Use local locks in SharedPreferencesImpl. (ac6f7e41) · Commits · e / os / android_frameworks_base

core/java/android/app/SharedPreferencesImpl.java

+90 −59

Original line number	Diff line number	Diff line
		@@ -54,23 +54,34 @@ import libcore.io.IoUtils;
		final class SharedPreferencesImpl implements SharedPreferences {
		private static final String TAG = "SharedPreferencesImpl";
		private static final boolean DEBUG = false;
		private static final Object CONTENT = new Object();

		// Lock ordering rules:
		// - acquire SharedPreferencesImpl.this before EditorImpl.this
		// - acquire mWritingToDiskLock before EditorImpl.this
		// - acquire SharedPreferencesImpl.mLock before EditorImpl.mLock
		// - acquire mWritingToDiskLock before EditorImpl.mLock

		private final File mFile;
		private final File mBackupFile;
		private final int mMode;
		private final Object mLock = new Object();
		private final Object mWritingToDiskLock = new Object();

		private Map<String, Object> mMap; // guarded by 'this'
		private int mDiskWritesInFlight = 0; // guarded by 'this'
		private boolean mLoaded = false; // guarded by 'this'
		private long mStatTimestamp; // guarded by 'this'
		private long mStatSize; // guarded by 'this'
		@GuardedBy("mLock")
		private Map<String, Object> mMap;

		private final Object mWritingToDiskLock = new Object();
		private static final Object mContent = new Object();
		@GuardedBy("mLock")
		private int mDiskWritesInFlight = 0;

		@GuardedBy("mLock")
		private boolean mLoaded = false;

		@GuardedBy("mLock")
		private long mStatTimestamp;

		@GuardedBy("mLock")
		private long mStatSize;

		@GuardedBy("mLock")
		private final WeakHashMap<OnSharedPreferenceChangeListener, Object> mListeners =
		new WeakHashMap<OnSharedPreferenceChangeListener, Object>();

		@@ -92,7 +103,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}

		private void startLoadFromDisk() {
		synchronized (this) {
		synchronized (mLock) {
		mLoaded = false;
		}
		new Thread("SharedPreferencesImpl-load") {
		@@ -103,7 +114,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}

		private void loadFromDisk() {
		synchronized (SharedPreferencesImpl.this) {
		synchronized (mLock) {
		if (mLoaded) {
		return;
		}
		@@ -138,7 +149,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		/* ignore */
		}

		synchronized (SharedPreferencesImpl.this) {
		synchronized (mLock) {
		mLoaded = true;
		if (map != null) {
		mMap = map;
		@@ -147,7 +158,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		} else {
		mMap = new HashMap<>();
		}
		notifyAll();
		mLock.notifyAll();
		}
		}

		@@ -156,7 +167,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}

		void startReloadIfChangedUnexpectedly() {
		synchronized (this) {
		synchronized (mLock) {
		// TODO: wait for any pending writes to disk?
		if (!hasFileChangedUnexpectedly()) {
		return;
		@@ -168,7 +179,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		// Has the file changed out from under us? i.e. writes that
		// we didn't instigate.
		private boolean hasFileChangedUnexpectedly() {
		synchronized (this) {
		synchronized (mLock) {
		if (mDiskWritesInFlight > 0) {
		// If we know we caused it, it's not unexpected.
		if (DEBUG) Log.d(TAG, "disk write in flight, not unexpected.");
		@@ -188,19 +199,19 @@ final class SharedPreferencesImpl implements SharedPreferences {
		return true;
		}

		synchronized (this) {
		synchronized (mLock) {
		return mStatTimestamp != stat.st_mtime \|\| mStatSize != stat.st_size;
		}
		}

		public void registerOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener listener) {
		synchronized(this) {
		mListeners.put(listener, mContent);
		synchronized(mLock) {
		mListeners.put(listener, CONTENT);
		}
		}

		public void unregisterOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener listener) {
		synchronized(this) {
		synchronized(mLock) {
		mListeners.remove(listener);
		}
		}
		@@ -214,14 +225,14 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}
		while (!mLoaded) {
		try {
		wait();
		mLock.wait();
		} catch (InterruptedException unused) {
		}
		}
		}

		public Map<String, ?> getAll() {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		//noinspection unchecked
		return new HashMap<String, Object>(mMap);
		@@ -230,7 +241,7 @@ final class SharedPreferencesImpl implements SharedPreferences {

