AMS -> Activity
刚才讲到在startSpecificActivityLocked()中，会判断app是否running，如果不是在running会先去启这个app，如果已经running了，会跑realStartActivityLocked()。
/frameworks/base/services/core/java/com/android/server/am/ActivityStackSupervisor.java - realStartActivityLocked()
final boolean realStartActivityLocked(ActivityRecord r, ProcessRecord app, boolean andResume, boolean checkConfig) throws RemoteException { ///M: Add debug trace tag
Trace.traceBegin(TRACE_TAG_ACTIVITY_MANAGER, "realStartActivityLocked"); if (!allPausedActivitiesComplete()) { // While there are activities pausing we skipping starting any new activities until
// pauses are complete. NOTE: that we also do this for activities that are starting in
// the paused state because they will first be resumed then paused on the client side.
if (DEBUG_SWITCH || DEBUG_PAUSE || DEBUG_STATES) Slog.v(TAG_PAUSE, "realStartActivityLocked: Skipping start of r=" + r
+ " some activities pausing..."); return false;
} final TaskRecord task = r.getTask(); final ActivityStack stack = task.getStack();
beginDeferResume(); try {
r.startFreezingScreenLocked(app, 0); // schedule launch ticks to collect information about slow apps.
r.startLaunchTickingLocked();
r.setProcess(app); if (getKeyguardController().isKeyguardLocked()) {
r.notifyUnknownVisibilityLaunched();
} // Have the window manager re-evaluate the orientation of the screen based on the new
// activity order. Note that as a result of this, it can call back into the activity
// manager with a new orientation. We don't care about that, because the activity is
// not currently running so we are just restarting it anyway.
if (checkConfig) { // Deferring resume here because we're going to launch new activity shortly.
// We don't want to perform a redundant launch of the same record while ensuring
// configurations and trying to resume top activity of focused stack.
ensureVisibilityAndConfig(r, r.getDisplayId(), false /* markFrozenIfConfigChanged */, true /* deferResume */);
} if (r.getStack().checkKeyguardVisibility(r, true /* shouldBeVisible */, true /* isTop */)) { // We only set the visibility to true if the activity is allowed to be visible
// based on
// keyguard state. This avoids setting this into motion in window manager that is
// later cancelled due to later calls to ensure visible activities that set
// visibility back to false.
r.setVisibility(true);
} final int applicationInfoUid =
(r.info.applicationInfo != null) ? r.info.applicationInfo.uid : -1; if ((r.userId != app.userId) || (r.appInfo.uid != applicationInfoUid)) {
Slog.wtf(TAG, "User ID for activity changing for " + r
+ " appInfo.uid=" + r.appInfo.uid
+ " info.ai.uid=" + applicationInfoUid
+ " old=" + r.app + " new=" + app);
}
app.waitingToKill = null;
r.launchCount++;
r.lastLaunchTime = SystemClock.uptimeMillis(); if (DEBUG_ALL) Slog.v(TAG, "Launching: " + r); int idx = app.activities.indexOf(r); if (idx < 0) {
app.activities.add(r);
}
mService.updateLruProcessLocked(app, true, null);
mService.mHandler.post(mService::updateOomAdj); final LockTaskController lockTaskController = mService.getLockTaskController(); if (task.mLockTaskAuth == LOCK_TASK_AUTH_LAUNCHABLE
|| task.mLockTaskAuth == LOCK_TASK_AUTH_LAUNCHABLE_PRIV
|| (task.mLockTaskAuth == LOCK_TASK_AUTH_WHITELISTED
&& lockTaskController.getLockTaskModeState()
== LOCK_TASK_MODE_LOCKED)) {
lockTaskController.startLockTaskMode(task, false, 0 /* blank UID */);
} try { if (app.thread == null) { throw new RemoteException();
}
List<ResultInfo> results = null;
List<ReferrerIntent> newIntents = null; if (andResume) { // We don't need to deliver new intents and/or set results if activity is going
// to pause immediately after launch.
