// Copyright 2017 The Abseil Authors.
//
// 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
//
// https://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.
// Utilities for testing exception-safety
#ifndef ABSL_BASE_INTERNAL_EXCEPTION_SAFETY_TESTING_H_
#define ABSL_BASE_INTERNAL_EXCEPTION_SAFETY_TESTING_H_
#include "absl/base/config.h"
#ifdef ABSL_HAVE_EXCEPTIONS
#include <cstddef>
#include <cstdint>
#include <functional>
#include <initializer_list>
#include <iosfwd>
#include <string>
#include <tuple>
#include <unordered_map>
#include "gtest/gtest.h"
#include "absl/base/internal/pretty_function.h"
#include "absl/memory/memory.h"
#include "absl/meta/type_traits.h"
#include "absl/strings/string_view.h"
#include "absl/strings/substitute.h"
#include "absl/utility/utility.h"
namespace testing {
enum class TypeSpec;
enum class AllocSpec;
constexpr TypeSpec operator|(TypeSpec a, TypeSpec b) {
using T = absl::underlying_type_t<TypeSpec>;
return static_cast<TypeSpec>(static_cast<T>(a) | static_cast<T>(b));
}
constexpr TypeSpec operator&(TypeSpec a, TypeSpec b) {
using T = absl::underlying_type_t<TypeSpec>;
return static_cast<TypeSpec>(static_cast<T>(a) & static_cast<T>(b));
}
constexpr AllocSpec operator|(AllocSpec a, AllocSpec b) {
using T = absl::underlying_type_t<AllocSpec>;
return static_cast<AllocSpec>(static_cast<T>(a) | static_cast<T>(b));
}
constexpr AllocSpec operator&(AllocSpec a, AllocSpec b) {
using T = absl::underlying_type_t<AllocSpec>;
return static_cast<AllocSpec>(static_cast<T>(a) & static_cast<T>(b));
}
namespace exceptions_internal {
std::string GetSpecString(TypeSpec);
std::string GetSpecString(AllocSpec);
struct NoThrowTag {};
struct StrongGuaranteeTagType {};
// A simple exception class. We throw this so that test code can catch
// exceptions specifically thrown by ThrowingValue.
class TestException {
public:
explicit TestException(absl::string_view msg) : msg_(msg) {}
virtual ~TestException() {}
virtual const char* what() const noexcept { return msg_.c_str(); }
private:
std::string msg_;
};
// TestBadAllocException exists because allocation functions must throw an
// exception which can be caught by a handler of std::bad_alloc. We use a child
// class of std::bad_alloc so we can customise the error message, and also
// derive from TestException so we don't accidentally end up catching an actual
// bad_alloc exception in TestExceptionSafety.
class TestBadAllocException : public std::bad_alloc, public TestException {
public:
explicit TestBadAllocException(absl::string_view msg) : TestException(msg) {}
using TestException::what;
};
extern int countdown;
// Allows the countdown variable to be set manually (defaulting to the initial
// value of 0)
inline void SetCountdown(int i = 0) { countdown = i; }
// Sets the countdown to the terminal value -1
inline void UnsetCountdown() { SetCountdown(-1); }
void MaybeThrow(absl::string_view msg, bool throw_bad_alloc = false);
testing::AssertionResult FailureMessage(const TestException& e,
int countdown) noexcept;
struct TrackedAddress {
bool is_alive;
std::string description;
};
// Inspects the constructions and destructions of anything inheriting from
// TrackedObject. This allows us to safely "leak" TrackedObjects, as
// ConstructorTracker will destroy everything left over in its destructor.
