681 lines
21 KiB
C++
681 lines
21 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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*
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* Author: Eric Niebler <eniebler@fb.com>
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*/
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#include <folly/Portability.h>
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namespace folly {
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template <class Fn>
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struct exception_wrapper::arg_type_
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: public arg_type_<decltype(&Fn::operator())> {};
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template <class Ret, class Class, class Arg>
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struct exception_wrapper::arg_type_<Ret (Class::*)(Arg)> {
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using type = Arg;
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};
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template <class Ret, class Class, class Arg>
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struct exception_wrapper::arg_type_<Ret (Class::*)(Arg) const> {
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using type = Arg;
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};
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template <class Ret, class Arg>
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struct exception_wrapper::arg_type_<Ret(Arg)> {
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using type = Arg;
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};
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template <class Ret, class Arg>
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struct exception_wrapper::arg_type_<Ret (*)(Arg)> {
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using type = Arg;
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};
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template <class Ret, class Class>
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struct exception_wrapper::arg_type_<Ret (Class::*)(...)> {
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using type = AnyException;
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};
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template <class Ret, class Class>
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struct exception_wrapper::arg_type_<Ret (Class::*)(...) const> {
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using type = AnyException;
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};
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template <class Ret>
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struct exception_wrapper::arg_type_<Ret(...)> {
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using type = AnyException;
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};
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template <class Ret>
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struct exception_wrapper::arg_type_<Ret (*)(...)> {
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using type = AnyException;
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};
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template <class Ret, class... Args>
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inline Ret exception_wrapper::noop_(Args...) {
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return Ret();
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}
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inline std::type_info const* exception_wrapper::uninit_type_(
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exception_wrapper const*) {
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return &typeid(void);
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}
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template <class Ex, typename... As>
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inline exception_wrapper::Buffer::Buffer(in_place_type_t<Ex>, As&&... as_) {
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::new (static_cast<void*>(&buff_)) Ex(std::forward<As>(as_)...);
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}
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template <class Ex>
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inline Ex& exception_wrapper::Buffer::as() noexcept {
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return *static_cast<Ex*>(static_cast<void*>(&buff_));
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}
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template <class Ex>
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inline Ex const& exception_wrapper::Buffer::as() const noexcept {
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return *static_cast<Ex const*>(static_cast<void const*>(&buff_));
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}
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inline std::exception const* exception_wrapper::as_exception_or_null_(
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std::exception const& ex) {
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return &ex;
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}
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inline std::exception const* exception_wrapper::as_exception_or_null_(
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AnyException) {
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return nullptr;
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}
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static_assert(
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!kMicrosoftAbiVer || (kMicrosoftAbiVer >= 1900 && kMicrosoftAbiVer <= 2000),
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"exception_wrapper is untested and possibly broken on your version of "
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"MSVC");
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inline std::uintptr_t exception_wrapper::ExceptionPtr::as_int_(
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std::exception_ptr const& ptr,
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std::exception const& e) noexcept {
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if (!kMicrosoftAbiVer) {
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return reinterpret_cast<std::uintptr_t>(&e);
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} else {
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// On Windows, as of MSVC2017, all thrown exceptions are copied to the stack
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// first. Thus, we cannot depend on exception references associated with an
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// exception_ptr to be live for the duration of the exception_ptr. We need
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// to directly access the heap allocated memory inside the exception_ptr.
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//
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// std::exception_ptr is an opaque reinterpret_cast of
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// std::shared_ptr<__ExceptionPtr>
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// __ExceptionPtr is a non-virtual class with two members, a union and a
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// bool. The union contains the now-undocumented EHExceptionRecord, which
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// contains a struct which contains a void* which points to the heap
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// allocated exception.
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// We derive the offset to pExceptionObject via manual means.