results = r.results;
newIntents = r.newIntents;
} if (DEBUG_SWITCH) Slog.v(TAG_SWITCH, "Launching: " + r + " icicle=" + r.icicle + " with results=" + results
+ " newIntents=" + newIntents + " andResume=" + andResume);
EventLog.writeEvent(EventLogTags.AM_RESTART_ACTIVITY, r.userId,
System.identityHashCode(r), task.taskId, r.shortComponentName); if (r.isActivityTypeHome()) { // Home process is the root process of the task.
mService.mHomeProcess = task.mActivities.get(0).app;
}
mService.notifyPackageUse(r.intent.getComponent().getPackageName(),
PackageManager.NOTIFY_PACKAGE_USE_ACTIVITY);
r.sleeping = false;
r.forceNewConfig = false;
mService.getAppWarningsLocked().onStartActivity(r);
mService.showAskCompatModeDialogLocked(r);
r.compat = mService.compatibilityInfoForPackageLocked(r.info.applicationInfo);
ProfilerInfo profilerInfo = null; if (mService.mProfileApp != null && mService.mProfileApp.equals(app.processName)) { if (mService.mProfileProc == null || mService.mProfileProc == app) {
mService.mProfileProc = app;
ProfilerInfo profilerInfoSvc = mService.mProfilerInfo; if (profilerInfoSvc != null && profilerInfoSvc.profileFile != null) { if (profilerInfoSvc.profileFd != null) { try {
profilerInfoSvc.profileFd = profilerInfoSvc.profileFd.dup();
} catch (IOException e) {
profilerInfoSvc.closeFd();
}
}
profilerInfo = new ProfilerInfo(profilerInfoSvc);
}
}
}
app.hasShownUi = true;
app.pendingUiClean = true;
app.forceProcessStateUpTo(mService.mTopProcessState); // Because we could be starting an Activity in the system process this may not go
// across a Binder interface which would create a new Configuration. Consequently
// we have to always create a new Configuration here.
final MergedConfiguration mergedConfiguration = new MergedConfiguration(
mService.getGlobalConfiguration(), r.getMergedOverrideConfiguration());
r.setLastReportedConfiguration(mergedConfiguration);
logIfTransactionTooLarge(r.intent, r.icicle); ///M: Add debug trace tag
Trace.traceBegin(TRACE_TAG_ACTIVITY_MANAGER, "LaunchActivityItem"); // Create activity launch transaction.
final ClientTransaction clientTransaction = ClientTransaction.obtain(app.thread,
r.appToken);
clientTransaction.addCallback(LaunchActivityItem.obtain(new Intent(r.intent),
System.identityHashCode(r), r.info, // TODO: Have this take the merged configuration instead of separate global
// and override configs.
mergedConfiguration.getGlobalConfiguration(),
mergedConfiguration.getOverrideConfiguration(), r.compat,
r.launchedFromPackage, task.voiceInteractor, app.repProcState, r.icicle,
r.persistentState, results, newIntents, mService.isNextTransitionForward(),
profilerInfo)); // Set desired final state.
final ActivityLifecycleItem lifecycleItem; if (andResume) {
lifecycleItem = ResumeActivityItem.obtain(mService.isNextTransitionForward());
} else {
lifecycleItem = PauseActivityItem.obtain();
}
clientTransaction.setLifecycleStateRequest(lifecycleItem); // Schedule transaction.
mService.getLifecycleManager().scheduleTransaction(clientTransaction); ///M: Add debug trace tag
Trace.traceEnd(TRACE_TAG_ACTIVITY_MANAGER); if ((app.info.privateFlags & ApplicationInfo.PRIVATE_FLAG_CANT_SAVE_STATE) != 0
&& mService.mHasHeavyWeightFeature) { // This may be a heavy-weight process! Note that the package
// manager will ensure that only activity can run in the main
// process of the .apk, which is the only thing that will be
// considered heavy-weight.
if (app.processName.equals(app.info.packageName)) { if (mService.mHeavyWeightProcess != null
&& mService.mHeavyWeightProcess != app) {
Slog.w(TAG, "Starting new heavy weight process " + app
+ " when already running "
+ mService.mHeavyWeightProcess);
}
mService.mHeavyWeightProcess = app;
Message msg = mService.mHandler.obtainMessage(
ActivityManagerService.POST_HEAVY_NOTIFICATION_MSG);
msg.obj = r;
mService.mHandler.sendMessage(msg);
}
}
} catch (RemoteException e) { if (r.launchFailed) { // This is the second time we failed -- finish activity
// and give up.
