AMS:startActivity桌面启动应用

startActivity桌面启动应用

android12-security-release

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Launcher点击应用图标

packages/apps/Launcher3/src/com/android/launcher3/touch/ItemClickHandler.java
packages/apps/Launcher3/src/com/android/launcher3/Launcher.java
packages/apps/Launcher3/src/com/android/launcher3/BaseDraggingActivity.java

onClickAppShortcut -> startAppShortcutOrInfoActivity -> launcher.startActivitySafely -> startActivity()最后调用到Activity.java中。

intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); Activity在新的任务栈中启动

Activity.java

frameworks/base/core/java/android/app/Activity.java
frameworks/base/core/java/android/app/Instrumentation.java

startActivity() -> startActivityForResult -> mInstrumentation.execStartActivity -> ActivityTaskManager.getService().startActivity

• mParent应用首次启动所以mParent为空。
• mMainThread.getApplicationThread() 获取ApplicationThread成员变量，是一个Binder对象
• ActivityTaskManager.getService() 获取的是Context.ACTIVITY_TASK_SERVICE 即是 ActivityTaskManagerService
• Instrumentation.java用来监控应用程序和系统的交互
• checkStartActivityResult(result, intent);检查是否启动成功

ActivityTaskManagerService

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
frameworks/base/services/core/java/com/android/server/wm/ActivityStartController.java
frameworks/base/services/core/java/com/android/server/wm/ActivityStarter.java

ActivityTaskManager.getService().startActivity -> startActivityAsUser() -> getActivityStartController().obtainStarter ........ execute() -> executeRequest(mRequest) -> startActivityUnchecked() -> startActivityInner()

• obtainStarter获取ActivityStarter
• executeRequest(mRequest)这里输出START u日志，一般定制都会加上pid打印
  
• ActivityRecord r,sourceRecord信息
• startActivityInner()该方法有许多参数处理，如setInitialState\computeLaunchingTaskFlags\computeSourceStack\mIntent.setFlags(mLaunchFlags)\computeLaunchParams
• startActivityInner() 这里wm_create_task、wm_create_activity
  
  
• mDoResume移到栈顶显示resumeFocusedTasksTopActivities
  

Task / ActivityRecord

frameworks/base/services/core/java/com/android/server/wm/RootWindowContainer.java
frameworks/base/services/core/java/com/android/server/wm/Task.java
frameworks/base/services/core/java/com/android/server/wm/ActivityStackSupervisor.java
frameworks/base/services/core/java/com/android/server/wm/ActivityRecord.java

mRootWindowContainer.resumeFocusedTasksTopActivities -> focusedRoot.resumeTopActivityUncheckedLocked -> resumeTopActivityInnerLocked -> 先startPausingLocked后next.setState(RESUMED, "resumeTopActivityInnerLocked")

• mResumedActivity != null时先startPausingLocked() 执行Pausing过程，并输出日志wm_pause_activity

if (mResumedActivity != null) {
    
    ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivityLocked: Pausing %s", mResumedActivity);
    pausing |= startPausingLocked(false /* uiSleeping */, next,
            "resumeTopActivityInnerLocked");
}

ProtoLog.v(WM_DEBUG_STATES, "Moving to PAUSING: %s", prev);

EventLogTags.writeWmPauseActivity(prev.mUserId, System.identityHashCode(prev),
        prev.shortComponentName, "userLeaving=" + userLeaving, reason);

