Add persistence for app hibernation states

Persist hibernation states to disk. This CL persists the user-level
and global hibernation states to disk.

Bug: 175829330
Test: atest AppHibernationServiceTest
Test: atest HibernationStateDiskStoreTest
Change-Id: If58d648d720bed1693b9346c4d0e85074daec931

11 files changed, 888 insertions, 43 deletions

diff --git a/core/proto/OWNERS b/core/proto/OWNERS
index 748b4b4f5743..99fd21592411 100644
--- a/core/proto/OWNERS
+++ b/core/proto/OWNERS
@@ -16,6 +16,7 @@ ogunwale@google.com
 jjaggi@google.com
 roosa@google.com
 per-file usagestatsservice.proto, usagestatsservice_v2.proto = mwachens@google.com
+per-file apphibernationservice.proto = file:/core/java/android/apphibernation/OWNERS
 
 # Biometrics
 kchyn@google.com
diff --git a/core/proto/android/server/apphibernationservice.proto b/core/proto/android/server/apphibernationservice.proto
new file mode 100644
index 000000000000..d341c4b2f0a8
--- /dev/null
+++ b/core/proto/android/server/apphibernationservice.proto
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+syntax = "proto2";
+package com.android.server.apphibernation;
+
+option java_multiple_files = true;
+
+// Proto for hibernation states for all packages for a user.
+message UserLevelHibernationStatesProto {
+  repeated UserLevelHibernationStateProto hibernation_state = 1;
+}
+
+// Proto for com.android.server.apphibernation.UserLevelState.
+message UserLevelHibernationStateProto {
+  optional string package_name = 1;
+  optional bool hibernated = 2;
+}
+
+// Proto for global hibernation states for all packages.
+message GlobalLevelHibernationStatesProto {
+  repeated GlobalLevelHibernationStateProto hibernation_state = 1;
+}
+
+// Proto for com.android.server.apphibernation.GlobalLevelState
+message GlobalLevelHibernationStateProto {
+  optional string package_name = 1;
+  optional bool hibernated = 2;
+}
\ No newline at end of file
diff --git a/services/core/java/com/android/server/apphibernation/AppHibernationService.java b/services/core/java/com/android/server/apphibernation/AppHibernationService.java
index ef5e78f4179a..e97f0b47380a 100644
--- a/services/core/java/com/android/server/apphibernation/AppHibernationService.java
+++ b/services/core/java/com/android/server/apphibernation/AppHibernationService.java
@@ -20,7 +20,7 @@ import static android.content.Intent.ACTION_PACKAGE_ADDED;
 import static android.content.Intent.ACTION_PACKAGE_REMOVED;
 import static android.content.Intent.EXTRA_REMOVED_FOR_ALL_USERS;
 import static android.content.Intent.EXTRA_REPLACING;
-import static android.content.pm.PackageManager.MATCH_ALL;
+import static android.content.pm.PackageManager.MATCH_ANY_USER;
 import static android.provider.DeviceConfig.NAMESPACE_APP_HIBERNATION;
 
 import android.annotation.NonNull;
@@ -34,7 +34,9 @@ import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.IPackageManager;
 import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
 import android.os.Binder;
+import android.os.Environment;
 import android.os.RemoteException;
 import android.os.ResultReceiver;
 import android.os.ServiceManager;
@@ -52,10 +54,14 @@ import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.SystemService;
 
+import java.io.File;
 import java.io.FileDescriptor;
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
 
 /**
  * System service that manages app hibernation state, a state apps can enter that means they are
@@ -64,6 +70,11 @@ import java.util.Set;
  */
 public final class AppHibernationService extends SystemService {
     private static final String TAG = "AppHibernationService";
+    private static final int PACKAGE_MATCH_FLAGS =
+            PackageManager.MATCH_DIRECT_BOOT_AWARE
+                    | PackageManager.MATCH_DIRECT_BOOT_UNAWARE
+                    | PackageManager.MATCH_UNINSTALLED_PACKAGES
+                    | PackageManager.MATCH_DISABLED_COMPONENTS;
 
     /**
      * Lock for accessing any in-memory hibernation state
@@ -74,9 +85,13 @@ public final class AppHibernationService extends SystemService {
     private final IActivityManager mIActivityManager;
     private final UserManager mUserManager;
     @GuardedBy("mLock")
-    private final SparseArray<Map<String, UserPackageState>> mUserStates = new SparseArray<>();
+    private final SparseArray<Map<String, UserLevelState>> mUserStates = new SparseArray<>();
+    private final SparseArray<HibernationStateDiskStore<UserLevelState>> mUserDiskStores =
+            new SparseArray<>();
     @GuardedBy("mLock")
-    private final Set<String> mGloballyHibernatedPackages = new ArraySet<>();
+    private final Map<String, GlobalLevelState> mGlobalHibernationStates = new ArrayMap<>();
+    private final HibernationStateDiskStore<GlobalLevelState> mGlobalLevelHibernationDiskStore;
+    private final Injector mInjector;
 
