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Start pybind11/detail/smart_holder_type_caster_support.h, move unique_ptr_to_python() there, add smart_holder_from_unique_ptr()

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Ralf W. Grosse-Kunstleve 2024-07-01 15:50:24 -07:00
parent 6ff547e18a
commit ae08f51e38
4 changed files with 173 additions and 18 deletions
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7
include/pybind11/cast.h
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@ -12,6 +12,7 @@
#include "detail/common.h"
#include "detail/descr.h"
#include "detail/smart_holder_type_caster_support.h"
#include "detail/type_caster_base.h"
#include "detail/typeid.h"
#include "pytypes.h"
@ -931,8 +932,10 @@ struct move_only_holder_caster<type, std::unique_ptr<type, deleter>> {
static_assert(std::is_base_of<type_caster_base<type>, type_caster<type>>::value,
"Holder classes are only supported for custom types");
static handle cast(std::unique_ptr<type, deleter> &&src, return_value_policy, handle) {
return type_caster_base<type>::unique_ptr_to_python(std::move(src));
static handle
cast(std::unique_ptr<type, deleter> &&src, return_value_policy policy, handle parent) {
return smart_holder_type_caster_support::unique_ptr_to_python(
std::move(src), policy, parent);
}
static constexpr auto name = type_caster_base<type>::name;
};

107
include/pybind11/detail/smart_holder_type_caster_support.h Normal file
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@ -0,0 +1,107 @@
#pragma once
#include "../pytypes.h"
#include "../trampoline_self_life_support.h"
#include "common.h"
#include "dynamic_raw_ptr_cast_if_possible.h"
#include "internals.h"
#include "type_caster_base.h"
#include "typeid.h"
#include <cstdint>
#include <iterator>
#include <string>
#include <type_traits>
#include <typeinfo>
#include <utility>
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
PYBIND11_NAMESPACE_BEGIN(detail)
PYBIND11_NAMESPACE_BEGIN(smart_holder_type_caster_support)
template <typename T, typename D>
handle smart_holder_from_unique_ptr(std::unique_ptr<T, D> &&src,
return_value_policy policy,
handle parent,
const std::pair<const void *, const type_info *> &st) {
if (policy != return_value_policy::automatic
&& policy != return_value_policy::automatic_reference
&& policy != return_value_policy::reference_internal
&& policy != return_value_policy::move) {
// SMART_HOLDER_WIP: IMPROVABLE: Error message.
throw cast_error("Invalid return_value_policy for unique_ptr.");
}
if (!src) {
return none().release();
}
void *src_raw_void_ptr = const_cast<void *>(st.first);
assert(st.second != nullptr);
const detail::type_info *tinfo = st.second;
if (handle existing_inst = find_registered_python_instance(src_raw_void_ptr, tinfo)) {
auto *self_life_support
= dynamic_raw_ptr_cast_if_possible<trampoline_self_life_support>(src.get());
if (self_life_support != nullptr) {
value_and_holder &v_h = self_life_support->v_h;
if (v_h.inst != nullptr && v_h.vh != nullptr) {
auto &holder = v_h.holder<pybindit::memory::smart_holder>();
if (!holder.is_disowned) {
pybind11_fail("smart_holder_from_unique_ptr: unexpected "
"smart_holder.is_disowned failure.");
}
// Critical transfer-of-ownership section. This must stay together.
self_life_support->deactivate_life_support();
holder.reclaim_disowned();
(void) src.release();
// Critical section end.
return existing_inst;
}
}
throw cast_error("Invalid unique_ptr: another instance owns this pointer already.");
}
auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
auto *inst_raw_ptr = reinterpret_cast<instance *>(inst.ptr());
inst_raw_ptr->owned = true;
void *&valueptr = values_and_holders(inst_raw_ptr).begin()->value_ptr();
valueptr = src_raw_void_ptr;
if (static_cast<void *>(src.get()) == src_raw_void_ptr) {
// This is a multiple-inheritance situation that is incompatible with the current
// shared_from_this handling (see PR #3023).
// SMART_HOLDER_WIP: IMPROVABLE: Is there a better solution?
src_raw_void_ptr = nullptr;
}
auto smhldr
= pybindit::memory::smart_holder::from_unique_ptr(std::move(src), src_raw_void_ptr);
tinfo->init_instance(inst_raw_ptr, static_cast<const void *>(&smhldr));
if (policy == return_value_policy::reference_internal) {
keep_alive_impl(inst, parent);
}
return inst.release();
}
template <typename T, typename D>
handle
unique_ptr_to_python(std::unique_ptr<T, D> &&unq_ptr, return_value_policy policy, handle parent) {
auto *src = unq_ptr.get();
auto st = type_caster_base<T>::src_and_type(src);
if (st.second == nullptr) {
return handle(); // no type info: error will be set already
}
if (st.second->default_holder) {
return smart_holder_from_unique_ptr(std::move(unq_ptr), policy, parent, st);
}
return type_caster_generic::cast(st.first,
return_value_policy::take_ownership,
{},
st.second,
nullptr,
nullptr,
std::addressof(unq_ptr));
}
PYBIND11_NAMESPACE_END(smart_holder_type_caster_support)
PYBIND11_NAMESPACE_END(detail)
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)

