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test_interpreter.cpp
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R7581 SP4E Homework
test_interpreter.cpp
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#include <pybind11/embed.h>
#ifdef _MSC_VER
// Silence MSVC C++17 deprecation warning from Catch regarding std::uncaught_exceptions (up to catch
// 2.0.1; this should be fixed in the next catch release after 2.0.1).
# pragma warning(disable: 4996)
#endif
#include <catch.hpp>
#include <thread>
#include <fstream>
#include <functional>
namespace py = pybind11;
using namespace py::literals;
class Widget {
public:
Widget(std::string message) : message(message) { }
virtual ~Widget() = default;
std::string the_message() const { return message; }
virtual int the_answer() const = 0;
private:
std::string message;
};
class PyWidget final : public Widget {
using Widget::Widget;
int the_answer() const override { PYBIND11_OVERLOAD_PURE(int, Widget, the_answer); }
};
PYBIND11_EMBEDDED_MODULE(widget_module, m) {
py::class_<Widget, PyWidget>(m, "Widget")
.def(py::init<std::string>())
.def_property_readonly("the_message", &Widget::the_message);
m.def("add", [](int i, int j) { return i + j; });
}
PYBIND11_EMBEDDED_MODULE(throw_exception, ) {
throw std::runtime_error("C++ Error");
}
PYBIND11_EMBEDDED_MODULE(throw_error_already_set, ) {
auto d = py::dict();
d["missing"].cast<py::object>();
}
TEST_CASE("Pass classes and data between modules defined in C++ and Python") {
auto module = py::module::import("test_interpreter");
REQUIRE(py::hasattr(module, "DerivedWidget"));
auto locals = py::dict("hello"_a="Hello, World!", "x"_a=5, **module.attr("__dict__"));
py::exec(R"(
widget = DerivedWidget("{} - {}".format(hello, x))
message = widget.the_message
)", py::globals(), locals);
REQUIRE(locals["message"].cast<std::string>() == "Hello, World! - 5");
auto py_widget = module.attr("DerivedWidget")("The question");
auto message = py_widget.attr("the_message");
REQUIRE(message.cast<std::string>() == "The question");
const auto &cpp_widget = py_widget.cast<const Widget &>();
REQUIRE(cpp_widget.the_answer() == 42);
}
TEST_CASE("Import error handling") {
REQUIRE_NOTHROW(py::module::import("widget_module"));
REQUIRE_THROWS_WITH(py::module::import("throw_exception"),
"ImportError: C++ Error");
REQUIRE_THROWS_WITH(py::module::import("throw_error_already_set"),
Catch::Contains("ImportError: KeyError"));
}
TEST_CASE("There can be only one interpreter") {
static_assert(std::is_move_constructible<py::scoped_interpreter>::value, "");
static_assert(!std::is_move_assignable<py::scoped_interpreter>::value, "");
static_assert(!std::is_copy_constructible<py::scoped_interpreter>::value, "");
static_assert(!std::is_copy_assignable<py::scoped_interpreter>::value, "");
REQUIRE_THROWS_WITH(py::initialize_interpreter(), "The interpreter is already running");
REQUIRE_THROWS_WITH(py::scoped_interpreter(), "The interpreter is already running");
py::finalize_interpreter();
REQUIRE_NOTHROW(py::scoped_interpreter());
{
auto pyi1 = py::scoped_interpreter();
auto pyi2 = std::move(pyi1);
}
py::initialize_interpreter();
}
bool has_pybind11_internals_builtin() {
auto builtins = py::handle(PyEval_GetBuiltins());
return builtins.contains(PYBIND11_INTERNALS_ID);
};
bool has_pybind11_internals_static() {
auto **&ipp = py::detail::get_internals_pp();
return ipp && *ipp;
}
TEST_CASE("Restart the interpreter") {
// Verify pre-restart state.
REQUIRE(py::module::import("widget_module").attr("add")(1, 2).cast<int>() == 3);
REQUIRE(has_pybind11_internals_builtin());
REQUIRE(has_pybind11_internals_static());
REQUIRE(py::module::import("external_module").attr("A")(123).attr("value").cast<int>() == 123);
// local and foreign module internals should point to the same internals:
REQUIRE(reinterpret_cast<uintptr_t>(*py::detail::get_internals_pp()) ==
py::module::import("external_module").attr("internals_at")().cast<uintptr_t>());
// Restart the interpreter.
py::finalize_interpreter();
REQUIRE(Py_IsInitialized() == 0);
py::initialize_interpreter();
REQUIRE(Py_IsInitialized() == 1);
// Internals are deleted after a restart.
