Activity启动源码分析-基于Android10(三)

文章目录

  • Activity启动-IPC后续
    • 1.ActivityStarter
    • 二.RootActivityContainer
    • 三.ActivityStack

在这里插入图片描述

  • Instrumentation
    负责调用Activity和Application生命周期。
  • ActivityTaskManagerService
    负责Activity管理和调度等工作。android10中新增的
  • ActivityManagerService
    负责管理四大组件和进程,包括生命周期和状态切换。
  • ActivityTaskManagerInternal
    ActivityTaskManagerService对外提供的一个抽象类,真正的实现在ActivityTaskManagerService#LocalService
  • ActivityThread
    管理应用程序进程中主线程的执行
  • ActivityStackSupervisor
    负责所有Activity栈的管理
  • TransactionExecutor
    主要作用是执行ClientTransaction
  • ClientLifecycleManager
    生命周期的管理调用

Activity启动-IPC后续

1.ActivityStarter

上一篇文章阐述了Activity到ActivityTaskManagerService的通讯机制Activity启动流程-基于Android10(二)今天将更加深入的学习启动流程。
ActivityTaskManagerService#startActivityAsUser:

frameworks\base\services\core\java\com\android\server\wm\ActivityTaskManagerService.java

int startActivityAsUser(IApplicationThread caller, String callingPackage,
            Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
            int startFlags, ProfilerInfo profilerInfo, Bundle bOptions, int userId,
            boolean validateIncomingUser) {
        enforceNotIsolatedCaller("startActivityAsUser");

        userId = getActivityStartController().checkTargetUser(userId, validateIncomingUser,
                Binder.getCallingPid(), Binder.getCallingUid(), "startActivityAsUser");

        // TODO: Switch to user app stacks here.
        return getActivityStartController().obtainStarter(intent, "startActivityAsUser")
                .setCaller(caller)
                .setCallingPackage(callingPackage)
                .setResolvedType(resolvedType)
                .setResultTo(resultTo)
                .setResultWho(resultWho)
                .setRequestCode(requestCode)
                .setStartFlags(startFlags)
                .setProfilerInfo(profilerInfo)
                .setActivityOptions(bOptions)
                .setMayWait(userId)
                .execute();

    }
    
	// ...省略部分代码
	
	ActivityStartController getActivityStartController() {
        return mActivityStartController;
    }
frameworks\base\services\core\java\com\android\server\wm\ActivityStartController.java

	/**
     * @return A starter to configure and execute starting an activity. It is valid until after
     *         {@link ActivityStarter#execute} is invoked. At that point, the starter should be
     *         considered invalid and no longer modified or used.
     */
    ActivityStarter obtainStarter(Intent intent, String reason) {
        return mFactory.obtain().setIntent(intent).setReason(reason);
    }

Activity通过IActivityTaskManager.aidl调用了startActivityAsUser方法。最后调用了ActivityStarter的execute方法。

