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Commit c349e59f authored by Christopher Tate's avatar Christopher Tate
Browse files

Accommodate service disconnect / package update race 

Ordering of delivery of package monitoring messages and service
disconnect callbacks is indeterminate, but we need to make decisions
about service disconnect based on the package update state.  We
address the race by explicitly deferring our reset/timeout logic by
a short time to allow the package monitor to process any pending
updates on the same looper thread before we take action.

Bug 34356215
Test: manual

Change-Id: Icffedbaf19b8eac8830c22fc05f299eb96b54acd
parent 33532e02

services/core/java/com/android/server/wallpaper/WallpaperManagerService.java

+35 −8
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ import android.os.Bundle; 
import android.os.Environment;

import android.os.FileObserver;

import android.os.FileUtils;

import android.os.Handler;

import android.os.IBinder;

import android.os.IRemoteCallback;

import android.os.Process;
@@ -663,13 +664,35 @@ public class WallpaperManagerService extends IWallpaperManager.Stub { 
        @Override

        public void onServiceDisconnected(ComponentName name) {

            synchronized (mLock) {

                Slog.w(TAG, "Wallpaper service gone: " + name);

                if (!Objects.equals(name, mWallpaper.wallpaperComponent)) {

                    Slog.e(TAG, "Does not match expected wallpaper component "

                            + mWallpaper.wallpaperComponent);

                }

                mService = null;

                mEngine = null;

                if (mWallpaper.connection == this) {

                    // There is an inherent ordering race between this callback and the

                    // package monitor that receives notice that a package is being updated,

                    // so we cannot quite trust at this moment that we know for sure that

                    // this is not an update.  If we think this is a genuine non-update

                    // wallpaper outage, we do our "wait for reset" work as a continuation,

                    // a short time in the future, specifically to allow any pending package

                    // update message on this same looper thread to be processed.

                    if (!mWallpaper.wallpaperUpdating) {

                        mContext.getMainThreadHandler().postDelayed(() -> processDisconnect(this),

                                1000);

                    }

                }

            }

        }



        private void processDisconnect(final ServiceConnection connection) {

            synchronized (mLock) {

                // The wallpaper disappeared.  If this isn't a system-default one, track

                // crashes and fall back to default if it continues to misbehave.

                if (connection == mWallpaper.connection) {

                    final ComponentName wpService = mWallpaper.wallpaperComponent;

                    Slog.w(TAG, "Wallpaper service gone: " + wpService);

                    if (!mWallpaper.wallpaperUpdating

                            && mWallpaper.userId == mCurrentUserId

                            && !Objects.equals(mDefaultWallpaperComponent, wpService)
@@ -690,18 +713,22 @@ public class WallpaperManagerService extends IWallpaperManager.Stub { 


                            // If we didn't reset it right away, do so after we couldn't connect to

                            // it for an extended amount of time to avoid having a black wallpaper.

                            FgThread.getHandler().removeCallbacks(mResetRunnable);

                            FgThread.getHandler().postDelayed(mResetRunnable,

                                    WALLPAPER_RECONNECT_TIMEOUT_MS);

                            final Handler fgHandler = FgThread.getHandler();

                            fgHandler.removeCallbacks(mResetRunnable);

                            fgHandler.postDelayed(mResetRunnable, WALLPAPER_RECONNECT_TIMEOUT_MS);

                            if (DEBUG_LIVE) {

                                Slog.i(TAG, "Started wallpaper reconnect timeout for " + wpService);

                            }

                        }

                        final String flattened = name.flattenToString();

                        final String flattened = wpService.flattenToString();

                        EventLog.writeEvent(EventLogTags.WP_WALLPAPER_CRASHED,

                                flattened.substring(0, Math.min(flattened.length(),

                                        MAX_WALLPAPER_COMPONENT_LOG_LENGTH)));

                    }

                } else {

                    if (DEBUG_LIVE) {

                        Slog.i(TAG, "Wallpaper changed during disconnect tracking; ignoring");

                    }

                }

            }

        }