REQUIRE_FALSE(has_pybind11_internals_builtin());
REQUIRE_FALSE(has_pybind11_internals_static());
pybind11::detail::get_internals();
REQUIRE(has_pybind11_internals_builtin());
REQUIRE(has_pybind11_internals_static());
REQUIRE(reinterpret_cast<uintptr_t>(*py::detail::get_internals_pp()) ==
py::module::import("external_module").attr("internals_at")().cast<uintptr_t>());
// Make sure that an interpreter with no get_internals() created until finalize still gets the
// internals destroyed
py::finalize_interpreter();
py::initialize_interpreter();
bool ran = false;
py::module::import("__main__").attr("internals_destroy_test") =
py::capsule(&ran, [](void *ran) { py::detail::get_internals(); *static_cast<bool *>(ran) = true; });
REQUIRE_FALSE(has_pybind11_internals_builtin());
REQUIRE_FALSE(has_pybind11_internals_static());
REQUIRE_FALSE(ran);
py::finalize_interpreter();
REQUIRE(ran);
py::initialize_interpreter();
REQUIRE_FALSE(has_pybind11_internals_builtin());
REQUIRE_FALSE(has_pybind11_internals_static());
// C++ modules can be reloaded.
auto cpp_module = py::module::import("widget_module");
REQUIRE(cpp_module.attr("add")(1, 2).cast<int>() == 3);
// C++ type information is reloaded and can be used in python modules.
auto py_module = py::module::import("test_interpreter");
auto py_widget = py_module.attr("DerivedWidget")("Hello after restart");
REQUIRE(py_widget.attr("the_message").cast<std::string>() == "Hello after restart");
}
TEST_CASE("Subinterpreter") {
// Add tags to the modules in the main interpreter and test the basics.
py::module::import("__main__").attr("main_tag") = "main interpreter";
{
auto m = py::module::import("widget_module");
m.attr("extension_module_tag") = "added to module in main interpreter";
REQUIRE(m.attr("add")(1, 2).cast<int>() == 3);
}
REQUIRE(has_pybind11_internals_builtin());
REQUIRE(has_pybind11_internals_static());
/// Create and switch to a subinterpreter.
auto main_tstate = PyThreadState_Get();
auto sub_tstate = Py_NewInterpreter();
// Subinterpreters get their own copy of builtins. detail::get_internals() still
// works by returning from the static variable, i.e. all interpreters share a single
// global pybind11::internals;
REQUIRE_FALSE(has_pybind11_internals_builtin());
REQUIRE(has_pybind11_internals_static());
// Modules tags should be gone.
REQUIRE_FALSE(py::hasattr(py::module::import("__main__"), "tag"));
{
auto m = py::module::import("widget_module");
REQUIRE_FALSE(py::hasattr(m, "extension_module_tag"));
// Function bindings should still work.
REQUIRE(m.attr("add")(1, 2).cast<int>() == 3);
}
// Restore main interpreter.
Py_EndInterpreter(sub_tstate);
PyThreadState_Swap(main_tstate);
REQUIRE(py::hasattr(py::module::import("__main__"), "main_tag"));
REQUIRE(py::hasattr(py::module::import("widget_module"), "extension_module_tag"));
}
TEST_CASE("Execution frame") {
// When the interpreter is embedded, there is no execution frame, but `py::exec`
// should still function by using reasonable globals: `__main__.__dict__`.
py::exec("var = dict(number=42)");
REQUIRE(py::globals()["var"]["number"].cast<int>() == 42);
}
TEST_CASE("Threads") {
// Restart interpreter to ensure threads are not initialized
py::finalize_interpreter();
py::initialize_interpreter();
REQUIRE_FALSE(has_pybind11_internals_static());
constexpr auto num_threads = 10;
auto locals = py::dict("count"_a=0);
{
py::gil_scoped_release gil_release{};
REQUIRE(has_pybind11_internals_static());
auto threads = std::vector<std::thread>();
for (auto i = 0; i < num_threads; ++i) {
threads.emplace_back([&]() {
py::gil_scoped_acquire gil{};
locals["count"] = locals["count"].cast<int>() + 1;
});
}
for (auto &thread : threads) {
thread.join();
}
}
REQUIRE(locals["count"].cast<int>() == num_threads);
}
// Scope exit utility https://stackoverflow.com/a/36644501/7255855
struct scope_exit {
std::function<void()> f_;
explicit scope_exit(std::function<void()> f) noexcept : f_(std::move(f)) {}
~scope_exit() { if (f_) f_(); }
};
TEST_CASE("Reload module from file") {
// Disable generation of cached bytecode (.pyc files) for this test, otherwise
// Python might pick up an old version from the cache instead of the new versions
// of the .py files generated below
auto sys = py::module::import("sys");
bool dont_write_bytecode = sys.attr("dont_write_bytecode").cast<bool>();
sys.attr("dont_write_bytecode") = true;
// Reset the value at scope exit
scope_exit reset_dont_write_bytecode([&]() {
sys.attr("dont_write_bytecode") = dont_write_bytecode;
});
std::string module_name = "test_module_reload";
std::string module_file = module_name + ".py";
// Create the module .py file
std::ofstream test_module(module_file);
test_module << "def test():\n";
test_module << " return 1\n";
test_module.close();
// Delete the file at scope exit
scope_exit delete_module_file([&]() {
std::remove(module_file.c_str());
});
// Import the module from file
auto module = py::module::import(module_name.c_str());
int result = module.attr("test")().cast<int>();
REQUIRE(result == 1);
// Update the module .py file with a small change
test_module.open(module_file);
test_module << "def test():\n";
test_module << " return 2\n";
test_module.close();
// Reload the module
module.reload();
result = module.attr("test")().cast<int>();
REQUIRE(result == 2);
}
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