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FOLLY_PACK_PUSH
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struct Win32ExceptionPtr {
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char offset[8 + 4 * sizeof(void*)];
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void* exceptionObject;
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} FOLLY_PACK_ATTR;
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FOLLY_PACK_POP
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auto* win32ExceptionPtr =
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reinterpret_cast<std::shared_ptr<Win32ExceptionPtr> const*>(&ptr)
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->get();
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return reinterpret_cast<std::uintptr_t>(win32ExceptionPtr->exceptionObject);
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}
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}
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inline std::uintptr_t exception_wrapper::ExceptionPtr::as_int_(
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std::exception_ptr const&,
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AnyException e) noexcept {
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return reinterpret_cast<std::uintptr_t>(e.typeinfo_) + 1;
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}
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inline bool exception_wrapper::ExceptionPtr::has_exception_() const {
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return 0 == exception_or_type_ % 2;
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}
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inline std::exception const* exception_wrapper::ExceptionPtr::as_exception_()
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const {
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return reinterpret_cast<std::exception const*>(exception_or_type_);
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}
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inline std::type_info const* exception_wrapper::ExceptionPtr::as_type_() const {
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return reinterpret_cast<std::type_info const*>(exception_or_type_ - 1);
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}
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inline void exception_wrapper::ExceptionPtr::copy_(
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exception_wrapper const* from,
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exception_wrapper* to) {
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::new (static_cast<void*>(&to->eptr_)) ExceptionPtr(from->eptr_);
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}
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inline void exception_wrapper::ExceptionPtr::move_(
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exception_wrapper* from,
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exception_wrapper* to) {
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::new (static_cast<void*>(&to->eptr_)) ExceptionPtr(std::move(from->eptr_));
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delete_(from);
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}
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inline void exception_wrapper::ExceptionPtr::delete_(exception_wrapper* that) {
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that->eptr_.~ExceptionPtr();
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that->vptr_ = &uninit_;
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}
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[[noreturn]] inline void exception_wrapper::ExceptionPtr::throw_(
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exception_wrapper const* that) {
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std::rethrow_exception(that->eptr_.ptr_);
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}
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inline std::type_info const* exception_wrapper::ExceptionPtr::type_(
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exception_wrapper const* that) {
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if (auto e = get_exception_(that)) {
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return &typeid(*e);
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}
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return that->eptr_.as_type_();
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}
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inline std::exception const* exception_wrapper::ExceptionPtr::get_exception_(
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exception_wrapper const* that) {
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return that->eptr_.has_exception_() ? that->eptr_.as_exception_() : nullptr;
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}
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inline exception_wrapper exception_wrapper::ExceptionPtr::get_exception_ptr_(
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exception_wrapper const* that) {
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return *that;
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}
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template <class Ex>
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inline void exception_wrapper::InPlace<Ex>::copy_(
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exception_wrapper const* from,
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exception_wrapper* to) {
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::new (static_cast<void*>(std::addressof(to->buff_.as<Ex>())))
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Ex(from->buff_.as<Ex>());
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}
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template <class Ex>
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inline void exception_wrapper::InPlace<Ex>::move_(
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exception_wrapper* from,
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exception_wrapper* to) {
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::new (static_cast<void*>(std::addressof(to->buff_.as<Ex>())))
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Ex(std::move(from->buff_.as<Ex>()));
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delete_(from);
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}
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template <class Ex>
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inline void exception_wrapper::InPlace<Ex>::delete_(exception_wrapper* that) {
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that->buff_.as<Ex>().~Ex();
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that->vptr_ = &uninit_;
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}
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template <class Ex>
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[[noreturn]] inline void exception_wrapper::InPlace<Ex>::throw_(
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exception_wrapper const* that) {
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throw that->buff_.as<Ex>();
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}
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template <class Ex>
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inline std::type_info const* exception_wrapper::InPlace<Ex>::type_(
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exception_wrapper const*) {
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return &typeid(Ex);
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}
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template <class Ex>
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inline std::exception const* exception_wrapper::InPlace<Ex>::get_exception_(
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exception_wrapper const* that) {
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return as_exception_or_null_(that->buff_.as<Ex>());
