代码解读

112 阅读5分钟

TaskFragment.java

    final boolean resumeTopActivity(ActivityRecord prev, ActivityOptions options,
            boolean skipPause) {
        ActivityRecord next = topRunningActivity(true /* focusableOnly */);
        if (next == null || !next.canResumeByCompat()) {
            return false;
        }

        next.delayedResume = false;

        if (!skipPause && !mRootWindowContainer.allPausedActivitiesComplete()) {
            // If we aren't skipping pause, then we have to wait for currently pausing activities.
            ProtoLog.v(WM_DEBUG_STATES, "resumeTopActivity: Skip resume: some activity pausing.");
            return false;
        }

        final TaskDisplayArea taskDisplayArea = getDisplayArea();
        // If the top activity is the resumed one, nothing to do.
        if (mResumedActivity == next && next.isState(RESUMED)
                && taskDisplayArea.allResumedActivitiesComplete()) {
            // Ensure the visibility gets updated before execute app transition.
            taskDisplayArea.ensureActivitiesVisible(null /* starting */, 0 /* configChanges */,
                    false /* preserveWindows */, true /* notifyClients */);
            // Make sure we have executed any pending transitions, since there
            // should be nothing left to do at this point.
            executeAppTransition(options);

            // In a multi-resumed environment, like in a freeform device, the top
            // activity can be resumed, but it might not be the focused app.
            // Set focused app when top activity is resumed
            if (taskDisplayArea.inMultiWindowMode() && taskDisplayArea.mDisplayContent != null
                    && taskDisplayArea.mDisplayContent.mFocusedApp != next) {
                taskDisplayArea.mDisplayContent.setFocusedApp(next);
            }
            ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivity: Top activity "
                    + "resumed %s", next);
            return false;
        }

        // If we are sleeping, and there is no resumed activity, and the top activity is paused,
        // well that is the state we want.
        if (mLastPausedActivity == next && shouldSleepOrShutDownActivities()) {
            // Make sure we have executed any pending transitions, since there
            // should be nothing left to do at this point.
            executeAppTransition(options);
            ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivity: Going to sleep and"
                    + " all paused");
            return false;
        }

        // Make sure that the user who owns this activity is started.  If not,
        // we will just leave it as is because someone should be bringing
        // another user's activities to the top of the stack.
        if (!mAtmService.mAmInternal.hasStartedUserState(next.mUserId)) {
            Slog.w(TAG, "Skipping resume of top activity " + next
                    + ": user " + next.mUserId + " is stopped");
            return false;
        }

        // The activity may be waiting for stop, but that is no longer
        // appropriate for it.
        mTaskSupervisor.mStoppingActivities.remove(next);

        if (DEBUG_SWITCH) Slog.v(TAG_SWITCH, "Resuming " + next);

        mTaskSupervisor.setLaunchSource(next.info.applicationInfo.uid);

        ActivityRecord lastResumed = null;
        final Task lastFocusedRootTask = taskDisplayArea.getLastFocusedRootTask();
        if (lastFocusedRootTask != null && lastFocusedRootTask != getRootTaskFragment().asTask()) {
            // So, why aren't we using prev here??? See the param comment on the method. prev
            // doesn't represent the last resumed activity. However, the last focus stack does if
            // it isn't null.
            lastResumed = lastFocusedRootTask.getTopResumedActivity();
        }

