SettingsState.java revision 2849465ee19febd5135cb6ab8cb548a3c8ac6a24
1/* 2 * Copyright (C) 2015 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 17package com.android.providers.settings; 18 19import android.os.Handler; 20import android.os.Message; 21import android.os.SystemClock; 22import android.provider.Settings; 23import android.text.TextUtils; 24import android.util.ArrayMap; 25import android.util.AtomicFile; 26import android.util.Slog; 27import android.util.Xml; 28import com.android.internal.annotations.GuardedBy; 29import com.android.internal.os.BackgroundThread; 30import libcore.io.IoUtils; 31import libcore.util.Objects; 32import org.xmlpull.v1.XmlPullParser; 33import org.xmlpull.v1.XmlPullParserException; 34import org.xmlpull.v1.XmlSerializer; 35 36import java.io.File; 37import java.io.FileInputStream; 38import java.io.FileNotFoundException; 39import java.io.FileOutputStream; 40import java.io.IOException; 41import java.util.ArrayList; 42import java.util.List; 43 44/** 45 * This class contains the state for one type of settings. It is responsible 46 * for saving the state asynchronously to an XML file after a mutation and 47 * loading the from an XML file on construction. 48 * <p> 49 * This class uses the same lock as the settings provider to ensure that 50 * multiple changes made by the settings provider, e,g, upgrade, bulk insert, 51 * etc, are atomically persisted since the asynchronous persistence is using 52 * the same lock to grab the current state to write to disk. 53 * </p> 54 */ 55final class SettingsState { 56 private static final boolean DEBUG = false; 57 private static final boolean DEBUG_PERSISTENCE = false; 58 59 private static final String LOG_TAG = "SettingsState"; 60 61 private static final long WRITE_SETTINGS_DELAY_MILLIS = 200; 62 private static final long MAX_WRITE_SETTINGS_DELAY_MILLIS = 2000; 63 64 public static final int MAX_BYTES_PER_APP_PACKAGE_UNLIMITED = -1; 65 public static final int MAX_BYTES_PER_APP_PACKAGE_LIMITED = 20000; 66 67 public static final String SYSTEM_PACKAGE_NAME = "android"; 68 69 public static final int VERSION_UNDEFINED = -1; 70 71 private static final String TAG_SETTINGS = "settings"; 72 private static final String TAG_SETTING = "setting"; 73 private static final String ATTR_PACKAGE = "package"; 74 75 private static final String ATTR_VERSION = "version"; 76 private static final String ATTR_ID = "id"; 77 private static final String ATTR_NAME = "name"; 78 private static final String ATTR_VALUE = "value"; 79 80 private static final String NULL_VALUE = "null"; 81 82 private final Object mLock; 83 84 private final Handler mHandler = new MyHandler(); 85 86 @GuardedBy("mLock") 87 private final ArrayMap<String, Setting> mSettings = new ArrayMap<>(); 88 89 @GuardedBy("mLock") 90 private final ArrayMap<String, Integer> mPackageToMemoryUsage; 91 92 @GuardedBy("mLock") 93 private final int mMaxBytesPerAppPackage; 94 95 @GuardedBy("mLock") 96 private final File mStatePersistFile; 97 98 public final int mKey; 99 100 @GuardedBy("mLock") 101 private int mVersion = VERSION_UNDEFINED; 102 103 @GuardedBy("mLock") 104 private long mLastNotWrittenMutationTimeMillis; 105 106 @GuardedBy("mLock") 107 private boolean mDirty; 108 109 @GuardedBy("mLock") 110 private boolean mWriteScheduled; 111 112 public SettingsState(Object lock, File file, int key, int maxBytesPerAppPackage) { 113 // It is important that we use the same lock as the settings provider 114 // to ensure multiple mutations on this state are atomicaly persisted 115 // as the async persistence should be blocked while we make changes. 116 mLock = lock; 117 mStatePersistFile = file; 118 mKey = key; 119 if (maxBytesPerAppPackage == MAX_BYTES_PER_APP_PACKAGE_LIMITED) { 120 mMaxBytesPerAppPackage = maxBytesPerAppPackage; 121 mPackageToMemoryUsage = new ArrayMap<>(); 122 } else { 123 mMaxBytesPerAppPackage = maxBytesPerAppPackage; 124 mPackageToMemoryUsage = null; 125 } 126 synchronized (mLock) { 127 readStateSyncLocked(); 128 } 129 } 130 131 // The settings provider must hold its lock when calling here. 132 public int getVersionLocked() { 133 return mVersion; 134 } 135 136 // The settings provider must hold its lock when calling here. 137 public void setVersionLocked(int version) { 138 if (version == mVersion) { 139 return; 140 } 141 mVersion = version; 142 143 scheduleWriteIfNeededLocked(); 144 } 145 146 // The settings provider must hold its lock when calling here. 147 public void onPackageRemovedLocked(String packageName) { 148 boolean removedSomething = false; 149 150 final int settingCount = mSettings.size(); 151 for (int i = settingCount - 1; i >= 0; i--) { 152 String name = mSettings.keyAt(i); 153 // Settings defined by use are never dropped. 