Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4049d0fd authored by Kweku Adams's avatar Kweku Adams
Browse files

Improve forEach. 

The default implementation of Collection.forEach() uses the
iterator(). Switch to a simple for loop iterating through the array
since the iterator is an inefficient way to access the array contents.

Benchmark results:

Before:

android.util.ArrayMapPerfTest#testForEach_Large:
	forEach_Large_min (ns): 599759
	forEach_Large_median (ns): 655845
	forEach_Large_mean (ns): 636927
	forEach_Large_standardDeviation: 34373
android.util.ArrayMapPerfTest#testForEach_Small:
	forEach_Small_min (ns): 118822
	forEach_Small_median (ns): 121422
	forEach_Small_mean (ns): 121695
	forEach_Small_standardDeviation: 2079

After:

android.util.ArrayMapPerfTest#testForEach_Large:
	forEach_Large_min (ns): 403562
	forEach_Large_median (ns): 441364
	forEach_Large_mean (ns): 442301
	forEach_Large_standardDeviation: 24917
android.util.ArrayMapPerfTest#testForEach_Small:
	forEach_Small_min (ns): 81889
	forEach_Small_median (ns): 87889
	forEach_Small_mean (ns): 86905
	forEach_Small_standardDeviation: 2880

Bug: 194098491
Test: atest CorePerfTests:ArrayMapPerfTest (see results above)
Test: atest CtsUtilTestCases:ArrayMapTest
Test: atest FrameworksCoreTests:ArrayMapTest
Change-Id: Id528fe24f1d17af01a2d639753d42e2ad21144d2
parent 1548f793

apct-tests/perftests/core/src/android/util/ArrayMapPerfTest.java

0 → 100644
+72 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2018 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.util;



import android.perftests.utils.BenchmarkState;

import android.perftests.utils.PerfStatusReporter;



import androidx.test.filters.LargeTest;

import androidx.test.runner.AndroidJUnit4;



import org.junit.Rule;

import org.junit.Test;

import org.junit.runner.RunWith;



import java.util.function.BiConsumer;



@RunWith(AndroidJUnit4.class)

@LargeTest

public class ArrayMapPerfTest {

    private static final int NUM_ITERATIONS = 100;

    private static final int SET_SIZE_SMALL = 10;

    private static final int SET_SIZE_LARGE = 50;



    @Rule

    public PerfStatusReporter mPerfStatusReporter = new PerfStatusReporter();



    @Test

    public void testForEach_Small() {

        BenchmarkState state = mPerfStatusReporter.getBenchmarkState();

        BiConsumer<String, Integer> consumer = (s, i) -> {

        };

        while (state.keepRunning()) {

            for (int i = 0; i < NUM_ITERATIONS; ++i) {

                ArrayMap<String, Integer> map = new ArrayMap<>();

                for (int j = 0; j < SET_SIZE_SMALL; j++) {

                    map.put(Integer.toString(j), j);

                }

                map.forEach(consumer);

            }

        }

    }



    @Test

    public void testForEach_Large() {

        BenchmarkState state = mPerfStatusReporter.getBenchmarkState();

        BiConsumer<String, Integer> consumer = (s, i) -> {

        };

        while (state.keepRunning()) {

            for (int i = 0; i < NUM_ITERATIONS; ++i) {

                ArrayMap<String, Integer> map = new ArrayMap<>();

                for (int j = 0; j < SET_SIZE_LARGE; j++) {

                    map.put(Integer.toString(j), j);

                }

                map.forEach(consumer);

            }

        }

    }

}

core/java/android/util/ArrayMap.java

+23 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ import java.util.Collection; 
import java.util.ConcurrentModificationException;

import java.util.Map;

import java.util.Set;

import java.util.function.BiConsumer;



/**

 * ArrayMap is a generic key->value mapping data structure that is
@@ -979,6 +980,28 @@ public final class ArrayMap<K, V> implements Map<K, V> { 
        return MapCollections.containsAllHelper(this, collection);

    }



    /**

     * Performs the given action for all elements in the stored order. This implementation overrides

     * the default implementation to avoid iterating using the {@link #entrySet()} and iterates in

     * the key-value order consistent with {@link #keyAt(int)} and {@link #valueAt(int)}.

     *

     * @param action The action to be performed for each element

     */

    @Override

    public void forEach(BiConsumer<? super K, ? super V> action) {

        if (action == null) {

            throw new NullPointerException("action must not be null");

        }



        final int size = mSize;

        for (int i = 0; i < size; ++i) {

            if (size != mSize) {

                throw new ConcurrentModificationException();

            }

            action.accept(keyAt(i), valueAt(i));

        }

    }



    /**

     * Perform a {@link #put(Object, Object)} of all key/value pairs in <var>map</var>

     * @param map The map whose contents are to be retrieved.