class ConstructorTracker {
public:
explicit ConstructorTracker(int count) : countdown_(count) {
assert(current_tracker_instance_ == nullptr);
current_tracker_instance_ = this;
}
~ConstructorTracker() {
assert(current_tracker_instance_ == this);
current_tracker_instance_ = nullptr;
for (auto& it : address_map_) {
void* address = it.first;
TrackedAddress& tracked_address = it.second;
if (tracked_address.is_alive) {
ADD_FAILURE() << ErrorMessage(address, tracked_address.description,
countdown_, "Object was not destroyed.");
}
}
}
static void ObjectConstructed(void* address, std::string description) {
if (!CurrentlyTracking()) return;
TrackedAddress& tracked_address =
current_tracker_instance_->address_map_[address];
if (tracked_address.is_alive) {
ADD_FAILURE() << ErrorMessage(
address, tracked_address.description,
current_tracker_instance_->countdown_,
"Object was re-constructed. Current object was constructed by " +
description);
}
tracked_address = {true, std::move(description)};
}
static void ObjectDestructed(void* address) {
if (!CurrentlyTracking()) return;
auto it = current_tracker_instance_->address_map_.find(address);
// Not tracked. Ignore.
if (it == current_tracker_instance_->address_map_.end()) return;
TrackedAddress& tracked_address = it->second;
if (!tracked_address.is_alive) {
ADD_FAILURE() << ErrorMessage(address, tracked_address.description,
current_tracker_instance_->countdown_,
"Object was re-destroyed.");
}
tracked_address.is_alive = false;
}
private:
static bool CurrentlyTracking() {
return current_tracker_instance_ != nullptr;
}
static std::string ErrorMessage(void* address,
const std::string& address_description,
int countdown,
const std::string& error_description) {
return absl::Substitute(
"With coundtown at $0:\n"
" $1\n"
" Object originally constructed by $2\n"
" Object address: $3\n",
countdown, error_description, address_description, address);
}
std::unordered_map<void*, TrackedAddress> address_map_;
int countdown_;
static ConstructorTracker* current_tracker_instance_;
};
class TrackedObject {
public:
TrackedObject(const TrackedObject&) = delete;
TrackedObject(TrackedObject&&) = delete;
protected:
explicit TrackedObject(std::string description) {
ConstructorTracker::ObjectConstructed(this, std::move(description));
}
~TrackedObject() noexcept { ConstructorTracker::ObjectDestructed(this); }
};
} // namespace exceptions_internal
extern exceptions_internal::NoThrowTag nothrow_ctor;
extern exceptions_internal::StrongGuaranteeTagType strong_guarantee;
// A test class which is convertible to bool. The conversion can be
// instrumented to throw at a controlled time.
class ThrowingBool {
public:
ThrowingBool(bool b) noexcept : b_(b) {} // NOLINT(runtime/explicit)
operator bool() const { // NOLINT
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return b_;
}
private:
bool b_;
};
/*
* Configuration enum for the ThrowingValue type that defines behavior for the
* lifetime of the instance. Use testing::nothrow_ctor to prevent the integer
* constructor from throwing.
*
* kEverythingThrows: Every operation can throw an exception
* kNoThrowCopy: Copy construction and copy assignment will not throw
* kNoThrowMove: Move construction and move assignment will not throw
* kNoThrowNew: Overloaded operators new and new[] will not throw
*/
enum class TypeSpec {
kEverythingThrows = 0,
kNoThrowCopy = 1,
kNoThrowMove = 1 << 1,
kNoThrowNew = 1 << 2,
};
/*
* A testing class instrumented to throw an exception at a controlled time.
*
* ThrowingValue implements a slightly relaxed version of the Regular concept --
* that is it's a value type with the expected semantics. It also implements
* arithmetic operations. It doesn't implement member and pointer operators
* like operator-> or operator[].