		@Nullable
		public String getString(String key, @Nullable String defValue) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		String v = (String)mMap.get(key);
		return v != null ? v : defValue;
		@@ -239,7 +250,7 @@ final class SharedPreferencesImpl implements SharedPreferences {

		@Nullable
		public Set<String> getStringSet(String key, @Nullable Set<String> defValues) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		Set<String> v = (Set<String>) mMap.get(key);
		return v != null ? v : defValues;
		@@ -247,28 +258,28 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}

		public int getInt(String key, int defValue) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		Integer v = (Integer)mMap.get(key);
		return v != null ? v : defValue;
		}
		}
		public long getLong(String key, long defValue) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		Long v = (Long)mMap.get(key);
		return v != null ? v : defValue;
		}
		}
		public float getFloat(String key, float defValue) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		Float v = (Float)mMap.get(key);
		return v != null ? v : defValue;
		}
		}
		public boolean getBoolean(String key, boolean defValue) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		Boolean v = (Boolean)mMap.get(key);
		return v != null ? v : defValue;
		@@ -276,7 +287,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}

		public boolean contains(String key) {
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		return mMap.containsKey(key);
		}
		@@ -290,7 +301,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		// context.getSharedPreferences(..).edit().putString(..).apply()
		//
		// ... all without blocking.
		synchronized (this) {
		synchronized (mLock) {
		awaitLoadedLocked();
		}

		@@ -299,70 +310,86 @@ final class SharedPreferencesImpl implements SharedPreferences {

		// Return value from EditorImpl#commitToMemory()
		private static class MemoryCommitResult {
		public long memoryStateGeneration;
		public List<String> keysModified; // may be null
		public Set<OnSharedPreferenceChangeListener> listeners; // may be null
		public Map<?, ?> mapToWriteToDisk;
		public final CountDownLatch writtenToDiskLatch = new CountDownLatch(1);
		public volatile boolean writeToDiskResult = false;

		public void setDiskWriteResult(boolean result) {
		final long memoryStateGeneration;
		@Nullable final List<String> keysModified;
		@Nullable final Set<OnSharedPreferenceChangeListener> listeners;
		final Map<String, Object> mapToWriteToDisk;
		final CountDownLatch writtenToDiskLatch = new CountDownLatch(1);

		@GuardedBy("mWritingToDiskLock")
		volatile boolean writeToDiskResult = false;

		private MemoryCommitResult(long memoryStateGeneration, @Nullable List<String> keysModified,
		@Nullable Set<OnSharedPreferenceChangeListener> listeners,
		Map<String, Object> mapToWriteToDisk) {
		this.memoryStateGeneration = memoryStateGeneration;
		this.keysModified = keysModified;
		this.listeners = listeners;
		this.mapToWriteToDisk = mapToWriteToDisk;
		}

		void setDiskWriteResult(boolean result) {
		writeToDiskResult = result;
		writtenToDiskLatch.countDown();
		}
		}

		public final class EditorImpl implements Editor {
		private final Object mLock = new Object();

		@GuardedBy("mLock")
		private final Map<String, Object> mModified = Maps.newHashMap();

