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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 <folly/synchronization/CallOnce.h>
- #include <deque>
- #include <mutex>
- #include <thread>
- #include <folly/Benchmark.h>
- #include <glog/logging.h>
- DEFINE_int32(threads, 16, "benchmark concurrency");
- template <typename CallOnceFunc>
- void bm_impl(CallOnceFunc&& fn, size_t iters) {
- std::deque<std::thread> threads;
- for (size_t i = 0u; i < size_t(FLAGS_threads); ++i) {
- threads.emplace_back([&fn, iters] {
- for (size_t j = 0u; j < iters; ++j) {
- fn();
- }
- });
- }
- for (std::thread& t : threads) {
- t.join();
- }
- }
- BENCHMARK(StdCallOnceBench, iters) {
- std::once_flag flag;
- int out = 0;
- bm_impl([&] { std::call_once(flag, [&] { ++out; }); }, iters);
- CHECK_EQ(1, out);
- }
- BENCHMARK(FollyCallOnceBench, iters) {
- folly::once_flag flag;
- int out = 0;
- bm_impl([&] { folly::call_once(flag, [&] { ++out; }); }, iters);
- CHECK_EQ(1, out);
- }
- /*
- $ call_once_benchmark --bm_min_iters=100000000 --threads=16
- ============================================================================
- folly/synchronization/test/CallOnceBenchmark.cpprelative time/iter iters/s
- ============================================================================
- StdCallOnceBench 2.40ns 416.78M
- FollyCallOnceBench 651.94ps 1.53G
- ============================================================================
- */
- int main(int argc, char** argv) {
- gflags::ParseCommandLineFlags(&argc, &argv, true);
- folly::runBenchmarks();
- return 0;
- }
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