#else
# define FOLLY_ALWAYS_INLINE inline
#endif
+
+// attribute hidden
+#if _MSC_VER
+#define FOLLY_ATTR_VISIBILITY_HIDDEN
+#elif defined(__clang__) || defined(__GNUC__)
+#define FOLLY_ATTR_VISIBILITY_HIDDEN __attribute__((__visibility__("hidden")))
+#else
+#define FOLLY_ATTR_VISIBILITY_HIDDEN
+#endif
--- /dev/null
+/*
+ * Copyright 2017-present Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ *
+ * Author: Eric Niebler <eniebler@fb.com>
+ */
+
+namespace folly {
+
+template <class Fn>
+struct exception_wrapper::arg_type2_ {};
+template <class Ret, class Class, class Arg>
+struct exception_wrapper::arg_type2_<Ret (Class::*)(Arg)> {
+ using type = Arg;
+};
+template <class Ret, class Class, class Arg>
+struct exception_wrapper::arg_type2_<Ret (Class::*)(Arg) const> {
+ using type = Arg;
+};
+template <class Ret, class Class>
+struct exception_wrapper::arg_type2_<Ret (Class::*)(...)> {
+ using type = AnyException;
+};
+template <class Ret, class Class>
+struct exception_wrapper::arg_type2_<Ret (Class::*)(...) const> {
+ using type = AnyException;
+};
+
+template <class Fn, class>
+struct exception_wrapper::arg_type_ {};
+template <class Fn>
+struct exception_wrapper::arg_type_<Fn, void_t<decltype(&Fn::operator())>>
+ : public arg_type2_<decltype(&Fn::operator())> {};
+template <class Ret, class Arg>
+struct exception_wrapper::arg_type_<Ret (*)(Arg)> {
+ using type = Arg;
+};
+template <class Ret>
+struct exception_wrapper::arg_type_<Ret (*)(...)> {
+ using type = AnyException;
+};
+
+template <class Ret, class... Args>
+inline Ret exception_wrapper::noop_(Args...) {
+ return Ret();
+}
+
+inline std::type_info const* exception_wrapper::uninit_type_(
+ exception_wrapper const*) {
+ return &typeid(void);
+}
+
+template <class Ex, class DEx>
+inline exception_wrapper::Buffer::Buffer(in_place_t, Ex&& ex) {
+ ::new (static_cast<void*>(&buff_)) DEx(std::forward<Ex>(ex));
+}
+
+template <class Ex>
+inline Ex& exception_wrapper::Buffer::as() noexcept {
+ return *static_cast<Ex*>(static_cast<void*>(&buff_));
+}
+template <class Ex>
+inline Ex const& exception_wrapper::Buffer::as() const noexcept {
+ return *static_cast<Ex const*>(static_cast<void const*>(&buff_));
+}
+
+inline std::exception const* exception_wrapper::as_exception_or_null_(
+ std::exception const& ex) {
+ return &ex;
+}
+inline std::exception const* exception_wrapper::as_exception_or_null_(
+ AnyException) {
+ return nullptr;
+}
+
+inline std::uintptr_t exception_wrapper::ExceptionPtr::as_int_(
+ std::exception const& e) {
+ return reinterpret_cast<std::uintptr_t>(&e);
+}
+inline std::uintptr_t exception_wrapper::ExceptionPtr::as_int_(AnyException e) {
+ return reinterpret_cast<std::uintptr_t>(e.typeinfo_) + 1;
+}
+inline bool exception_wrapper::ExceptionPtr::has_exception_() const {
+ return 0 == exception_or_type_ % 2;
+}
+inline std::exception const* exception_wrapper::ExceptionPtr::as_exception_()
+ const {
+ return reinterpret_cast<std::exception const*>(exception_or_type_);
+}
+inline std::type_info const* exception_wrapper::ExceptionPtr::as_type_() const {
+ return reinterpret_cast<std::type_info const*>(exception_or_type_ - 1);
+}
+
+inline void exception_wrapper::ExceptionPtr::copy_(
+ exception_wrapper const* from, exception_wrapper* to) {
+ ::new (static_cast<void*>(&to->eptr_)) ExceptionPtr(from->eptr_);
+}
+inline void exception_wrapper::ExceptionPtr::move_(
+ exception_wrapper* from, exception_wrapper* to) {
+ ::new (static_cast<void*>(&to->eptr_))
+ ExceptionPtr(std::move(from->eptr_));
+ delete_(from);
+}
+inline void exception_wrapper::ExceptionPtr::delete_(
+ exception_wrapper* that) {
+ that->eptr_.~ExceptionPtr();
+ that->vptr_ = &uninit_;
+}
+[[noreturn]] inline void exception_wrapper::ExceptionPtr::throw_(
+ exception_wrapper const* that) {
+ std::rethrow_exception(that->eptr_.ptr_);
+}
+inline std::type_info const* exception_wrapper::ExceptionPtr::type_(
+ exception_wrapper const* that) {
+ if (auto e = get_exception_(that)) {
+ return &typeid(*e);
+ }
+ return that->eptr_.as_type_();
+}
+inline std::exception const* exception_wrapper::ExceptionPtr::get_exception_(
+ exception_wrapper const* that) {
+ return that->eptr_.has_exception_() ? that->eptr_.as_exception_()
+ : nullptr;
+}
+inline exception_wrapper exception_wrapper::ExceptionPtr::get_exception_ptr_(
+ exception_wrapper const* that) {
+ return *that;
+}
+
+template <class Ex>
+inline void exception_wrapper::InPlace<Ex>::copy_(
+ exception_wrapper const* from, exception_wrapper* to) {
+ ::new (static_cast<void*>(std::addressof(to->buff_.as<Ex>())))
+ Ex(from->buff_.as<Ex>());
+}
+template <class Ex>
+inline void exception_wrapper::InPlace<Ex>::move_(
+ exception_wrapper* from, exception_wrapper* to) {
+ ::new (static_cast<void*>(std::addressof(to->buff_.as<Ex>())))
+ Ex(std::move(from->buff_.as<Ex>()));
+ delete_(from);
+}
+template <class Ex>
+inline void exception_wrapper::InPlace<Ex>::delete_(
+ exception_wrapper* that) {
+ that->buff_.as<Ex>().~Ex();
+ that->vptr_ = &uninit_;
+}
+template <class Ex>
+[[noreturn]] inline void exception_wrapper::InPlace<Ex>::throw_(
+ exception_wrapper const* that) {
+ throw that->buff_.as<Ex>(); // @nolint
+}
+template <class Ex>
+inline std::type_info const* exception_wrapper::InPlace<Ex>::type_(
+ exception_wrapper const*) {
+ return &typeid(Ex);
+}
+template <class Ex>
+inline std::exception const* exception_wrapper::InPlace<Ex>::get_exception_(
+ exception_wrapper const* that) {
+ return as_exception_or_null_(that->buff_.as<Ex>());
+}
+template <class Ex>
+inline exception_wrapper exception_wrapper::InPlace<Ex>::get_exception_ptr_(
+ exception_wrapper const* that) {
+ try {
+ throw_(that);
+ } catch (Ex const& ex) {
+ return exception_wrapper{std::current_exception(), ex};
+ }
+}
+
+template <class Ex>
+[[noreturn]] inline void
+exception_wrapper::SharedPtr::Impl<Ex>::throw_() const {
+ throw ex_; // @nolint
+}
+template <class Ex>
+inline std::exception const*
+exception_wrapper::SharedPtr::Impl<Ex>::get_exception_() const noexcept {
+ return as_exception_or_null_(ex_);
+}
+template <class Ex>
+inline exception_wrapper
+exception_wrapper::SharedPtr::Impl<Ex>::get_exception_ptr_() const noexcept {
+ try {
+ throw_();
+ } catch (Ex& ex) {
+ return exception_wrapper{std::current_exception(), ex};
+ }
+}
+inline void exception_wrapper::SharedPtr::copy_(
+ exception_wrapper const* from, exception_wrapper* to) {
+ ::new (static_cast<void*>(std::addressof(to->sptr_)))
+ SharedPtr(from->sptr_);
+}
+inline void exception_wrapper::SharedPtr::move_(
+ exception_wrapper* from, exception_wrapper* to) {
+ ::new (static_cast<void*>(std::addressof(to->sptr_)))
+ SharedPtr(std::move(from->sptr_));
+ delete_(from);
+}
+inline void exception_wrapper::SharedPtr::delete_(
+ exception_wrapper* that) {
+ that->sptr_.~SharedPtr();
+ that->vptr_ = &uninit_;
+}
+[[noreturn]] inline void exception_wrapper::SharedPtr::throw_(
+ exception_wrapper const* that) {
+ that->sptr_.ptr_->throw_();
+ folly::assume_unreachable();
+}
+inline std::type_info const* exception_wrapper::SharedPtr::type_(
+ exception_wrapper const* that) {
+ return that->sptr_.ptr_->info_;
+}
+inline std::exception const* exception_wrapper::SharedPtr::get_exception_(
+ exception_wrapper const* that) {
+ return that->sptr_.ptr_->get_exception_();
+}
+inline exception_wrapper exception_wrapper::SharedPtr::get_exception_ptr_(
+ exception_wrapper const* that) {
+ return that->sptr_.ptr_->get_exception_ptr_();
+}
+
+template <class Ex, class DEx>
+inline exception_wrapper::exception_wrapper(Ex&& ex, OnHeapTag)
+ : sptr_{std::make_shared<SharedPtr::Impl<DEx>>(std::forward<Ex>(ex))},
+ vptr_(&SharedPtr::ops_) {}
+
+template <class Ex, class DEx>
+inline exception_wrapper::exception_wrapper(Ex&& ex, InSituTag)
+ : buff_{in_place, std::forward<Ex>(ex)}, vptr_(&InPlace<DEx>::ops_) {}
+
+inline exception_wrapper::exception_wrapper(exception_wrapper&& that) noexcept
+ : exception_wrapper{} {
+ (vptr_ = that.vptr_)->move_(&that, this); // Move into *this, won't throw
+}
+
+inline exception_wrapper::exception_wrapper(
+ exception_wrapper const& that) : exception_wrapper{} {
+ that.vptr_->copy_(&that, this); // could throw
+ vptr_ = that.vptr_;
+}
+
+// If `this == &that`, this move assignment operator leaves the object in a
+// valid but unspecified state.