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}
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template <class Ex>
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inline exception_wrapper exception_wrapper::InPlace<Ex>::get_exception_ptr_(
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exception_wrapper const* that) {
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try {
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throw_(that);
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} catch (Ex const& ex) {
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return exception_wrapper{std::current_exception(), ex};
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}
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}
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template <class Ex>
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[[noreturn]] inline void exception_wrapper::SharedPtr::Impl<Ex>::throw_()
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const {
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throw ex_;
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}
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template <class Ex>
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inline std::exception const*
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exception_wrapper::SharedPtr::Impl<Ex>::get_exception_() const noexcept {
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return as_exception_or_null_(ex_);
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}
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template <class Ex>
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inline exception_wrapper
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exception_wrapper::SharedPtr::Impl<Ex>::get_exception_ptr_() const noexcept {
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try {
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throw_();
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} catch (Ex& ex) {
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return exception_wrapper{std::current_exception(), ex};
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}
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}
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inline void exception_wrapper::SharedPtr::copy_(
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exception_wrapper const* from,
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exception_wrapper* to) {
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::new (static_cast<void*>(std::addressof(to->sptr_))) SharedPtr(from->sptr_);
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}
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inline void exception_wrapper::SharedPtr::move_(
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exception_wrapper* from,
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exception_wrapper* to) {
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::new (static_cast<void*>(std::addressof(to->sptr_)))
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SharedPtr(std::move(from->sptr_));
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delete_(from);
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}
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inline void exception_wrapper::SharedPtr::delete_(exception_wrapper* that) {
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that->sptr_.~SharedPtr();
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that->vptr_ = &uninit_;
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}
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[[noreturn]] inline void exception_wrapper::SharedPtr::throw_(
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exception_wrapper const* that) {
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that->sptr_.ptr_->throw_();
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folly::assume_unreachable();
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}
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inline std::type_info const* exception_wrapper::SharedPtr::type_(
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exception_wrapper const* that) {
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return that->sptr_.ptr_->info_;
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}
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inline std::exception const* exception_wrapper::SharedPtr::get_exception_(
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exception_wrapper const* that) {
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return that->sptr_.ptr_->get_exception_();
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}
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inline exception_wrapper exception_wrapper::SharedPtr::get_exception_ptr_(
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exception_wrapper const* that) {
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return that->sptr_.ptr_->get_exception_ptr_();
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}
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template <class Ex, typename... As>
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inline exception_wrapper::exception_wrapper(
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ThrownTag,
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in_place_type_t<Ex>,
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As&&... as)
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: eptr_{std::make_exception_ptr(Ex(std::forward<As>(as)...)),
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reinterpret_cast<std::uintptr_t>(std::addressof(typeid(Ex))) + 1u},
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vptr_(&ExceptionPtr::ops_) {}
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template <class Ex, typename... As>
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inline exception_wrapper::exception_wrapper(
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OnHeapTag,
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in_place_type_t<Ex>,
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As&&... as)
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: sptr_{std::make_shared<SharedPtr::Impl<Ex>>(std::forward<As>(as)...)},
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vptr_(&SharedPtr::ops_) {}
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template <class Ex, typename... As>
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inline exception_wrapper::exception_wrapper(
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InSituTag,
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in_place_type_t<Ex>,
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As&&... as)
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: buff_{in_place_type<Ex>, std::forward<As>(as)...},
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vptr_(&InPlace<Ex>::ops_) {}
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inline exception_wrapper::exception_wrapper(exception_wrapper&& that) noexcept
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: exception_wrapper{} {
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(vptr_ = that.vptr_)->move_(&that, this); // Move into *this, won't throw
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}
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inline exception_wrapper::exception_wrapper(
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exception_wrapper const& that) noexcept
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: exception_wrapper{} {
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that.vptr_->copy_(&that, this); // Copy into *this, won't throw
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vptr_ = that.vptr_;
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}
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// If `this == &that`, this move assignment operator leaves the object in a
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// valid but unspecified state.