154 if (Settings.System.PUBLIC_SETTINGS.contains(name) 155 || Settings.System.PRIVATE_SETTINGS.contains(name)) { 156 continue; 157 } 158 Setting setting = mSettings.valueAt(i); 159 if (packageName.equals(setting.packageName)) { 160 mSettings.removeAt(i); 161 removedSomething = true; 162 } 163 } 164 165 if (removedSomething) { 166 scheduleWriteIfNeededLocked(); 167 } 168 } 169 170 // The settings provider must hold its lock when calling here. 171 public List<String> getSettingNamesLocked() { 172 ArrayList<String> names = new ArrayList<>(); 173 final int settingsCount = mSettings.size(); 174 for (int i = 0; i < settingsCount; i++) { 175 String name = mSettings.keyAt(i); 176 names.add(name); 177 } 178 return names; 179 } 180 181 // The settings provider must hold its lock when calling here. 182 public Setting getSettingLocked(String name) { 183 if (TextUtils.isEmpty(name)) { 184 return null; 185 } 186 return mSettings.get(name); 187 } 188 189 // The settings provider must hold its lock when calling here. 190 public boolean updateSettingLocked(String name, String value, String packageName) { 191 if (!hasSettingLocked(name)) { 192 return false; 193 } 194 195 return insertSettingLocked(name, value, packageName); 196 } 197 198 // The settings provider must hold its lock when calling here. 199 public boolean insertSettingLocked(String name, String value, String packageName) { 200 if (TextUtils.isEmpty(name)) { 201 return false; 202 } 203 204 Setting oldState = mSettings.get(name); 205 String oldValue = (oldState != null) ? oldState.value : null; 206 207 if (oldState != null) { 208 if (!oldState.update(value, packageName)) { 209 return false; 210 } 211 } else { 212 Setting state = new Setting(name, value, packageName); 213 mSettings.put(name, state); 214 } 215 216 updateMemoryUsagePerPackageLocked(packageName, oldValue, value); 217 218 scheduleWriteIfNeededLocked(); 219 220 return true; 221 } 222 223 // The settings provider must hold its lock when calling here. 224 public void persistSyncLocked() { 225 mHandler.removeMessages(MyHandler.MSG_PERSIST_SETTINGS); 226 doWriteState(); 227 } 228 229 // The settings provider must hold its lock when calling here. 230 public boolean deleteSettingLocked(String name) { 231 if (TextUtils.isEmpty(name) || !hasSettingLocked(name)) { 232 return false; 233 } 234 235 Setting oldState = mSettings.remove(name); 236 237 updateMemoryUsagePerPackageLocked(oldState.packageName, oldState.value, null); 238 239 scheduleWriteIfNeededLocked(); 240 241 return true; 242 } 243 244 // The settings provider must hold its lock when calling here. 245 public void destroyLocked(Runnable callback) { 246 mHandler.removeMessages(MyHandler.MSG_PERSIST_SETTINGS); 247 if (callback != null) { 248 if (mDirty) { 249 // Do it without a delay. 250 mHandler.obtainMessage(MyHandler.MSG_PERSIST_SETTINGS, 251 callback).sendToTarget(); 252 return; 253 } 254 callback.run(); 255 } 256 } 257 258 private void updateMemoryUsagePerPackageLocked(String packageName, String oldValue, 259 String newValue) { 260 if (mMaxBytesPerAppPackage == MAX_BYTES_PER_APP_PACKAGE_UNLIMITED) { 261 return; 262 } 263 264 if (SYSTEM_PACKAGE_NAME.equals(packageName)) { 265 return; 266 } 267 268 final int oldValueSize = (oldValue != null) ? oldValue.length() : 0; 269 final int newValueSize = (newValue != null) ? newValue.length() : 0; 270 final int deltaSize = newValueSize - oldValueSize; 271 272 Integer currentSize = mPackageToMemoryUsage.get(packageName); 273 final int newSize = Math.max((currentSize != null) 274 ? currentSize + deltaSize : deltaSize, 0); 275 276 if (newSize > mMaxBytesPerAppPackage) { 277 throw new IllegalStateException("You are adding too many system settings. " 278 + "You should stop using system settings for app specific data" 279 + " package: " + packageName); 280 } 281 282 if (DEBUG) { 283 Slog.i(LOG_TAG, "Settings for package: " + packageName 284 + " size: " + newSize + " bytes."); 285 } 286 287 mPackageToMemoryUsage.put(packageName, newSize); 288 } 289 290 private boolean hasSettingLocked(String name) { 291 return mSettings.indexOfKey(name) >= 0; 292 } 293 294 private void scheduleWriteIfNeededLocked() { 295 // If dirty then we have a write already scheduled. 