        boolean pausing = !skipPause && taskDisplayArea.pauseBackTasks(next);
        if (mResumedActivity != null) {
            ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivity: Pausing %s", mResumedActivity);
            pausing |= startPausing(mTaskSupervisor.mUserLeaving, false /* uiSleeping */,
                    next, "resumeTopActivity");
        }
        if (pausing) {
            ProtoLog.v(WM_DEBUG_STATES, "resumeTopActivity: Skip resume: need to"
                    + " start pausing");
            // At this point we want to put the upcoming activity's process
            // at the top of the LRU list, since we know we will be needing it
            // very soon and it would be a waste to let it get killed if it
            // happens to be sitting towards the end.
            if (next.attachedToProcess()) {
                next.app.updateProcessInfo(false /* updateServiceConnectionActivities */,
                        true /* activityChange */, false /* updateOomAdj */,
                        false /* addPendingTopUid */);
            } else if (!next.isProcessRunning()) {
                // Since the start-process is asynchronous, if we already know the process of next
                // activity isn't running, we can start the process earlier to save the time to wait
                // for the current activity to be paused.
                final boolean isTop = this == taskDisplayArea.getFocusedRootTask();
                mAtmService.startProcessAsync(next, false /* knownToBeDead */, isTop,
                        isTop ? HostingRecord.HOSTING_TYPE_NEXT_TOP_ACTIVITY
                                : HostingRecord.HOSTING_TYPE_NEXT_ACTIVITY);
            }
            if (lastResumed != null) {
                lastResumed.setWillCloseOrEnterPip(true);
            }
            return true;
        } else if (mResumedActivity == next && next.isState(RESUMED)
                && taskDisplayArea.allResumedActivitiesComplete()) {
            // It is possible for the activity to be resumed when we paused back stacks above if the
            // next activity doesn't have to wait for pause to complete.
            // So, nothing else to-do except:
            // Make sure we have executed any pending transitions, since there
            // should be nothing left to do at this point.
            executeAppTransition(options);
            ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivity: Top activity resumed "
                    + "(dontWaitForPause) %s", next);
            return true;
        }

        // If the most recent activity was noHistory but was only stopped rather
        // than stopped+finished because the device went to sleep, we need to make
        // sure to finish it as we're making a new activity topmost.
        if (shouldSleepActivities()) {
            mTaskSupervisor.finishNoHistoryActivitiesIfNeeded(next);
        }

        if (prev != null && prev != next && next.nowVisible) {
            // The next activity is already visible, so hide the previous
            // activity's windows right now so we can show the new one ASAP.
            // We only do this if the previous is finishing, which should mean
            // it is on top of the one being resumed so hiding it quickly
            // is good.  Otherwise, we want to do the normal route of allowing
            // the resumed activity to be shown so we can decide if the
            // previous should actually be hidden depending on whether the
            // new one is found to be full-screen or not.
            if (prev.finishing) {
                prev.setVisibility(false);
                if (DEBUG_SWITCH) {
                    Slog.v(TAG_SWITCH, "Not waiting for visible to hide: " + prev
                            + ", nowVisible=" + next.nowVisible);
                }
            } else {
                if (DEBUG_SWITCH) {
                    Slog.v(TAG_SWITCH, "Previous already visible but still waiting to hide: " + prev
                            + ", nowVisible=" + next.nowVisible);
                }
            }
        }

        try {
            mTaskSupervisor.getActivityMetricsLogger()
                    .notifyBeforePackageUnstopped(next.packageName);
            mAtmService.getPackageManagerInternalLocked().notifyComponentUsed(
                    next.packageName, next.mUserId,
                    next.packageName, next.toString()); /* TODO: Verify if correct userid */
        } catch (IllegalArgumentException e) {
            Slog.w(TAG, "Failed trying to unstop package "
                    + next.packageName + ": " + e);
        }

