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- /*
- * Copyright 2016-present Facebook, Inc.
- *
- * 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.
- */
- #include <deque>
- #include <mutex>
- #include <thread>
- #include <folly/portability/GTest.h>
- #include <folly/synchronization/CallOnce.h>
- static size_t const kNumThreads = 16;
- template <typename CallOnceFunc>
- void bm_impl(CallOnceFunc&& fn, size_t iters) {
- std::deque<std::thread> threads;
- for (size_t i = 0u; i < kNumThreads; ++i) {
- threads.emplace_back([&fn, iters] {
- for (size_t j = 0u; j < iters; ++j) {
- fn();
- }
- });
- }
- for (std::thread& t : threads) {
- t.join();
- }
- }
- TEST(FollyCallOnce, Simple) {
- folly::once_flag flag;
- auto fn = [&](int* outp) { ++*outp; };
- int out = 0;
- folly::call_once(flag, fn, &out);
- folly::call_once(flag, fn, &out);
- ASSERT_EQ(1, out);
- }
- TEST(FollyCallOnce, Exception) {
- struct ExpectedException {};
- folly::once_flag flag;
- size_t numCalls = 0;
- EXPECT_THROW(
- folly::call_once(
- flag,
- [&] {
- ++numCalls;
- throw ExpectedException();
- }),
- ExpectedException);
- EXPECT_EQ(1, numCalls);
- folly::call_once(flag, [&] { ++numCalls; });
- EXPECT_EQ(2, numCalls);
- }
- TEST(FollyCallOnce, Stress) {
- for (int i = 0; i < 100; ++i) {
- folly::once_flag flag;
- int out = 0;
- bm_impl([&] { folly::call_once(flag, [&] { ++out; }); }, 100);
- ASSERT_EQ(1, out);
- }
- }
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