+inline exception_wrapper& exception_wrapper::operator=(
+ exception_wrapper&& that) noexcept {
+ vptr_->delete_(this); // Free the current exception
+ (vptr_ = that.vptr_)->move_(&that, this); // Move into *this, won't throw
+ return *this;
+}
+
+inline exception_wrapper& exception_wrapper::operator=(
+ exception_wrapper const& that) {
+ exception_wrapper(that).swap(*this);
+ return *this;
+}
+
+inline exception_wrapper::~exception_wrapper() {
+ reset();
+}
+
+template <class Ex>
+inline exception_wrapper::exception_wrapper(std::exception_ptr ptr, Ex& ex)
+ : eptr_{std::move(ptr), ExceptionPtr::as_int_(ex)},
+ vptr_(&ExceptionPtr::ops_) {
+ assert(eptr_.ptr_);
+}
+
+template <
+ class Ex,
+ class Ex_,
+ FOLLY_REQUIRES_DEF(
+ Conjunction<
+ exception_wrapper::IsStdException<Ex_>,
+ exception_wrapper::IsRegularExceptionType<Ex_>>())>
+inline exception_wrapper::exception_wrapper(Ex&& ex)
+ : exception_wrapper{std::forward<Ex>(ex), PlacementOf<Ex_>{}} {
+ // Don't slice!!!
+ assert(typeid(ex) == typeid(Ex_) ||
+ !"Dynamic and static exception types don't match. Exception would "
+ "be sliced when storing in exception_wrapper.");
+}
+
+template <
+ class Ex,
+ class Ex_,
+ FOLLY_REQUIRES_DEF(
+ exception_wrapper::IsRegularExceptionType<Ex_>())>
+inline exception_wrapper::exception_wrapper(in_place_t, Ex&& ex)
+ : exception_wrapper{std::forward<Ex>(ex), PlacementOf<Ex_>{}} {
+ // Don't slice!!!
+ assert(typeid(ex) == typeid(Ex_) ||
+ !"Dynamic and static exception types don't match. Exception would "
+ "be sliced when storing in exception_wrapper.");
+}
+
+inline void exception_wrapper::swap(exception_wrapper& that) noexcept {
+ exception_wrapper tmp(std::move(that));
+ that = std::move(*this);
+ *this = std::move(tmp);
+}
+
+inline exception_wrapper::operator bool() const noexcept {
+ return vptr_ != &uninit_;
+}
+
+inline bool exception_wrapper::operator!() const noexcept {
+ return !static_cast<bool>(*this);
+}
+
+inline void exception_wrapper::reset() {
+ vptr_->delete_(this);
+}
+
+inline bool exception_wrapper::has_exception_ptr() const noexcept {
+ return vptr_ == &ExceptionPtr::ops_;
+}
+
+inline std::exception* exception_wrapper::get_exception() noexcept {
+ return const_cast<std::exception*>(vptr_->get_exception_(this));
+}
+inline std::exception const* exception_wrapper::get_exception() const noexcept {
+ return vptr_->get_exception_(this);
+}
+
+inline std::exception_ptr const& exception_wrapper::to_exception_ptr()
+ noexcept {
+ // Computing an exception_ptr is expensive so cache the result.
+ return (*this = vptr_->get_exception_ptr_(this)).eptr_.ptr_;
+}
+inline std::exception_ptr exception_wrapper::to_exception_ptr() const noexcept {
+ return vptr_->get_exception_ptr_(this).eptr_.ptr_;
+}
+
+inline std::type_info const& exception_wrapper::none() noexcept {
+ return typeid(void);
+}
+inline std::type_info const& exception_wrapper::unknown() noexcept {
+ return typeid(Unknown);
+}
+
+inline std::type_info const& exception_wrapper::type() const noexcept {
+ return *vptr_->type_(this);
+}
+
+inline folly::fbstring exception_wrapper::what() const {
+ if (auto e = get_exception()) {
+ return class_name() + ": " + e->what();
+ }
+ return class_name();
+}
+
+inline folly::fbstring exception_wrapper::class_name() const {
+ auto& ti = type();
+ return ti == none()
+ ? ""
+ : ti == unknown() ? "<unknown exception>" : folly::demangle(ti);
+}
+
+template <class Ex>
+inline bool exception_wrapper::is_compatible_with() const noexcept {
+ return with_exception([](Ex const&) {});
+}
+
+[[noreturn]] inline void exception_wrapper::throwException() const {
+ vptr_->throw_(this);
+ onNoExceptionError();
+}
+
+template <class CatchFn, bool IsConst>
+struct exception_wrapper::ExceptionTypeOf {
+ using type = arg_type<_t<std::decay<CatchFn>>>;
+ static_assert(
+ std::is_reference<type>::value,
+ "Always catch exceptions by reference.");
+ static_assert(
+ !IsConst || std::is_const<_t<std::remove_reference<type>>>::value,
+ "handle() or with_exception() called on a const exception_wrapper "
+ "and asked to catch a non-const exception. Handler will never fire. "
+ "Catch exception by const reference to fix this.");
+};
+
+// Nests a throw in the proper try/catch blocks
+template <bool IsConst>
+struct exception_wrapper::HandleReduce {
+ bool* handled_;
+
+ 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, 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<_t<std::add_pointer<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_.throwException(); },
+ 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 (StdEx* e = impl(continuation)) {
+ throw *e; // Not handled. Throw.
+ }
+}
+
+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();
+ }
+ 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();
+ }
+ this->handle_(AllStdEx{}, *this, fns...);
+}
+
+} // namespace folly
*/
#include <folly/ExceptionWrapper.h>
-#include <exception>
#include <iostream>
+#include <folly/Logging.h>
+
namespace folly {
-[[noreturn]] void exception_wrapper::throwException() const {
- if (throwfn_) {
- throwfn_(*item_);
- } else if (eptr_) {
- std::rethrow_exception(eptr_);
+constexpr exception_wrapper::VTable const exception_wrapper::uninit_;
+constexpr exception_wrapper::VTable const exception_wrapper::ExceptionPtr::ops_;
+constexpr exception_wrapper::VTable const exception_wrapper::SharedPtr::ops_;
+
+namespace {
+std::exception const* get_std_exception_(std::exception_ptr eptr) noexcept {
+ try {
+ std::rethrow_exception(eptr);
+ } catch (const std::exception& ex) {
+ return &ex;
+ } catch (...) {
+ return nullptr;
}
- std::ios_base::Init ioinit_; // ensure std::cerr is alive
- std::cerr
- << "Cannot use `throwException` with an empty folly::exception_wrapper"
- << std::endl;
- std::terminate();
+}
}
-fbstring exception_wrapper::class_name() const {
- if (item_) {
- auto& i = *item_;
- return demangle(typeid(i));
- } else if (eptr_ && eobj_) {
- return demangle(typeid(*eobj_));
- } else if (eptr_ && etype_) {
- return demangle(*etype_);
- } else {
- return fbstring();
+exception_wrapper::exception_wrapper(std::exception_ptr ptr) noexcept
+ : exception_wrapper{} {
+ if (ptr) {
+ if (auto e = get_std_exception_(ptr)) {
+ LOG(DFATAL)
+ << "Performance error: Please construct exception_wrapper with a "
+ "reference to the std::exception along with the "
+ "std::exception_ptr.";
+ *this = exception_wrapper{std::move(ptr), *e};
+ } else {
+ Unknown uk;
+ *this = exception_wrapper{ptr, uk};
+ }
}
}
-fbstring exception_wrapper::what() const {
- if (item_) {
- return exceptionStr(*item_);
- } else if (eptr_ && eobj_) {
- return class_name() + ": " + eobj_->what();
- } else if (eptr_ && etype_) {
- return class_name();
- } else {
- return class_name();
- }
+[[noreturn]] void exception_wrapper::onNoExceptionError() {
+ std::ios_base::Init ioinit_; // ensure std::cerr is alive
+ std::cerr
+ << "Cannot use `throwException` with an empty folly::exception_wrapper"
+ << std::endl;
+ std::terminate();
}
-fbstring exceptionStr(const exception_wrapper& ew) {
+fbstring exceptionStr(exception_wrapper const& ew) {
return ew.what();
}
/*
- * Copyright 2017 Facebook, Inc.
+ * Copyright 2017-present Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
+/*
+ * Author: Eric Niebler <eniebler@fb.com>
+ */
#pragma once
+#include <cassert>
+#include <cstdint>
#include <exception>
+#include <iosfwd>
#include <memory>
-#include <string>
-#include <tuple>
+#include <new>
#include <type_traits>
+#include <typeinfo>
#include <utility>
+#include <folly/Assume.h>
+#include <folly/CPortability.h>
+#include <folly/Demangle.h>
#include <folly/ExceptionString.h>
#include <folly/FBString.h>
#include <folly/Traits.h>
+#ifdef __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wpotentially-evaluated-expression"
+// GCC gets confused about lambda scopes and issues shadow-local warnings for
+// parameters in totally different functions.
