一 前言
Android 系统服务进程 system_server，进入消息循环前的最后一步，就是调用 AMS 的 systemReady() 方法。今天我们分析一下这里的流程。
二 systemReady 第一部分
ActivityManagerService.java
public void systemReady(final Runnable goingCallback, TimingsTraceLog traceLog) {
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);
mActivityTaskManager.onSystemReady();
// Make sure we have the current profile info, since it is needed for security checks.
mUserController.onSystemReady();
mAppOpsService.systemReady();
mSystemReady = true;
}
......
}
这里 mSystemReady 是 false，所以回调方法不会在这里被执行。接下来会调用一些关联类的 systemReady() 方法，然后把标志位 mSystemReady 置为 true。
ArrayList
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
}
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);
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.
mProcessesReady = true;
}
清理进程，把不允许在开机阶段运行的进程都结束掉。判断标准是：应用程序的 AM 配置文件是否有配置 android:persistent 属性。
mAtmInternal.updateTopComponentForFactoryTest();
工厂测试相关的逻辑，正常情况下这个条件不成立，所以不管它。
if (goingCallback != null) goingCallback.run();
执行 systemReady() 传入的回调方法，在 SystemServer.java 类中
三 systemReady 第二部分之回调方法
SystemServer.java 这个回调方法很长，足有 200 行，我们单独作为一节来分析。
traceBeginAndSlog("StartActivityManagerReadyPhase");
mSystemServiceManager.startBootPhase(
SystemService.PHASE_ACTIVITY_MANAGER_READY);
traceEnd();
AMS 启动完成，系统进入阶段 PHASE_ACTIVITY_MANAGER_READY，对其它服务调用 onBootPhase() 方法传出这个PHASE。
traceBeginAndSlog("StartObservingNativeCrashes");
try {
mActivityManagerService.startObservingNativeCrashes();
} catch (Throwable e) {
reportWtf("observing native crashes", e);
}
traceEnd();
启动 native crash监测。
// 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;
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);
}
这里判断要不要启动 webview。
traceBeginAndSlog("StartSystemUI");
try {
startSystemUi(context, windowManagerF);
} catch (Throwable e) {
reportWtf("starting System UI", e);
}
traceEnd();
启动 SystemUI。
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();
}
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();
调用一堆网络相关服务的 systemReady() 方法。
// 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);
}
mSystemServiceManager.startBootPhase(
SystemService.PHASE_THIRD_PARTY_APPS_CAN_START);
traceEnd();
系统进入阶段 PHASE_THIRD_PARTY_APPS_CAN_START。对其它服务调用 onBootPhase() 方法传出这个 PHASE。
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();
对其他相关服务调用 systemRunning() 方法。包括：位置、国家检测、网络时间、输入管理、网络评分等等。 至此回调方法分析结束。
四 systemReady第三部分
继续回到 AMS 的 systemReady() 方法。
// Only start up encryption-aware persistent apps; once user is
// unlocked we'll come back around and start unaware apps
startPersistentApps(PackageManager.MATCH_DIRECT_BOOT_AWARE);
启动锁屏状态下的应用，通过应用配置文件的 android:directBoot 属性过滤。
if (bootingSystemUser) {
mAtmInternal.startHomeOnAllDisplays(currentUserId, "systemReady");
}
启动 Home 程序。这个在下一节分析。
mAtmInternal.showSystemReadyErrorDialogsIfNeeded();
public void showSystemReadyErrorDialogsIfNeeded() {
synchronized (mGlobalLock) {
try {
if (AppGlobals.getPackageManager().hasSystemUidErrors()) {
Slog.e(TAG, "UIDs on the system are inconsistent, you need to wipe your"
+ " data partition or your device will be unstable.");
mUiHandler.post(() -> {
if (mShowDialogs) {
AlertDialog d = new BaseErrorDialog(mUiContext);
d.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ERROR);
d.setCancelable(false);
d.setTitle(mUiContext.getText(R.string.android_system_label));
d.setMessage(mUiContext.getText(R.string.system_error_wipe_data));
d.setButton(DialogInterface.BUTTON_POSITIVE,
mUiContext.getText(R.string.ok),
mUiHandler.obtainMessage(DISMISS_DIALOG_UI_MSG, d));
d.show();
}
});
}
} catch (RemoteException e) {
}
if (!Build.isBuildConsistent()) {
Slog.e(TAG, "Build fingerprint is not consistent, warning user");
mUiHandler.post(() -> {
if (mShowDialogs) {
AlertDialog d = new BaseErrorDialog(mUiContext);
d.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ERROR);
d.setCancelable(false);
d.setTitle(mUiContext.getText(R.string.android_system_label));
d.setMessage(mUiContext.getText(R.string.system_error_manufacturer));
d.setButton(DialogInterface.BUTTON_POSITIVE,
mUiContext.getText(R.string.ok),
mUiHandler.obtainMessage(DISMISS_DIALOG_UI_MSG, d));
d.show();
}
});
}
}
}
检查 uid 和 fingerprint，如果有异常会弹出 Android System 的弹框。
if (bootingSystemUser) {
final int callingUid = Binder.getCallingUid();
final int callingPid = Binder.getCallingPid();
long ident = Binder.clearCallingIdentity();
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, OP_NONE,
null, false, false, MY_PID, SYSTEM_UID, callingUid, callingPid,
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}, 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);
}
} else {
Slog.i(TAG, "Not sending multi-user broadcasts for non-system user "
+ currentUserId);
}
发送两个广播:ACTION_USER_STARTED、ACTION_USER_STARTING。
4.1 Home 启动
@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) {
homeIntent = mService.getHomeIntent();
aInfo = resolveHomeActivity(userId, homeIntent);
} else if (shouldPlaceSecondaryHomeOnDisplay(displayId)) {
Pair
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;
}
ActivityStartController.java
void startHomeActivity(Intent intent, ActivityInfo aInfo, String reason, int displayId) {
final ActivityOptions options = ActivityOptions.makeBasic();
options.setLaunchWindowingMode(WINDOWING_MODE_FULLSCREEN);
if (!ActivityRecord.isResolverActivity(aInfo.name)) {
// The resolver activity shouldn't be put in home stack because when the foreground is
// standard type activity, the resolver activity should be put on the top of current
// foreground instead of bring home stack to front.
options.setLaunchActivityType(ACTIVITY_TYPE_HOME);
}
options.setLaunchDisplayId(displayId);
mLastHomeActivityStartResult = obtainStarter(intent, "startHomeActivity: " + reason)
.setOutActivity(tmpOutRecord)
.setCallingUid(0)
.setActivityInfo(aInfo)
.setActivityOptions(options.toBundle())
.execute(); // 根据 Intent,启动 Home 的主 Activity
mLastHomeActivityStartRecord = tmpOutRecord[0];
final ActivityDisplay display =
mService.mRootActivityContainer.getActivityDisplay(displayId);
final ActivityStack homeStack = display != null ? display.getHomeStack() : null;
if (homeStack != null && homeStack.mInResumeTopActivity) {
// If we are in resume section already, home activity will be initialized, but not
// resumed (to avoid recursive resume) and will stay that way until something pokes it
// again. We need to schedule another resume.
mSupervisor.scheduleResumeTopActivities();
}
}
根据 Intent，启动 Home 的主 Activity。
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