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inline exception_wrapper& exception_wrapper::operator=(
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exception_wrapper&& that) noexcept {
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vptr_->delete_(this); // Free the current exception
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(vptr_ = that.vptr_)->move_(&that, this); // Move into *this, won't throw
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return *this;
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}
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inline exception_wrapper& exception_wrapper::operator=(
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exception_wrapper const& that) noexcept {
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exception_wrapper(that).swap(*this);
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return *this;
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}
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inline exception_wrapper::~exception_wrapper() {
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reset();
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}
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template <class Ex>
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inline exception_wrapper::exception_wrapper(
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std::exception_ptr ptr,
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Ex& ex) noexcept
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: eptr_{ptr, ExceptionPtr::as_int_(ptr, ex)}, vptr_(&ExceptionPtr::ops_) {
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assert(eptr_.ptr_);
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}
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namespace exception_wrapper_detail {
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template <class Ex>
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Ex&& dont_slice(Ex&& ex) {
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assert(typeid(ex) == typeid(std::decay_t<Ex>) ||
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!"Dynamic and static exception types don't match. Exception would "
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"be sliced when storing in exception_wrapper.");
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return std::forward<Ex>(ex);
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}
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} // namespace exception_wrapper_detail
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template <
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class Ex,
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class Ex_,
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FOLLY_REQUIRES_DEF(Conjunction<
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exception_wrapper::IsStdException<Ex_>,
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exception_wrapper::IsRegularExceptionType<Ex_>>::value)>
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inline exception_wrapper::exception_wrapper(Ex&& ex)
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: exception_wrapper{
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PlacementOf<Ex_>{},
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in_place_type<Ex_>,
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exception_wrapper_detail::dont_slice(std::forward<Ex>(ex))} {}
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template <
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class Ex,
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class Ex_,
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FOLLY_REQUIRES_DEF(exception_wrapper::IsRegularExceptionType<Ex_>::value)>
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inline exception_wrapper::exception_wrapper(in_place_t, Ex&& ex)
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: exception_wrapper{
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PlacementOf<Ex_>{},
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in_place_type<Ex_>,
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exception_wrapper_detail::dont_slice(std::forward<Ex>(ex))} {}
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template <
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class Ex,
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typename... As,
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FOLLY_REQUIRES_DEF(exception_wrapper::IsRegularExceptionType<Ex>::value)>
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inline exception_wrapper::exception_wrapper(in_place_type_t<Ex>, As&&... as)
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: exception_wrapper{PlacementOf<Ex>{},
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in_place_type<Ex>,
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std::forward<As>(as)...} {}
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inline void exception_wrapper::swap(exception_wrapper& that) noexcept {
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exception_wrapper tmp(std::move(that));
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that = std::move(*this);
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*this = std::move(tmp);
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}
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inline exception_wrapper::operator bool() const noexcept {
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return vptr_ != &uninit_;
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}
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inline bool exception_wrapper::operator!() const noexcept {
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return !static_cast<bool>(*this);
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}
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inline void exception_wrapper::reset() {
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vptr_->delete_(this);
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}
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inline bool exception_wrapper::has_exception_ptr() const noexcept {
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return vptr_ == &ExceptionPtr::ops_;
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}
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inline std::exception* exception_wrapper::get_exception() noexcept {
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return const_cast<std::exception*>(vptr_->get_exception_(this));
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}
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inline std::exception const* exception_wrapper::get_exception() const noexcept {
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return vptr_->get_exception_(this);
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}
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template <typename Ex>
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inline Ex* exception_wrapper::get_exception() noexcept {
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Ex* object{nullptr};
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with_exception([&](Ex& ex) { object = &ex; });
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return object;
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}
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template <typename Ex>
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inline Ex const* exception_wrapper::get_exception() const noexcept {
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Ex const* object{nullptr};
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with_exception([&](Ex const& ex) { object = &ex; });
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return object;
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}
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inline std::exception_ptr exception_wrapper::to_exception_ptr() noexcept {
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if (*this) {
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// Computing an exception_ptr is expensive so cache the result.