+#pragma GCC diagnostic ignored "-Wshadow-local"
+#pragma GCC diagnostic ignored "-Wshadow-compatible-local"
+#endif
+
+#define FOLLY_EXCEPTION_WRAPPER_H_INCLUDED
+
namespace folly {
-/*
- * Throwing exceptions can be a convenient way to handle errors. Storing
- * exceptions in an exception_ptr makes it easy to handle exceptions in a
- * different thread or at a later time. exception_ptr can also be used in a very
- * generic result/exception wrapper.
- *
- * However, there are some issues with throwing exceptions and
- * std::exception_ptr. These issues revolve around throw being expensive,
- * particularly in a multithreaded environment (see
- * ExceptionWrapperBenchmark.cpp).
- *
- * Imagine we have a library that has an API which returns a result/exception
- * wrapper. Let's consider some approaches for implementing this wrapper.
- * First, we could store a std::exception. This approach loses the derived
- * exception type, which can make exception handling more difficult for users
- * that prefer rethrowing the exception. We could use a folly::dynamic for every
- * possible type of exception. This is not very flexible - adding new types of
- * exceptions requires a change to the result/exception wrapper. We could use an
- * exception_ptr. However, constructing an exception_ptr as well as accessing
- * the error requires a call to throw. That means that there will be two calls
- * to throw in order to process the exception. For performance sensitive
- * applications, this may be unacceptable.
- *
- * exception_wrapper is designed to handle exception management for both
- * convenience and high performance use cases. make_exception_wrapper is
- * templated on derived type, allowing us to rethrow the exception properly for
- * users that prefer convenience. These explicitly named exception types can
- * therefore be handled without any peformance penalty. exception_wrapper is
- * also flexible enough to accept any type. If a caught exception is not of an
- * explicitly named type, then std::exception_ptr is used to preserve the
- * exception state. For performance sensitive applications, the accessor methods
- * can test or extract a pointer to a specific exception type with very little
- * overhead.
- *
- * \par Example usage:
- * \par
- * \code
- * exception_wrapper globalExceptionWrapper;
- *
- * // Thread1
- * void doSomethingCrazy() {
- * int rc = doSomethingCrazyWithLameReturnCodes();
- * if (rc == NAILED_IT) {
- * globalExceptionWrapper = exception_wrapper();
- * } else if (rc == FACE_PLANT) {
- * globalExceptionWrapper = make_exception_wrapper<FacePlantException>();
- * } else if (rc == FAIL_WHALE) {
- * globalExceptionWrapper = make_exception_wrapper<FailWhaleException>();
- * }
- * }
- *
- * // Thread2: Exceptions are ok!
- * void processResult() {
- * try {
- * globalExceptionWrapper.throwException();
- * } catch (const FacePlantException& e) {
- * LOG(ERROR) << "FACEPLANT!";
- * } catch (const FailWhaleException& e) {
- * LOG(ERROR) << "FAILWHALE!";
- * }
- * }
- *
- * // Thread2: Exceptions are bad!
- * void processResult() {
- * globalExceptionWrapper.with_exception(
- * [&](FacePlantException& faceplant) {
- * LOG(ERROR) << "FACEPLANT";
- * }) ||
- * globalExceptionWrapper.with_exception(
- * [&](FailWhaleException& failwhale) {
- * LOG(ERROR) << "FAILWHALE!";
- * }) ||
- * LOG(FATAL) << "Unrecognized exception";
- * }
- * \endcode
- *
- */
-class exception_wrapper {
- private:
- template <typename T>
- using is_exception_ = std::is_base_of<std::exception, T>;
+#define FOLLY_REQUIRES_DEF(...) \
+ _t<std::enable_if<static_cast<bool>(__VA_ARGS__), long>>
- public:
- exception_wrapper() = default;
+#define FOLLY_REQUIRES(...) FOLLY_REQUIRES_DEF(__VA_ARGS__) = __LINE__
- template <
- typename Ex,
- typename DEx = _t<std::decay<Ex>>,
- typename = _t<std::enable_if<is_exception_<DEx>::value>>,
- typename = decltype(DEx(std::forward<Ex>(std::declval<Ex&&>())))>
- /* implicit */ exception_wrapper(Ex&& exn) {
- assign_sptr<DEx>(std::forward<Ex>(exn));
- }
+namespace exception_wrapper_detail {
- // The following two constructors are meant to emulate the behavior of
- // try_and_catch in performance sensitive code as well as to be flexible
- // enough to wrap exceptions of unknown type. There is an overload that
- // takes an exception reference so that the wrapper can extract and store
- // the exception's type and what() when possible.
- //
- // The canonical use case is to construct an all-catching exception wrapper
- // with minimal overhead like so:
- //
- // try {
- // // some throwing code
- // } catch (const std::exception& e) {
- // // won't lose e's type and what()
- // exception_wrapper ew{std::current_exception(), e};
- // } catch (...) {
- // // everything else
- // exception_wrapper ew{std::current_exception()};
- // }
- //
- // try_and_catch is cleaner and preferable. Use it unless you're sure you need
- // something like this instead.
- template <typename Ex>
- explicit exception_wrapper(std::exception_ptr eptr, Ex& exn) {
- assign_eptr(eptr, exn);
- }
+template <template <class> class T, class... As>
+using AllOf = StrictConjunction<T<As>...>;
- explicit exception_wrapper(std::exception_ptr eptr) {
- assign_eptr(eptr);
- }
+template <bool If, class T>
+using AddConstIf = _t<std::conditional<If, const T, T>>;
- // If the exception_wrapper does not contain an exception, std::terminate()
- // is invoked to assure the [[noreturn]] behaviour.
- [[noreturn]] void throwException() const;
+template <class Fn, class A>
+FOLLY_ALWAYS_INLINE FOLLY_ATTR_VISIBILITY_HIDDEN
+auto fold(Fn&&, A&& a) {
+ return static_cast<A&&>(a);
+}
- explicit operator bool() const {
- return item_ || eptr_;
- }
+template <class Fn, class A, class B, class... Bs>
+FOLLY_ALWAYS_INLINE FOLLY_ATTR_VISIBILITY_HIDDEN
+auto fold(Fn&& fn, A&& a, B&& b, Bs&&... bs) {
+ return fold(
+ // This looks like a use of fn after a move of fn, but in reality, this is
+ // just a cast and not a move. That's because regardless of which fold
+ // overload is selected, fn gets bound to a &&. Had fold taken fn by value
+ // there would indeed be a problem here.
+ static_cast<Fn&&>(fn),
+ static_cast<Fn&&>(fn)(static_cast<A&&>(a), static_cast<B&&>(b)),
+ static_cast<Bs&&>(bs)...);
+}
- // This implementation is similar to std::exception_ptr's implementation
- // where two exception_wrappers are equal when the address in the underlying
- // reference field both point to the same exception object. The reference
- // field remains the same when the exception_wrapper is copied or when
- // the exception_wrapper is "rethrown".
- bool operator==(const exception_wrapper& a) const {
- if (item_) {
- return a.item_ && item_.get() == a.item_.get();
- } else {
- return eptr_ == a.eptr_;
- }
- }
+} // namespace exception_wrapper_detail
+
+//! Throwing exceptions can be a convenient way to handle errors. Storing
+//! exceptions in an `exception_ptr` makes it easy to handle exceptions in a
+//! different thread or at a later time. `exception_ptr` can also be used in a
+//! very generic result/exception wrapper.
+//!
+//! However, there are some issues with throwing exceptions and
+//! `std::exception_ptr`. These issues revolve around `throw` being expensive,
+//! particularly in a multithreaded environment (see
+//! ExceptionWrapperBenchmark.cpp).
+//!
+//! Imagine we have a library that has an API which returns a result/exception
+//! wrapper. Let's consider some approaches for implementing this wrapper.
+//! First, we could store a `std::exception`. This approach loses the derived
+//! exception type, which can make exception handling more difficult for users
+//! that prefer rethrowing the exception. We could use a `folly::dynamic` for
+//! every possible type of exception. This is not very flexible - adding new
+//! types of exceptions requires a change to the result/exception wrapper. We
+//! could use an `exception_ptr`. However, constructing an `exception_ptr` as
+//! well as accessing the error requires a call to throw. That means that there
+//! will be two calls to throw in order to process the exception. For
+//! performance sensitive applications, this may be unacceptable.
+//!
+//! `exception_wrapper` is designed to handle exception management for both
+//! convenience and high performance use cases. `make_exception_wrapper` is
+//! templated on derived type, allowing us to rethrow the exception properly for
+//! users that prefer convenience. These explicitly named exception types can
+//! therefore be handled without any peformance penalty. `exception_wrapper` is
+//! also flexible enough to accept any type. If a caught exception is not of an
+//! explicitly named type, then `std::exception_ptr` is used to preserve the
+//! exception state. For performance sensitive applications, the accessor
+//! methods can test or extract a pointer to a specific exception type with very
+//! little overhead.
+//!
+//! \par Example usage:
+//! \par
+//! \code
+//! exception_wrapper globalExceptionWrapper;
+//!
+//! // Thread1
+//! void doSomethingCrazy() {
+//! int rc = doSomethingCrazyWithLameReturnCodes();
+//! if (rc == NAILED_IT) {
+//! globalExceptionWrapper = exception_wrapper();
+//! } else if (rc == FACE_PLANT) {
+//! globalExceptionWrapper = make_exception_wrapper<FacePlantException>();
+//! } else if (rc == FAIL_WHALE) {
+//! globalExceptionWrapper = make_exception_wrapper<FailWhaleException>();
+//! }
+//! }
+//!
+//! // Thread2: Exceptions are ok!
