementF.systemReady();
if (networkStatsF != null) networkStatsF.systemReady();
if (locationF != null) locationF.systemRunning();
...//等等，很多類似方法
總結
AMS啟動簡要概括：
1、new AMS 準備Handler、初始化四大組件相關、權限、多用戶、看門狗
2、setSystemProcess 加載framework-res.apk,和systemserver進程建立關系
3、installSystemProviders 配置ContentProvider即SettingsProvider
4、systemReady 最后工作，啟動launcher,systemUI,發送啟動廣播，其他各類組件準備好
Read the fucking sources code!
