pybind11/tests/test_iostream.cpp

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/*
tests/test_iostream.cpp -- Usage of scoped_output_redirect
Copyright (c) 2017 Henry F. Schreiner
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#include <pybind11/iostream.h>
#include "pybind11_tests.h"
#include <atomic>
#include <iostream>
#include <mutex>
#include <string>
#include <thread>
void noisy_function(const std::string &msg, bool flush) {
std::cout << msg;
if (flush) {
std::cout << std::flush;
}
}
void noisy_funct_dual(const std::string &msg, const std::string &emsg) {
std::cout << msg;
std::cerr << emsg;
}
// object to manage C++ thread
// simply repeatedly write to std::cerr until stopped
// redirect is called at some point to test the safety of scoped_estream_redirect
struct TestThread {
TestThread() : stop_{false} {
auto thread_f = [this] {
static std::mutex cout_mutex;
while (!stop_) {
{
// #HelpAppreciated: Work on iostream.h thread safety.
// Without this lock, the clang ThreadSanitizer (tsan) reliably reports a
// data race, and this test is predictably flakey on Windows.
// For more background see the discussion under
// https://github.com/pybind/pybind11/pull/2982 and
// https://github.com/pybind/pybind11/pull/2995.
const std::lock_guard<std::mutex> lock(cout_mutex);
std::cout << "x" << std::flush;
}
std::this_thread::sleep_for(std::chrono::microseconds(50));
}
};
t_ = new std::thread(std::move(thread_f));
}
~TestThread() { delete t_; }
void stop() { stop_ = true; }
void join() const {
py::gil_scoped_release gil_lock;
t_->join();
}
void sleep() {
py::gil_scoped_release gil_lock;
std::this_thread::sleep_for(std::chrono::milliseconds(50));
}
std::thread *t_{nullptr};
std::atomic<bool> stop_;
};
TEST_SUBMODULE(iostream, m) {
add_ostream_redirect(m);
// test_evals
m.def("captured_output_default", [](const std::string &msg) {
py::scoped_ostream_redirect redir;
std::cout << msg << std::flush;
});
m.def("captured_output", [](const std::string &msg) {
py::scoped_ostream_redirect redir(std::cout, py::module_::import("sys").attr("stdout"));
std::cout << msg << std::flush;
});
m.def("guard_output",
&noisy_function,
py::call_guard<py::scoped_ostream_redirect>(),
py::arg("msg"),
py::arg("flush") = true);
m.def("captured_err", [](const std::string &msg) {
py::scoped_ostream_redirect redir(std::cerr, py::module_::import("sys").attr("stderr"));
std::cerr << msg << std::flush;
});
m.def("noisy_function", &noisy_function, py::arg("msg"), py::arg("flush") = true);
m.def("dual_guard",
&noisy_funct_dual,
py::call_guard<py::scoped_ostream_redirect, py::scoped_estream_redirect>(),
py::arg("msg"),
py::arg("emsg"));
m.def("raw_output", [](const std::string &msg) { std::cout << msg << std::flush; });
m.def("raw_err", [](const std::string &msg) { std::cerr << msg << std::flush; });
m.def("captured_dual", [](const std::string &msg, const std::string &emsg) {
py::scoped_ostream_redirect redirout(std::cout, py::module_::import("sys").attr("stdout"));
py::scoped_ostream_redirect redirerr(std::cerr, py::module_::import("sys").attr("stderr"));
std::cout << msg << std::flush;
std::cerr << emsg << std::flush;
});
py::class_<TestThread>(m, "TestThread")
.def(py::init<>())
.def("stop", &TestThread::stop)
.def("join", &TestThread::join)
.def("sleep", &TestThread::sleep);
}