+//! void processResult() {
+//! try {
+//! globalExceptionWrapper.throwException();
+//! } catch (const FacePlantException& e) {
+//! LOG(ERROR) << "FACEPLANT!";
+//! } catch (const FailWhaleException& e) {
+//! LOG(ERROR) << "FAILWHALE!";
+//! }
+//! }
+//!
+//! // Thread2: Exceptions are bad!
+//! void processResult() {
+//! globalExceptionWrapper.handle(
+//! [&](FacePlantException& faceplant) {
+//! LOG(ERROR) << "FACEPLANT";
+//! },
+//! [&](FailWhaleException& failwhale) {
+//! LOG(ERROR) << "FAILWHALE!";
+//! },
+//! [](...) {
+//! LOG(FATAL) << "Unrecognized exception";
+//! });
+//! }
+//! \endcode
+class exception_wrapper final {
+ private:
+ struct AnyException : std::exception {
+ std::type_info const* typeinfo_;
+ template <class T>
+ /* implicit */ AnyException(T&& t) noexcept : typeinfo_(&typeid(t)) {}
+ };
- bool operator!=(const exception_wrapper& a) const {
- return !(*this == a);
- }
+ template <class Fn>
+ struct arg_type2_;
+ template <class Fn, class = void>
+ struct arg_type_;
+ template <class Fn>
+ using arg_type = _t<arg_type_<Fn>>;
+
+ // exception_wrapper is implemented as a simple variant over four
+ // different representations:
+ // 0. Empty, no exception.
+ // 1. An small object stored in-situ.
+ // 2. A larger object stored on the heap and referenced with a
+ // std::shared_ptr.
+ // 3. A std::exception_ptr, together with either:
+ // a. A pointer to the referenced std::exception object, or
+ // b. A pointer to a std::type_info object for the referenced exception,
+ // or for an unspecified type if the type is unknown.
+ // This is accomplished with the help of a union and a pointer to a hand-
+ // rolled virtual table. This virtual table contains pointers to functions
+ // that know which field of the union is active and do the proper action.
+ // The class invariant ensures that the vtable ptr and the union stay in sync.
+ struct VTable {
+ void (*copy_)(exception_wrapper const*, exception_wrapper*);
+ void (*move_)(exception_wrapper*, exception_wrapper*);
+ void (*delete_)(exception_wrapper*);
+ void (*throw_)(exception_wrapper const*);
+ std::type_info const* (*type_)(exception_wrapper const*);
+ std::exception const* (*get_exception_)(exception_wrapper const*);
+ exception_wrapper (*get_exception_ptr_)(exception_wrapper const*);
+ };
- // This will return a non-nullptr only if the exception is held as a
- // copy. It is the only interface which will distinguish between an
- // exception held this way, and by exception_ptr. You probably
- // shouldn't use it at all.
- std::exception* getCopied() { return item_.get(); }
- const std::exception* getCopied() const { return item_.get(); }
+ [[noreturn]] static void onNoExceptionError();
- fbstring what() const;
- fbstring class_name() const;
+ template <class Ret, class... Args>
+ static Ret noop_(Args...);
- template <class Ex>
- bool is_compatible_with() const {
- return with_exception<Ex>([](const Ex&) {});
- }
+ static std::type_info const* uninit_type_(exception_wrapper const*);
- template <class F>
- bool with_exception(F&& f) {
- using arg_type = _t<std::decay<typename functor_traits<F>::arg_type>>;
- return with_exception<arg_type>(std::forward<F>(f));
- }
+ static constexpr VTable const uninit_{
+ &noop_<void, exception_wrapper const*, exception_wrapper*>,
+ &noop_<void, exception_wrapper*, exception_wrapper*>,
+ &noop_<void, exception_wrapper*>,
+ &noop_<void, exception_wrapper const*>,
+ &uninit_type_,
+ &noop_<std::exception const*, exception_wrapper const*>,
+ &noop_<exception_wrapper, exception_wrapper const*>};
- template <class F>
- bool with_exception(F&& f) const {
- using arg_type = _t<std::decay<typename functor_traits<F>::arg_type>>;
- return with_exception<arg_type>(std::forward<F>(f));
- }
+ template <class Ex>
+ using IsStdException = std::is_base_of<std::exception, _t<std::decay<Ex>>>;
+ template <bool B, class T>
+ using AddConstIf = exception_wrapper_detail::AddConstIf<B, T>;
+ template <class CatchFn>
+ using IsCatchAll =
+ std::is_same<arg_type<_t<std::decay<CatchFn>>>, AnyException>;
+
+ struct Unknown {};
+
+ // Sadly, with the gcc-4.9 platform, std::logic_error and std::runtime_error
+ // do not fit here. They also don't have noexcept copy-ctors, so the internal
+ // storage wouldn't be used anyway. For the gcc-5 platform, both logic_error
+ // and runtime_error can be safely stored internally.
+ struct Buffer {
+ using Storage =
+ _t<std::aligned_storage<2 * sizeof(void*), alignof(std::exception)>>;
+ Storage buff_;
+
+ Buffer() : buff_{} {}
+
+ template <class Ex, class DEx = _t<std::decay<Ex>>>
+ Buffer(in_place_t, Ex&& ex);
+ template <class Ex>
+ Ex& as() noexcept;
+ template <class Ex>
+ Ex const& as() const noexcept;
+ };
- // If this exception wrapper wraps an exception of type Ex, with_exception
- // will call f with the wrapped exception as an argument and return true, and
- // will otherwise return false.
- template <class Ex, class F>
- bool with_exception(F f) {
- return with_exception1<_t<std::decay<Ex>>>(std::forward<F>(f), this);
- }
+ enum class Placement { kInSitu, kOnHeap };
+ template <class T>
+ using PlacementOf = std::integral_constant<
+ Placement,
+ sizeof(T) <= sizeof(Buffer::Storage) &&
+ alignof(T) <= alignof(Buffer::Storage) &&
+ noexcept(T(std::declval<T&&>()))
+ ? Placement::kInSitu
+ : Placement::kOnHeap>;
+
+ using InSituTag = std::integral_constant<Placement, Placement::kInSitu>;
+ using OnHeapTag = std::integral_constant<Placement, Placement::kOnHeap>;
+
+ static std::exception const* as_exception_or_null_(std::exception const& ex);
+ static std::exception const* as_exception_or_null_(AnyException);
+
+ struct ExceptionPtr {
+ std::exception_ptr ptr_;
+ std::uintptr_t exception_or_type_; // odd for type_info
+ static_assert(
+ 1 < alignof(std::exception) && 1 < alignof(std::type_info),
+ "Surprise! std::exception and std::type_info don't have alignment "
+ "greater than one. as_int_ below will not work!");
+
+ static std::uintptr_t as_int_(std::exception const& e);
+ static std::uintptr_t as_int_(AnyException e);
+ bool has_exception_() const;
+ std::exception const* as_exception_() const;
+ std::type_info const* as_type_() const;
+ static void copy_(exception_wrapper const* from, exception_wrapper* to);
+ static void move_(exception_wrapper* from, exception_wrapper* to);
+ static void delete_(exception_wrapper* that);
+ [[noreturn]] static void throw_(exception_wrapper const* that);
+ static std::type_info const* type_(exception_wrapper const* that);
+ static std::exception const* get_exception_(exception_wrapper const* that);
+ static exception_wrapper get_exception_ptr_(exception_wrapper const* that);
+ static constexpr VTable const ops_{copy_,
+ move_,
+ delete_,
+ throw_,
+ type_,
+ get_exception_,
+ get_exception_ptr_};
+ };
- // Const overload
- template <class Ex, class F>
- bool with_exception(F f) const {
- return with_exception1<_t<std::decay<Ex>>>(std::forward<F>(f), this);
- }
+ template <class Ex>
+ struct InPlace {
+ static void copy_(exception_wrapper const* from, exception_wrapper* to);
+ static void move_(exception_wrapper* from, exception_wrapper* to);
+ static void delete_(exception_wrapper* that);
+ [[noreturn]] static void throw_(exception_wrapper const* that);
+ static std::type_info const* type_(exception_wrapper const*);
+ static std::exception const* get_exception_(exception_wrapper const* that);
+ static exception_wrapper get_exception_ptr_(exception_wrapper const* that);
+ static constexpr VTable const ops_{copy_,
+ move_,
+ delete_,
+ throw_,
+ type_,
+ get_exception_,
+ get_exception_ptr_};
+ };
- std::exception_ptr to_exception_ptr() const {
- if (eptr_) {
- return eptr_;
- }
-
- try {
- if (*this) {
- throwException();
- }
- } catch (...) {
- return std::current_exception();
- }
- return std::exception_ptr();
- }
+ struct SharedPtr {
+ struct Base {
+ std::type_info const* info_;
+ Base() = default;
+ explicit Base(std::type_info const& info) : info_(&info) {}
+ virtual ~Base() {}
+ virtual void throw_() const = 0;
+ virtual std::exception const* get_exception_() const noexcept = 0;
+ virtual exception_wrapper get_exception_ptr_() const noexcept = 0;
+ };
+ template <class Ex>
+ struct Impl final : public Base {
+ Ex ex_;
+ Impl() = default;
+ explicit Impl(Ex const& ex) : Base{typeid(ex)}, ex_(ex) {}
+ explicit Impl(Ex&& ex)
+ : Base{typeid(ex)},
+ ex_(std::move(ex)){}[[noreturn]] void throw_() const override;
+ std::exception const* get_exception_() const noexcept override;
+ exception_wrapper get_exception_ptr_() const noexcept override;
+ };
+ std::shared_ptr<Base> ptr_;
+
+ static void copy_(exception_wrapper const* from, exception_wrapper* to);
+ static void move_(exception_wrapper* from, exception_wrapper* to);
+ static void delete_(exception_wrapper* that);
+ [[noreturn]] static void throw_(exception_wrapper const* that);
+ static std::type_info const* type_(exception_wrapper const* that);
+ static std::exception const* get_exception_(exception_wrapper const* that);
+ static exception_wrapper get_exception_ptr_(exception_wrapper const* that);
+ static constexpr VTable ops_{copy_,
+ move_,
+ delete_,
+ throw_,
+ type_,
+ get_exception_,
+ get_exception_ptr_};
+ };
- private:
- template <typename Ex, typename... Args>
- void assign_sptr(Args&&... args) {
- this->item_ = std::make_shared<Ex>(std::forward<Args>(args)...);
- this->throwfn_ = Thrower<Ex>::doThrow;
- }
+ union {
+ Buffer buff_{};
+ ExceptionPtr eptr_;
+ SharedPtr sptr_;
+ };
+ VTable const* vptr_{&uninit_};
- template <typename Ex>
- _t<std::enable_if<is_exception_<Ex>::value>> assign_eptr(
- std::exception_ptr eptr,
- Ex& e) {
- this->eptr_ = eptr;
- this->eobj_ = &const_cast<_t<std::remove_const<Ex>>&>(e);
- }
+ template <class Ex, class DEx = _t<std::decay<Ex>>>
+ exception_wrapper(Ex&& ex, OnHeapTag);
- template <typename Ex>
- _t<std::enable_if<!is_exception_<Ex>::value>> assign_eptr(
- std::exception_ptr eptr,
- Ex& e) {
- this->eptr_ = eptr;
- this->etype_ = &typeid(e);
- }
+ template <class Ex, class DEx = _t<std::decay<Ex>>>
+ exception_wrapper(Ex&& ex, InSituTag);
- void assign_eptr(std::exception_ptr eptr) {
- this->eptr_ = eptr;
- }
+ template <class T>
+ struct IsRegularExceptionType
+ : StrictConjunction<
+ std::is_copy_constructible<T>,
+ Negation<std::is_base_of<exception_wrapper, T>>,
+ Negation<std::is_abstract<T>>> {};
- // Optimized case: if we know what type the exception is, we can
- // store a copy of the concrete type, and a helper function so we
- // can rethrow it.
