Make getSharedPreference() async, blocking on first access. (4cd50b8d) · Commits · e / os / android_frameworks_base

core/java/android/app/ContextImpl.java

+6 −45

Original line number	Diff line number	Diff line
		@@ -532,10 +532,6 @@ class ContextImpl extends Context {
		throw new RuntimeException("Not supported in system context");
		}

		static File makeBackupFile(File prefsFile) {
		return new File(prefsFile.getPath() + ".bak");
		}

		public File getSharedPrefsFile(String name) {
		return makeFilename(getPreferencesDir(), name + ".xml");
		}
		@@ -543,54 +539,19 @@ class ContextImpl extends Context {
		@Override
		public SharedPreferences getSharedPreferences(String name, int mode) {
		SharedPreferencesImpl sp;
		File prefsFile;
		boolean needInitialLoad = false;
		synchronized (sSharedPrefs) {
		sp = sSharedPrefs.get(name);
		if (sp != null && !sp.hasFileChangedUnexpectedly()) {
		return sp;
		}
		prefsFile = getSharedPrefsFile(name);
		if (sp == null) {
		sp = new SharedPreferencesImpl(prefsFile, mode, null);
		File prefsFile = getSharedPrefsFile(name);
		sp = new SharedPreferencesImpl(prefsFile, mode);
		sSharedPrefs.put(name, sp);
		needInitialLoad = true;
		}
		}

		synchronized (sp) {
		if (needInitialLoad && sp.isLoaded()) {
		// lost the race to load; another thread handled it
		return sp;
		}
		File backup = makeBackupFile(prefsFile);
		if (backup.exists()) {
		prefsFile.delete();
		backup.renameTo(prefsFile);
		}

		// Debugging
		if (prefsFile.exists() && !prefsFile.canRead()) {
		Log.w(TAG, "Attempt to read preferences file " + prefsFile + " without permission");
		}

		Map map = null;
		FileStatus stat = new FileStatus();
		if (FileUtils.getFileStatus(prefsFile.getPath(), stat) && prefsFile.canRead()) {
		try {
		FileInputStream str = new FileInputStream(prefsFile);
		map = XmlUtils.readMapXml(str);
		str.close();
		} catch (XmlPullParserException e) {
		Log.w(TAG, "getSharedPreferences", e);
		} catch (FileNotFoundException e) {
		Log.w(TAG, "getSharedPreferences", e);
		} catch (IOException e) {
		Log.w(TAG, "getSharedPreferences", e);
		}
		}
		sp.replace(map, stat);
		}
		// If somebody else (some other process) changed the prefs
		// file behind our back, we reload it. This has been the
		// historical (if undocumented) behavior.
		sp.startReloadIfChangedUnexpectedly();
		return sp;
		}

core/java/android/app/SharedPreferencesImpl.java

+106 −26

Original line number	Diff line number	Diff line
		@@ -25,9 +25,12 @@ import android.util.Log;
		import com.google.android.collect.Maps;
		import com.android.internal.util.XmlUtils;

		import dalvik.system.BlockGuard;

		import org.xmlpull.v1.XmlPullParserException;

		import java.io.File;
		import java.io.FileInputStream;
		import java.io.FileNotFoundException;
		import java.io.FileOutputStream;
		import java.io.IOException;
		@@ -61,32 +64,88 @@ final class SharedPreferencesImpl implements SharedPreferences {

		private final Object mWritingToDiskLock = new Object();
		private static final Object mContent = new Object();
		private final WeakHashMap<OnSharedPreferenceChangeListener, Object> mListeners;
		private final WeakHashMap<OnSharedPreferenceChangeListener, Object> mListeners =
		new WeakHashMap<OnSharedPreferenceChangeListener, Object>();

		SharedPreferencesImpl(
		File file, int mode, Map initialContents) {
		SharedPreferencesImpl(File file, int mode) {
		mFile = file;
		mBackupFile = ContextImpl.makeBackupFile(file);
		mBackupFile = makeBackupFile(file);
		mMode = mode;
		mLoaded = initialContents != null;
		mMap = initialContents != null ? initialContents : new HashMap<String, Object>();
		mLoaded = false;
		mMap = null;
		startLoadFromDisk();
		}

		private void startLoadFromDisk() {
		synchronized (this) {
		mLoaded = false;
		}
		new Thread("SharedPreferencesImpl-load") {
		public void run() {
		synchronized (SharedPreferencesImpl.this) {
		loadFromDiskLocked();
		}
		}
		}.start();
		}

		private void loadFromDiskLocked() {
		if (mLoaded) {
		return;
		}
		if (mBackupFile.exists()) {
		mFile.delete();
		mBackupFile.renameTo(mFile);
		}

		// Debugging
		if (mFile.exists() && !mFile.canRead()) {
		Log.w(TAG, "Attempt to read preferences file " + mFile + " without permission");
		}