        // We are starting up the next activity, so tell the window manager
        // that the previous one will be hidden soon.  This way it can know
        // to ignore it when computing the desired screen orientation.
        boolean anim = true;
        final DisplayContent dc = taskDisplayArea.mDisplayContent;
        if (prev != null) {
            if (prev.finishing) {
                if (DEBUG_TRANSITION) {
                    Slog.v(TAG_TRANSITION, "Prepare close transition: prev=" + prev);
                }
                if (mTaskSupervisor.mNoAnimActivities.contains(prev)) {
                    anim = false;
                    dc.prepareAppTransition(TRANSIT_NONE);
                } else {
                    dc.prepareAppTransition(TRANSIT_CLOSE);
                }
                prev.setVisibility(false);
            } else {
                if (DEBUG_TRANSITION) {
                    Slog.v(TAG_TRANSITION, "Prepare open transition: prev=" + prev);
                }
                if (mTaskSupervisor.mNoAnimActivities.contains(next)) {
                    anim = false;
                    dc.prepareAppTransition(TRANSIT_NONE);
                } else {
                    dc.prepareAppTransition(TRANSIT_OPEN,
                            next.mLaunchTaskBehind ? TRANSIT_FLAG_OPEN_BEHIND : 0);
                }
            }
        } else {
            if (DEBUG_TRANSITION) Slog.v(TAG_TRANSITION, "Prepare open transition: no previous");
            if (mTaskSupervisor.mNoAnimActivities.contains(next)) {
                anim = false;
                dc.prepareAppTransition(TRANSIT_NONE);
            } else {
                dc.prepareAppTransition(TRANSIT_OPEN);
            }
        }

        if (anim) {
            next.applyOptionsAnimation();
        } else {
            next.abortAndClearOptionsAnimation();
        }

        mTaskSupervisor.mNoAnimActivities.clear();

        if (next.attachedToProcess()) {
            if (DEBUG_SWITCH) {
                Slog.v(TAG_SWITCH, "Resume running: " + next + " stopped=" + next.mAppStopped
                        + " visibleRequested=" + next.isVisibleRequested());
            }

            // If the previous activity is translucent, force a visibility update of
            // the next activity, so that it's added to WM's opening app list, and
            // transition animation can be set up properly.
            // For example, pressing Home button with a translucent activity in focus.
            // Launcher is already visible in this case. If we don't add it to opening
            // apps, maybeUpdateTransitToWallpaper() will fail to identify this as a
            // TRANSIT_WALLPAPER_OPEN animation, and run some funny animation.
            final boolean lastActivityTranslucent = inMultiWindowMode()
                    || mLastPausedActivity != null && !mLastPausedActivity.occludesParent();

            // This activity is now becoming visible.
            if (!next.isVisibleRequested() || next.mAppStopped || lastActivityTranslucent) {
                next.app.addToPendingTop();
                next.setVisibility(true);
            }

            // schedule launch ticks to collect information about slow apps.
            next.startLaunchTickingLocked();

            ActivityRecord lastResumedActivity =
                    lastFocusedRootTask == null ? null
                            : lastFocusedRootTask.getTopResumedActivity();
            final ActivityRecord.State lastState = next.getState();

            mAtmService.updateCpuStats();

            ProtoLog.v(WM_DEBUG_STATES, "Moving to RESUMED: %s (in existing)", next);

            next.setState(RESUMED, "resumeTopActivity");

            // Have the window manager re-evaluate the orientation of
            // the screen based on the new activity order.
            boolean notUpdated = true;

            // Activity should also be visible if set mLaunchTaskBehind to true (see
            // ActivityRecord#shouldBeVisibleIgnoringKeyguard()).
            if (shouldBeVisible(next)) {
                // We have special rotation behavior when here is some active activity that
                // requests specific orientation or Keyguard is locked. Make sure all activity
                // visibilities are set correctly as well as the transition is updated if needed
                // to get the correct rotation behavior. Otherwise the following call to update
                // the orientation may cause incorrect configurations delivered to client as a
                // result of invisible window resize.
                // TODO: Remove this once visibilities are set correctly immediately when
                // starting an activity.
                notUpdated = !mRootWindowContainer.ensureVisibilityAndConfig(next, getDisplayId(),
                        false /* deferResume */);
            }

            if (notUpdated) {
                // The configuration update wasn't able to keep the existing
                // instance of the activity, and instead started a new one.
                // We should be all done, but let's just make sure our activity
                // is still at the top and schedule another run if something
                // weird happened.
                ActivityRecord nextNext = topRunningActivity();
                ProtoLog.i(WM_DEBUG_STATES, "Activity config changed during resume: "
                        + "%s, new next: %s", next, nextNext);
                if (nextNext != next) {
                    // Do over!
                    mTaskSupervisor.scheduleResumeTopActivities();
                }
                if (!next.isVisibleRequested() || next.mAppStopped) {
                    next.setVisibility(true);
                }
                next.completeResumeLocked();
                return true;
            }