- std::shared_ptr<std::exception> item_;
- void (*throwfn_)(std::exception&){nullptr};
- // Fallback case: store the library wrapper, which is less efficient
- // but gets the job done. Also store exceptionPtr() the name of the
- // exception type, so we can at least get those back out without
- // having to rethrow.
- std::exception_ptr eptr_;
- std::exception* eobj_{nullptr};
- const std::type_info* etype_{nullptr};
-
- template <class T, class... Args>
- friend exception_wrapper make_exception_wrapper(Args&&... args);
+ template <class CatchFn, bool IsConst = false>
+ struct ExceptionTypeOf;
- private:
- template <typename F>
- struct functor_traits {
- template <typename T>
- struct impl;
- template <typename C, typename R, typename A>
- struct impl<R(C::*)(A)> { using arg_type = A; };
- template <typename C, typename R, typename A>
- struct impl<R(C::*)(A) const> { using arg_type = A; };
- using functor_op = decltype(&_t<std::decay<F>>::operator());
- using arg_type = typename impl<functor_op>::arg_type;
- };
+ template <bool IsConst>
+ struct HandleReduce;
- template <class T>
- class Thrower {
- public:
- static void doThrow(std::exception& obj) {
- throw static_cast<T&>(obj);
- }
- };
+ template <bool IsConst>
+ struct HandleStdExceptReduce;
- template <typename T, typename F>
- static _t<std::enable_if<is_exception_<T>::value, T*>>
- try_dynamic_cast_exception(F* from) {
- return dynamic_cast<T*>(from);
- }
- template <typename T, typename F>
- static _t<std::enable_if<!is_exception_<T>::value, T*>>
- try_dynamic_cast_exception(F*) {
- return nullptr;
- }
+ template <class This, class... CatchFns>
+ static void handle_(std::false_type, This& this_, CatchFns&... fns);
- // What makes this useful is that T can be exception_wrapper* or
- // const exception_wrapper*, and the compiler will use the
- // instantiation which works with F.
- template <class Ex, class F, class T>
- static bool with_exception1(F f, T* that) {
- using CEx = _t<std::conditional<std::is_const<T>::value, const Ex, Ex>>;
- if (is_exception_<Ex>::value &&
- (that->item_ || (that->eptr_ && that->eobj_))) {
- auto raw =
- that->item_ ? that->item_.get() : that->eptr_ ? that->eobj_ : nullptr;
- if (auto ex = try_dynamic_cast_exception<CEx>(raw)) {
- f(*ex);
- return true;
- }
- } else if (that->eptr_) {
- try {
- std::rethrow_exception(that->eptr_);
- } catch (CEx& e) {
- f(e);
- return true;
- } catch (...) {
- // fall through
- }
- }
- return false;
- }
-};
+ template <class This, class... CatchFns>
+ static void handle_(std::true_type, This& this_, CatchFns&... fns);
-template <class Ex, class... Args>
-exception_wrapper make_exception_wrapper(Args&&... args) {
- exception_wrapper ew;
- ew.assign_sptr<Ex>(std::forward<Args>(args)...);
- return ew;
-}
+ template <class Ex, class This, class Fn>
+ static bool with_exception_(This& this_, Fn fn_);
-// For consistency with exceptionStr() functions in ExceptionString.h
-fbstring exceptionStr(const exception_wrapper& ew);
+ public:
+ //! Default-constructs an empty `exception_wrapper`
+ //! \post `type() == none()`
+ exception_wrapper() noexcept {}
+
+ //! Move-constructs an `exception_wrapper`
+ //! \post `*this` contains the value of `that` prior to the move
+ //! \post `that.type() == none()`
+ exception_wrapper(exception_wrapper&& that) noexcept;
+
+ //! Copy-constructs an `exception_wrapper`
+ //! \post `*this` contains a copy of `that`, and `that` is unmodified
+ //! \post `type() == that.type()`
+ exception_wrapper(exception_wrapper const& that);
+
+ //! Move-assigns an `exception_wrapper`
+ //! \pre `this != &that`
+ //! \post `*this` contains the value of `that` prior to the move
+ //! \post `that.type() == none()`
+ exception_wrapper& operator=(exception_wrapper&& that) noexcept;
+
+ //! Copy-assigns an `exception_wrapper`
+ //! \post `*this` contains a copy of `that`, and `that` is unmodified
+ //! \post `type() == that.type()`
+ exception_wrapper& operator=(exception_wrapper const& that);
+
+ ~exception_wrapper();
+
+ //! \pre `ptr` is empty, or it holds a reference to an exception that is not
+ //! derived from `std::exception`.
+ //! \post `!ptr || bool(*this)`
+ //! \post `hasThrownException() == true`
+ //! \post `type() == unknown()`
+ explicit exception_wrapper(std::exception_ptr ptr) noexcept;
+
+ //! \pre `ptr` holds a reference to `ex`.
+ //! \post `hasThrownException() == true`
+ //! \post `bool(*this)`
+ //! \post `type() == typeid(ex)`
+ template <class Ex>
+ exception_wrapper(std::exception_ptr ptr, Ex& ex);
+
+ //! \pre `typeid(ex) == typeid(typename decay<Ex>::type)`
+ //! \post `bool(*this)`
+ //! \post `hasThrownException() == false`
+ //! \post `type() == typeid(ex)`
+ //! \note Exceptions of types derived from `std::exception` can be implicitly
+ //! converted to an `exception_wrapper`.
+ template <
+ class Ex,
+ class Ex_ = _t<std::decay<Ex>>,
+ FOLLY_REQUIRES(
+ Conjunction<IsStdException<Ex_>, IsRegularExceptionType<Ex_>>())>
+ /* implicit */ exception_wrapper(Ex&& ex);
+
+ //! \pre `typeid(ex) == typeid(typename decay<Ex>::type)`
+ //! \post `bool(*this)`
+ //! \post `hasThrownException() == false`
+ //! \post `type() == typeid(ex)`
+ //! \note Exceptions of types not derived from `std::exception` can still be
+ //! used to construct an `exception_wrapper`, but you must specify
+ //! `folly::in_place` as the first parameter.
+ template <
+ class Ex,
+ class Ex_ = _t<std::decay<Ex>>,
+ FOLLY_REQUIRES(IsRegularExceptionType<Ex_>())>
+ exception_wrapper(in_place_t, Ex&& ex);
+
+ //! Swaps the value of `*this` with the value of `that`
+ void swap(exception_wrapper& that) noexcept;
+
+ //! \return `true` if `*this` is not holding an exception.
+ explicit operator bool() const noexcept;
+
+ //! \return `!bool(*this)`
+ bool operator!() const noexcept;
+
+ //! Make this `exception_wrapper` empty
+ //! \post `!*this`
+ void reset();
+
+ //! \return `true` if this `exception_wrapper` holds a reference to an
+ //! exception that was thrown (i.e., if it was constructed with
+ //! a `std::exception_ptr`, or if `to_exception_ptr()` was called on a
+ //! (non-const) reference to `*this`).
+ bool has_exception_ptr() const noexcept;
+
+ //! \return a pointer to the `std::exception` held by `*this`, if it holds
+ //! one; otherwise, returns `nullptr`.
+ //! \note This function does not mutate the `exception_wrapper` object.
+ //! \note This function never causes an exception to be thrown.
+ std::exception* get_exception() noexcept;
+ //! \overload
+ std::exception const* get_exception() const noexcept;
+
+ //! \return A `std::exception_ptr` that references either the exception held
+ //! by `*this`, or a copy of same.