     /**
      * Initializes the system service.
@@ -98,6 +113,8 @@ public final class AppHibernationService extends SystemService {
         mIPackageManager = injector.getPackageManager();
         mIActivityManager = injector.getActivityManager();
         mUserManager = injector.getUserManager();
+        mGlobalLevelHibernationDiskStore = injector.getGlobalLevelDiskStore();
+        mInjector = injector;
 
         final Context userAllContext = mContext.createContextAsUser(UserHandle.ALL, 0 /* flags */);
 
@@ -113,6 +130,17 @@ public final class AppHibernationService extends SystemService {
         publishBinderService(Context.APP_HIBERNATION_SERVICE, mServiceStub);
     }
 
+    @Override
+    public void onBootPhase(int phase) {
+        if (phase == PHASE_BOOT_COMPLETED) {
+            List<GlobalLevelState> states =
+                    mGlobalLevelHibernationDiskStore.readHibernationStates();
+            synchronized (mLock) {
+                initializeGlobalHibernationStates(states);
+            }
+        }
+    }
+
     /**
      * Whether a package is hibernating for a given user.
      *
@@ -128,8 +156,8 @@ public final class AppHibernationService extends SystemService {
             return false;
         }
         synchronized (mLock) {
-            final Map<String, UserPackageState> packageStates = mUserStates.get(userId);
-            final UserPackageState pkgState = packageStates.get(packageName);
+            final Map<String, UserLevelState> packageStates = mUserStates.get(userId);
+            final UserLevelState pkgState = packageStates.get(packageName);
             if (pkgState == null) {
                 throw new IllegalArgumentException(
                         String.format("Package %s is not installed for user %s",
@@ -147,7 +175,12 @@ public final class AppHibernationService extends SystemService {
      */
     boolean isHibernatingGlobally(String packageName) {
         synchronized (mLock) {
-            return mGloballyHibernatedPackages.contains(packageName);
+            GlobalLevelState state = mGlobalHibernationStates.get(packageName);
+            if (state == null) {
+                throw new IllegalArgumentException(
+                        String.format("Package %s is not installed", packageName));
+            }
+            return state.hibernated;
         }
     }
 
@@ -166,8 +199,8 @@ public final class AppHibernationService extends SystemService {
             return;
         }
         synchronized (mLock) {
-            Map<String, UserPackageState> packageStates = mUserStates.get(userId);
-            UserPackageState pkgState = packageStates.get(packageName);
+            final Map<String, UserLevelState> packageStates = mUserStates.get(userId);
+            final UserLevelState pkgState = packageStates.get(packageName);
             if (pkgState == null) {
                 throw new IllegalArgumentException(
                         String.format("Package %s is not installed for user %s",
@@ -183,6 +216,8 @@ public final class AppHibernationService extends SystemService {
             } else {
                 unhibernatePackageForUser(packageName, userId, pkgState);
             }
+            List<UserLevelState> states = new ArrayList<>(mUserStates.get(userId).values());
+            mUserDiskStores.get(userId).scheduleWriteHibernationStates(states);
         }
     }
 
@@ -194,13 +229,20 @@ public final class AppHibernationService extends SystemService {
      * @param isHibernating new hibernation state
      */
     void setHibernatingGlobally(String packageName, boolean isHibernating) {
-        if (isHibernating != mGloballyHibernatedPackages.contains(packageName)) {
-            synchronized (mLock) {
+        synchronized (mLock) {
+            GlobalLevelState state = mGlobalHibernationStates.get(packageName);
+            if (state == null) {
+                throw new IllegalArgumentException(
+                        String.format("Package %s is not installed for any user", packageName));
+            }
+            if (state.hibernated != isHibernating) {
                 if (isHibernating) {
-                    hibernatePackageGlobally(packageName);
+                    hibernatePackageGlobally(packageName, state);
                 } else {
-                    unhibernatePackageGlobally(packageName);
+                    unhibernatePackageGlobally(packageName, state);
                 }
+                List<GlobalLevelState> states = new ArrayList<>(mGlobalHibernationStates.values());
+                mGlobalLevelHibernationDiskStore.scheduleWriteHibernationStates(states);
             }
         }
     }
@@ -212,7 +254,7 @@ public final class AppHibernationService extends SystemService {
      */
     @GuardedBy("mLock")
     private void hibernatePackageForUser(@NonNull String packageName, int userId,
-            @NonNull UserPackageState pkgState) {
+            @NonNull UserLevelState pkgState) {
         Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "hibernatePackage");
         final long caller = Binder.clearCallingIdentity();
         try {
@@ -236,7 +278,7 @@ public final class AppHibernationService extends SystemService {
      */
     @GuardedBy("mLock")
     private void unhibernatePackageForUser(@NonNull String packageName, int userId,
-            UserPackageState pkgState) {
+            UserLevelState pkgState) {
         Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "unhibernatePackage");
         final long caller = Binder.clearCallingIdentity();
         try {
@@ -255,10 +297,10 @@ public final class AppHibernationService extends SystemService {
      * Put a package into global hibernation, optimizing its storage at a package / APK level.
      */
     @GuardedBy("mLock")
-    private void hibernatePackageGlobally(@NonNull String packageName) {
+    private void hibernatePackageGlobally(@NonNull String packageName, GlobalLevelState state) {
         Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "hibernatePackageGlobally");
         // TODO(175830194): Delete vdex/odex when DexManager API is built out
-        mGloballyHibernatedPackages.add(packageName);
+        state.hibernated = true;
         Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
     }
 
