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Commit be78258e authored by Jeff Sharkey's avatar Jeff Sharkey
Browse files

Add path cache to avoid SharedPreferences jank. 

The old getSharedPreferences() API had a side-effect behavior that
subsequent calls wouldn't touch disk if there was a cache hit.  Now
that we're using File as the cache key, we were generating the path
every time, which resulted in touching disk.

To bring back the old behavior, let's add yet another cache!

Bug: 26979210
Change-Id: Ib8346c6f69ae25f8f164e3b7e05bc6358de38906
parent 115d2c18

core/java/android/app/ContextImpl.java

+23 −6
Original line number Diff line number Diff line
@@ -134,7 +134,14 @@ class ContextImpl extends Context { 
    /**

     * Map from package name, to preference name, to cached preferences.

     */

    private static ArrayMap<String, ArrayMap<File, SharedPreferencesImpl>> sSharedPrefs;

    @GuardedBy("ContextImpl.class")

    private static ArrayMap<String, ArrayMap<File, SharedPreferencesImpl>> sSharedPrefsCache;



    /**

     * Map from preference name to generated path.

     */

    @GuardedBy("ContextImpl.class")

    private ArrayMap<String, File> mSharedPrefsPaths;



    final ActivityThread mMainThread;

    final LoadedApk mPackageInfo;
@@ -335,7 +342,17 @@ class ContextImpl extends Context { 
            }

        }



        final File file = getSharedPreferencesPath(name);

        File file;

        synchronized (ContextImpl.class) {

            if (mSharedPrefsPaths == null) {

                mSharedPrefsPaths = new ArrayMap<>();

            }

            file = mSharedPrefsPaths.get(name);

            if (file == null) {

                file = getSharedPreferencesPath(name);

                mSharedPrefsPaths.put(name, file);

            }

        }

        return getSharedPreferences(file, mode);

    }
@@ -363,15 +380,15 @@ class ContextImpl extends Context { 
    }



    private ArrayMap<File, SharedPreferencesImpl> getSharedPreferencesCacheLocked() {

        if (sSharedPrefs == null) {

            sSharedPrefs = new ArrayMap<>();

        if (sSharedPrefsCache == null) {

            sSharedPrefsCache = new ArrayMap<>();

        }



        final String packageName = getPackageName();

        ArrayMap<File, SharedPreferencesImpl> packagePrefs = sSharedPrefs.get(packageName);

        ArrayMap<File, SharedPreferencesImpl> packagePrefs = sSharedPrefsCache.get(packageName);

        if (packagePrefs == null) {

            packagePrefs = new ArrayMap<>();

            sSharedPrefs.put(packageName, packagePrefs);

            sSharedPrefsCache.put(packageName, packagePrefs);

        }



        return packagePrefs;