*
* ThrowingValue can be instrumented to have certain operations be noexcept by
* using compile-time bitfield template arguments. That is, to make an
* ThrowingValue which has noexcept move construction/assignment and noexcept
* copy construction/assignment, use the following:
* ThrowingValue<testing::kNoThrowMove | testing::kNoThrowCopy> my_thrwr{val};
*/
template <TypeSpec Spec = TypeSpec::kEverythingThrows>
class ThrowingValue : private exceptions_internal::TrackedObject {
static constexpr bool IsSpecified(TypeSpec spec) {
return static_cast<bool>(Spec & spec);
}
static constexpr int kDefaultValue = 0;
static constexpr int kBadValue = 938550620;
public:
ThrowingValue() : TrackedObject(GetInstanceString(kDefaultValue)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ = kDefaultValue;
}
ThrowingValue(const ThrowingValue& other) noexcept(
IsSpecified(TypeSpec::kNoThrowCopy))
: TrackedObject(GetInstanceString(other.dummy_)) {
if (!IsSpecified(TypeSpec::kNoThrowCopy)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
}
dummy_ = other.dummy_;
}
ThrowingValue(ThrowingValue&& other) noexcept(
IsSpecified(TypeSpec::kNoThrowMove))
: TrackedObject(GetInstanceString(other.dummy_)) {
if (!IsSpecified(TypeSpec::kNoThrowMove)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
}
dummy_ = other.dummy_;
}
explicit ThrowingValue(int i) : TrackedObject(GetInstanceString(i)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ = i;
}
ThrowingValue(int i, exceptions_internal::NoThrowTag) noexcept
: TrackedObject(GetInstanceString(i)), dummy_(i) {}
// absl expects nothrow destructors
~ThrowingValue() noexcept = default;
ThrowingValue& operator=(const ThrowingValue& other) noexcept(
IsSpecified(TypeSpec::kNoThrowCopy)) {
dummy_ = kBadValue;
if (!IsSpecified(TypeSpec::kNoThrowCopy)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
}
dummy_ = other.dummy_;
return *this;
}
ThrowingValue& operator=(ThrowingValue&& other) noexcept(
IsSpecified(TypeSpec::kNoThrowMove)) {
dummy_ = kBadValue;
if (!IsSpecified(TypeSpec::kNoThrowMove)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
}
dummy_ = other.dummy_;
return *this;
}
// Arithmetic Operators
ThrowingValue operator+(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ + other.dummy_, nothrow_ctor);
}
ThrowingValue operator+() const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_, nothrow_ctor);
}
ThrowingValue operator-(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ - other.dummy_, nothrow_ctor);
}
ThrowingValue operator-() const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(-dummy_, nothrow_ctor);
}
ThrowingValue& operator++() {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
++dummy_;
return *this;
}
ThrowingValue operator++(int) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
auto out = ThrowingValue(dummy_, nothrow_ctor);
++dummy_;
return out;
}
ThrowingValue& operator--() {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
--dummy_;
return *this;
}
ThrowingValue operator--(int) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
auto out = ThrowingValue(dummy_, nothrow_ctor);
--dummy_;
return out;
}
ThrowingValue operator*(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ * other.dummy_, nothrow_ctor);
}
ThrowingValue operator/(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ / other.dummy_, nothrow_ctor);
}
ThrowingValue operator%(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ % other.dummy_, nothrow_ctor);
}
ThrowingValue operator<<(int shift) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ << shift, nothrow_ctor);
}
ThrowingValue operator>>(int shift) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ >> shift, nothrow_ctor);
}
// Comparison Operators
// NOTE: We use `ThrowingBool` instead of `bool` because most STL
// types/containers requires T to be convertible to bool.