@@ -266,52 +308,127 @@ public final class AppHibernationService extends SystemService {
      * Unhibernate a package from global hibernation.
      */
     @GuardedBy("mLock")
-    private void unhibernatePackageGlobally(@NonNull String packageName) {
+    private void unhibernatePackageGlobally(@NonNull String packageName, GlobalLevelState state) {
         Trace.traceBegin(Trace.TRACE_TAG_SYSTEM_SERVER, "unhibernatePackageGlobally");
-        mGloballyHibernatedPackages.remove(packageName);
+        state.hibernated = false;
         Trace.traceEnd(Trace.TRACE_TAG_SYSTEM_SERVER);
     }
 
     /**
-     * Populates {@link #mUserStates} with the users installed packages.
+     * Initializes in-memory store of user-level hibernation states for the given user
      *
      * @param userId user id to add installed packages for
+     * @param diskStates states pulled from disk, if available
+     */
+    @GuardedBy("mLock")
+    private void initializeUserHibernationStates(int userId,
+            @Nullable List<UserLevelState> diskStates) {
+        List<PackageInfo> packages;
+        try {
+            packages = mIPackageManager.getInstalledPackages(PACKAGE_MATCH_FLAGS, userId).getList();
+        } catch (RemoteException e) {
+            throw new IllegalStateException("Package manager not available", e);
+        }
+
+        Map<String, UserLevelState> userLevelStates = new ArrayMap<>();
+
+        for (int i = 0, size = packages.size(); i < size; i++) {
+            String packageName = packages.get(i).packageName;
+            UserLevelState state = new UserLevelState();
+            state.packageName = packageName;
+            userLevelStates.put(packageName, state);
+        }
+
+        if (diskStates != null) {
+            Set<String> installedPackages = new ArraySet<>();
+            for (int i = 0, size = packages.size(); i < size; i++) {
+                installedPackages.add(packages.get(i).packageName);
+            }
+            for (int i = 0, size = diskStates.size(); i < size; i++) {
+                String packageName = diskStates.get(i).packageName;
+                if (!installedPackages.contains(packageName)) {
+                    Slog.w(TAG, String.format(
+                            "No hibernation state associated with package %s user %d. Maybe"
+                                    + "the package was uninstalled? ", packageName, userId));
+                    continue;
+                }
+                userLevelStates.put(packageName, diskStates.get(i));
+            }
+        }
+        mUserStates.put(userId, userLevelStates);
+    }
+
+    /**
+     * Initialize in-memory store of global level hibernation states.
+     *
+     * @param diskStates global level hibernation states pulled from disk, if available
      */
     @GuardedBy("mLock")
-    private void addUserPackageStates(int userId) {
-        Map<String, UserPackageState> packages = new ArrayMap<>();
-        List<PackageInfo> packageList;
+    private void initializeGlobalHibernationStates(@Nullable List<GlobalLevelState> diskStates) {
+        List<PackageInfo> packages;
         try {
-            packageList = mIPackageManager.getInstalledPackages(MATCH_ALL, userId).getList();
+            packages = mIPackageManager.getInstalledPackages(
+                    PACKAGE_MATCH_FLAGS | MATCH_ANY_USER, 0 /* userId */).getList();
         } catch (RemoteException e) {
-            throw new IllegalStateException("Package manager not available.", e);
+            throw new IllegalStateException("Package manager not available", e);
         }
 
-        for (int i = 0, size = packageList.size(); i < size; i++) {
-            packages.put(packageList.get(i).packageName, new UserPackageState());
+        for (int i = 0, size = packages.size(); i < size; i++) {
+            String packageName = packages.get(i).packageName;
+            GlobalLevelState state = new GlobalLevelState();
+            state.packageName = packageName;
+            mGlobalHibernationStates.put(packageName, state);
+        }
+        if (diskStates != null) {
+            Set<String> installedPackages = new ArraySet<>();
+            for (int i = 0, size = packages.size(); i < size; i++) {
+                installedPackages.add(packages.get(i).packageName);
+            }
+            for (int i = 0, size = diskStates.size(); i < size; i++) {
+                GlobalLevelState state = diskStates.get(i);
+                if (!installedPackages.contains(state.packageName)) {
+                    Slog.w(TAG, String.format(
+                            "No hibernation state associated with package %s. Maybe the "
+                                    + "package was uninstalled? ", state.packageName));
+                    continue;
+                }
+                mGlobalHibernationStates.put(state.packageName, state);
+            }
         }
-        mUserStates.put(userId, packages);
     }
 
     @Override
     public void onUserUnlocking(@NonNull TargetUser user) {
-        // TODO: Pull from persistent disk storage. For now, just make from scratch.
+        int userId = user.getUserIdentifier();
+        HibernationStateDiskStore<UserLevelState> diskStore =
+                mInjector.getUserLevelDiskStore(userId);
+        mUserDiskStores.put(userId, diskStore);
+        List<UserLevelState> storedStates = diskStore.readHibernationStates();
         synchronized (mLock) {
-            addUserPackageStates(user.getUserIdentifier());
+            initializeUserHibernationStates(userId, storedStates);
         }
     }
 
