1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.providers.settings; 18 19 import android.os.Bundle; 20 import android.os.UserManager; 21 import android.provider.Settings; 22 import android.util.MemoryIntArray; 23 import android.util.Slog; 24 import android.util.SparseIntArray; 25 import com.android.internal.annotations.GuardedBy; 26 27 import java.io.IOException; 28 29 /** 30 * This class tracks changes for global/secure/system tables on a 31 * per user basis and updates a shared memory region which client 32 * processes can read to determine if their local caches are stale, 33 */ 34 final class GenerationRegistry { 35 private static final String LOG_TAG = "GenerationTracker"; 36 37 private static final boolean DEBUG = false; 38 39 private final Object mLock; 40 41 @GuardedBy("mLock") 42 private final SparseIntArray mKeyToIndexMap = new SparseIntArray(); 43 44 @GuardedBy("mLock") 45 private MemoryIntArray mBackingStore; 46 GenerationRegistry(Object lock)47 public GenerationRegistry(Object lock) { 48 mLock = lock; 49 } 50 incrementGeneration(int key)51 public void incrementGeneration(int key) { 52 synchronized (mLock) { 53 MemoryIntArray backingStore = getBackingStoreLocked(); 54 if (backingStore != null) { 55 try { 56 final int index = getKeyIndexLocked(key, mKeyToIndexMap, backingStore); 57 if (index >= 0) { 58 final int generation = backingStore.get(index) + 1; 59 backingStore.set(index, generation); 60 } 61 } catch (IOException e) { 62 Slog.e(LOG_TAG, "Error updating generation id", e); 63 destroyBackingStore(); 64 } 65 } 66 } 67 } 68 addGenerationData(Bundle bundle, int key)69 public void addGenerationData(Bundle bundle, int key) { 70 synchronized (mLock) { 71 MemoryIntArray backingStore = getBackingStoreLocked(); 72 try { 73 if (backingStore != null) { 74 final int index = getKeyIndexLocked(key, mKeyToIndexMap, backingStore); 75 if (index >= 0) { 76 bundle.putParcelable(Settings.CALL_METHOD_TRACK_GENERATION_KEY, 77 backingStore); 78 bundle.putInt(Settings.CALL_METHOD_GENERATION_INDEX_KEY, index); 79 bundle.putInt(Settings.CALL_METHOD_GENERATION_KEY, 80 backingStore.get(index)); 81 if (DEBUG) { 82 Slog.i(LOG_TAG, "Exported index:" + index + " for key:" 83 + SettingsProvider.keyToString(key)); 84 } 85 } 86 } 87 } catch (IOException e) { 88 Slog.e(LOG_TAG, "Error adding generation data", e); 89 destroyBackingStore(); 90 } 91 } 92 } 93 onUserRemoved(int userId)94 public void onUserRemoved(int userId) { 95 synchronized (mLock) { 96 MemoryIntArray backingStore = getBackingStoreLocked(); 97 if (backingStore != null && mKeyToIndexMap.size() > 0) { 98 try { 99 final int secureKey = SettingsProvider.makeKey( 100 SettingsProvider.SETTINGS_TYPE_SECURE, userId); 101 resetSlotForKeyLocked(secureKey, mKeyToIndexMap, backingStore); 102 103 final int systemKey = SettingsProvider.makeKey( 104 SettingsProvider.SETTINGS_TYPE_SYSTEM, userId); 105 resetSlotForKeyLocked(systemKey, mKeyToIndexMap, backingStore); 106 } catch (IOException e) { 107 Slog.e(LOG_TAG, "Error cleaning up for user", e); 108 destroyBackingStore(); 109 } 110 } 111 } 112 } 113 getBackingStoreLocked()114 private MemoryIntArray getBackingStoreLocked() { 115 if (mBackingStore == null) { 116 // One for the global table, two for system and secure tables for a 117 // managed profile (managed profile is not included in the max user 118 // count), ten for partially deleted users if users are quickly removed, 119 // and twice max user count for system and secure. 120 final int size = 1 + 2 + 10 + 2 * UserManager.getMaxSupportedUsers(); 121 try { 122 mBackingStore = new MemoryIntArray(size, false); 123 } catch (IOException e) { 124 Slog.e(LOG_TAG, "Error creating generation tracker", e); 125 } 126 } 127 return mBackingStore; 128 } 129 destroyBackingStore()130 private void destroyBackingStore() { 131 if (mBackingStore != null) { 132 try { 133 mBackingStore.close(); 134 } catch (IOException e) { 135 Slog.e(LOG_TAG, "Cannot close generation memory array", e); 136 } 137 mBackingStore = null; 138 } 139 } 140 resetSlotForKeyLocked(int key, SparseIntArray keyToIndexMap, MemoryIntArray backingStore)141 private static void resetSlotForKeyLocked(int key, SparseIntArray keyToIndexMap, 142 MemoryIntArray backingStore) throws IOException { 143 final int index = keyToIndexMap.get(key, -1); 144 if (index >= 0) { 145 keyToIndexMap.delete(key); 146 backingStore.set(index, 0); 147 if (DEBUG) { 148 Slog.i(LOG_TAG, "Freed index:" + index + " for key:" 149 + SettingsProvider.keyToString(key)); 150 } 151 } 152 } 153 getKeyIndexLocked(int key, SparseIntArray keyToIndexMap, MemoryIntArray backingStore)154 private static int getKeyIndexLocked(int key, SparseIntArray keyToIndexMap, 155 MemoryIntArray backingStore) throws IOException { 156 int index = keyToIndexMap.get(key, -1); 157 if (index < 0) { 158 index = findNextEmptyIndex(backingStore); 159 if (index >= 0) { 160 backingStore.set(index, 1); 161 keyToIndexMap.append(key, index); 162 if (DEBUG) { 163 Slog.i(LOG_TAG, "Allocated index:" + index + " for key:" 164 + SettingsProvider.keyToString(key)); 165 } 166 } else { 167 Slog.e(LOG_TAG, "Could not allocate generation index"); 168 } 169 } 170 return index; 171 } 172 findNextEmptyIndex(MemoryIntArray backingStore)173 private static int findNextEmptyIndex(MemoryIntArray backingStore) throws IOException { 174 final int size = backingStore.size(); 175 for (int i = 0; i < size; i++) { 176 if (backingStore.get(i) == 0) { 177 return i; 178 } 179 } 180 return -1; 181 } 182 }