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Merge "Fix a race between requesting/loading/writing SharedPreferences." into gingerbread

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This commit is contained in:
Brad Fitzpatrick
2010-09-07 20:06:26 -07:00
committed by Android (Google) Code Review
parent d580eee29b 6194c53754
commit 6459100940
1 changed files with 65 additions and 43 deletions
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108
core/java/android/app/ContextImpl.java
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@@ -325,7 +325,7 @@ class ContextImpl extends Context {
}
throw new RuntimeException("Not supported in system context");
}
private static File makeBackupFile(File prefsFile) {
return new File(prefsFile.getPath() + ".bak");
}
@@ -337,55 +337,54 @@ 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.hasFileChanged()) {
//Log.i(TAG, "Returning existing prefs " + name + ": " + sp);
if (sp != null && !sp.hasFileChangedUnexpectedly()) {
return sp;
}
}
File f = getSharedPrefsFile(name);
FileInputStream str = null;
File backup = makeBackupFile(f);
if (backup.exists()) {
f.delete();
backup.renameTo(f);
}
// Debugging
if (f.exists() && !f.canRead()) {
Log.w(TAG, "Attempt to read preferences file " + f + " without permission");
}
Map map = null;
if (f.exists() && f.canRead()) {
try {
str = new FileInputStream(f);
map = XmlUtils.readMapXml(str);
str.close();
} catch (org.xmlpull.v1.XmlPullParserException e) {
Log.w(TAG, "getSharedPreferences", e);
} catch (FileNotFoundException e) {
Log.w(TAG, "getSharedPreferences", e);
} catch (IOException e) {
Log.w(TAG, "getSharedPreferences", e);
prefsFile = getSharedPrefsFile(name);
if (sp == null) {
sp = new SharedPreferencesImpl(prefsFile, mode, null);
sSharedPrefs.put(name, sp);
needInitialLoad = true;
}
}
synchronized (sSharedPrefs) {
if (sp != null) {
//Log.i(TAG, "Updating existing prefs " + name + " " + sp + ": " + map);
sp.replace(map);
} else {
sp = sSharedPrefs.get(name);
if (sp == null) {
sp = new SharedPreferencesImpl(f, mode, map);
sSharedPrefs.put(name, sp);
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;
if (prefsFile.exists() && prefsFile.canRead()) {
try {
FileInputStream str = new FileInputStream(prefsFile);
map = XmlUtils.readMapXml(str);
str.close();
} catch (org.xmlpull.v1.XmlPullParserException e) {
Log.w(TAG, "getSharedPreferences", e);
} catch (FileNotFoundException e) {
Log.w(TAG, "getSharedPreferences", e);
} catch (IOException e) {
Log.w(TAG, "getSharedPreferences", e);
}
}
return sp;
sp.replace(map);
}
return sp;
}
private File getPreferencesDir() {
@@ -2712,6 +2711,10 @@ class ContextImpl extends Context {
private static final class SharedPreferencesImpl implements SharedPreferences {
// Lock ordering rules:
// - acquire SharedPreferencesImpl.this before EditorImpl.this
// - acquire mWritingToDiskLock before EditorImpl.this
private final File mFile;
private final File mBackupFile;
private final int mMode;
@@ -2719,6 +2722,7 @@ class ContextImpl extends Context {
private Map<String, Object> mMap; // guarded by 'this'
private long mTimestamp; // guarded by 'this'
private int mDiskWritesInFlight = 0; // guarded by 'this'
private boolean mLoaded = false; // guarded by 'this'
private final Object mWritingToDiskLock = new Object();
private static final Object mContent = new Object();
@@ -2729,6 +2733,7 @@ class ContextImpl extends Context {
mFile = file;
mBackupFile = makeBackupFile(file);
mMode = mode;
mLoaded = initialContents != null;
mMap = initialContents != null ? initialContents : new HashMap<String, Object>();
FileStatus stat = new FileStatus();
if (FileUtils.getFileStatus(file.getPath(), stat)) {
@@ -2737,7 +2742,23 @@ class ContextImpl extends Context {
mListeners = new WeakHashMap<OnSharedPreferenceChangeListener, Object>();
}
public boolean hasFileChanged() {
// Has this SharedPreferences ever had values assigned to it?
boolean isLoaded() {
synchronized (this) {
return mLoaded;
}
}
// Has the file changed out from under us? i.e. writes that
// we didn't instigate.
public boolean hasFileChangedUnexpectedly() {
synchronized (this) {
if (mDiskWritesInFlight > 0) {
// If we know we caused it, it's not unexpected.
Log.d(TAG, "disk write in flight, not unexpected.");
return false;
}
}
FileStatus stat = new FileStatus();
if (!FileUtils.getFileStatus(mFile.getPath(), stat)) {
return true;
@@ -2748,8 +2769,9 @@ class ContextImpl extends Context {
}
public void replace(Map newContents) {
if (newContents != null) {
synchronized (this) {
synchronized (this) {
mLoaded = true;
if (newContents != null) {
mMap = newContents;
}
}