296 if (!mDirty) { 297 mDirty = true; 298 writeStateAsyncLocked(); 299 } 300 } 301 302 private void writeStateAsyncLocked() { 303 final long currentTimeMillis = SystemClock.uptimeMillis(); 304 305 if (mWriteScheduled) { 306 mHandler.removeMessages(MyHandler.MSG_PERSIST_SETTINGS); 307 308 // If enough time passed, write without holding off anymore. 309 final long timeSinceLastNotWrittenMutationMillis = currentTimeMillis 310 - mLastNotWrittenMutationTimeMillis; 311 if (timeSinceLastNotWrittenMutationMillis >= MAX_WRITE_SETTINGS_DELAY_MILLIS) { 312 mHandler.obtainMessage(MyHandler.MSG_PERSIST_SETTINGS).sendToTarget(); 313 return; 314 } 315 316 // Hold off a bit more as settings are frequently changing. 317 final long maxDelayMillis = Math.max(mLastNotWrittenMutationTimeMillis 318 + MAX_WRITE_SETTINGS_DELAY_MILLIS - currentTimeMillis, 0); 319 final long writeDelayMillis = Math.min(WRITE_SETTINGS_DELAY_MILLIS, maxDelayMillis); 320 321 Message message = mHandler.obtainMessage(MyHandler.MSG_PERSIST_SETTINGS); 322 mHandler.sendMessageDelayed(message, writeDelayMillis); 323 } else { 324 mLastNotWrittenMutationTimeMillis = currentTimeMillis; 325 Message message = mHandler.obtainMessage(MyHandler.MSG_PERSIST_SETTINGS); 326 mHandler.sendMessageDelayed(message, WRITE_SETTINGS_DELAY_MILLIS); 327 mWriteScheduled = true; 328 } 329 } 330 331 private void doWriteState() { 332 if (DEBUG_PERSISTENCE) { 333 Slog.i(LOG_TAG, "[PERSIST START]"); 334 } 335 336 AtomicFile destination = new AtomicFile(mStatePersistFile); 337 338 final int version; 339 final ArrayMap<String, Setting> settings; 340 341 synchronized (mLock) { 342 version = mVersion; 343 settings = new ArrayMap<>(mSettings); 344 mDirty = false; 345 mWriteScheduled = false; 346 } 347 348 FileOutputStream out = null; 349 try { 350 out = destination.startWrite(); 351 352 XmlSerializer serializer = Xml.newSerializer(); 353 serializer.setOutput(out, "utf-8"); 354 serializer.startDocument(null, true); 355 serializer.startTag(null, TAG_SETTINGS); 356 serializer.attribute(null, ATTR_VERSION, String.valueOf(version)); 357 358 final int settingCount = settings.size(); 359 for (int i = 0; i < settingCount; i++) { 360 Setting setting = settings.valueAt(i); 361 362 serializer.startTag(null, TAG_SETTING); 363 serializer.attribute(null, ATTR_ID, setting.getId()); 364 serializer.attribute(null, ATTR_NAME, setting.getName()); 365 serializer.attribute(null, ATTR_VALUE, packValue(setting.getValue())); 366 serializer.attribute(null, ATTR_PACKAGE, packValue(setting.getPackageName())); 367 serializer.endTag(null, TAG_SETTING); 368 369 if (DEBUG_PERSISTENCE) { 370 Slog.i(LOG_TAG, "[PERSISTED]" + setting.getName() + "=" + setting.getValue()); 371 } 372 } 373 374 serializer.endTag(null, TAG_SETTINGS); 375 serializer.endDocument(); 376 destination.finishWrite(out); 377 378 if (DEBUG_PERSISTENCE) { 379 Slog.i(LOG_TAG, "[PERSIST END]"); 380 } 381 382 } catch (IOException e) { 383 Slog.w(LOG_TAG, "Failed to write settings, restoring backup", e); 384 destination.failWrite(out); 385 } finally { 386 IoUtils.closeQuietly(out); 387 } 388 } 389 390 private void readStateSyncLocked() { 391 FileInputStream in; 392 if (!mStatePersistFile.exists()) { 393 return; 394 } 395 try { 396 in = new FileInputStream(mStatePersistFile); 397 } catch (FileNotFoundException fnfe) { 398 Slog.i(LOG_TAG, "No settings state"); 399 return; 400 } 401 try { 402 XmlPullParser parser = Xml.newPullParser(); 403 parser.setInput(in, null); 404 parseStateLocked(parser); 405 } catch (XmlPullParserException | IOException ise) { 406 throw new IllegalStateException("Failed parsing settings file: " 407 + mStatePersistFile , ise); 408 } finally { 409 IoUtils.closeQuietly(in); 410 } 411 } 412 413 private void