friend ThrowingBool operator==(const ThrowingValue& a,
const ThrowingValue& b) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return a.dummy_ == b.dummy_;
}
friend ThrowingBool operator!=(const ThrowingValue& a,
const ThrowingValue& b) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return a.dummy_ != b.dummy_;
}
friend ThrowingBool operator<(const ThrowingValue& a,
const ThrowingValue& b) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return a.dummy_ < b.dummy_;
}
friend ThrowingBool operator<=(const ThrowingValue& a,
const ThrowingValue& b) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return a.dummy_ <= b.dummy_;
}
friend ThrowingBool operator>(const ThrowingValue& a,
const ThrowingValue& b) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return a.dummy_ > b.dummy_;
}
friend ThrowingBool operator>=(const ThrowingValue& a,
const ThrowingValue& b) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return a.dummy_ >= b.dummy_;
}
// Logical Operators
ThrowingBool operator!() const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return !dummy_;
}
ThrowingBool operator&&(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return dummy_ && other.dummy_;
}
ThrowingBool operator||(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return dummy_ || other.dummy_;
}
// Bitwise Logical Operators
ThrowingValue operator~() const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(~dummy_, nothrow_ctor);
}
ThrowingValue operator&(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ & other.dummy_, nothrow_ctor);
}
ThrowingValue operator|(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ | other.dummy_, nothrow_ctor);
}
ThrowingValue operator^(const ThrowingValue& other) const {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return ThrowingValue(dummy_ ^ other.dummy_, nothrow_ctor);
}
// Compound Assignment operators
ThrowingValue& operator+=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ += other.dummy_;
return *this;
}
ThrowingValue& operator-=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ -= other.dummy_;
return *this;
}
ThrowingValue& operator*=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ *= other.dummy_;
return *this;
}
ThrowingValue& operator/=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ /= other.dummy_;
return *this;
}
ThrowingValue& operator%=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ %= other.dummy_;
return *this;
}
ThrowingValue& operator&=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ &= other.dummy_;
return *this;
}
ThrowingValue& operator|=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ |= other.dummy_;
return *this;
}
ThrowingValue& operator^=(const ThrowingValue& other) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ ^= other.dummy_;
return *this;
}
ThrowingValue& operator<<=(int shift) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ <<= shift;
return *this;
}
ThrowingValue& operator>>=(int shift) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ >>= shift;
return *this;
}
// Pointer operators
void operator&() const = delete; // NOLINT(runtime/operator)
// Stream operators
friend std::ostream& operator<<(std::ostream& os, const ThrowingValue& tv) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return os << GetInstanceString(tv.dummy_);
}
friend std::istream& operator>>(std::istream& is, const ThrowingValue&) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
return is;
}
// Memory management operators
static void* operator new(size_t s) noexcept(
IsSpecified(TypeSpec::kNoThrowNew)) {
if (!IsSpecified(TypeSpec::kNoThrowNew)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION, true);
}
return ::operator new(s);
}
static void* operator new[](size_t s) noexcept(
IsSpecified(TypeSpec::kNoThrowNew)) {
if (!IsSpecified(TypeSpec::kNoThrowNew)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION, true);
}
return ::operator new[](s);
}
template <typename... Args>
static void* operator new(size_t s, Args&&... args) noexcept(
IsSpecified(TypeSpec::kNoThrowNew)) {
if (!IsSpecified(TypeSpec::kNoThrowNew)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION, true);
}
return ::operator new(s, std::forward<Args>(args)...);
}
template <typename... Args>
static void* operator new[](size_t s, Args&&... args) noexcept(
IsSpecified(TypeSpec::kNoThrowNew)) {
if (!IsSpecified(TypeSpec::kNoThrowNew)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION, true);
}
return ::operator new[](s, std::forward<Args>(args)...);
}
// Abseil doesn't support throwing overloaded operator delete. These are
// provided so a throwing operator-new can clean up after itself.
void operator delete(void* p) noexcept { ::operator delete(p); }
template <typename... Args>
void operator delete(void* p, Args&&... args) noexcept {
::operator delete(p, std::forward<Args>(args)...);
}
void operator delete[](void* p) noexcept { return ::operator delete[](p); }
template <typename... Args>
void operator delete[](void* p, Args&&... args) noexcept {
return ::operator delete[](p, std::forward<Args>(args)...);
}
// Non-standard access to the actual contained value. No need for this to
// throw.
int& Get() noexcept { return dummy_; }
const int& Get() const noexcept { return dummy_; }
private:
static std::string GetInstanceString(int dummy) {
return absl::StrCat("ThrowingValue<",
exceptions_internal::GetSpecString(Spec), ">(", dummy,
")");
}
int dummy_;
};
// While not having to do with exceptions, explicitly delete comma operator, to
// make sure we don't use it on user-supplied types.
template <TypeSpec Spec, typename T>
void operator,(const ThrowingValue<Spec>&, T&&) = delete;
template <TypeSpec Spec, typename T>
void operator,(T&&, const ThrowingValue<Spec>&) = delete;
/*
* Configuration enum for the ThrowingAllocator type that defines behavior for
* the lifetime of the instance.