     @Override
     public void onUserStopping(@NonNull TargetUser user) {
+        int userId = user.getUserIdentifier();
+        // TODO: Flush any scheduled writes to disk immediately on user stopping / power off.
         synchronized (mLock) {
-            // TODO: Flush to disk when persistence is implemented
-            mUserStates.remove(user.getUserIdentifier());
+            mUserDiskStores.remove(userId);
+            mUserStates.remove(userId);
         }
     }
 
     private void onPackageAdded(@NonNull String packageName, int userId) {
         synchronized (mLock) {
-            mUserStates.get(userId).put(packageName, new UserPackageState());
+            UserLevelState userState = new UserLevelState();
+            userState.packageName = packageName;
+            mUserStates.get(userId).put(packageName, userState);
+            if (!mGlobalHibernationStates.containsKey(packageName)) {
+                GlobalLevelState globalState = new GlobalLevelState();
+                globalState.packageName = packageName;
+                mGlobalHibernationStates.put(packageName, globalState);
+            }
         }
     }
 
@@ -323,7 +440,7 @@ public final class AppHibernationService extends SystemService {
 
     private void onPackageRemovedForAllUsers(@NonNull String packageName) {
         synchronized (mLock) {
-            mGloballyHibernatedPackages.remove(packageName);
+            mGlobalHibernationStates.remove(packageName);
         }
     }
 
@@ -424,14 +541,6 @@ public final class AppHibernationService extends SystemService {
     }
 
     /**
-     * Data class that contains hibernation state info of a package for a user.
-     */
-    private static final class UserPackageState {
-        public boolean hibernated;
-        // TODO: Track whether hibernation is exempted by the user
-    }
-
-    /**
      * Dependency injector for {@link #AppHibernationService)}.
      */
     interface Injector {
@@ -442,13 +551,22 @@ public final class AppHibernationService extends SystemService {
         IActivityManager getActivityManager();
 
         UserManager getUserManager();
+
+        HibernationStateDiskStore<GlobalLevelState> getGlobalLevelDiskStore();
+
+        HibernationStateDiskStore<UserLevelState> getUserLevelDiskStore(int userId);
     }
 
     private static final class InjectorImpl implements Injector {
+        private static final String HIBERNATION_DIR_NAME = "hibernation";
         private final Context mContext;
+        private final ScheduledExecutorService mScheduledExecutorService;
+        private final UserLevelHibernationProto mUserLevelHibernationProto;
 
         InjectorImpl(Context context) {
             mContext = context;
+            mScheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
+            mUserLevelHibernationProto = new UserLevelHibernationProto();
         }
 