frameworks\base\services\core\java\com\android\server\wm\ActivityStarter.java
	
	/**
     * Starts an activity based on the request parameters provided earlier.
     * @return The starter result.
     */
    int execute() {
        try {
            // TODO(b/64750076): Look into passing request directly to these methods to allow
            // for transactional diffs and preprocessing.
            if (mRequest.mayWait) {
                return startActivityMayWait(mRequest.caller, mRequest.callingUid,
                        mRequest.callingPackage, mRequest.realCallingPid, mRequest.realCallingUid,
                        mRequest.intent, mRequest.resolvedType,
                        mRequest.voiceSession, mRequest.voiceInteractor, mRequest.resultTo,
                        mRequest.resultWho, mRequest.requestCode, mRequest.startFlags,
                        mRequest.profilerInfo, mRequest.waitResult, mRequest.globalConfig,
                        mRequest.activityOptions, mRequest.ignoreTargetSecurity, mRequest.userId,
                        mRequest.inTask, mRequest.reason,
                        mRequest.allowPendingRemoteAnimationRegistryLookup,
                        mRequest.originatingPendingIntent, mRequest.allowBackgroundActivityStart);
            } else {
                return startActivity(mRequest.caller, mRequest.intent, mRequest.ephemeralIntent,
                        mRequest.resolvedType, mRequest.activityInfo, mRequest.resolveInfo,
                        mRequest.voiceSession, mRequest.voiceInteractor, mRequest.resultTo,
                        mRequest.resultWho, mRequest.requestCode, mRequest.callingPid,
                        mRequest.callingUid, mRequest.callingPackage, mRequest.realCallingPid,
                        mRequest.realCallingUid, mRequest.startFlags, mRequest.activityOptions,
                        mRequest.ignoreTargetSecurity, mRequest.componentSpecified,
                        mRequest.outActivity, mRequest.inTask, mRequest.reason,
                        mRequest.allowPendingRemoteAnimationRegistryLookup,
                        mRequest.originatingPendingIntent, mRequest.allowBackgroundActivityStart);
            }
        } finally {
            onExecutionComplete();
        }
    }

mayWait的赋值是在startActivityAsUser中的setMayWait中,这里传入的true。会走startActivityMayWait逻辑。实际上如果mayWait为false走startActivity逻辑,它们最后都会调用startActivityUnchecked方法。

frameworks\base\services\core\java\com\android\server\wm\ActivityStarter.java

private int startActivity(final ActivityRecord r, ActivityRecord sourceRecord,
                IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
                int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
                ActivityRecord[] outActivity) {
        //...省略部分代码
            result = startActivityUnchecked(r, sourceRecord, voiceSession, voiceInteractor,
                    startFlags, doResume, options, inTask, outActivity);
       // ...省略部分代码

        postStartActivityProcessing(r, result, mTargetStack);

        return result;
}

   // Note: This method should only be called from {@link startActivity}.
    private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
            IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
            int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
            ActivityRecord[] outActivity, boolean restrictedBgActivity) {
        
        //1. 初始化环境和lunchModeFlags
        setInitialState(r, options, inTask, doResume, startFlags, sourceRecord, voiceSession,
                voiceInteractor, restrictedBgActivity);

        final int preferredWindowingMode = mLaunchParams.mWindowingMode;

        computeLaunchingTaskFlags();

        computeSourceStack();

        mIntent.setFlags(mLaunchFlags);
		
		//2. 复用activity逻辑
        ActivityRecord reusedActivity = getReusableIntentActivity();

		//...省略部分代码
		
		// 各种flags的判断
        if (reusedActivity != null) {

		// ...省略部分代码
                
        final ActivityStack topStack = mRootActivityContainer.getTopDisplayFocusedStack();
        final ActivityRecord topFocused = topStack.getTopActivity();
        final ActivityRecord top = topStack.topRunningNonDelayedActivityLocked(mNotTop);
        final boolean dontStart = top != null && mStartActivity.resultTo == null
                && top.mActivityComponent.equals(mStartActivity.mActivityComponent)
                && top.mUserId == mStartActivity.mUserId
                && top.attachedToProcess()
                && ((mLaunchFlags & FLAG_ACTIVITY_SINGLE_TOP) != 0
                || isLaunchModeOneOf(LAUNCH_SINGLE_TOP, LAUNCH_SINGLE_TASK))
                // This allows home activity to automatically launch on secondary display when
                // display added, if home was the top activity on default display, instead of
                // sending new intent to the home activity on default display.
                && (!top.isActivityTypeHome() || top.getDisplayId() == mPreferredDisplayId);
                
        //singleTop 或者singleInstance的处理
        if (dontStart) {
            // For paranoia, make sure we have correctly resumed the top activity.
            topStack.mLastPausedActivity = null;
            if (mDoResume) {
                mRootActivityContainer.resumeFocusedStacksTopActivities();
            }
            ActivityOptions.abort(mOptions);
            if ((mStartFlags & START_FLAG_ONLY_IF_NEEDED) != 0) {
                // We don't need to start a new activity, and the client said not to do
                // anything if that is the case, so this is it!
                return START_RETURN_INTENT_TO_CALLER;
            }

            deliverNewIntent(top);