*
* kEverythingThrows: Calls to the member functions may throw
* kNoThrowAllocate: Calls to the member functions will not throw
*/
enum class AllocSpec {
kEverythingThrows = 0,
kNoThrowAllocate = 1,
};
/*
* An allocator type which is instrumented to throw at a controlled time, or not
* to throw, using AllocSpec. The supported settings are the default of every
* function which is allowed to throw in a conforming allocator possibly
* throwing, or nothing throws, in line with the ABSL_ALLOCATOR_THROWS
* configuration macro.
*/
template <typename T, AllocSpec Spec = AllocSpec::kEverythingThrows>
class ThrowingAllocator : private exceptions_internal::TrackedObject {
static constexpr bool IsSpecified(AllocSpec spec) {
return static_cast<bool>(Spec & spec);
}
public:
using pointer = T*;
using const_pointer = const T*;
using reference = T&;
using const_reference = const T&;
using void_pointer = void*;
using const_void_pointer = const void*;
using value_type = T;
using size_type = size_t;
using difference_type = ptrdiff_t;
using is_nothrow =
std::integral_constant<bool, Spec == AllocSpec::kNoThrowAllocate>;
using propagate_on_container_copy_assignment = std::true_type;
using propagate_on_container_move_assignment = std::true_type;
using propagate_on_container_swap = std::true_type;
using is_always_equal = std::false_type;
ThrowingAllocator() : TrackedObject(GetInstanceString(next_id_)) {
exceptions_internal::MaybeThrow(ABSL_PRETTY_FUNCTION);
dummy_ = std::make_shared<const int>(next_id_++);
}
template <typename U>
ThrowingAllocator(const ThrowingAllocator<U, Spec>& other) noexcept // NOLINT
: TrackedObject(GetInstanceString(*other.State())),
dummy_(other.State()) {}
// According to C++11 standard [17.6.3.5], Table 28, the move/copy ctors of
// allocator shall not exit via an exception, thus they are marked noexcept.
ThrowingAllocator(const ThrowingAllocator& other) noexcept
: TrackedObject(GetInstanceString(*other.State())),
dummy_(other.State()) {}
template <typename U>
ThrowingAllocator(ThrowingAllocator<U, Spec>&& other) noexcept // NOLINT
: TrackedObject(GetInstanceString(*other.State())),
dummy_(std::move(other.State())) {}
ThrowingAllocator(ThrowingAllocator&& other) noexcept
: TrackedObject(GetInstanceString(*other.State())),
dummy_(std::move(other.State())) {}
~ThrowingAllocator() noexcept = default;
ThrowingAllocator& operator=(const ThrowingAllocator& other) noexcept {
dummy_ = other.State();
return *this;
}
template <typename U>
ThrowingAllocator& operator=(
const ThrowingAllocator<U, Spec>& other) noexcept {
dummy_ = other.State();
return *this;
}
template <typename U>
ThrowingAllocator& operator=(ThrowingAllocator<U, Spec>&& other) noexcept {
dummy_ = std::move(other.State());
return *this;
}
template <typename U>
struct rebind {
using other = ThrowingAllocator<U, Spec>;
};
pointer allocate(size_type n) noexcept(
IsSpecified(AllocSpec::kNoThrowAllocate)) {
ReadStateAndMaybeThrow(ABSL_PRETTY_FUNCTION);
return static_cast<pointer>(::operator new(n * sizeof(T)));
}
pointer allocate(size_type n, const_void_pointer) noexcept(
IsSpecified(AllocSpec::kNoThrowAllocate)) {
return allocate(n);
}
void deallocate(pointer ptr, size_type) noexcept {
ReadState();
::operator delete(static_cast<void*>(ptr));
}
template <typename U, typename... Args>
void construct(U* ptr, Args&&... args) noexcept(
IsSpecified(AllocSpec::kNoThrowAllocate)) {
ReadStateAndMaybeThrow(ABSL_PRETTY_FUNCTION);
::new (static_cast<void*>(ptr)) U(std::forward<Args>(args)...);
}
template <typename U>
void destroy(U* p) noexcept {
ReadState();
p->~U();
}
size_type max_size() const noexcept {
return (std::numeric_limits<difference_type>::max)() / sizeof(value_type);
