2 * Copyright 2014 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #include <folly/Baton.h>
18 #include <folly/test/DeterministicSchedule.h>
20 #include <semaphore.h>
21 #include <gflags/gflags.h>
22 #include <gtest/gtest.h>
23 #include <folly/Benchmark.h>
25 using namespace folly;
26 using namespace folly::test;
28 typedef DeterministicSchedule DSched;
36 template <template<typename> class Atom>
37 void run_pingpong_test(int numRounds) {
38 Baton<Atom> batons[17];
39 Baton<Atom>& a = batons[0];
40 Baton<Atom>& b = batons[16]; // to get it on a different cache line
41 auto thr = DSched::thread([&]{
42 for (int i = 0; i < numRounds; ++i) {
48 for (int i = 0; i < numRounds; ++i) {
56 TEST(Baton, pingpong) {
57 DSched sched(DSched::uniform(0));
59 run_pingpong_test<DeterministicAtomic>(1000);
62 BENCHMARK(baton_pingpong, iters) {
63 run_pingpong_test<std::atomic>(iters);
66 BENCHMARK(posix_sem_pingpong, iters) {
69 sem_t* b = sems + 2; // to get it on a different cache line
73 auto thr = std::thread([=]{
74 for (int i = 0; i < iters; ++i) {
79 for (int i = 0; i < iters; ++i) {
86 template <template<typename> class Atom>
87 void run_basic_timed_wait_tests() {
90 // tests if early delivery works fine
91 EXPECT_TRUE(b.timed_wait(std::chrono::system_clock::now()));
94 template <template<typename> class Atom>
95 void run_timed_wait_tmo_tests() {
98 auto thr = DSched::thread([&]{
99 bool rv = b.timed_wait(std::chrono::system_clock::now() +
100 std::chrono::milliseconds(1));
101 // main thread is guaranteed to not post until timeout occurs
107 template <template<typename> class Atom>
108 void run_timed_wait_regular_test() {
111 auto thr = DSched::thread([&] {
112 bool rv = b.timed_wait(
113 std::chrono::time_point<std::chrono::system_clock>::max());
114 if (std::is_same<Atom<int>, std::atomic<int>>::value) {
115 // We can only ensure this for std::atomic
120 if (std::is_same<Atom<int>, std::atomic<int>>::value) {
121 // If we are using std::atomic, then a sleep here guarantees to a large
122 // extent that 'thr' will execute wait before we post it, thus testing
123 // late delivery. For DeterministicAtomic, we just rely on
124 // DeterministicSchedule to do the scheduling
125 std::this_thread::sleep_for(std::chrono::milliseconds(2));
132 TEST(Baton, timed_wait_basic) {
133 run_basic_timed_wait_tests<std::atomic>();
134 run_basic_timed_wait_tests<DeterministicAtomic>();
137 TEST(Baton, timed_wait_timeout) {
138 run_timed_wait_tmo_tests<std::atomic>();
139 run_timed_wait_tmo_tests<DeterministicAtomic>();
142 TEST(Baton, timed_wait) {
143 run_timed_wait_regular_test<std::atomic>();
144 run_timed_wait_regular_test<DeterministicAtomic>();
147 template <template<typename> class Atom>
148 void run_try_wait_tests() {
150 EXPECT_FALSE(b.try_wait());
152 EXPECT_TRUE(b.try_wait());
155 TEST(Baton, try_wait) {
156 run_try_wait_tests<std::atomic>();
157 run_try_wait_tests<DeterministicAtomic>();
160 // I am omitting a benchmark result snapshot because these microbenchmarks
161 // mainly illustrate that PreBlockAttempts is very effective for rapid
162 // handoffs. The performance of Baton and sem_t is essentially identical
163 // to the required futex calls for the blocking case
165 int main(int argc, char** argv) {
166 testing::InitGoogleTest(&argc, argv);
167 gflags::ParseCommandLineFlags(&argc, &argv, true);
169 auto rv = RUN_ALL_TESTS();
170 if (!rv && FLAGS_benchmark) {
171 folly::runBenchmarks();