pybind11/tests/test_class_sh_shared_from_this.cpp
Ralf W. Grosse-Kunstleve 0e4b38e34d Minor clang-tidy fix.
2021-06-30 07:04:31 -07:00

240 lines
8.7 KiB
C++

#include "pybind11_tests.h"
#include "object.h"
#include <pybind11/smart_holder.h>
#include <iostream>
#include <stdexcept>
namespace shared_from_this_custom_deleters {
template <typename T>
struct labeled_delete {
std::string label;
explicit labeled_delete(const std::string &label) : label{label} {}
void operator()(T *raw_ptr) {
std::cout << "labeled_delete::operator() " << label << std::endl;
if (label != "SkipDelete") {
delete raw_ptr;
}
}
};
struct Atype : std::enable_shared_from_this<Atype> {};
#define SHOW_USE_COUNTS \
std::cout << "obj1, obj2 use_counts: " << obj1.use_count() << ", " << obj2.use_count() \
<< std::endl;
void obj1_owns() {
std::cout << "\nobj1_owns()" << std::endl;
std::shared_ptr<Atype> obj1(new Atype, labeled_delete<Atype>("1st"));
std::shared_ptr<Atype> obj2(obj1.get(), labeled_delete<Atype>("SkipDelete"));
SHOW_USE_COUNTS
auto sft1 = obj1->shared_from_this();
SHOW_USE_COUNTS
auto sft2 = obj2->shared_from_this();
SHOW_USE_COUNTS
}
void obj2_owns() {
std::cout << "\nobj2_owns()" << std::endl;
std::shared_ptr<Atype> obj1(new Atype, labeled_delete<Atype>("SkipDelete"));
std::shared_ptr<Atype> obj2(obj1.get(), labeled_delete<Atype>("2nd"));
SHOW_USE_COUNTS
auto sft1 = obj1->shared_from_this();
SHOW_USE_COUNTS
auto sft2 = obj2->shared_from_this();
SHOW_USE_COUNTS
}
void obj_sft_reset() {
std::cout << "\nobj_sft_reset()" << std::endl;
std::shared_ptr<Atype> obj1(new Atype, labeled_delete<Atype>("SkipDelete"));
std::shared_ptr<Atype> obj2(obj1.get(), labeled_delete<Atype>("ThisDeletes"));
std::shared_ptr<Atype> *obj_sft = nullptr;
std::shared_ptr<Atype> *obj_ign = nullptr;
{
auto sft1 = obj1->shared_from_this();
auto sft2 = obj2->shared_from_this();
long uc1 = obj1.use_count();
long uc2 = obj2.use_count();
if (uc1 == 3 && uc2 == 1) {
std::cout << "SHARED_FROM_THIS_REFERENT: 1" << std::endl;
obj_sft = &obj1;
obj_ign = &obj2;
} else if (uc1 == 1 && uc2 == 3) {
std::cout << "SHARED_FROM_THIS_REFERENT: 2" << std::endl;
obj_sft = &obj2;
obj_ign = &obj1;
} else {
std::cout << "SHARED_FROM_THIS_REFERENT: UNKNOWN" << std::endl;
}
}
if (obj_sft == nullptr)
throw std::runtime_error("Unexpected `use_count`s.");
(*obj_sft).reset();
#if defined(_MSC_VER) && _MSC_VER < 1912
std::cout << "Preempting \"Windows fatal exception: access violation\": "
"(*obj_ign)->shared_from_this()"
<< std::endl;
#else
bool got_bad_weak_ptr = false;
try {
static_cast<void>((*obj_ign)->shared_from_this());
} catch (const std::bad_weak_ptr &) {
got_bad_weak_ptr = true;
}
std::cout << "got_bad_weak_ptr: " << got_bad_weak_ptr << std::endl;
std::shared_ptr<Atype> obj3(obj2.get(), labeled_delete<Atype>("SkipDelete"));
// Working again based on the shared_ptr that was created after obj_sft was reset:
static_cast<void>((*obj_ign)->shared_from_this());
#endif
}
} // namespace shared_from_this_custom_deleters
namespace shared_ptr_reset_and_rescue_pointee_model {
struct ToBeWrapped : std::enable_shared_from_this<ToBeWrapped> {};
struct RescuingDeleter;
struct PyWrapper {
std::unique_ptr<RescuingDeleter> rdel;
std::shared_ptr<ToBeWrapped> wobj;
std::shared_ptr<PyWrapper> self;
};
struct RescuingDeleter {
PyWrapper *pyw;
explicit RescuingDeleter(PyWrapper *pyw) : pyw{pyw} {}
void operator()(ToBeWrapped *raw_ptr) {
if (pyw->self != nullptr) {
#if defined(__cpp_lib_enable_shared_from_this) && (!defined(_MSC_VER) || _MSC_VER >= 1912)
assert(raw_ptr->weak_from_this().expired()); // CRITICAL
#endif
pyw->wobj = std::shared_ptr<ToBeWrapped>(raw_ptr, *this);
pyw->self.reset();
} else {
delete raw_ptr;
}
}
};
std::shared_ptr<ToBeWrapped> release_to_cpp(const std::shared_ptr<PyWrapper> &pyw) {
std::shared_ptr<ToBeWrapped> return_value = pyw->wobj;
pyw->wobj.reset();
pyw->self = pyw;
return return_value;
}
void proof_of_concept() {
std::shared_ptr<PyWrapper> pyw(new PyWrapper);
pyw->rdel = std::unique_ptr<RescuingDeleter>(new RescuingDeleter(pyw.get()));
