SettingsProvider: defensively cap size of settings kept cached in memory. (342984a1) · Commits · e / os / android_frameworks_base

packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java

+28 −12

Original line number	Diff line number	Diff line
		@@ -60,6 +60,11 @@ public class SettingsProvider extends ContentProvider {
		private static final SettingsCache sSystemCache = new SettingsCache();
		private static final SettingsCache sSecureCache = new SettingsCache();

		// Over this size we don't reject loading or saving settings but
		// we do consider them broken/malicious and don't keep them in
		// memory at least:
		private static final int MAX_CACHE_ENTRY_SIZE = 500;

		private static final Bundle NULL_SETTING = Bundle.forPair("value", null);

		protected DatabaseHelper mOpenHelper;
		@@ -264,10 +269,7 @@ public class SettingsProvider extends ContentProvider {
		null, null, null, null);
		if (cursor != null && cursor.getCount() == 1) {
		cursor.moveToFirst();
		String value = cursor.getString(0);
		Bundle bundle = (value == null) ? NULL_SETTING : Bundle.forPair("value", value);
		cache.putIfAbsentLocked(key, bundle);
		return bundle;
		return cache.putIfAbsent(key, cursor.getString(0));
		}
		} catch (SQLiteException e) {
		Log.w(TAG, "settings lookup error", e);
		@@ -275,7 +277,7 @@ public class SettingsProvider extends ContentProvider {
		} finally {
		if (cursor != null) cursor.close();
		}
		cache.putIfAbsentLocked(key, NULL_SETTING);
		cache.putIfAbsent(key, null);
		return NULL_SETTING;
		}

		@@ -592,6 +594,7 @@ public class SettingsProvider extends ContentProvider {
		* database.
		*/
		private static final class SettingsCache extends LinkedHashMap<String, Bundle> {

		public SettingsCache() {
		super(MAX_CACHE_ENTRIES, 0.75f /* load factor /, true / access ordered */);
		}
		@@ -601,14 +604,23 @@ public class SettingsProvider extends ContentProvider {
		return size() > MAX_CACHE_ENTRIES;
		}

		public void putIfAbsentLocked(String key, Bundle value) {
		/**
		* Atomic cache population, conditional on size of value and if
		* we lost a race.
		*
		* @returns a Bundle to send back to the client from call(), even
		* if we lost the race.
		*/
		public Bundle putIfAbsent(String key, String value) {
		Bundle bundle = (value == null) ? NULL_SETTING : Bundle.forPair("value", value);
		if (value == null \|\| value.length() <= MAX_CACHE_ENTRY_SIZE) {
		synchronized (this) {
		if (containsKey(key)) {
		// Lost a race.
		return;
		if (!containsKey(key)) {
		put(key, bundle);
		}
		}
		put(key, value);
		}
		return bundle;
		}

		public static SettingsCache forTable(String tableName) {
		@@ -635,7 +647,11 @@ public class SettingsProvider extends ContentProvider {
		}
		String value = contentValues.getAsString(Settings.NameValueTable.VALUE);
		synchronized (cache) {
		if (value == null \|\| value.length() <= MAX_CACHE_ENTRY_SIZE) {
		cache.put(name, Bundle.forPair(Settings.NameValueTable.VALUE, value));
		} else {
		cache.remove(name);
		}
		}
		}