            // Don't use mStartActivity.task to show the toast. We're not starting a new activity
            // but reusing 'top'. Fields in mStartActivity may not be fully initialized.
            mSupervisor.handleNonResizableTaskIfNeeded(top.getTaskRecord(), preferredWindowingMode,
                    mPreferredDisplayId, topStack);

            return START_DELIVERED_TO_TOP;
        }

        boolean newTask = false;
        final TaskRecord taskToAffiliate = (mLaunchTaskBehind && mSourceRecord != null)
                ? mSourceRecord.getTaskRecord() : null;

        // 设置对应task并带到前台
        int result = START_SUCCESS;
        if (mStartActivity.resultTo == null && mInTask == null && !mAddingToTask
                && (mLaunchFlags & FLAG_ACTIVITY_NEW_TASK) != 0) {
            newTask = true;
            result = setTaskFromReuseOrCreateNewTask(taskToAffiliate);
        } else if (mSourceRecord != null) {
            result = setTaskFromSourceRecord();
        } else if (mInTask != null) {
            result = setTaskFromInTask();
        } else {
            // This not being started from an existing activity, and not part of a new task...
            // just put it in the top task, though these days this case should never happen.
            result = setTaskToCurrentTopOrCreateNewTask();
        }

		// ...省略部分代码

		// 启动Activity
        mTargetStack.startActivityLocked(mStartActivity, topFocused, newTask, mKeepCurTransition,
                mOptions);
                
        // 使Activity可见
        if (mDoResume) {
        	// 获取栈顶Activity
            final ActivityRecord topTaskActivity =
                    mStartActivity.getTaskRecord().topRunningActivityLocked();
            if (!mTargetStack.isFocusable()
                    || (topTaskActivity != null && topTaskActivity.mTaskOverlay
                    && mStartActivity != topTaskActivity)) {
                // If the activity is not focusable, we can't resume it, but still would like to
                // make sure it becomes visible as it starts (this will also trigger entry
                // animation). An example of this are PIP activities.
                // Also, we don't want to resume activities in a task that currently has an overlay
                // as the starting activity just needs to be in the visible paused state until the
                // over is removed.
                mTargetStack.ensureActivitiesVisibleLocked(mStartActivity, 0, !PRESERVE_WINDOWS);
                // Go ahead and tell window manager to execute app transition for this activity
                // since the app transition will not be triggered through the resume channel.
                mTargetStack.getDisplay().mDisplayContent.executeAppTransition();
            } else {
                // If the target stack was not previously focusable (previous top running activity
                // on that stack was not visible) then any prior calls to move the stack to the
                // will not update the focused stack.  If starting the new activity now allows the
                // task stack to be focusable, then ensure that we now update the focused stack
                // accordingly.
                if (mTargetStack.isFocusable()
                        && !mRootActivityContainer.isTopDisplayFocusedStack(mTargetStack)) {
                    mTargetStack.moveToFront("startActivityUnchecked");
                }
				
				// 重要代码
                mRootActivityContainer.resumeFocusedStacksTopActivities(
                        mTargetStack, mStartActivity, mOptions);
            }
        } else if (mStartActivity != null) {
            mSupervisor.mRecentTasks.add(mStartActivity.getTaskRecord());
        }
        mRootActivityContainer.updateUserStack(mStartActivity.mUserId, mTargetStack);

        mSupervisor.handleNonResizableTaskIfNeeded(mStartActivity.getTaskRecord(),
                preferredWindowingMode, mPreferredDisplayId, mTargetStack);

        return START_SUCCESS;
    }
             

ActivityStarter的startActivityUnchecked里面有许多关于flags的判断。这里面用到了一个小技术。关于按位或与的判断,关于这个知识点可以参考Android中巧妙的位运算文章。