         @Override
@@ -470,5 +588,19 @@ public final class AppHibernationService extends SystemService {
         public UserManager getUserManager() {
             return mContext.getSystemService(UserManager.class);
         }
+
+        @Override
+        public HibernationStateDiskStore<GlobalLevelState> getGlobalLevelDiskStore() {
+            File dir = new File(Environment.getDataSystemDirectory(), HIBERNATION_DIR_NAME);
+            return new HibernationStateDiskStore<>(
+                    dir, new GlobalLevelHibernationProto(), mScheduledExecutorService);
+        }
+
+        @Override
+        public HibernationStateDiskStore<UserLevelState> getUserLevelDiskStore(int userId) {
+            File dir = new File(Environment.getDataSystemCeDirectory(userId), HIBERNATION_DIR_NAME);
+            return new HibernationStateDiskStore<>(
+                    dir, mUserLevelHibernationProto, mScheduledExecutorService);
+        }
     }
 }
diff --git a/services/core/java/com/android/server/apphibernation/GlobalLevelHibernationProto.java b/services/core/java/com/android/server/apphibernation/GlobalLevelHibernationProto.java
new file mode 100644
index 000000000000..79e995b038fa
--- /dev/null
+++ b/services/core/java/com/android/server/apphibernation/GlobalLevelHibernationProto.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.util.Slog;
+import android.util.proto.ProtoInputStream;
+import android.util.proto.ProtoOutputStream;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Reads and writes protos for {@link GlobalLevelState} hiberation states.
+ */
+final class GlobalLevelHibernationProto implements ProtoReadWriter<List<GlobalLevelState>> {
+    private static final String TAG = "GlobalLevelHibernationProtoReadWriter";
+
+    @Override
+    public void writeToProto(@NonNull ProtoOutputStream stream,
+            @NonNull List<GlobalLevelState> data) {
+        for (int i = 0, size = data.size(); i < size; i++) {
+            long token = stream.start(GlobalLevelHibernationStatesProto.HIBERNATION_STATE);
+            GlobalLevelState state = data.get(i);
+            stream.write(GlobalLevelHibernationStateProto.PACKAGE_NAME, state.packageName);
+            stream.write(GlobalLevelHibernationStateProto.HIBERNATED, state.hibernated);
+            stream.end(token);
+        }
+    }
+
+    @Override
+    public @Nullable List<GlobalLevelState> readFromProto(@NonNull ProtoInputStream stream)
+            throws IOException {
+        List<GlobalLevelState> list = new ArrayList<>();
+        while (stream.nextField() != ProtoInputStream.NO_MORE_FIELDS) {
+            if (stream.getFieldNumber()
+                    != (int) GlobalLevelHibernationStatesProto.HIBERNATION_STATE) {
+                continue;
+            }
+            GlobalLevelState state = new GlobalLevelState();
+            long token = stream.start(GlobalLevelHibernationStatesProto.HIBERNATION_STATE);
+            while (stream.nextField() != ProtoInputStream.NO_MORE_FIELDS) {
+                switch (stream.getFieldNumber()) {
+                    case (int) GlobalLevelHibernationStateProto.PACKAGE_NAME:
+                        state.packageName =
+                                stream.readString(GlobalLevelHibernationStateProto.PACKAGE_NAME);
+                        break;
+                    case (int) GlobalLevelHibernationStateProto.HIBERNATED:
+                        state.hibernated =
+                                stream.readBoolean(GlobalLevelHibernationStateProto.HIBERNATED);
+                        break;
+                    default:
+                        Slog.w(TAG, "Undefined field in proto: " + stream.getFieldNumber());
+                }
+            }
+            stream.end(token);
+            list.add(state);
+        }
+        return list;
+    }
+}
diff --git a/services/core/java/com/android/server/apphibernation/GlobalLevelState.java b/services/core/java/com/android/server/apphibernation/GlobalLevelState.java
new file mode 100644
index 000000000000..4f756756c2ab
--- /dev/null
+++ b/services/core/java/com/android/server/apphibernation/GlobalLevelState.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+/**
+ * Data class that contains global hibernation state for a package.
+ */
+final class GlobalLevelState {
+    public String packageName;
+    public boolean hibernated;
+}
diff --git a/services/core/java/com/android/server/apphibernation/HibernationStateDiskStore.java b/services/core/java/com/android/server/apphibernation/HibernationStateDiskStore.java
new file mode 100644
index 000000000000..c83659d2ff56
--- /dev/null
+++ b/services/core/java/com/android/server/apphibernation/HibernationStateDiskStore.java
@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.annotation.WorkerThread;
+import android.text.format.DateUtils;
+import android.util.AtomicFile;
+import android.util.Slog;
+import android.util.proto.ProtoInputStream;
+import android.util.proto.ProtoOutputStream;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Disk store utility class for hibernation states.
+ *
+ * @param <T> the type of hibernation state data
+ */
+class HibernationStateDiskStore<T> {
+    private static final String TAG = "HibernationStateDiskStore";
+
+    // Time to wait before actually writing. Saves extra writes if data changes come in batches.
+    private static final long DISK_WRITE_DELAY = 1L * DateUtils.MINUTE_IN_MILLIS;
+    private static final String STATES_FILE_NAME = "states";
+
+    private final File mHibernationFile;
+    private final ScheduledExecutorService mExecutorService;
+    private final ProtoReadWriter<List<T>> mProtoReadWriter;
+    private List<T> mScheduledStatesToWrite = new ArrayList<>();
+    private ScheduledFuture<?> mFuture;
+
+    /**
+     * Initialize a disk store for hibernation states in the given directory.
+     *
+     * @param hibernationDir directory to write/read states file
+     * @param readWriter writer/reader of states proto
+     * @param executorService scheduled executor for writing data
+     */
+    HibernationStateDiskStore(@NonNull File hibernationDir,
+            @NonNull ProtoReadWriter<List<T>> readWriter,
+            @NonNull ScheduledExecutorService executorService) {
+        this(hibernationDir, readWriter, executorService, STATES_FILE_NAME);
+    }
+
+    @VisibleForTesting
+    HibernationStateDiskStore(@NonNull File hibernationDir,
+            @NonNull ProtoReadWriter<List<T>> readWriter,
+            @NonNull ScheduledExecutorService executorService,
+            @NonNull String fileName) {
+        mHibernationFile = new File(hibernationDir, fileName);
+        mExecutorService = executorService;
+        mProtoReadWriter = readWriter;
+    }
+
+    /**
+     * Schedule a full write of all the hibernation states to the file on disk. Does not run
+     * immediately and subsequent writes override previous ones.
+     *
+     * @param hibernationStates list of hibernation states to write to disk
+     */
+    void scheduleWriteHibernationStates(@NonNull List<T> hibernationStates) {
+        synchronized (this) {
+            mScheduledStatesToWrite = hibernationStates;
+            if (mExecutorService.isShutdown()) {