+ //! \note This function may need to throw an exception to complete the action.
+ //! \note The non-const overload of this function mutates `*this` to cache the
+ //! computed `std::exception_ptr`; that is, this function may cause
+ //! `has_exception_ptr()` to change from `false` to `true`.
+ std::exception_ptr const& to_exception_ptr() noexcept;
+ //! \overload
+ std::exception_ptr to_exception_ptr() const noexcept;
+
+ //! \return the `typeid` of an unspecified type used by
+ //! `exception_wrapper::type()` to denote an empty `exception_wrapper`.
+ static std::type_info const& none() noexcept;
+ //! \return the `typeid` of an unspecified type used by
+ //! `exception_wrapper::type()` to denote an `exception_wrapper` that
+ //! holds an exception of unknown type.
+ static std::type_info const& unknown() noexcept;
+
+ //! Returns the `typeid` of the wrapped exception object. If there is no
+ //! wrapped exception object, returns `exception_wrapper::none()`. If
+ //! this instance wraps an exception of unknown type not derived from
+ //! `std::exception`, returns `exception_wrapper::unknown()`.
+ std::type_info const& type() const noexcept;
+
+ //! \return If `get_exception() != nullptr`, `class_name() + ": " +
+ //! get_exception()->what()`; otherwise, `class_name()`.
+ folly::fbstring what() const;
+
+ //! \return If `!*this`, the empty string; otherwise, if
+ //! `type() == unknown()`, the string `"<unknown exception>"`; otherwise,
+ //! the result of `type().name()` after demangling.
+ folly::fbstring class_name() const;
+
+ //! \tparam Ex The expression type to check for compatibility with.
+ //! \return `true` if and only if `*this` wraps an exception that would be
+ //! caught with a `catch(Ex const&)` clause.
+ //! \note If `*this` is empty, this function returns `false`.
+ template <class Ex>
+ bool is_compatible_with() const noexcept;
-/*
- * try_and_catch is a simple replacement for try {} catch(){} that allows you to
- * specify which derived exceptions you would like to catch and store in an
- * exception_wrapper.
- *
- * Because we cannot build an equivalent of std::current_exception(), we need
- * to catch every derived exception that we are interested in catching.
- *
- * Exceptions should be listed in the reverse order that you would write your
- * catch statements (that is, std::exception& should be first).
- *
- * NOTE: Although implemented as a derived class (for syntactic delight), don't
- * be confused - you should not pass around try_and_catch objects!
- *
- * Example Usage:
- *
- * // This catches my runtime_error and if I call throwException() on ew, it
- * // will throw a runtime_error
- * auto ew = folly::try_and_catch<std::exception, std::runtime_error>([=]() {
- * if (badThingHappens()) {
- * throw std::runtime_error("ZOMG!");
- * }
- * });
- *
- * // This will catch the exception and if I call throwException() on ew, it
- * // will throw a std::exception
- * auto ew = folly::try_and_catch<std::exception, std::runtime_error>([=]() {
- * if (badThingHappens()) {
- * throw std::exception();
- * }
- * });
- *
- * // This will not catch the exception and it will be thrown.
- * auto ew = folly::try_and_catch<std::runtime_error>([=]() {
- * if (badThingHappens()) {
- * throw std::exception();
- * }
- * });
- */
+ //! \pre `bool(*this)`
+ //! Throws the wrapped expression.
+ [[noreturn]] void throwException() const;
-namespace try_and_catch_detail {
+ //! Call `fn` with the wrapped exception (if any), if `fn` can accept it.
+ //! \par Example
+ //! \code
+ //! exception_wrapper ew{std::runtime_error("goodbye cruel world")};
+ //!
+ //! assert( ew.with_exception([](std::runtime_error& e){/*...*/}) );
+ //!
+ //! assert( !ew.with_exception([](int& e){/*...*/}) );
+ //!
+ //! assert( !exception_wrapper{}.with_exception([](int& e){/*...*/}) );
+ //! \endcode
+ //! \tparam Ex Optionally, the type of the exception that `fn` accepts.
+ //! \tparam Fn The type of a monomophic function object.
+ //! \param fn A function object to call with the wrapped exception
+ //! \return `true` if and only if `fn` was called.
+ //! \note Optionally, you may explicitly specify the type of the exception
+ //! that `fn` expects, as in
+ //! \code
+ //! ew.with_exception<std::runtime_error>([](auto&& e) { /*...*/; });
+ //! \endcode
+ //! \note The handler may or may not be invoked with an active exception.
+ //! **Do not try to rethrow the exception with `throw;` from within your
+ //! handler -- that is, a throw expression with no operand.** This may
+ //! cause your process to terminate. (It is perfectly ok to throw from
+ //! a handler so long as you specify the exception to throw, as in
+ //! `throw e;`.)
+ template <class Ex = void const, class Fn>
+ bool with_exception(Fn fn);
+ //! \overload
+ template <class Ex = void const, class Fn>
+ bool with_exception(Fn fn) const;
+
+ //! Handle the wrapped expression as if with a series of `catch` clauses,
+ //! propagating the exception if no handler matches.
+ //! \par Example
+ //! \code
+ //! exception_wrapper ew{std::runtime_error("goodbye cruel world")};
+ //!
+ //! ew.handle(
+ //! [&](std::logic_error const& e) {
+ //! LOG(DFATAL) << "ruh roh";
+ //! ew.throwException(); // rethrow the active exception without
+ //! // slicing it. Will not be caught by other
+ //! // handlers in this call.
+ //! },
+ //! [&](std::exception const& e) {
+ //! LOG(ERROR) << ew.what();
+ //! });
+ //! \endcode
+ //! In the above example, any exception _not_ derived from `std::exception`
+ //! will be propagated. To specify a catch-all clause, pass a lambda that
+ //! takes a C-style elipses, as in:
+ //! \code
+ //! ew.handle(/*...* /, [](...) { /* handle unknown exception */ } )
+ //! \endcode
+ //! \pre `!*this`
+ //! \tparam CatchFns... A pack of unary monomorphic function object types.
+ //! \param fns A pack of unary monomorphic function objects to be treated as
+ //! an ordered list of potential exception handlers.
+ //! \note The handlers may or may not be invoked with an active exception.
+ //! **Do not try to rethrow the exception with `throw;` from within your
+ //! handler -- that is, a throw expression with no operand.** This may
+ //! cause your process to terminate. (It is perfectly ok to throw from
+ //! a handler so long as you specify the exception to throw, as in
+ //! `throw e;`.)
+ template <class... CatchFns>
+ void handle(CatchFns... fns);
+ //! \overload
+ template <class... CatchFns>
+ void handle(CatchFns... fns) const;
+};
-template <typename... Args>
-using is_wrap_ctor = std::is_constructible<exception_wrapper, Args...>;
+template <class Ex>
+constexpr exception_wrapper::VTable exception_wrapper::InPlace<Ex>::ops_;
-template <typename Ex>
-inline _t<std::enable_if<!is_wrap_ctor<Ex&>::value, exception_wrapper>> make(
- Ex& ex) {
- return exception_wrapper(std::current_exception(), ex);
+/**
+ * \return An `exception_wrapper` that wraps an instance of type `Ex`
+ * that has been constructed with arguments `std::forward<As>(as)...`.
+ */
+template <class Ex, typename... As>
+exception_wrapper make_exception_wrapper(As&&... as) {
+ return exception_wrapper{Ex{std::forward<As>(as)...}};
}
-template <typename Ex>
-inline _t<std::enable_if<is_wrap_ctor<Ex&>::value, exception_wrapper>> make(
- Ex& ex) {
- return typeid(Ex&) == typeid(ex)
- ? exception_wrapper(ex)
- : exception_wrapper(std::current_exception(), ex);
+/**
+ * Inserts `ew.what()` into the ostream `sout`.
+ * \return `sout`
+ */
+template <class Ch>
+std::basic_ostream<Ch>& operator<<(
+ std::basic_ostream<Ch>& sout,
+ exception_wrapper const& ew) {
+ return sout << ew.what();
+}
+
+/**
+ * Swaps the value of `a` with the value of `b`.
+ */
+inline void swap(exception_wrapper& a, exception_wrapper& b) noexcept {
+ a.swap(b);
}
+// For consistency with exceptionStr() functions in ExceptionString.h
+fbstring exceptionStr(exception_wrapper const& ew);
+
+namespace detail {
template <typename F>
-inline exception_wrapper impl(F&& f) {
+inline exception_wrapper try_and_catch_(F&& f) {
return (f(), exception_wrapper());
}
template <typename F, typename Ex, typename... Exs>
-inline exception_wrapper impl(F&& f) {
+inline exception_wrapper try_and_catch_(F&& f) {
try {
- return impl<F, Exs...>(std::forward<F>(f));
+ return try_and_catch_<F, Exs...>(std::forward<F>(f));
} catch (Ex& ex) {
- return make(ex);
+ return exception_wrapper(std::current_exception(), ex);
}
}
-} // try_and_catch_detail
-
+} // detail
+
+//! `try_and_catch` is a simple replacement for `try {} catch(){}`` that allows
+//! you to specify which derived exceptions you would like to catch and store in
+//! an `exception_wrapper`.
+//!
+//! Because we cannot build an equivalent of `std::current_exception()`, we need
+//! to catch every derived exception that we are interested in catching.
+//!
+//! Exceptions should be listed in the reverse order that you would write your
+//! catch statements (that is, `std::exception&` should be first).
+//!
+//! \par Example Usage:
+//! \code
+//! // This catches my runtime_error and if I call throwException() on ew, it
+//! // will throw a runtime_error
+//! auto ew = folly::try_and_catch<std::exception, std::runtime_error>([=]() {
+//! if (badThingHappens()) {
+//! throw std::runtime_error("ZOMG!");
+//! }
+//! });
+//!