• next.setState(RESUMED, "resumeTopActivityInnerLocked");设置ActivityRecord的RESUMED状态，最终通过Task调用到ATMS中setResumedActivityUncheckLocked，并输出wm_set_resumed_activity

    void onActivityStateChanged(ActivityRecord record, ActivityState state, String reason) {
    
        warnForNonLeafTask("onActivityStateChanged");
        if (record == mResumedActivity && state != RESUMED) {
    
            setResumedActivity(null, reason + " - onActivityStateChanged");
        }

        if (state == RESUMED) {
    
            if (ActivityTaskManagerDebugConfig.DEBUG_ROOT_TASK) {
    
                Slog.v(TAG_ROOT_TASK, "set resumed activity to:" + record + " reason:" + reason);
            }
            setResumedActivity(record, reason + " - onActivityStateChanged");
            if (record == mRootWindowContainer.getTopResumedActivity()) {
    
                mAtmService.setResumedActivityUncheckLocked(record, reason);
            }
            mTaskSupervisor.mRecentTasks.add(record.getTask());
        }
    }

EventLogTags.writeWmSetResumedActivity(
        r == null ? -1 : r.mUserId,
        r == null ? "NULL" : r.shortComponentName,
        reason);

• resumeTopActivityInnerLocked()这里输出wm_resume_activity

EventLogTags.writeWmResumeActivity(next.mUserId, System.identityHashCode(next),
        next.getTask().mTaskId, next.shortComponentName);

• mTaskSupervisor.startSpecificActivity已经启动，执行realStartActivityLocked()；没有启动执行mService.startProcessAsync()

ActivityTaskSupervisor / ProcessList

frameworks/base/services/core/java/com/android/server/wm/ActivityTaskSupervisor.java
frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
frameworks/base/services/core/java/com/android/server/am/ProcessList.java
frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
Task.resumeTopActivityInnerLocked -> realStartActivityLocked / mService.startProcessAsync

void startSpecificActivity(ActivityRecord r, boolean andResume, boolean checkConfig) {
    
    // Is this activity's application already running?
    final WindowProcessController wpc =
            mService.getProcessController(r.processName, r.info.applicationInfo.uid);

    boolean knownToBeDead = false;
    if (wpc != null && wpc.hasThread()) {
    
        try {
    
            realStartActivityLocked(r, wpc, andResume, checkConfig);
            return;
        } catch (RemoteException e) {
    
            Slog.w(TAG, "Exception when starting activity "
                    + r.intent.getComponent().flattenToShortString(), e);
        }

        // If a dead object exception was thrown -- fall through to
        // restart the application.
        knownToBeDead = true;
    }

    r.notifyUnknownVisibilityLaunchedForKeyguardTransition();

    final boolean isTop = andResume && r.isTopRunningActivity();
    mService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");
}

• 执行realStartActivityLocked()真正启动APP
• startProcessAsync通过ActivityManagerService走到ProcessList.java中startProcess()调用Process.start,最终ZYGOTE_PROCESS.startfork生成进程
• startProcessAsync通过ActivityManagerService走到ProcessList.java中handleProcessStartedLocked输出am_proc_start:

EventLog.writeEvent(EventLogTags.AM_PROC_START,
        UserHandle.getUserId(app.getStartUid()), pid, app.getStartUid(),
        app.processName, app.getHostingRecord().getType(),
        app.getHostingRecord().getName() != null ? app.getHostingRecord().getName() : "");

startProcess

frameworks/base/services/core/java/com/android/server/am/ProcessList.java
frameworks/base/core/java/android/os/Process.java
frameworks/base/core/java/android/os/ZygoteProcess.java
frameworks/base/core/java/android/app/ActivityThread.java

• Process.start为应用创建进程，最后执行到 ActivityThread.main() 方法
• openZygoteSocketIfNeeded跟zygote进程建立连接ZygoteConnection

synchronized(mLock) {
    
    // The USAP pool can not be used if the application will not use the systems graphics
    // driver. If that driver is requested use the Zygote application start path.
    return zygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi),
                                      zygotePolicyFlags,
                                      argsForZygote);
}

待续~~~ 后面还有很长一段路程

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Log关键字：
ActivityTaskManager: START u|ActivityTaskManager: Displayed
wm_create_activity|wm_set_resumed_activity|wm_resume_activity|wm_on_resume_called|wm_activity_launch_time

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