		Map map = null;
		FileStatus stat = new FileStatus();
		if (FileUtils.getFileStatus(file.getPath(), stat)) {
		if (FileUtils.getFileStatus(mFile.getPath(), stat) && mFile.canRead()) {
		try {
		FileInputStream str = new FileInputStream(mFile);
		map = XmlUtils.readMapXml(str);
		str.close();
		} catch (XmlPullParserException e) {
		Log.w(TAG, "getSharedPreferences", e);
		} catch (FileNotFoundException e) {
		Log.w(TAG, "getSharedPreferences", e);
		} catch (IOException e) {
		Log.w(TAG, "getSharedPreferences", e);
		}
		}
		mLoaded = true;
		if (map != null) {
		mMap = map;
		mStatTimestamp = stat.mtime;
		mStatSize = stat.size;
		} else {
		mMap = new HashMap<String, Object>();
		}
		mListeners = new WeakHashMap<OnSharedPreferenceChangeListener, Object>();
		notifyAll();
		}

		// Has this SharedPreferences ever had values assigned to it?
		boolean isLoaded() {
		private static File makeBackupFile(File prefsFile) {
		return new File(prefsFile.getPath() + ".bak");
		}

		void startReloadIfChangedUnexpectedly() {
		synchronized (this) {
		return mLoaded;
		// TODO: wait for any pending writes to disk?
		if (!hasFileChangedUnexpectedly()) {
		return;
		}
		startLoadFromDisk();
		}
		}

		// Has the file changed out from under us? i.e. writes that
		// we didn't instigate.
		public boolean hasFileChangedUnexpectedly() {
		private boolean hasFileChangedUnexpectedly() {
		synchronized (this) {
		if (mDiskWritesInFlight > 0) {
		// If we know we caused it, it's not unexpected.
		@@ -103,19 +162,6 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}
		}

		/package/ void replace(Map newContents, FileStatus stat) {
		synchronized (this) {
		mLoaded = true;
		if (newContents != null) {
		mMap = newContents;
		}
		if (stat != null) {
		mStatTimestamp = stat.mtime;
		mStatSize = stat.size;
		}
		}
		}

		public void registerOnSharedPreferenceChangeListener(OnSharedPreferenceChangeListener listener) {
		synchronized(this) {
		mListeners.put(listener, mContent);
		@@ -128,8 +174,24 @@ final class SharedPreferencesImpl implements SharedPreferences {
		}
		}

		private void awaitLoadedLocked() {
		if (!mLoaded) {
		// Raise an explicit StrictMode onReadFromDisk for this
		// thread, since the real read will be in a different
		// thread and otherwise ignored by StrictMode.
		BlockGuard.getThreadPolicy().onReadFromDisk();
		}
		while (!mLoaded) {
		try {
		wait();
		} catch (InterruptedException unused) {
		}
		}
		}

		public Map<String, ?> getAll() {
		synchronized (this) {
		awaitLoadedLocked();
		//noinspection unchecked
		return new HashMap<String, Object>(mMap);
		}
		@@ -137,6 +199,7 @@ final class SharedPreferencesImpl implements SharedPreferences {

		public String getString(String key, String defValue) {
		synchronized (this) {
		awaitLoadedLocked();
		String v = (String)mMap.get(key);
		return v != null ? v : defValue;
		}
		@@ -144,6 +207,7 @@ final class SharedPreferencesImpl implements SharedPreferences {

		public Set<String> getStringSet(String key, Set<String> defValues) {
		synchronized (this) {
		awaitLoadedLocked();
		Set<String> v = (Set<String>) mMap.get(key);
		return v != null ? v : defValues;
		}
		@@ -151,24 +215,28 @@ final class SharedPreferencesImpl implements SharedPreferences {

		public int getInt(String key, int defValue) {
		synchronized (this) {
		awaitLoadedLocked();
		Integer v = (Integer)mMap.get(key);
		return v != null ? v : defValue;
		}
		}
		public long getLong(String key, long defValue) {
		synchronized (this) {
		awaitLoadedLocked();
		Long v = (Long)mMap.get(key);
		return v != null ? v : defValue;
		}
		}
		public float getFloat(String key, float defValue) {
		synchronized (this) {
		awaitLoadedLocked();
		Float v = (Float)mMap.get(key);
		return v != null ? v : defValue;
		}
		}
		public boolean getBoolean(String key, boolean defValue) {
		synchronized (this) {
		awaitLoadedLocked();
		Boolean v = (Boolean)mMap.get(key);
		return v != null ? v : defValue;
		}
		@@ -176,11 +244,23 @@ final class SharedPreferencesImpl implements SharedPreferences {

		public boolean contains(String key) {
		synchronized (this) {
		awaitLoadedLocked();
		return mMap.containsKey(key);
		}
		}

		public Editor edit() {
		// TODO: remove the need to call awaitLoadedLocked() when
		// requesting an editor. will require some work on the
		// Editor, but then we should be able to do:
		//
		// context.getSharedPreferences(..).edit().putString(..).apply()
		//
		// ... all without blocking.
		synchronized (this) {
		awaitLoadedLocked();
		}

		return new EditorImpl();
		}