Slog.e(TAG, "Second failure launching "
+ r.intent.getComponent().flattenToShortString()
+ ", giving up", e);
mService.appDiedLocked(app);
stack.requestFinishActivityLocked(r.appToken, Activity.RESULT_CANCELED, null, "2nd-crash", false); return false;
} // This is the first time we failed -- restart process and
// retry.
r.launchFailed = true;
app.activities.remove(r); throw e;
}
} finally {
endDeferResume();
}
r.launchFailed = false; if (stack.updateLRUListLocked(r)) {
Slog.w(TAG, "Activity " + r + " being launched, but already in LRU list");
} // TODO(lifecycler): Resume or pause requests are done as part of launch transaction,
// so updating the state should be done accordingly.
if (andResume && readyToResume()) { // As part of the process of launching, ActivityThread also performs
// a resume.
stack.minimalResumeActivityLocked(r);
} else { // This activity is not starting in the resumed state... which should look like we asked
// it to pause+stop (but remain visible), and it has done so and reported back the
// current icicle and other state.
if (DEBUG_STATES) Slog.v(TAG_STATES, "Moving to PAUSED: " + r + " (starting in paused state)");
r.setState(PAUSED, "realStartActivityLocked");
} // Launch the new version setup screen if needed. We do this -after-
// launching the initial activity (that is, home), so that it can have
// a chance to initialize itself while in the background, making the
// switch back to it faster and look better.
if (isFocusedStack(stack)) {
mService.getActivityStartController().startSetupActivity();
} // Update any services we are bound to that might care about whether
// their client may have activities.
if (r.app != null) {
mService.mServices.updateServiceConnectionActivitiesLocked(r.app);
} ///M: Add debug trace tag
Trace.traceEnd(TRACE_TAG_ACTIVITY_MANAGER); return true;
}通过ActivityLifecycleItem(ActivityLifecycleItem extends ClientTransactionItem)这个类的实例去设置了Activity的状态（lifecycle的那几种状态），然后调用了mService.getLifecycleManager().scheduleTransaction(clientTransaction);这里的mService是AMS，mService.getLifecycleManager()返回的是ClientLifecycleManager类型，那么这句话其实调用了ClientLifecycleManager的scheduleTransaction()函数。
在Android8.0中，是通过ApplicationThread.scheduleLaunchActivity()对相关数据进行封装，然后通过调用ActivityThread类的sendMessage()发送出去。
但是在Android9.0中，引入了ClientLifecycleManager和ClientTransactionHandler来辅助管理Activity生命周期。
/frameworks/base/services/core/java/com/android/server/am/ClientLifecycleManager.java - scheduleTransaction()
void scheduleTransaction(ClientTransaction transaction) throws RemoteException { ///M: Add debug trace tag
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "CLM.scheduleTransaction"); final IApplicationThread client = transaction.getClient();
transaction.schedule(); if (!(client instanceof Binder)) { // If client is not an instance of Binder - it's a remote call and at this point it is
// safe to recycle the object. All objects used for local calls will be recycled after
// the transaction is executed on client in ActivityThread.
transaction.recycle();
} ///M: Add debug trace tag
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);
}这里调用了ClientTransaction 的schedule()
/frameworks/base/core/java/android/app/servertransaction/ClientTransaction.java - schedule()
/**
* Schedule the transaction after it was initialized. It will be send to client and all its
* individual parts will be applied in the following sequence:
* 1. The client calls {@link #preExecute(ClientTransactionHandler)}, which triggers all work
* that needs to be done before actually scheduling the transaction for callbacks and
* lifecycle state request.
* 2. The transaction message is scheduled.