+                Slog.e(TAG, "Scheduled executor service is shut down.");
+                return;
+            }
+
+            // Already have write scheduled
+            if (mFuture != null) {
+                Slog.i(TAG, "Write already scheduled. Skipping schedule.");
+                return;
+            }
+
+            mFuture = mExecutorService.schedule(this::writeHibernationStates, DISK_WRITE_DELAY,
+                    TimeUnit.MILLISECONDS);
+        }
+    }
+
+    /**
+     * Read hibernation states from disk.
+     *
+     * @return the parsed list of hibernation states, null if file does not exist
+     */
+    @Nullable
+    List<T> readHibernationStates() {
+        synchronized (this) {
+            if (!mHibernationFile.exists()) {
+                Slog.i(TAG, "No hibernation file on disk for file " + mHibernationFile.getPath());
+                return null;
+            }
+            AtomicFile atomicFile = new AtomicFile(mHibernationFile);
+
+            try {
+                FileInputStream inputStream = atomicFile.openRead();
+                ProtoInputStream protoInputStream = new ProtoInputStream(inputStream);
+                return mProtoReadWriter.readFromProto(protoInputStream);
+            } catch (IOException e) {
+                Slog.e(TAG, "Failed to read states protobuf.", e);
+                return null;
+            }
+        }
+    }
+
+    @WorkerThread
+    private void writeHibernationStates() {
+        synchronized (this) {
+            writeStateProto(mScheduledStatesToWrite);
+            mScheduledStatesToWrite.clear();
+            mFuture = null;
+        }
+    }
+
+    @WorkerThread
+    private void writeStateProto(List<T> states) {
+        AtomicFile atomicFile = new AtomicFile(mHibernationFile);
+
+        FileOutputStream fileOutputStream;
+        try {
+            fileOutputStream = atomicFile.startWrite();
+        } catch (IOException e) {
+            Slog.e(TAG, "Failed to start write to states protobuf.", e);
+            return;
+        }
+
+        try {
+            ProtoOutputStream protoOutputStream = new ProtoOutputStream(fileOutputStream);
+            mProtoReadWriter.writeToProto(protoOutputStream, states);
+            protoOutputStream.flush();
+            atomicFile.finishWrite(fileOutputStream);
+        } catch (Exception e) {
+            Slog.e(TAG, "Failed to finish write to states protobuf.", e);
+            atomicFile.failWrite(fileOutputStream);
+        }
+    }
+}
diff --git a/services/core/java/com/android/server/apphibernation/ProtoReadWriter.java b/services/core/java/com/android/server/apphibernation/ProtoReadWriter.java
new file mode 100644
index 000000000000..0cbc09a7a99d
--- /dev/null
+++ b/services/core/java/com/android/server/apphibernation/ProtoReadWriter.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.util.proto.ProtoInputStream;
+import android.util.proto.ProtoOutputStream;
+
+import java.io.IOException;
+
+/**
+ * Proto utility that reads and writes proto for some data.
+ *
+ * @param <T> data that can be written and read from a proto
+ */
+interface ProtoReadWriter<T> {
+
+    /**
+     * Write data to a proto stream
+     */
+    void writeToProto(@NonNull ProtoOutputStream stream, @NonNull T data);
+
+    /**
+     * Parse data from the proto stream and return
+     */
+    @Nullable T readFromProto(@NonNull ProtoInputStream stream) throws IOException;
+}
diff --git a/services/core/java/com/android/server/apphibernation/UserLevelHibernationProto.java b/services/core/java/com/android/server/apphibernation/UserLevelHibernationProto.java
new file mode 100644
index 000000000000..a24c4c575975
--- /dev/null
+++ b/services/core/java/com/android/server/apphibernation/UserLevelHibernationProto.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.util.Slog;
+import android.util.proto.ProtoInputStream;
+import android.util.proto.ProtoOutputStream;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Reads and writes protos for {@link UserLevelState} hiberation states.
+ */
+final class UserLevelHibernationProto implements ProtoReadWriter<List<UserLevelState>> {
+    private static final String TAG = "UserLevelHibernationProtoReadWriter";
+
+    @Override
+    public void writeToProto(@NonNull ProtoOutputStream stream,
+            @NonNull List<UserLevelState> data) {
+        for (int i = 0, size = data.size(); i < size; i++) {
+            long token = stream.start(UserLevelHibernationStatesProto.HIBERNATION_STATE);
+            UserLevelState state = data.get(i);
+            stream.write(UserLevelHibernationStateProto.PACKAGE_NAME, state.packageName);
+            stream.write(UserLevelHibernationStateProto.HIBERNATED, state.hibernated);
+            stream.end(token);
+        }
+    }
+
+    @Override
+    public @Nullable List<UserLevelState> readFromProto(@NonNull ProtoInputStream stream)
+            throws IOException {
+        List<UserLevelState> list = new ArrayList<>();
+        while (stream.nextField() != ProtoInputStream.NO_MORE_FIELDS) {
+            if (stream.getFieldNumber()
+                    != (int) UserLevelHibernationStatesProto.HIBERNATION_STATE) {
+                continue;
+            }
+            UserLevelState state = new UserLevelState();
+            long token = stream.start(UserLevelHibernationStatesProto.HIBERNATION_STATE);
+            while (stream.nextField() != ProtoInputStream.NO_MORE_FIELDS) {
+                switch (stream.getFieldNumber()) {
+                    case (int) UserLevelHibernationStateProto.PACKAGE_NAME:
+                        state.packageName =
+                                stream.readString(UserLevelHibernationStateProto.PACKAGE_NAME);
+                        break;
+                    case (int) UserLevelHibernationStateProto.HIBERNATED:
+                        state.hibernated =
+                                stream.readBoolean(UserLevelHibernationStateProto.HIBERNATED);
+                        break;
+                    default:
+                        Slog.w(TAG, "Undefined field in proto: " + stream.getFieldNumber());
+                }
+            }
+            stream.end(token);
+            list.add(state);
+        }
+        return list;
+    }
+}
diff --git a/services/core/java/com/android/server/apphibernation/UserLevelState.java b/services/core/java/com/android/server/apphibernation/UserLevelState.java
new file mode 100644
index 000000000000..c66dad87c891
--- /dev/null
+++ b/services/core/java/com/android/server/apphibernation/UserLevelState.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+/**
+ * Data class that contains hibernation state info of a package for a user.
+ */
+final class UserLevelState {
+    public String packageName;
+    public boolean hibernated;
+}
diff --git a/services/tests/servicestests/src/com/android/server/apphibernation/AppHibernationServiceTest.java b/services/tests/servicestests/src/com/android/server/apphibernation/AppHibernationServiceTest.java
index f2e09984728f..1328b91d03f9 100644
--- a/services/tests/servicestests/src/com/android/server/apphibernation/AppHibernationServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/apphibernation/AppHibernationServiceTest.java
@@ -16,12 +16,15 @@
 