            try {
                final IApplicationThread appThread = next.app.getThread();
                final ClientTransaction transaction = Flags.bundleClientTransactionFlag()
                        ? null
                        : ClientTransaction.obtain(appThread);
                // Deliver all pending results.
                final ArrayList<ResultInfo> a = next.results;
                if (a != null) {
                    final int size = a.size();
                    if (!next.finishing && size > 0) {
                        if (DEBUG_RESULTS) {
                            Slog.v(TAG_RESULTS, "Delivering results to " + next + ": " + a);
                        }
                        final ActivityResultItem activityResultItem = ActivityResultItem.obtain(
                                next.token, a);
                        if (transaction == null) {
                            mAtmService.getLifecycleManager().scheduleTransactionItem(
                                    appThread, activityResultItem);
                        } else {
                            transaction.addCallback(activityResultItem);
                        }
                    }
                }

                if (next.newIntents != null) {
                    final NewIntentItem newIntentItem = NewIntentItem.obtain(
                            next.token, next.newIntents, true /* resume */);
                    if (transaction == null) {
                        mAtmService.getLifecycleManager().scheduleTransactionItem(
                                appThread, newIntentItem);
                    } else {
                        transaction.addCallback(newIntentItem);
                    }
                }

                // Well the app will no longer be stopped.
                // Clear app token stopped state in window manager if needed.
                next.notifyAppResumed();

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

                mAtmService.getAppWarningsLocked().onResumeActivity(next);
                final int topProcessState = mAtmService.mTopProcessState;
                next.app.setPendingUiCleanAndForceProcessStateUpTo(topProcessState);
                next.abortAndClearOptionsAnimation();
                final ResumeActivityItem resumeActivityItem = ResumeActivityItem.obtain(
                        next.token, topProcessState, dc.isNextTransitionForward(),
                        next.shouldSendCompatFakeFocus());
                if (transaction == null) {
                    mAtmService.getLifecycleManager().scheduleTransactionItem(
                            appThread, resumeActivityItem);
                } else {
                    transaction.setLifecycleStateRequest(resumeActivityItem);
                    mAtmService.getLifecycleManager().scheduleTransaction(transaction);
                }

                ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivity: Resumed %s", next);
            } catch (Exception e) {
                // Whoops, need to restart this activity!
                ProtoLog.v(WM_DEBUG_STATES, "Resume failed; resetting state to %s: "
                        + "%s", 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 && lastFocusedRootTask != null
                        && lastFocusedRootTask.isTopRootTaskInDisplayArea()) {
                    next.showStartingWindow(false /* taskSwitch */);
                }
                mTaskSupervisor.startSpecificActivity(next, true, false);
                return true;
            }

            // From this point on, if something goes wrong there is no way
            // to recover the activity.
            try {
                next.completeResumeLocked();
            } catch (Exception e) {
                // If any exception gets thrown, toss away this
                // activity and try the next one.
                Slog.w(TAG, "Exception thrown during resume of " + next, e);
                next.finishIfPossible("resume-exception", true /* oomAdj */);
                return true;
            }
        } else {
            // Whoops, need to restart this activity!
            if (!next.hasBeenLaunched) {
                next.hasBeenLaunched = true;
            } else {
                if (SHOW_APP_STARTING_PREVIEW) {
                    next.showStartingWindow(false /* taskSwich */);
                }
                if (DEBUG_SWITCH) Slog.v(TAG_SWITCH, "Restarting: " + next);
            }
            ProtoLog.d(WM_DEBUG_STATES, "resumeTopActivity: Restarting %s", next);
            mTaskSupervisor.startSpecificActivity(next, true, true);
        }

        return true;
    }