		@GuardedBy("mLock")
		private boolean mClear = false;

		public Editor putString(String key, @Nullable String value) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key, value);
		return this;
		}
		}
		public Editor putStringSet(String key, @Nullable Set<String> values) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key,
		(values == null) ? null : new HashSet<String>(values));
		return this;
		}
		}
		public Editor putInt(String key, int value) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key, value);
		return this;
		}
		}
		public Editor putLong(String key, long value) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key, value);
		return this;
		}
		}
		public Editor putFloat(String key, float value) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key, value);
		return this;
		}
		}
		public Editor putBoolean(String key, boolean value) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key, value);
		return this;
		}
		}

		public Editor remove(String key) {
		synchronized (this) {
		synchronized (mLock) {
		mModified.put(key, this);
		return this;
		}
		}

		public Editor clear() {
		synchronized (this) {
		synchronized (mLock) {
		mClear = true;
		return this;
		}
		@@ -399,8 +426,12 @@ final class SharedPreferencesImpl implements SharedPreferences {

		// Returns true if any changes were made
		private MemoryCommitResult commitToMemory() {
		MemoryCommitResult mcr = new MemoryCommitResult();
		synchronized (SharedPreferencesImpl.this) {
		long memoryStateGeneration;
		List<String> keysModified = null;
		Set<OnSharedPreferenceChangeListener> listeners = null;
		Map<String, Object> mapToWriteToDisk;

		synchronized (SharedPreferencesImpl.this.mLock) {
		// We optimistically don't make a deep copy until
		// a memory commit comes in when we're already
		// writing to disk.
		@@ -411,17 +442,16 @@ final class SharedPreferencesImpl implements SharedPreferences {
		// noinspection unchecked
		mMap = new HashMap<String, Object>(mMap);
		}
		mcr.mapToWriteToDisk = mMap;
		mapToWriteToDisk = mMap;
		mDiskWritesInFlight++;

		boolean hasListeners = mListeners.size() > 0;
		if (hasListeners) {
		mcr.keysModified = new ArrayList<String>();
		mcr.listeners =
		new HashSet<OnSharedPreferenceChangeListener>(mListeners.keySet());
		keysModified = new ArrayList<String>();
		listeners = new HashSet<OnSharedPreferenceChangeListener>(mListeners.keySet());
		}

		synchronized (this) {
		synchronized (mLock) {
		boolean changesMade = false;

		if (mClear) {
		@@ -455,7 +485,7 @@ final class SharedPreferencesImpl implements SharedPreferences {

		changesMade = true;
		if (hasListeners) {
		mcr.keysModified.add(k);
		keysModified.add(k);
		}
		}

		@@ -465,10 +495,11 @@ final class SharedPreferencesImpl implements SharedPreferences {
		mCurrentMemoryStateGeneration++;
		}

		mcr.memoryStateGeneration = mCurrentMemoryStateGeneration;
		memoryStateGeneration = mCurrentMemoryStateGeneration;
		}
		}
		return mcr;
		return new MemoryCommitResult(memoryStateGeneration, keysModified, listeners,
		mapToWriteToDisk);
		}

		public boolean commit() {
		@@ -534,7 +565,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		synchronized (mWritingToDiskLock) {
		writeToFile(mcr, isFromSyncCommit);
		}
		synchronized (SharedPreferencesImpl.this) {
		synchronized (mLock) {
		mDiskWritesInFlight--;
		}
		if (postWriteRunnable != null) {
		@@ -547,7 +578,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		// the current thread.
		if (isFromSyncCommit) {
		boolean wasEmpty = false;
		synchronized (SharedPreferencesImpl.this) {
		synchronized (mLock) {
		wasEmpty = mDiskWritesInFlight == 1;
		}
		if (wasEmpty) {
		@@ -597,7 +628,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		if (isFromSyncCommit) {
		needsWrite = true;
		} else {
		synchronized (this) {
		synchronized (mLock) {
		// No need to persist intermediate states. Just wait for the latest state to
		// be persisted.
		if (mCurrentMemoryStateGeneration == mcr.memoryStateGeneration) {
		@@ -647,7 +678,7 @@ final class SharedPreferencesImpl implements SharedPreferences {
		ContextImpl.setFilePermissionsFromMode(mFile.getPath(), mMode, 0);
		try {
		final StructStat stat = Os.stat(mFile.getPath());
		synchronized (this) {
		synchronized (mLock) {
		mStatTimestamp = stat.st_mtime;
		mStatSize = stat.st_size;
		}