2 * Copyright 2016-present 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/portability/GTest.h>
22 #include <folly/synchronization/CallOnce.h>
24 static size_t const kNumThreads = 16;
26 template <typename CallOnceFunc>
27 void bm_impl(CallOnceFunc&& fn, size_t iters) {
28 std::deque<std::thread> threads;
29 for (size_t i = 0u; i < kNumThreads; ++i) {
30 threads.emplace_back([&fn, iters] {
31 for (size_t j = 0u; j < iters; ++j) {
36 for (std::thread& t : threads) {
41 TEST(FollyCallOnce, Simple) {
42 folly::once_flag flag;
43 auto fn = [&](int* outp) { ++*outp; };
45 folly::call_once(flag, fn, &out);
46 folly::call_once(flag, fn, &out);
50 TEST(FollyCallOnce, Exception) {
51 struct ExpectedException {};
52 folly::once_flag flag;
59 throw ExpectedException();
62 EXPECT_EQ(1, numCalls);
63 folly::call_once(flag, [&] { ++numCalls; });
64 EXPECT_EQ(2, numCalls);
67 TEST(FollyCallOnce, Stress) {
68 for (int i = 0; i < 100; ++i) {
69 folly::once_flag flag;
71 bm_impl([&] { folly::call_once(flag, [&] { ++out; }); }, 100);