1 /*
2 * Copyright (C) 2023 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "gtest/gtest.h"
18
19 #include <atomic>
20 #include <cstdint>
21 #include <thread>
22
23 namespace {
24
LockContentionWorkLoad(std::atomic<uint32_t> * data,int data_size)25 void LockContentionWorkLoad(std::atomic<uint32_t>* data, int data_size) {
26 for (int k = 0; k < 10000; k++) {
27 // Contend for the set of the atomics to make sure they are locked independently.
28 for (int i = 0; i < data_size; i++) {
29 data[i].fetch_add(1, std::memory_order_relaxed);
30 }
31 }
32 }
33
34 } // namespace
35
TEST(Atomics,CompareAndSwap)36 TEST(Atomics, CompareAndSwap) {
37 std::atomic<int> data = {0};
38 int data_expected = 1;
39 int data_desired = -1;
40 // data != data_expected, data_expected is assigned with the value of data, data is unchanged.
41 ASSERT_FALSE(data.compare_exchange_strong(data_expected, data_desired));
42 ASSERT_EQ(data_expected, 0);
43 ASSERT_EQ(data.load(), 0);
44 // data == data_expected, data is assigned with the value of data_desired, data_expected is
45 // unchanged.
46 ASSERT_TRUE(data.compare_exchange_strong(data_expected, data_desired));
47 ASSERT_EQ(data_expected, 0);
48 ASSERT_EQ(data.load(), -1);
49 }
50
TEST(Atomics,LockContentionTest)51 TEST(Atomics, LockContentionTest) {
52 std::atomic<uint32_t> data[10];
53 std::thread threads[16];
54 for (int i = 0; i < 10; i++) {
55 data[i].store(0, std::memory_order_relaxed);
56 }
57 for (int i = 0; i < 16; i++) {
58 threads[i] = std::thread(LockContentionWorkLoad, data, 10);
59 }
60 for (int i = 0; i < 16; i++) {
61 threads[i].join();
62 }
63 for (int i = 0; i < 10; i++) {
64 ASSERT_EQ(data[i].load(std::memory_order_relaxed), 160000U);
65 }
66 }
67