二.RootActivityContainer

startActivityUnchecked方法最后一段代码:

frameworks\base\services\core\java\com\android\server\wm\ActivityStarter.java

private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
            IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
            int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
            ActivityRecord[] outActivity, boolean restrictedBgActivity) {

//...省略部分代码

	if (mDoResume) {
            final ActivityRecord topTaskActivity =
                    mStartActivity.getTaskRecord().topRunningActivityLocked();
            if (!mTargetStack.isFocusable()
                    || (topTaskActivity != null && topTaskActivity.mTaskOverlay
                    && mStartActivity != topTaskActivity)) {
                // If the activity is not focusable, we can't resume it, but still would like to
                // make sure it becomes visible as it starts (this will also trigger entry
                // animation). An example of this are PIP activities.
                // Also, we don't want to resume activities in a task that currently has an overlay
                // as the starting activity just needs to be in the visible paused state until the
                // over is removed.
                mTargetStack.ensureActivitiesVisibleLocked(mStartActivity, 0, !PRESERVE_WINDOWS);
                // Go ahead and tell window manager to execute app transition for this activity
                // since the app transition will not be triggered through the resume channel.
                mTargetStack.getDisplay().mDisplayContent.executeAppTransition();
            } else {
                // If the target stack was not previously focusable (previous top running activity
                // on that stack was not visible) then any prior calls to move the stack to the
                // will not update the focused stack.  If starting the new activity now allows the
                // task stack to be focusable, then ensure that we now update the focused stack
                // accordingly.
                if (mTargetStack.isFocusable()
                        && !mRootActivityContainer.isTopDisplayFocusedStack(mTargetStack)) {
                    mTargetStack.moveToFront("startActivityUnchecked");
                }
				
				// 重要代码
                mRootActivityContainer.resumeFocusedStacksTopActivities(
                        mTargetStack, mStartActivity, mOptions);
            }
        } else if (mStartActivity != null) {
            mSupervisor.mRecentTasks.add(mStartActivity.getTaskRecord());
        }
        mRootActivityContainer.updateUserStack(mStartActivity.mUserId, mTargetStack);

        mSupervisor.handleNonResizableTaskIfNeeded(mStartActivity.getTaskRecord(),
                preferredWindowingMode, mPreferredDisplayId, mTargetStack);

        return START_SUCCESS;
}

如果栈顶的Activity获取焦点,调用RootActivityContainer的resumeFocusedStacksTopActivities方法

frameworks\base\services\core\java\com\android\server\wm\RootActivityContainer.java

boolean resumeFocusedStacksTopActivities(
            ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {

        if (!mStackSupervisor.readyToResume()) {
            return false;
        }

        boolean result = false;
        if (targetStack != null && (targetStack.isTopStackOnDisplay()
                || getTopDisplayFocusedStack() == targetStack)) {
            result = targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
        }

        for (int displayNdx = mActivityDisplays.size() - 1; displayNdx >= 0; --displayNdx) {
            boolean resumedOnDisplay = false;
            final ActivityDisplay display = mActivityDisplays.get(displayNdx);
            for (int stackNdx = display.getChildCount() - 1; stackNdx >= 0; --stackNdx) {
                final ActivityStack stack = display.getChildAt(stackNdx);
                final ActivityRecord topRunningActivity = stack.topRunningActivityLocked();
                if (!stack.isFocusableAndVisible() || topRunningActivity == null) {
                    continue;
                }
                if (stack == targetStack) {
                    // Simply update the result for targetStack because the targetStack had
                    // already resumed in above. We don't want to resume it again, especially in
                    // some cases, it would cause a second launch failure if app process was dead.
                    resumedOnDisplay |= result;
                    continue;
                }
                if (display.isTopStack(stack) && topRunningActivity.isState(RESUMED)) {
                    // Kick off any lingering app transitions form the MoveTaskToFront operation,
                    // but only consider the top task and stack on that display.
                    stack.executeAppTransition(targetOptions);
                } else {
                    resumedOnDisplay |= topRunningActivity.makeActiveIfNeeded(target);
                }
            }
            if (!resumedOnDisplay) {
                // In cases when there are no valid activities (e.g. device just booted or launcher
                // crashed) it's possible that nothing was resumed on a display. Requesting resume
                // of top activity in focused stack explicitly will make sure that at least home
                // activity is started and resumed, and no recursion occurs.
                final ActivityStack focusedStack = display.getFocusedStack();
                if (focusedStack != null) {
                    focusedStack.resumeTopActivityUncheckedLocked(target, targetOptions);
                }
            }
        }