parseStateLocked(XmlPullParser parser) 414 throws IOException, XmlPullParserException { 415 parser.next(); 416 skipEmptyTextTags(parser); 417 expect(parser, XmlPullParser.START_TAG, TAG_SETTINGS); 418 419 mVersion = Integer.parseInt(parser.getAttributeValue(null, ATTR_VERSION)); 420 421 parser.next(); 422 423 while (parseSettingLocked(parser)) { 424 parser.next(); 425 } 426 427 skipEmptyTextTags(parser); 428 expect(parser, XmlPullParser.END_TAG, TAG_SETTINGS); 429 } 430 431 private boolean parseSettingLocked(XmlPullParser parser) 432 throws IOException, XmlPullParserException { 433 skipEmptyTextTags(parser); 434 if (!accept(parser, XmlPullParser.START_TAG, TAG_SETTING)) { 435 return false; 436 } 437 438 String id = parser.getAttributeValue(null, ATTR_ID); 439 String name = parser.getAttributeValue(null, ATTR_NAME); 440 String value = parser.getAttributeValue(null, ATTR_VALUE); 441 String packageName = parser.getAttributeValue(null, ATTR_PACKAGE); 442 mSettings.put(name, new Setting(name, unpackValue(value), 443 unpackValue(packageName), id)); 444 445 if (DEBUG_PERSISTENCE) { 446 Slog.i(LOG_TAG, "[RESTORED] " + name + "=" + value); 447 } 448 449 parser.next(); 450 451 skipEmptyTextTags(parser); 452 expect(parser, XmlPullParser.END_TAG, TAG_SETTING); 453 454 return true; 455 } 456 457 private void expect(XmlPullParser parser, int type, String tag) 458 throws IOException, XmlPullParserException { 459 if (!accept(parser, type, tag)) { 460 throw new XmlPullParserException("Expected event: " + type 461 + " and tag: " + tag + " but got event: " + parser.getEventType() 462 + " and tag:" + parser.getName()); 463 } 464 } 465 466 private void skipEmptyTextTags(XmlPullParser parser) 467 throws IOException, XmlPullParserException { 468 while (accept(parser, XmlPullParser.TEXT, null) 469 && "\n".equals(parser.getText())) { 470 parser.next(); 471 } 472 } 473 474 private boolean accept(XmlPullParser parser, int type, String tag) 475 throws IOException, XmlPullParserException { 476 if (parser.getEventType() != type) { 477 return false; 478 } 479 if (tag != null) { 480 if (!tag.equals(parser.getName())) { 481 return false; 482 } 483 } else if (parser.getName() != null) { 484 return false; 485 } 486 return true; 487 } 488 489 private final class MyHandler extends Handler { 490 public static final int MSG_PERSIST_SETTINGS = 1; 491 492 public MyHandler() { 493 super(BackgroundThread.getHandler().getLooper()); 494 } 495 496 @Override 497 public void handleMessage(Message message) { 498 switch (message.what) { 499 case MSG_PERSIST_SETTINGS: { 500 Runnable callback = (Runnable) message.obj; 501 doWriteState(); 502 if (callback != null) { 503 callback.run(); 504 } 505 } 506 break; 507 } 508 } 509 } 510 511 private static String packValue(String value) { 512 if (value == null) { 513 return NULL_VALUE; 514 } 515 return value; 516 } 517 518 private static String unpackValue(String value) { 519 if (NULL_VALUE.equals(value)) { 520 return null; 521 } 522 return value; 523 } 524 525 public static final class Setting { 526 private static long sNextId; 527 528 private String name; 529 private String value; 530 private String packageName; 531 private String id; 532 533 public Setting(String name, String value, String packageName) { 534 init(name, value, packageName, String.valueOf(sNextId++)); 535 } 536 537 public Setting(String name, String value, String packageName, String id) { 538 sNextId = Math.max(sNextId, Long.valueOf(id)); 539 init(name, value, packageName, String.valueOf(sNextId)); 540 } 541 542 private void init(String name, String value, String packageName, String id) { 543 this.name = name; 544 this.value = value; 545 this.packageName = packageName; 546 this.id = id; 547 } 548 549 public String getName() { 550 return name; 551 } 552 553 public String getValue() { 554 return value; 555 } 556 557 public String getPackageName() { 558 return packageName; 559 } 560 561 public String getId() { 562 return id; 563 } 564 565 public boolean update(String value, String packageName) { 566 if (Objects.equal(value, this.value)) { 567 return false; 568 } 569 this.value = value; 570 this.packageName = packageName; 571 this.id = String.valueOf(sNextId++); 572 return true; 573 } 574 } 575} 576