pyw->wobj = std::shared_ptr<ToBeWrapped>(new ToBeWrapped, *pyw->rdel);
std::shared_ptr<ToBeWrapped> cpp_owner = release_to_cpp(pyw);
assert(pyw->wobj.get() == nullptr);
assert(cpp_owner.use_count() == 1);
{
std::shared_ptr<ToBeWrapped> sft = cpp_owner->shared_from_this();
assert(cpp_owner.use_count() == 2);
}
assert(cpp_owner.use_count() == 1);
cpp_owner.reset();
assert(pyw->wobj.get() != nullptr);
assert(pyw->wobj.use_count() == 1);
{
std::shared_ptr<ToBeWrapped> sft = pyw->wobj->shared_from_this();
assert(pyw->wobj.use_count() == 2);
}
}
} // namespace shared_ptr_reset_and_rescue_pointee_model
namespace test_class_sh_shared_from_this {
// clang-format off
class MyObject3 : public std::enable_shared_from_this<MyObject3> {
public:
MyObject3(const MyObject3 &) = default;
MyObject3(int value) : value(value) { print_created(this, toString()); }
std::string toString() const { return "MyObject3[" + std::to_string(value) + "]"; }
virtual ~MyObject3() { print_destroyed(this); }
private:
int value;
};
struct SharedFromThisRef {
struct B : std::enable_shared_from_this<B> {
B() { print_created(this); }
B(const B &) : std::enable_shared_from_this<B>() { print_copy_created(this); }
B(B &&) : std::enable_shared_from_this<B>() { print_move_created(this); }
~B() { print_destroyed(this); }
};
B value = {};
std::shared_ptr<B> shared = std::make_shared<B>();
};
struct SharedFromThisVBase : std::enable_shared_from_this<SharedFromThisVBase> {
SharedFromThisVBase() = default;
SharedFromThisVBase(const SharedFromThisVBase &) = default;
virtual ~SharedFromThisVBase() = default;
};
struct SharedFromThisVirt : virtual SharedFromThisVBase {};
// clang-format on
} // namespace test_class_sh_shared_from_this
using namespace test_class_sh_shared_from_this;
PYBIND11_SMART_HOLDER_TYPE_CASTERS(MyObject3)
PYBIND11_SMART_HOLDER_TYPE_CASTERS(SharedFromThisRef::B)
PYBIND11_SMART_HOLDER_TYPE_CASTERS(SharedFromThisRef)
PYBIND11_SMART_HOLDER_TYPE_CASTERS(SharedFromThisVirt)
TEST_SUBMODULE(class_sh_shared_from_this, m) {
// clang-format off
py::classh<MyObject3>(m, "MyObject3")
.def(py::init<int>());
m.def("make_myobject3_1", []() { return new MyObject3(8); });
m.def("make_myobject3_2", []() { return std::make_shared<MyObject3>(9); });
m.def("print_myobject3_1", [](const MyObject3 *obj) { py::print(obj->toString()); });
m.def("print_myobject3_2", [](std::shared_ptr<MyObject3> obj) { py::print(obj->toString()); });
m.def("print_myobject3_3", [](const std::shared_ptr<MyObject3> &obj) { py::print(obj->toString()); });
// m.def("print_myobject3_4", [](const std::shared_ptr<MyObject3> *obj) { py::print((*obj)->toString()); });
using B = SharedFromThisRef::B;
py::classh<B>(m, "B");
py::classh<SharedFromThisRef>(m, "SharedFromThisRef")
.def(py::init<>())
.def_readonly("bad_wp", &SharedFromThisRef::value)
.def_property_readonly("ref", [](const SharedFromThisRef &s) -> const B & { return *s.shared; })
.def_property_readonly("copy", [](const SharedFromThisRef &s) { return s.value; },
py::return_value_policy::automatic) // XXX XXX XXX copy)
.def_readonly("holder_ref", &SharedFromThisRef::shared)
.def_property_readonly("holder_copy", [](const SharedFromThisRef &s) { return s.shared; },
py::return_value_policy::automatic) // XXX XXX XXX copy)
.def("set_ref", [](SharedFromThisRef &, const B &) { return true; })
.def("set_holder", [](SharedFromThisRef &, std::shared_ptr<B>) { return true; });
static std::shared_ptr<SharedFromThisVirt> sft(new SharedFromThisVirt());
py::classh<SharedFromThisVirt>(m, "SharedFromThisVirt")
.def_static("get", []() { return sft.get(); }, py::return_value_policy::reference);
// clang-format on
m.def("obj1_owns", shared_from_this_custom_deleters::obj1_owns);
m.def("obj2_owns", shared_from_this_custom_deleters::obj2_owns);
m.def("obj_sft_reset", shared_from_this_custom_deleters::obj_sft_reset);
m.def("shared_ptr_reset_and_rescue_pointee_model_proof_of_concept",
shared_ptr_reset_and_rescue_pointee_model::proof_of_concept);
}