        return result;
    }

最后调用了ActivityStack的resumeTopActivityUncheckedLocked方法。

三.ActivityStack

ActivityStack的resumeTopActivityUncheckedLocked代码:

frameworks\base\services\core\java\com\android\server\wm\ActivityStack.java

	@GuardedBy("mService")
    boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
        if (mInResumeTopActivity) {
            // Don't even start recursing.
            return false;
        }

        boolean result = false;
        try {
            // Protect against recursion.
            mInResumeTopActivity = true;
            result = resumeTopActivityInnerLocked(prev, options);

            // When resuming the top activity, it may be necessary to pause the top activity (for
            // example, returning to the lock screen. We suppress the normal pause logic in
            // {@link #resumeTopActivityUncheckedLocked}, since the top activity is resumed at the
            // end. We call the {@link ActivityStackSupervisor#checkReadyForSleepLocked} again here
            // to ensure any necessary pause logic occurs. In the case where the Activity will be
            // shown regardless of the lock screen, the call to
            // {@link ActivityStackSupervisor#checkReadyForSleepLocked} is skipped.
            final ActivityRecord next = topRunningActivityLocked(true /* focusableOnly */);
            if (next == null || !next.canTurnScreenOn()) {
                checkReadyForSleep();
            }
        } finally {
            mInResumeTopActivity = false;
        }

        return result;
    }

// ...省略部分代码

	@GuardedBy("mService")
    private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) {
    
		// ...省略部分代码
		} catch (Exception e) {
                // Whoops, need to restart this activity!
                if (DEBUG_STATES) Slog.v(TAG_STATES, "Resume failed; resetting state to "
                        + lastState + ": " + next);
                next.setState(lastState, "resumeTopActivityInnerLocked");

                // lastResumedActivity being non-null implies there is a lastStack present.
                if (lastResumedActivity != null) {
                    lastResumedActivity.setState(RESUMED, "resumeTopActivityInnerLocked");
                }

                Slog.i(TAG, "Restarting because process died: " + next);
                if (!next.hasBeenLaunched) {
                    next.hasBeenLaunched = true;
                } else  if (SHOW_APP_STARTING_PREVIEW && lastFocusedStack != null
                        && lastFocusedStack.isTopStackOnDisplay()) {
                    next.showStartingWindow(null /* prev */, false /* newTask */,
                            false /* taskSwitch */);
                }
                // 重要代码
                mStackSupervisor.startSpecificActivityLocked(next, true, false);
                return true;
            }
            
            // ...省略部分代码
            
            } else {
            // Whoops, need to restart this activity!
            if (!next.hasBeenLaunched) {
                next.hasBeenLaunched = true;
            } else {
                if (SHOW_APP_STARTING_PREVIEW) {
                    next.showStartingWindow(null /* prev */, false /* newTask */,
                            false /* taskSwich */);
                }
                if (DEBUG_SWITCH) Slog.v(TAG_SWITCH, "Restarting: " + next);
            }
            if (DEBUG_STATES) Slog.d(TAG_STATES, "resumeTopActivityLocked: Restarting " + next);
            // 重要代码
            mStackSupervisor.startSpecificActivityLocked(next, true, true);
        }
	}

通过代码知道最后调用了ActivityStackSupervisor的startSpecificActivityLocked方法。

Activity启动源码分析-基于Android10(四)

参考文章:Activity的启动流程-基于Android10源码

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