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Commit f3903e9f authored by John Reck's avatar John Reck
Browse files

Fix regression in getSharedPreferences performance 

Only do access checks if there's a cache miss. If there's
a cache hit then those checks have necessarily already
passed once so we don't need to repeatedly do them
on every access.

Before:
timeCachedGetSharedPreferences_mean=126084

After:
timeCachedGetSharedPreferences_mean=362

Test: ran perf test
Change-Id: I51f0186f8e66c05ea0e5a457930377d1460dea17
parent f6d33e57

apct-tests/perftests/core/src/android/os/SharedPreferencesTest.java

0 → 100644
+47 −0
Original line number Original line Diff line number Diff line 
/*

 * Copyright (C) 2017 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License"); you may not

 * use this file except in compliance with the License. You may obtain a copy of

 * the License at

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the

 * License for the specific language governing permissions and limitations under

 * the License.

 */



package android.os;



import android.content.Context;

import android.content.SharedPreferences;

import android.perftests.utils.BenchmarkState;

import android.perftests.utils.PerfStatusReporter;

import android.support.test.InstrumentationRegistry;

import android.support.test.filters.LargeTest;

import android.support.test.runner.AndroidJUnit4;



import org.junit.Rule;

import org.junit.Test;

import org.junit.runner.RunWith;



@RunWith(AndroidJUnit4.class)

@LargeTest

public class SharedPreferencesTest {

    @Rule

    public PerfStatusReporter mPerfStatusReporter = new PerfStatusReporter();



    @Test

    public void timeCachedGetSharedPreferences() {

        final BenchmarkState state = mPerfStatusReporter.getBenchmarkState();

        final Context context = InstrumentationRegistry.getTargetContext();

        // Do the real work once as we're only interested in cache-hit performance

        SharedPreferences prefs = context.getSharedPreferences("test", Context.MODE_PRIVATE);

        while (state.keepRunning()) {

            prefs = context.getSharedPreferences("test", Context.MODE_PRIVATE);

        }

    }

}

core/java/android/app/ContextImpl.java

+10 −11
Original line number Original line Diff line number Diff line
@@ -63,7 +63,6 @@ import android.os.ServiceManager; 
import android.os.SystemProperties;

import android.os.SystemProperties;

import android.os.Trace;

import android.os.Trace;

import android.os.UserHandle;

import android.os.UserHandle;

import android.os.UserManager;

import android.os.storage.IStorageManager;

import android.os.storage.IStorageManager;

import android.os.storage.StorageManager;

import android.os.storage.StorageManager;

import android.system.ErrnoException;

import android.system.ErrnoException;
@@ -373,6 +372,11 @@ class ContextImpl extends Context { 




    @Override

    @Override

    public SharedPreferences getSharedPreferences(File file, int mode) {

    public SharedPreferences getSharedPreferences(File file, int mode) {

        SharedPreferencesImpl sp;

        synchronized (ContextImpl.class) {

            final ArrayMap<File, SharedPreferencesImpl> cache = getSharedPreferencesCacheLocked();

            sp = cache.get(file);

            if (sp == null) {

                checkMode(mode);

                checkMode(mode);

                if (getApplicationInfo().targetSdkVersion >= android.os.Build.VERSION_CODES.O) {

                if (getApplicationInfo().targetSdkVersion >= android.os.Build.VERSION_CODES.O) {

                    if (isCredentialProtectedStorage()

                    if (isCredentialProtectedStorage()
@@ -383,11 +387,6 @@ class ContextImpl extends Context { 
                                + "storage are not available until after user is unlocked");

                                + "storage are not available until after user is unlocked");

                    }

                    }

                }

                }

        SharedPreferencesImpl sp;

        synchronized (ContextImpl.class) {

            final ArrayMap<File, SharedPreferencesImpl> cache = getSharedPreferencesCacheLocked();

            sp = cache.get(file);

            if (sp == null) {

                sp = new SharedPreferencesImpl(file, mode);

                sp = new SharedPreferencesImpl(file, mode);

                cache.put(file, sp);

                cache.put(file, sp);

                return sp;

                return sp;