| // Copyright 2020 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/at_exit.h" |
| #include "base/bind.h" |
| #include "base/command_line.h" |
| #include "base/logging.h" |
| #include "base/optional.h" |
| #include "base/run_loop.h" |
| #include "base/strings/string_number_conversions.h" |
| #include "base/task/thread_pool.h" |
| #include "base/test/task_environment.h" |
| #include "base/test/test_timeouts.h" |
| #include "base/threading/sequenced_task_runner_handle.h" |
| #include "base/time/time.h" |
| |
| namespace { |
| |
| base::Optional<int> FindNonTrivialFactor(int n) { |
| // Really naive algorithm. |
| for (int i = 2; i < n; ++i) { |
| if (n % i == 0) { |
| return i; |
| } |
| } |
| return base::nullopt; |
| } |
| |
| void FindNonTrivialFactorHelper(int n, base::Optional<int>* result) { |
| *result = FindNonTrivialFactor(n); |
| } |
| |
| void PrintStatusUpdate(base::TimeTicks start_time) { |
| double num_seconds = (base::TimeTicks::Now() - start_time).InSecondsF(); |
| LOG(INFO) << "Waited for " << num_seconds << " seconds...\n"; |
| } |
| |
| void PrintStatusUpdateRepeatedly(base::TimeTicks start_time, |
| base::TimeDelta print_interval) { |
| PrintStatusUpdate(start_time); |
| base::ThreadPool::PostDelayedTask( |
| FROM_HERE, |
| base::BindOnce(&PrintStatusUpdateRepeatedly, start_time, print_interval), |
| print_interval); |
| } |
| |
| } // namespace |
| |
| int main(int argc, char* argv[]) { |
| base::AtExitManager exit_manager; |
| base::CommandLine::Init(argc, argv); |
| TestTimeouts::Initialize(); |
| base::test::TaskEnvironment task_environment{ |
| base::test::TaskEnvironment::TimeSource::SYSTEM_TIME}; |
| |
| if (argc <= 1) { |
| LOG(INFO) << argv[0] << ": missing operand\n"; |
| return -1; |
| } |
| |
| int n = 0; |
| if (!base::StringToInt(argv[1], &n) || n < 2) { |
| LOG(INFO) << argv[0] << ": invalid n '" << argv[1] << "'"; |
| return -1; |
| } |
| |
| base::RunLoop run_loop; |
| |
| base::Optional<int> result; |
| // Notice that we're posting the long-running factoring operation to |
| // |base::ThreadPool| to avoid blocking the main thread |
| // |
| // |run_loop.QuitClosure()| will be called once the factoring task completes. |
| base::ThreadPool::PostTaskAndReply( |
| FROM_HERE, base::BindOnce(&FindNonTrivialFactorHelper, n, &result), |
| run_loop.QuitClosure()); |
| |
| base::ThreadPool::PostTask( |
| FROM_HERE, |
| base::BindOnce(&PrintStatusUpdateRepeatedly, base::TimeTicks::Now(), |
| base::TimeDelta::FromSeconds(1))); |
| |
| run_loop.Run(); |
| |
| if (result.has_value()) { |
| LOG(INFO) << "found non-trivial factor " << result.value() << " for " << n; |
| DCHECK_EQ(n % result.value(), 0); |
| } else { |
| LOG(INFO) << n << " is prime"; |
| } |
| |
| return 0; |
| } |