}
ThrowingAllocator select_on_container_copy_construction() noexcept(
IsSpecified(AllocSpec::kNoThrowAllocate)) {
ReadStateAndMaybeThrow(ABSL_PRETTY_FUNCTION);
return *this;
}
template <typename U>
bool operator==(const ThrowingAllocator<U, Spec>& other) const noexcept {
return dummy_ == other.dummy_;
}
template <typename U>
bool operator!=(const ThrowingAllocator<U, Spec>& other) const noexcept {
return dummy_ != other.dummy_;
}
template <typename, AllocSpec>
friend class ThrowingAllocator;
private:
static std::string GetInstanceString(int dummy) {
return absl::StrCat("ThrowingAllocator<",
exceptions_internal::GetSpecString(Spec), ">(", dummy,
")");
}
const std::shared_ptr<const int>& State() const { return dummy_; }
std::shared_ptr<const int>& State() { return dummy_; }
void ReadState() {
// we know that this will never be true, but the compiler doesn't, so this
// should safely force a read of the value.
if (*dummy_ < 0) std::abort();
}
void ReadStateAndMaybeThrow(absl::string_view msg) const {
if (!IsSpecified(AllocSpec::kNoThrowAllocate)) {
exceptions_internal::MaybeThrow(
absl::Substitute("Allocator id $0 threw from $1", *dummy_, msg));
}
}
static int next_id_;
std::shared_ptr<const int> dummy_;
};
template <typename T, AllocSpec Spec>
int ThrowingAllocator<T, Spec>::next_id_ = 0;
// Tests for resource leaks by attempting to construct a T using args repeatedly
// until successful, using the countdown method. Side effects can then be
// tested for resource leaks.
template <typename T, typename... Args>
void TestThrowingCtor(Args&&... args) {
struct Cleanup {
~Cleanup() { exceptions_internal::UnsetCountdown(); }
} c;
for (int count = 0;; ++count) {
exceptions_internal::ConstructorTracker ct(count);
exceptions_internal::SetCountdown(count);
try {
T temp(std::forward<Args>(args)...);
static_cast<void>(temp);
break;
} catch (const exceptions_internal::TestException&) {
}
}
}
// Tests the nothrow guarantee of the provided nullary operation. If the an
// exception is thrown, the result will be AssertionFailure(). Otherwise, it
// will be AssertionSuccess().
template <typename Operation>
testing::AssertionResult TestNothrowOp(const Operation& operation) {
struct Cleanup {
Cleanup() { exceptions_internal::SetCountdown(); }
~Cleanup() { exceptions_internal::UnsetCountdown(); }
} c;
try {
operation();
return testing::AssertionSuccess();
} catch (const exceptions_internal::TestException&) {
return testing::AssertionFailure()
<< "TestException thrown during call to operation() when nothrow "
"guarantee was expected.";
} catch (...) {
return testing::AssertionFailure()
<< "Unknown exception thrown during call to operation() when "
"nothrow guarantee was expected.";
}
}
namespace exceptions_internal {
// Dummy struct for ExceptionSafetyTestBuilder<> partial state.
struct UninitializedT {};
template <typename T>
class DefaultFactory {
public:
explicit DefaultFactory(const T& t) : t_(t) {}
std::unique_ptr<T> operator()() const { return absl::make_unique<T>(t_); }
private:
T t_;
};
template <size_t LazyContractsCount, typename LazyFactory,
typename LazyOperation>
using EnableIfTestable = typename absl::enable_if_t<
LazyContractsCount != 0 &&
!std::is_same<LazyFactory, UninitializedT>::value &&
!std::is_same<LazyOperation, UninitializedT>::value>;
template <typename Factory = UninitializedT,
typename Operation = UninitializedT, typename... Contracts>
class ExceptionSafetyTestBuilder;
} // namespace exceptions_internal
/*
* Constructs an empty ExceptionSafetyTestBuilder. All
* ExceptionSafetyTestBuilder objects are immutable and all With[thing] mutation
* methods return new instances of ExceptionSafetyTestBuilder.