+//! // This will catch the exception and if I call throwException() on ew, it
+//! // will throw a std::exception
+//! auto ew = folly::try_and_catch<std::exception, std::runtime_error>([=]() {
+//! if (badThingHappens()) {
+//! throw std::exception();
+//! }
+//! });
+//!
+//! // This will not catch the exception and it will be thrown.
+//! auto ew = folly::try_and_catch<std::runtime_error>([=]() {
+//! if (badThingHappens()) {
+//! throw std::exception();
+//! }
+//! });
+//! \endcode
template <typename... Exceptions, typename F>
exception_wrapper try_and_catch(F&& fn) {
- return try_and_catch_detail::impl<F, Exceptions...>(std::forward<F>(fn));
+ return detail::try_and_catch_<F, Exceptions...>(std::forward<F>(fn));
}
} // folly
+
+#include <folly/ExceptionWrapper-inl.h>
+
+#undef FOLLY_REQUIRES
+#undef FOLLY_REQUIRES_DEF
+#ifdef __GNUC__
+#pragma GCC diagnostic pop
+#endif
Exception.h \
ExceptionString.h \
ExceptionWrapper.h \
+ ExceptionWrapper-inl.h \
Executor.h \
Expected.h \
experimental/AsymmetricMemoryBarrier.h \
EXPECT_FALSE(f1.isReady());
try {
throw std::runtime_error("Oops");
- } catch (...) {
- p.setException(exception_wrapper(std::current_exception()));
+ } catch (std::exception& e) {
+ p.setException(exception_wrapper(std::current_exception(), e));
}
EXPECT_TRUE(f1.isReady());
EXPECT_TRUE(f1.hasException());
demangle(typeid(IntException)).toStdString();
const static std::string kIntClassName = demangle(typeid(int)).toStdString();
+template <typename T>
+T& from_eptr(std::exception_ptr& eptr) {
+ try {
+ std::rethrow_exception(eptr);
+ } catch (T& e) {
+ return e;
+ } catch (...) {
+ throw std::logic_error("impossible");
+ }
+}
+
// Tests that when we call throwException, the proper type is thrown (derived)
TEST(ExceptionWrapper, throw_test) {
std::runtime_error e("payload");
EXPECT_EQ(ew.class_name(), kRuntimeErrorClassName);
}
-TEST(ExceptionWrapper, equals) {
- std::runtime_error e("payload");
- auto ew1 = make_exception_wrapper<std::runtime_error>(e);
- auto ew2 = ew1;
- EXPECT_EQ(ew1, ew2);
-
- auto ew3 = try_and_catch<std::exception>([&]() {
- throw std::runtime_error("payload");
- });
- auto ew4 = try_and_catch<std::exception>([&]() {
- ew3.throwException();
- });
- EXPECT_EQ(ew3, ew4);
-}
-
-TEST(ExceptionWrapper, not_equals) {
- std::runtime_error e1("payload");
- std::runtime_error e2("payload");
- auto ew1 = make_exception_wrapper<std::runtime_error>(e1);
- auto ew2 = make_exception_wrapper<std::runtime_error>(e2);
- EXPECT_NE(ew1, ew2);
-
- auto ew3 = make_exception_wrapper<std::runtime_error>(e1);
- auto ew4 = make_exception_wrapper<std::runtime_error>(e1);
- EXPECT_NE(ew3, ew4);
-
- auto ew5 = try_and_catch<std::exception>([&]() {
- throw e1;
- });
- auto ew6 = try_and_catch<std::exception>([&]() {
- throw e1;
- });
- EXPECT_NE(ew5, ew6);
-}
-
TEST(ExceptionWrapper, try_and_catch_test) {
std::string expected = "payload";
throw std::runtime_error(expected);
});
EXPECT_TRUE(bool(ew));
- EXPECT_TRUE(ew.getCopied());
EXPECT_EQ(ew.what(), kRuntimeErrorClassName + ": payload");
EXPECT_EQ(ew.class_name(), kRuntimeErrorClassName);
auto rep = ew.is_compatible_with<std::runtime_error>();
});
EXPECT_TRUE(bool(ew2));
// We are catching a std::exception, not std::runtime_error.
- EXPECT_FALSE(ew2.getCopied());
// But, we can still get the actual type if we want it.
rep = ew2.is_compatible_with<std::runtime_error>();
EXPECT_TRUE(rep);
EXPECT_TRUE(bool(ew2));
EXPECT_EQ(ew2.what(), kIntExceptionClassName + ": int == 23");
EXPECT_EQ(ew2.class_name(), kIntExceptionClassName);
- EXPECT_TRUE(ew2.with_exception([&](AbstractIntException& ie) {
+ bool res = ew2.with_exception([&](AbstractIntException& ie) {
EXPECT_EQ(ie.getInt(), expected);
EXPECT_TRUE(dynamic_cast<IntException*>(&ie));
- }));
+ });
+ EXPECT_TRUE(res);
// Test with const this. If this compiles and does not crash due to
// infinite loop when it runs, it succeeds.
EXPECT_FALSE(eptr);
}
+TEST(ExceptionWrapper, with_exception_ptr_empty) {
+ auto ew = exception_wrapper(std::exception_ptr());
+ EXPECT_EQ(exception_wrapper::none(), ew.type());
+ EXPECT_FALSE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_FALSE(ew.has_exception_ptr());
+ EXPECT_EQ(nullptr, ew.to_exception_ptr());
+ EXPECT_FALSE(ew.has_exception_ptr());
+ EXPECT_EQ("", ew.class_name());
+ EXPECT_EQ("", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+ EXPECT_DEATH(ew.throwException(), "empty folly::exception_wrapper");
+}
+
+TEST(ExceptionWrapper, with_shared_ptr_test) {
+ auto ew = exception_wrapper(std::runtime_error("foo"));
+ EXPECT_TRUE(bool(ew));
+ EXPECT_EQ(typeid(std::runtime_error), ew.type());
+ EXPECT_NE(nullptr, ew.get_exception());
+ EXPECT_FALSE(ew.has_exception_ptr());
+ EXPECT_NE(nullptr, ew.to_exception_ptr());
+ EXPECT_TRUE(ew.has_exception_ptr());
+ EXPECT_EQ("std::runtime_error", ew.class_name());
+ EXPECT_EQ("std::runtime_error: foo", ew.what());
+ EXPECT_TRUE(ew.is_compatible_with<std::exception>());
+ EXPECT_TRUE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+ EXPECT_THROW(ew.throwException(), std::runtime_error);
+
+ exception_wrapper(std::move(ew));
+ EXPECT_FALSE(bool(ew));
+ EXPECT_EQ(exception_wrapper::none(), ew.type());
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_EQ(nullptr, ew.to_exception_ptr());
+ EXPECT_EQ("", ew.class_name());
+ EXPECT_EQ("", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+}
+
+TEST(ExceptionWrapper, with_exception_ptr_exn_test) {
+ auto ep = std::make_exception_ptr(std::runtime_error("foo"));
+ auto ew = exception_wrapper(ep, from_eptr<std::runtime_error>(ep));
+ EXPECT_TRUE(bool(ew));
+ EXPECT_EQ(typeid(std::runtime_error), ew.type());
+ EXPECT_NE(nullptr, ew.get_exception());
+ EXPECT_TRUE(ew.has_exception_ptr());
+ EXPECT_EQ(ep, ew.to_exception_ptr());
+ EXPECT_TRUE(ew.has_exception_ptr());
+ EXPECT_EQ("std::runtime_error", ew.class_name());
+ EXPECT_EQ("std::runtime_error: foo", ew.what());
+ EXPECT_TRUE(ew.is_compatible_with<std::exception>());
+ EXPECT_TRUE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+ EXPECT_THROW(ew.throwException(), std::runtime_error);
+
+ exception_wrapper(std::move(ew));
+ EXPECT_FALSE(bool(ew));
+ EXPECT_EQ(exception_wrapper::none(), ew.type());
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_EQ(nullptr, ew.to_exception_ptr());
+ EXPECT_EQ("", ew.class_name());
+ EXPECT_EQ("", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+}
+
+TEST(ExceptionWrapper, with_exception_ptr_any_test) {
+ auto ep = std::make_exception_ptr<int>(12);
+ auto ew = exception_wrapper(ep, from_eptr<int>(ep));
+ EXPECT_TRUE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_TRUE(ew.has_exception_ptr());
+ EXPECT_EQ(ep, ew.to_exception_ptr());
+ EXPECT_TRUE(ew.has_exception_ptr());
+ EXPECT_EQ("int", ew.class_name());
+ EXPECT_EQ("int", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_TRUE(ew.is_compatible_with<int>());
+ EXPECT_THROW(ew.throwException(), int);
+
+ exception_wrapper(std::move(ew));
+ EXPECT_FALSE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_EQ(nullptr, ew.to_exception_ptr());
+ EXPECT_FALSE(ew.has_exception_ptr());
+ EXPECT_EQ("", ew.class_name());
+ EXPECT_EQ("", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+}
+
+TEST(ExceptionWrapper, with_non_std_exception_test) {
+ auto ew = exception_wrapper(folly::in_place, 42);
+ EXPECT_TRUE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_FALSE(ew.has_exception_ptr());
+ EXPECT_EQ("int", ew.class_name());
+ EXPECT_EQ("int", ew.what());
+ EXPECT_NE(nullptr, ew.to_exception_ptr());
+ EXPECT_TRUE(ew.has_exception_ptr());
+ EXPECT_EQ("int", ew.class_name());
+ EXPECT_EQ("int", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_TRUE(ew.is_compatible_with<int>());
+ EXPECT_THROW(ew.throwException(), int);
+
+ exception_wrapper(std::move(ew));
+ EXPECT_FALSE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_EQ(nullptr, ew.to_exception_ptr());
+ EXPECT_FALSE(ew.has_exception_ptr());
+ EXPECT_EQ("", ew.class_name());
+ EXPECT_EQ("", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+}
+
+TEST(ExceptionWrapper, with_exception_ptr_any_nil_test) {
+ auto ep = std::make_exception_ptr<int>(12);
+ auto ew = exception_wrapper(ep); // concrete type is erased
+ EXPECT_TRUE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_EQ(ep, ew.to_exception_ptr());
+ EXPECT_EQ("<unknown exception>", ew.class_name()); // because concrete type is
+ // erased
+ EXPECT_EQ("<unknown exception>", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_TRUE(ew.is_compatible_with<int>());
+ EXPECT_THROW(ew.throwException(), int);
+
+ exception_wrapper(std::move(ew));