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return (*this = vptr_->get_exception_ptr_(this)).eptr_.ptr_;
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}
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return {};
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}
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inline std::exception_ptr exception_wrapper::to_exception_ptr() const noexcept {
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return vptr_->get_exception_ptr_(this).eptr_.ptr_;
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}
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inline std::type_info const& exception_wrapper::none() noexcept {
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return typeid(void);
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}
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inline std::type_info const& exception_wrapper::unknown() noexcept {
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return typeid(Unknown);
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}
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inline std::type_info const& exception_wrapper::type() const noexcept {
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return *vptr_->type_(this);
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}
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inline folly::fbstring exception_wrapper::what() const {
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if (auto e = get_exception()) {
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return class_name() + ": " + e->what();
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}
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return class_name();
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}
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inline folly::fbstring exception_wrapper::class_name() const {
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auto& ti = type();
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return ti == none()
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? ""
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: ti == unknown() ? "<unknown exception>" : folly::demangle(ti);
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}
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template <class Ex>
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inline bool exception_wrapper::is_compatible_with() const noexcept {
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return with_exception([](Ex const&) {});
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}
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[[noreturn]] inline void exception_wrapper::throw_exception() const {
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vptr_->throw_(this);
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onNoExceptionError(__func__);
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}
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template <class Ex>
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[[noreturn]] inline void exception_wrapper::throw_with_nested(Ex&& ex) const {
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try {
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throw_exception();
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} catch (...) {
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std::throw_with_nested(std::forward<Ex>(ex));
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}
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}
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template <class CatchFn, bool IsConst>
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struct exception_wrapper::ExceptionTypeOf {
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using type = arg_type<std::decay_t<CatchFn>>;
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static_assert(
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std::is_reference<type>::value,
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"Always catch exceptions by reference.");
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static_assert(
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!IsConst || std::is_const<std::remove_reference_t<type>>::value,
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"handle() or with_exception() called on a const exception_wrapper "
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"and asked to catch a non-const exception. Handler will never fire. "
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"Catch exception by const reference to fix this.");
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};
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// Nests a throw in the proper try/catch blocks
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template <bool IsConst>
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struct exception_wrapper::HandleReduce {
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bool* handled_;
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template <
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class ThrowFn,
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class CatchFn,
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FOLLY_REQUIRES(!IsCatchAll<CatchFn>::value)>
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auto operator()(ThrowFn&& th, CatchFn& ca) const {
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using Ex = _t<ExceptionTypeOf<CatchFn, IsConst>>;
|
|
return [th = std::forward<ThrowFn>(th), &ca, handled_ = handled_] {
|
|
try {
|
|
th();
|
|
} catch (Ex& e) {
|
|
// If we got here because a catch function threw, rethrow.
|
|
if (*handled_) {
|
|
throw;
|
|
}
|
|
*handled_ = true;
|
|
ca(e);
|
|
}
|
|
};
|
|
}
|
|
|
|
template <
|
|
class ThrowFn,
|
|
class CatchFn,
|
|
FOLLY_REQUIRES(IsCatchAll<CatchFn>::value)>
|
|
auto operator()(ThrowFn&& th, CatchFn& ca) const {
|
|
return [th = std::forward<ThrowFn>(th), &ca, handled_ = handled_] {
|
|
try {
|
|
th();
|
|
} catch (...) {
|
|
// If we got here because a catch function threw, rethrow.
|
|
if (*handled_) {
|
|
throw;
|
|
}
|
|
*handled_ = true;
|
|
ca();
|
|
}
|
|
};
|
|
}
|
|
};
|
|
|
|
// When all the handlers expect types derived from std::exception, we can
|
|
// sometimes invoke the handlers without throwing any exceptions.
|
|
template <bool IsConst>
|
|
struct exception_wrapper::HandleStdExceptReduce {
|
|
using StdEx = AddConstIf<IsConst, std::exception>;
|
|
|
|
template <
|
|
class ThrowFn,
|
|
class CatchFn,
|
|
FOLLY_REQUIRES(!IsCatchAll<CatchFn>::value)>
|
|
auto operator()(ThrowFn&& th, CatchFn& ca) const {
|
|
using Ex = _t<ExceptionTypeOf<CatchFn, IsConst>>;
|
|
return
|
|
[th = std::forward<ThrowFn>(th), &ca](auto&& continuation) -> StdEx* {
|
|
if (auto e = const_cast<StdEx*>(th(continuation))) {
|
|
if (auto e2 = dynamic_cast<std::add_pointer_t<Ex>>(e)) {
|
|
ca(*e2);
|
|
} else {
|
|
return e;
|
|
}
|
|
}
|
|
return nullptr;
|
|
};
|
|
}
|
|
|
|
template <
|
|
class ThrowFn,
|
|
class CatchFn,
|
|
FOLLY_REQUIRES(IsCatchAll<CatchFn>::value)>
|
|
auto operator()(ThrowFn&& th, CatchFn& ca) const {
|
|
return [th = std::forward<ThrowFn>(th), &ca](auto &&) -> StdEx* {
|
|
// The following continuation causes ca() to execute if *this contains
|
|
// an exception /not/ derived from std::exception.