*
* In order to test a T for exception safety, a factory for that T, a testable
* operation, and at least one contract callback returning an assertion
* result must be applied using the respective methods.
*/
exceptions_internal::ExceptionSafetyTestBuilder<> MakeExceptionSafetyTester();
namespace exceptions_internal {
template <typename T>
struct IsUniquePtr : std::false_type {};
template <typename T, typename D>
struct IsUniquePtr<std::unique_ptr<T, D>> : std::true_type {};
template <typename Factory>
struct FactoryPtrTypeHelper {
using type = decltype(std::declval<const Factory&>()());
static_assert(IsUniquePtr<type>::value, "Factories must return a unique_ptr");
};
template <typename Factory>
using FactoryPtrType = typename FactoryPtrTypeHelper<Factory>::type;
template <typename Factory>
using FactoryElementType = typename FactoryPtrType<Factory>::element_type;
template <typename T>
class ExceptionSafetyTest {
using Factory = std::function<std::unique_ptr<T>()>;
using Operation = std::function<void(T*)>;
using Contract = std::function<AssertionResult(T*)>;
public:
template <typename... Contracts>
explicit ExceptionSafetyTest(const Factory& f, const Operation& op,
const Contracts&... contracts)
: factory_(f), operation_(op), contracts_{WrapContract(contracts)...} {}
AssertionResult Test() const {
for (int count = 0;; ++count) {
exceptions_internal::ConstructorTracker ct(count);
for (const auto& contract : contracts_) {
auto t_ptr = factory_();
try {
SetCountdown(count);
operation_(t_ptr.get());
// Unset for the case that the operation throws no exceptions, which
// would leave the countdown set and break the *next* exception safety
// test after this one.
UnsetCountdown();
return AssertionSuccess();
} catch (const exceptions_internal::TestException& e) {
if (!contract(t_ptr.get())) {
return AssertionFailure() << e.what() << " failed contract check";
}
}
}
}
}
private:
template <typename ContractFn>
Contract WrapContract(const ContractFn& contract) {
return [contract](T* t_ptr) { return AssertionResult(contract(t_ptr)); };
}
Contract WrapContract(StrongGuaranteeTagType) {
return [this](T* t_ptr) { return AssertionResult(*factory_() == *t_ptr); };
}
Factory factory_;
Operation operation_;
std::vector<Contract> contracts_;
};
/*
* Builds a tester object that tests if performing a operation on a T follows
* exception safety guarantees. Verification is done via contract assertion
* callbacks applied to T instances post-throw.
*
* Template parameters for ExceptionSafetyTestBuilder:
*
* - Factory: The factory object (passed in via tester.WithFactory(...) or
* tester.WithInitialValue(...)) must be invocable with the signature
* `std::unique_ptr<T> operator()() const` where T is the type being tested.
* It is used for reliably creating identical T instances to test on.
*
* - Operation: The operation object (passed in via tester.WithOperation(...)
* or tester.Test(...)) must be invocable with the signature
* `void operator()(T*) const` where T is the type being tested. It is used
* for performing steps on a T instance that may throw and that need to be
* checked for exception safety. Each call to the operation will receive a
* fresh T instance so it's free to modify and destroy the T instances as it
* pleases.
*
* - Contracts...: The contract assertion callback objects (passed in via
* tester.WithContracts(...)) must be invocable with the signature
* `testing::AssertionResult operator()(T*) const` where T is the type being
* tested. Contract assertion callbacks are provided T instances post-throw.
* They must return testing::AssertionSuccess when the type contracts of the
* provided T instance hold. If the type contracts of the T instance do not
* hold, they must return testing::AssertionFailure. Execution order of
* Contracts... is unspecified. They will each individually get a fresh T
* instance so they are free to modify and destroy the T instances as they
* please.