 package com.android.server.apphibernation;
 
+import static android.content.pm.PackageManager.MATCH_ANY_USER;
+
 import static org.junit.Assert.assertTrue;
 import static org.mockito.AdditionalAnswers.returnsArgAt;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.ArgumentMatchers.intThat;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.verify;
@@ -47,6 +50,7 @@ import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 import org.mockito.Captor;
 import org.mockito.Mock;
+import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
 
 import java.util.ArrayList;
@@ -75,11 +79,15 @@ public final class AppHibernationServiceTest {
     private IActivityManager mIActivityManager;
     @Mock
     private UserManager mUserManager;
+    @Mock
+    private HibernationStateDiskStore<UserLevelState> mHibernationStateDiskStore;
     @Captor
     private ArgumentCaptor<BroadcastReceiver> mReceiverCaptor;
 
     @Before
     public void setUp() throws RemoteException {
+        // Share class loader to allow access to package-private classes
+        System.setProperty("dexmaker.share_classloader", "true");
         MockitoAnnotations.initMocks(this);
         doReturn(mContext).when(mContext).createContextAsUser(any(), anyInt());
 
@@ -93,6 +101,12 @@ public final class AppHibernationServiceTest {
         doAnswer(returnsArgAt(2)).when(mIActivityManager).handleIncomingUser(anyInt(), anyInt(),
                 anyInt(), anyBoolean(), anyBoolean(), any(), any());
 
+        List<PackageInfo> packages = new ArrayList<>();
+        packages.add(makePackageInfo(PACKAGE_NAME_1));
+        doReturn(new ParceledListSlice<>(packages)).when(mIPackageManager).getInstalledPackages(
+                intThat(arg -> (arg & MATCH_ANY_USER) != 0), anyInt());
+        mAppHibernationService.onBootPhase(SystemService.PHASE_BOOT_COMPLETED);
+
         UserInfo userInfo = addUser(USER_ID_1);
         mAppHibernationService.onUserUnlocking(new SystemService.TargetUser(userInfo));
         doReturn(true).when(mUserManager).isUserUnlockingOrUnlocked(USER_ID_1);
@@ -151,7 +165,7 @@ public final class AppHibernationServiceTest {
     }
 
     @Test
-    public void testSetHibernatingGlobally_packageIsHibernatingGlobally() {
+    public void testSetHibernatingGlobally_packageIsHibernatingGlobally() throws RemoteException {
         // WHEN we hibernate a package
         mAppHibernationService.setHibernatingGlobally(PACKAGE_NAME_1, true);
 
@@ -177,7 +191,7 @@ public final class AppHibernationServiceTest {
             userPackages.add(makePackageInfo(pkgName));
         }
         doReturn(new ParceledListSlice<>(userPackages)).when(mIPackageManager)
-                .getInstalledPackages(anyInt(), eq(userId));
+                .getInstalledPackages(intThat(arg -> (arg & MATCH_ANY_USER) == 0), eq(userId));
         return userInfo;
     }
 
