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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <optional>
#include "base/at_exit.h"
#include "base/command_line.h"
#include "base/functional/bind.h"
#include "base/logging.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/time/time.h"
namespace {
std::optional<int> FindNonTrivialFactor(int n) {
// Really naive algorithm.
for (int i = 2; i < n; ++i) {
if (n % i == 0) {
return i;
}
}
return std::nullopt;
}
void FindNonTrivialFactorHelper(int n, std::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 < 2) {
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;
std::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::Seconds(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;
}
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