+ EXPECT_FALSE(bool(ew));
+ EXPECT_EQ(nullptr, ew.get_exception());
+ EXPECT_EQ(nullptr, ew.to_exception_ptr());
+ EXPECT_EQ("", ew.class_name());
+ EXPECT_EQ("", ew.what());
+ EXPECT_FALSE(ew.is_compatible_with<std::exception>());
+ EXPECT_FALSE(ew.is_compatible_with<std::runtime_error>());
+ EXPECT_FALSE(ew.is_compatible_with<int>());
+}
+
TEST(ExceptionWrapper, with_exception_deduction) {
auto ew = make_exception_wrapper<std::runtime_error>("hi");
EXPECT_TRUE(ew.with_exception([](std::runtime_error&) {}));
testEW(e);
testEW(TestException());
}
+
+namespace {
+struct BaseException {
+ virtual ~BaseException() {}
+};
+struct DerivedException : BaseException {};
+exception_wrapper testNonStdException() {
+ try {
+ throw DerivedException{};
+ } catch (const BaseException& e) {
+ return exception_wrapper{std::current_exception(), e};
+ }
+}
+}
+
+TEST(ExceptionWrapper, base_derived_non_std_exception_test) {
+ auto ew = testNonStdException();
+ EXPECT_TRUE(ew.type() == typeid(DerivedException));
+ EXPECT_TRUE(ew.with_exception([](const DerivedException&) {}));
+}
+
+namespace {
+// Cannot be stored within an exception_wrapper
+struct BigRuntimeError : std::runtime_error {
+ using std::runtime_error::runtime_error;
+ char data_[sizeof(exception_wrapper) + 1]{};
+};
+
+struct BigNonStdError {
+ char data_[sizeof(exception_wrapper) + 1]{};
+};
+}
+
+TEST(ExceptionWrapper, handle_std_exception) {
+ auto ep = std::make_exception_ptr(std::runtime_error{"hello world"});
+ exception_wrapper const ew_eptr(ep, from_eptr<std::runtime_error>(ep));
+ exception_wrapper const ew_small(std::runtime_error{"hello world"});
+ exception_wrapper const ew_big(BigRuntimeError{"hello world"});
+
+ bool handled = false;
+ auto expect_runtime_error_yes_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::logic_error&) { EXPECT_TRUE(false); },
+ [&](const std::runtime_error&) { handled = true; },
+ [](const std::exception&) { EXPECT_TRUE(false); },
+ [](...) { EXPECT_TRUE(false); });
+ };
+
+ expect_runtime_error_yes_catch_all(ew_eptr);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_yes_catch_all(ew_small);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_yes_catch_all(ew_big);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ auto expect_runtime_error_no_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::logic_error&) { EXPECT_TRUE(false); },
+ [&](const std::runtime_error&) { handled = true; },
+ [](const std::exception&) { EXPECT_TRUE(false); });
+ };
+
+ expect_runtime_error_no_catch_all(ew_eptr);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_no_catch_all(ew_small);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_no_catch_all(ew_big);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ auto expect_runtime_error_catch_non_std = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::logic_error&) { EXPECT_TRUE(false); },
+ [&](const std::runtime_error&) { handled = true; },
+ [](const std::exception&) { EXPECT_TRUE(false); },
+ [](const int&) { EXPECT_TRUE(false); });
+ };
+
+ expect_runtime_error_catch_non_std(ew_eptr);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_catch_non_std(ew_small);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_catch_non_std(ew_big);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ // Test that an exception thrown from one handler is not caught by an
+ // outer handler:
+ auto expect_runtime_error_rethrow = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::logic_error&) { EXPECT_TRUE(false); },
+ [&](const std::runtime_error& e) {
+ handled = true;
+ throw e;
+ },
+ [](const std::exception&) { EXPECT_TRUE(false); });
+ };
+
+ EXPECT_THROW(expect_runtime_error_rethrow(ew_eptr), std::runtime_error);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ EXPECT_THROW(expect_runtime_error_rethrow(ew_small), std::runtime_error);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ EXPECT_THROW(expect_runtime_error_rethrow(ew_big), std::runtime_error);
+ EXPECT_EQ(true, handled);
+}
+
+TEST(ExceptionWrapper, handle_std_exception_unhandled) {
+ auto ep = std::make_exception_ptr(std::exception{});
+ exception_wrapper const ew_eptr(ep, from_eptr<std::exception>(ep));
+ exception_wrapper const ew_small(std::exception{});
+
+ bool handled = false;
+ auto expect_runtime_error_yes_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::logic_error&) { EXPECT_TRUE(false); },
+ [](const std::runtime_error&) { EXPECT_TRUE(false); },
+ [&](...) { handled = true; });
+ };
+
+ expect_runtime_error_yes_catch_all(ew_eptr);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_runtime_error_yes_catch_all(ew_small);
+ EXPECT_EQ(true, handled);
+}
+
+TEST(ExceptionWrapper, handle_non_std_exception_small) {
+ auto ep = std::make_exception_ptr(42);
+ exception_wrapper const ew_eptr1(ep);
+ exception_wrapper const ew_eptr2(ep, from_eptr<int>(ep));
+ exception_wrapper const ew_small(folly::in_place, 42);
+ bool handled = false;
+
+ auto expect_int_yes_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::exception&) { EXPECT_TRUE(false); },
+ [&](...) { handled = true; });
+ };
+
+ expect_int_yes_catch_all(ew_eptr1);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_yes_catch_all(ew_eptr2);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_yes_catch_all(ew_small);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ auto expect_int_no_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::exception&) { EXPECT_TRUE(false); },
+ [&](const int&) { handled = true; });
+ };
+
+ expect_int_no_catch_all(ew_eptr1);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all(ew_eptr2);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all(ew_small);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ auto expect_int_no_catch_all_2 = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [&](const int&) { handled = true; },
+ [](const std::exception&) { EXPECT_TRUE(false); });
+ };
+
+ expect_int_no_catch_all_2(ew_eptr1);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all_2(ew_eptr2);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all_2(ew_small);
+ EXPECT_EQ(true, handled);
+}
+
+TEST(ExceptionWrapper, handle_non_std_exception_big) {
+ auto ep = std::make_exception_ptr(BigNonStdError{});
+ exception_wrapper const ew_eptr1(ep);
+ exception_wrapper const ew_eptr2(ep, from_eptr<BigNonStdError>(ep));
+ exception_wrapper const ew_big(folly::in_place, BigNonStdError{});
+ bool handled = false;
+
+ auto expect_int_yes_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::exception&) { EXPECT_TRUE(false); },
+ [&](...) { handled = true; });
+ };
+
+ expect_int_yes_catch_all(ew_eptr1);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_yes_catch_all(ew_eptr2);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_yes_catch_all(ew_big);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ auto expect_int_no_catch_all = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [](const std::exception&) { EXPECT_TRUE(false); },
+ [&](const BigNonStdError&) { handled = true; });
+ };
+
+ expect_int_no_catch_all(ew_eptr1);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all(ew_eptr2);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all(ew_big);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ auto expect_int_no_catch_all_2 = [&](const exception_wrapper& ew) {
+ ew.handle(
+ [&](const BigNonStdError&) { handled = true; },
+ [](const std::exception&) { EXPECT_TRUE(false); });
+ };
+
+ expect_int_no_catch_all_2(ew_eptr1);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all_2(ew_eptr2);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ expect_int_no_catch_all_2(ew_big);
+ EXPECT_EQ(true, handled);
+ handled = false;
+
+ EXPECT_THROW(
+ expect_int_no_catch_all_2(exception_wrapper{folly::in_place, 42}), int);
+}
+
+TEST(ExceptionWrapper, handle_non_std_exception_rethrow_base_derived) {
+ auto ew = testNonStdException();
+ bool handled = false;
+ EXPECT_THROW(
+ ew.handle(
+ [&](const DerivedException& e) {
+ handled = true;
+ throw e;
+ },
+ [](const BaseException&) { EXPECT_TRUE(false); }),
+ DerivedException);
+ EXPECT_EQ(true, handled);
+ handled = false;
+ EXPECT_THROW(
+ ew.handle(
+ [&](const DerivedException& e) {
+ handled = true;
+ throw e;
+ },
+ [](...) { EXPECT_TRUE(false); }),
+ DerivedException);
+ EXPECT_EQ(true, handled);
+}
+
+TEST(ExceptionWrapper, self_swap_test) {
+ exception_wrapper ew(std::runtime_error("hello world"));
+ folly::swap(ew, ew);
+ EXPECT_STREQ("std::runtime_error: hello world", ew.what().c_str());
+ auto& ew2 = ew;
+ ew = std::move(ew2); // should not crash
+}
projects / folly.git / commitdiff