2 * Copyright 2016 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.
21 #include <folly/CallOnce.h>
22 #include <folly/portability/GFlags.h>
23 #include <folly/portability/GTest.h>
25 #include <glog/logging.h>
27 DEFINE_int32(threads, 16, "benchmark concurrency");
29 template <typename CallOnceFunc>
30 void bm_impl(CallOnceFunc&& fn, int64_t iters) {
31 std::deque<std::thread> threads;
32 for (int i = 0; i < FLAGS_threads; ++i) {
33 threads.emplace_back([&fn, iters] {
34 for (int64_t j = 0; j < iters; ++j) {
39 for (std::thread& t : threads) {
44 TEST(FollyCallOnce, Simple) {
45 folly::once_flag flag;
46 auto fn = [&](int* outp) { ++*outp; };
48 folly::call_once(flag, fn, &out);
49 folly::call_once(flag, fn, &out);
53 TEST(FollyCallOnce, Stress) {
54 for (int i = 0; i < 100; ++i) {
55 folly::once_flag flag;
57 bm_impl([&] { folly::call_once(flag, [&] { ++out; }); }, 100);