16
include/pybind11/detail/type_caster_base.h
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@ -1160,22 +1160,6 @@ public:
holder);
}
template <typename T, typename D>
static handle unique_ptr_to_python(std::unique_ptr<T, D> &&unq_ptr) {
auto *src = unq_ptr.get();
auto st = src_and_type(src);
if (st.second->default_holder) {
throw std::runtime_error("BAKEIN_WIP");
}
return type_caster_generic::cast(st.first,
return_value_policy::take_ownership,
{},
st.second,
nullptr,
nullptr,
std::addressof(unq_ptr));
}
template <typename T>
using cast_op_type = detail::cast_op_type<T>;

61
include/pybind11/trampoline_self_life_support.h Normal file
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@ -0,0 +1,61 @@
// Copyright (c) 2021 The Pybind Development Team.
// All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#pragma once
#include "detail/common.h"
#include "detail/smart_holder_poc.h"
#include "detail/type_caster_base.h"
PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
PYBIND11_NAMESPACE_BEGIN(detail)
// SMART_HOLDER_WIP: Needs refactoring of existing pybind11 code.
inline bool deregister_instance(instance *self, void *valptr, const type_info *tinfo);
PYBIND11_NAMESPACE_END(detail)
// The original core idea for this struct goes back to PyCLIF:
// https://github.com/google/clif/blob/07f95d7e69dca2fcf7022978a55ef3acff506c19/clif/python/runtime.cc#L37
// URL provided here mainly to give proper credit. To fully explain the `HoldPyObj` feature, more
// context is needed (SMART_HOLDER_WIP).
struct trampoline_self_life_support {
detail::value_and_holder v_h;
trampoline_self_life_support() = default;
void activate_life_support(const detail::value_and_holder &v_h_) {
Py_INCREF((PyObject *) v_h_.inst);
v_h = v_h_;
}
void deactivate_life_support() {
Py_DECREF((PyObject *) v_h.inst);
v_h = detail::value_and_holder();
}
~trampoline_self_life_support() {
if (v_h.inst != nullptr && v_h.vh != nullptr) {
void *value_void_ptr = v_h.value_ptr();
if (value_void_ptr != nullptr) {
PyGILState_STATE threadstate = PyGILState_Ensure();
v_h.value_ptr() = nullptr;
v_h.holder<pybindit::memory::smart_holder>().release_disowned();
detail::deregister_instance(v_h.inst, value_void_ptr, v_h.type);
Py_DECREF((PyObject *) v_h.inst); // Must be after deregister.
PyGILState_Release(threadstate);
}
}
}
// For the next two, the default implementations generate undefined behavior (ASAN failures
// manually verified). The reason is that v_h needs to be kept default-initialized.
trampoline_self_life_support(const trampoline_self_life_support &) {}
trampoline_self_life_support(trampoline_self_life_support &&) noexcept {}
// These should never be needed (please provide test cases if you think they are).
trampoline_self_life_support &operator=(const trampoline_self_life_support &) = delete;
trampoline_self_life_support &operator=(trampoline_self_life_support &&) = delete;
};
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)