|
|
auto continuation = [&ca](StdEx* e) {
|
|
return e != nullptr ? e : ((void)ca(), nullptr);
|
|
};
|
|
if (th(continuation) != nullptr) {
|
|
ca();
|
|
}
|
|
return nullptr;
|
|
};
|
|
}
|
|
};
|
|
|
|
// Called when some types in the catch clauses are not derived from
|
|
// std::exception.
|
|
template <class This, class... CatchFns>
|
|
inline void
|
|
exception_wrapper::handle_(std::false_type, This& this_, CatchFns&... fns) {
|
|
bool handled = false;
|
|
auto impl = exception_wrapper_detail::fold(
|
|
HandleReduce<std::is_const<This>::value>{&handled},
|
|
[&] { this_.throw_exception(); },
|
|
fns...);
|
|
impl();
|
|
}
|
|
|
|
// Called when all types in the catch clauses are either derived from
|
|
// std::exception or a catch-all clause.
|
|
template <class This, class... CatchFns>
|
|
inline void
|
|
exception_wrapper::handle_(std::true_type, This& this_, CatchFns&... fns) {
|
|
using StdEx = exception_wrapper_detail::
|
|
AddConstIf<std::is_const<This>::value, std::exception>;
|
|
auto impl = exception_wrapper_detail::fold(
|
|
HandleStdExceptReduce<std::is_const<This>::value>{},
|
|
[&](auto&& continuation) {
|
|
return continuation(
|
|
const_cast<StdEx*>(this_.vptr_->get_exception_(&this_)));
|
|
},
|
|
fns...);
|
|
// This continuation gets evaluated if CatchFns... does not include a
|
|
// catch-all handler. It is a no-op.
|
|
auto continuation = [](StdEx* ex) { return ex; };
|
|
if (nullptr != impl(continuation)) {
|
|
this_.throw_exception();
|
|
}
|
|
}
|
|
|
|
namespace exception_wrapper_detail {
|
|
template <class Ex, class Fn>
|
|
struct catch_fn {
|
|
Fn fn_;
|
|
auto operator()(Ex& ex) {
|
|
return fn_(ex);
|
|
}
|
|
};
|
|
|
|
template <class Ex, class Fn>
|
|
inline catch_fn<Ex, Fn> catch_(Ex*, Fn fn) {
|
|
return {std::move(fn)};
|
|
}
|
|
template <class Fn>
|
|
inline Fn catch_(void const*, Fn fn) {
|
|
return fn;
|
|
}
|
|
} // namespace exception_wrapper_detail
|
|
|
|
template <class Ex, class This, class Fn>
|
|
inline bool exception_wrapper::with_exception_(This& this_, Fn fn_) {
|
|
if (!this_) {
|
|
return false;
|
|
}
|
|
bool handled = true;
|
|
auto fn = exception_wrapper_detail::catch_(
|
|
static_cast<Ex*>(nullptr), std::move(fn_));
|
|
auto&& all = [&](...) { handled = false; };
|
|
handle_(IsStdException<arg_type<decltype(fn)>>{}, this_, fn, all);
|
|
return handled;
|
|
}
|
|
|
|
template <class Ex, class Fn>
|
|
inline bool exception_wrapper::with_exception(Fn fn) {
|
|
return with_exception_<Ex>(*this, std::move(fn));
|
|
}
|
|
template <class Ex, class Fn>
|
|
inline bool exception_wrapper::with_exception(Fn fn) const {
|
|
return with_exception_<Ex const>(*this, std::move(fn));
|
|
}
|
|
|
|
template <class... CatchFns>
|
|
inline void exception_wrapper::handle(CatchFns... fns) {
|
|
using AllStdEx =
|
|
exception_wrapper_detail::AllOf<IsStdException, arg_type<CatchFns>...>;
|
|
if (!*this) {
|
|
onNoExceptionError(__func__);
|
|
}
|
|
this->handle_(AllStdEx{}, *this, fns...);
|
|
}
|
|
template <class... CatchFns>
|
|
inline void exception_wrapper::handle(CatchFns... fns) const {
|
|
using AllStdEx =
|
|
exception_wrapper_detail::AllOf<IsStdException, arg_type<CatchFns>...>;
|
|
if (!*this) {
|
|
onNoExceptionError(__func__);
|
|
}
|
|
this->handle_(AllStdEx{}, *this, fns...);
|
|
}
|
|
|
|
} // namespace folly
|