@@ -213,5 +227,15 @@ public final class AppHibernationServiceTest {
         public UserManager getUserManager() {
             return mUserManager;
         }
+
+        @Override
+        public HibernationStateDiskStore<GlobalLevelState> getGlobalLevelDiskStore() {
+            return Mockito.mock(HibernationStateDiskStore.class);
+        }
+
+        @Override
+        public HibernationStateDiskStore<UserLevelState> getUserLevelDiskStore(int userId) {
+            return Mockito.mock(HibernationStateDiskStore.class);
+        }
     }
 }
diff --git a/services/tests/servicestests/src/com/android/server/apphibernation/HibernationStateDiskStoreTest.java b/services/tests/servicestests/src/com/android/server/apphibernation/HibernationStateDiskStoreTest.java
new file mode 100644
index 000000000000..59f3c35f2137
--- /dev/null
+++ b/services/tests/servicestests/src/com/android/server/apphibernation/HibernationStateDiskStoreTest.java
@@ -0,0 +1,236 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.apphibernation;
+
+import static org.junit.Assert.assertEquals;
+
+import android.os.FileUtils;
+import android.util.proto.ProtoInputStream;
+import android.util.proto.ProtoOutputStream;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.test.InstrumentationRegistry;
+import androidx.test.filters.SmallTest;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.Mockito;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+
+@SmallTest
+public class HibernationStateDiskStoreTest {
+    private static final String STATES_FILE_NAME = "states";
+    private final MockScheduledExecutorService mMockScheduledExecutorService =
+            new MockScheduledExecutorService();
+
+    private File mFile;
+    private HibernationStateDiskStore<String> mHibernationStateDiskStore;
+
+
+    @Before
+    public void setUp() {
+        mFile = new File(InstrumentationRegistry.getContext().getCacheDir(), "test");
+        mHibernationStateDiskStore = new HibernationStateDiskStore<>(mFile,
+                new MockProtoReadWriter(), mMockScheduledExecutorService, STATES_FILE_NAME);
+    }
+
+    @After
+    public void tearDown() {
+        FileUtils.deleteContentsAndDir(mFile);
+    }
+
+    @Test
+    public void testScheduleWriteHibernationStates_writesDataThatCanBeRead() {
+        // GIVEN some data to be written
+        List<String> toWrite = new ArrayList<>(Arrays.asList("A", "B"));
+
+        // WHEN the data is written
+        mHibernationStateDiskStore.scheduleWriteHibernationStates(toWrite);
+        mMockScheduledExecutorService.executeScheduledTask();
+
+        // THEN the read data is equal to what was written
+        List<String> storedStrings = mHibernationStateDiskStore.readHibernationStates();
+        for (int i = 0; i < toWrite.size(); i++) {
+            assertEquals(toWrite.get(i), storedStrings.get(i));
+        }
+    }
+
+    @Test
+    public void testScheduleWriteHibernationStates_laterWritesOverwritePrevious() {
+        // GIVEN store has some data it is scheduled to write
+        mHibernationStateDiskStore.scheduleWriteHibernationStates(
+                new ArrayList<>(Arrays.asList("C", "D")));
+
+        // WHEN a write is scheduled with new data
+        List<String> toWrite = new ArrayList<>(Arrays.asList("A", "B"));
+        mHibernationStateDiskStore.scheduleWriteHibernationStates(toWrite);
+        mMockScheduledExecutorService.executeScheduledTask();
+
+        // THEN the written data is the last scheduled data
+        List<String> storedStrings = mHibernationStateDiskStore.readHibernationStates();
+        for (int i = 0; i < toWrite.size(); i++) {
+            assertEquals(toWrite.get(i), storedStrings.get(i));
+        }
+    }
+
+    /**
+     * Mock proto read / writer that just writes and reads a list of String data.
+     */
+    private final class MockProtoReadWriter implements ProtoReadWriter<List<String>> {
+        private static final long FIELD_ID = 1;
+
+        @Override
+        public void writeToProto(@NonNull ProtoOutputStream stream,
+                @NonNull List<String> data) {
+            for (int i = 0, size = data.size(); i < size; i++) {
+                stream.write(FIELD_ID, data.get(i));
+            }
+        }
+
+        @Nullable
+        @Override
+        public List<String> readFromProto(@NonNull ProtoInputStream stream)
+                throws IOException {
+            ArrayList<String> list = new ArrayList<>();
+            while (stream.nextField() != ProtoInputStream.NO_MORE_FIELDS) {
+                list.add(stream.readString(FIELD_ID));
+            }
+            return list;
+        }
+    }
+
+    /**
+     * Mock scheduled executor service that has minimum implementation and can synchronously
+     * execute scheduled tasks.
+     */
+    private final class MockScheduledExecutorService implements ScheduledExecutorService {
+
+        Runnable mScheduledRunnable = null;
+
+        @Override
+        public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
+            mScheduledRunnable = command;
+            return Mockito.mock(ScheduledFuture.class);
+        }
+
+        @Override
+        public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay,
+                long period, TimeUnit unit) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay,
+                long delay, TimeUnit unit) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public void shutdown() {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public List<Runnable> shutdownNow() {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public boolean isShutdown() {
+            return false;
+        }
+
+        @Override
+        public boolean isTerminated() {
+            return false;
+        }
+
+        @Override
+        public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public <T> Future<T> submit(Callable<T> task) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public <T> Future<T> submit(Runnable task, T result) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public Future<?> submit(Runnable task) {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
+                throws InterruptedException {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout,
+                TimeUnit unit) throws InterruptedException {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
+                throws InterruptedException, ExecutionException {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
+                throws InterruptedException, ExecutionException, TimeoutException {
+            throw new UnsupportedOperationException();
+        }
+
+        @Override
+        public void execute(Runnable command) {
+            throw new UnsupportedOperationException();
+        }
+
+        void executeScheduledTask() {
+            mScheduledRunnable.run();
+        }
+    }
+}