* 3. The client calls {@link TransactionExecutor#execute(ClientTransaction)}, which executes
* all callbacks and necessary lifecycle transitions.
*/
public void schedule() throws RemoteException {
mClient.scheduleTransaction(this);
}mClient(private IApplicationThread mClient;)是一个IApplicationThread类型，这里其实是一个Binder，ActivityThread的内部类ApplicationThread派生这个接口类，因此这里实际调用了ActivityThread的scheduleTransaction()方法。
/frameworks/base/core/java/android/app/ActivityThread.java - scheduleTransaction(ClientTransaction transaction)
public void scheduleTransaction(ClientTransaction transaction) throws RemoteException {
ActivityThread.this.scheduleTransaction(transaction);
}这里调用了ActivityThread的父类ClientTransactionHandler的scheduleTransaction()
/frameworks/base/core/java/android/app/ClientTransactionHandler.java - scheduleTransaction()
/** Prepare and schedule transaction for execution. */
void scheduleTransaction(ClientTransaction transaction) {
transaction.preExecute(this);
sendMessage(ActivityThread.H.EXECUTE_TRANSACTION, transaction);
}然后再接着调用了sendMessage()，这个函数是由ClientTransactionHandler的子类ActivityThread实现的，这里代入了一个ActivityThread.H.EXECUTE_TRANSACTION的参数。
/frameworks/base/core/java/android/app/ActivityThread.java - sendMessage()
private void sendMessage(int what, Object obj, int arg1, int arg2, boolean async) { if (DEBUG_MESSAGES) Slog.v(
TAG, "SCHEDULE " + what + " " + mH.codeToString(what)
+ ": " + arg1 + " / " + obj);
Message msg = Message.obtain();
msg.what = what;
msg.obj = obj;
msg.arg1 = arg1;
msg.arg2 = arg2; if (async) {
msg.setAsynchronous(true);
}
mH.sendMessage(msg);
}在sendMessage()中调用了，ActivityThread的内部类H的sendMessage()，也是在H类里面去处理消息，也就是H类的handleMessage()函数。
/frameworks/base/core/java/android/app/ActivityThread.java - handleMessage(Message msg)
public void handleMessage(Message msg) { if (DEBUG_MESSAGES) Slog.v(TAG, ">>> handling: " + codeToString(msg.what)); switch (msg.what) { case BIND_APPLICATION:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "bindApplication");
AppBindData data = (AppBindData)msg.obj;
handleBindApplication(data);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case EXIT_APPLICATION: if (mInitialApplication != null) {
mInitialApplication.onTerminate();
}
Looper.myLooper().quit(); break; case RECEIVER:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "broadcastReceiveComp");
handleReceiver((ReceiverData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case CREATE_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, ("serviceCreate: " + String.valueOf(msg.obj)));
handleCreateService((CreateServiceData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case BIND_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "serviceBind");
handleBindService((BindServiceData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case UNBIND_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "serviceUnbind");
handleUnbindService((BindServiceData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case SERVICE_ARGS:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, ("serviceStart: " + String.valueOf(msg.obj)));
handleServiceArgs((ServiceArgsData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case STOP_SERVICE:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "serviceStop");
handleStopService((IBinder)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case CONFIGURATION_CHANGED:
handleConfigurationChanged((Configuration) msg.obj); break; case CLEAN_UP_CONTEXT:
ContextCleanupInfo cci = (ContextCleanupInfo)msg.obj;
cci.context.performFinalCleanup(cci.who, cci.what); break; case GC_WHEN_IDLE:
scheduleGcIdler(); break; case DUMP_SERVICE:
handleDumpService((DumpComponentInfo)msg.obj); break; case LOW_MEMORY:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "lowMemory");
handleLowMemory();
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case PROFILER_CONTROL:
handleProfilerControl(msg.arg1 != 0, (ProfilerInfo)msg.obj, msg.arg2); break; case CREATE_BACKUP_AGENT:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "backupCreateAgent");
handleCreateBackupAgent((CreateBackupAgentData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case DESTROY_BACKUP_AGENT:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "backupDestroyAgent");
handleDestroyBackupAgent((CreateBackupAgentData)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case SUICIDE:
Process.killProcess(Process.myPid()); break; case REMOVE_PROVIDER:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "providerRemove");
completeRemoveProvider((ProviderRefCount)msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case ENABLE_JIT:
ensureJitEnabled(); break; case DISPATCH_PACKAGE_BROADCAST:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "broadcastPackage");
handleDispatchPackageBroadcast(msg.arg1, (String[])msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case SCHEDULE_CRASH: throw new RemoteServiceException((String)msg.obj); case DUMP_HEAP:
handleDumpHeap((DumpHeapData) msg.obj); break; case DUMP_ACTIVITY:
handleDumpActivity((DumpComponentInfo)msg.obj); break; case DUMP_PROVIDER:
handleDumpProvider((DumpComponentInfo)msg.obj); break; case SLEEPING:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "sleeping");
handleSleeping((IBinder)msg.obj, msg.arg1 != 0);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case SET_CORE_SETTINGS:
Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "setCoreSettings");
handleSetCoreSettings((Bundle) msg.obj);
Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER); break; case UPDATE_PACKAGE_COMPATIBILITY_INFO:
handleUpdatePackageCompatibilityInfo((UpdateCompatibilityData)msg.obj); break; case UNSTABLE_PROVIDER_DIED:
handleUnstableProviderDied((IBinder)msg.obj, false); break; case REQUEST_ASSIST_CONTEXT_EXTRAS:
handleRequestAssistContextExtras((RequestAssistContextExtras)msg.obj); break; case TRANSLUCENT_CONVERSION_COMPLETE:
handleTranslucentConversionComplete((IBinder)msg.obj, msg.arg1 == 1); break; case INSTALL_PROVIDER:
handleInstallProvider((ProviderInfo) msg.obj); break; case ON_NEW_ACTIVITY_OPTIONS:
Pair<IBinder, ActivityOptions> pair = (Pair<IBinder, ActivityOptions>) msg.obj;
onNewActivityOptions(pair.first, pair.second); break; case ENTER_ANIMATION_COMPLETE:
handleEnterAnimationComplete((IBinder) msg.obj); break; case START_BINDER_TRACKING:
handleStartBinderTracking(); break; case STOP_BINDER_TRACKING_AND_DUMP:
handleStopBinderTrackingAndDump((ParcelFileDescriptor) msg.obj); break; case LOCAL_VOICE_INTERACTION_STARTED:
handleLocalVoiceInteractionStarted((IBinder) ((SomeArgs) msg.obj).arg1,
(IVoiceInteractor) ((SomeArgs) msg.obj).arg2); break; case ATTACH_AGENT: {
Application app = getApplication();
handleAttachAgent((String) msg.obj, app != null ? app.mLoadedApk : null); break;
} case APPLICATION_INFO_CHANGED:
mUpdatingSystemConfig = true; try {
handleApplicationInfoChanged((ApplicationInfo) msg.obj);
} finally {
mUpdatingSystemConfig = false;
} break; case RUN_ISOLATED_ENTRY_POINT:
handleRunIsolatedEntryPoint((String) ((SomeArgs) msg.obj).arg1,
(String[]) ((SomeArgs) msg.obj).arg2); break; case EXECUTE_TRANSACTION: final ClientTransaction transaction = (ClientTransaction) msg.obj;
mTransactionExecutor.execute(transaction); if (isSystem()) { // Client transactions inside system process are recycled on the client side
// instead of ClientLifecycleManager to avoid being cleared before this
// message is handled.
transaction.recycle();
} // TODO(lifecycler): Recycle locally scheduled transactions.
break; case RELAUNCH_ACTIVITY:
handleRelaunchActivityLocally((IBinder) msg.obj); break;
}
Object obj = msg.obj; if (obj instanceof SomeArgs) {
((SomeArgs) obj).recycle();
} if (DEBUG_MESSAGES) Slog.v(TAG, "<<< done: " + codeToString(msg.what));
}
}
作者：Dufre
链接：https://www.jianshu.com/p/dd730ce43487