*/
template <typename Factory, typename Operation, typename... Contracts>
class ExceptionSafetyTestBuilder {
public:
/*
* Returns a new ExceptionSafetyTestBuilder with an included T factory based
* on the provided T instance. The existing factory will not be included in
* the newly created tester instance. The created factory returns a new T
* instance by copy-constructing the provided const T& t.
*
* Preconditions for tester.WithInitialValue(const T& t):
*
* - The const T& t object must be copy-constructible where T is the type
* being tested. For non-copy-constructible objects, use the method
* tester.WithFactory(...).
*/
template <typename T>
ExceptionSafetyTestBuilder<DefaultFactory<T>, Operation, Contracts...>
WithInitialValue(const T& t) const {
return WithFactory(DefaultFactory<T>(t));
}
/*
* Returns a new ExceptionSafetyTestBuilder with the provided T factory
* included. The existing factory will not be included in the newly-created
* tester instance. This method is intended for use with types lacking a copy
* constructor. Types that can be copy-constructed should instead use the
* method tester.WithInitialValue(...).
*/
template <typename NewFactory>
ExceptionSafetyTestBuilder<absl::decay_t<NewFactory>, Operation, Contracts...>
WithFactory(const NewFactory& new_factory) const {
return {new_factory, operation_, contracts_};
}
/*
* Returns a new ExceptionSafetyTestBuilder with the provided testable
* operation included. The existing operation will not be included in the
* newly created tester.
*/
template <typename NewOperation>
ExceptionSafetyTestBuilder<Factory, absl::decay_t<NewOperation>, Contracts...>
WithOperation(const NewOperation& new_operation) const {
return {factory_, new_operation, contracts_};
}
/*
* Returns a new ExceptionSafetyTestBuilder with the provided MoreContracts...
* combined with the Contracts... that were already included in the instance
* on which the method was called. Contracts... cannot be removed or replaced
* once added to an ExceptionSafetyTestBuilder instance. A fresh object must
* be created in order to get an empty Contracts... list.
*
* In addition to passing in custom contract assertion callbacks, this method
* accepts `testing::strong_guarantee` as an argument which checks T instances
* post-throw against freshly created T instances via operator== to verify
* that any state changes made during the execution of the operation were
* properly rolled back.
*/
template <typename... MoreContracts>
ExceptionSafetyTestBuilder<Factory, Operation, Contracts...,
absl::decay_t<MoreContracts>...>
WithContracts(const MoreContracts&... more_contracts) const {
return {
factory_, operation_,
std::tuple_cat(contracts_, std::tuple<absl::decay_t<MoreContracts>...>(
more_contracts...))};
}
/*
* Returns a testing::AssertionResult that is the reduced result of the
* exception safety algorithm. The algorithm short circuits and returns
* AssertionFailure after the first contract callback returns an
* AssertionFailure. Otherwise, if all contract callbacks return an
* AssertionSuccess, the reduced result is AssertionSuccess.
*
* The passed-in testable operation will not be saved in a new tester instance
* nor will it modify/replace the existing tester instance. This is useful
* when each operation being tested is unique and does not need to be reused.
*
* Preconditions for tester.Test(const NewOperation& new_operation):
*
* - May only be called after at least one contract assertion callback and a
* factory or initial value have been provided.
*/
template <
typename NewOperation,
typename = EnableIfTestable<sizeof...(Contracts), Factory, NewOperation>>
testing::AssertionResult Test(const NewOperation& new_operation) const {
return TestImpl(new_operation, absl::index_sequence_for<Contracts...>());
}
/*
* Returns a testing::AssertionResult that is the reduced result of the
* exception safety algorithm. The algorithm short circuits and returns
* AssertionFailure after the first contract callback returns an
* AssertionFailure. Otherwise, if all contract callbacks return an
* AssertionSuccess, the reduced result is AssertionSuccess.
*
* Preconditions for tester.Test():
*
* - May only be called after at least one contract assertion callback, a
* factory or initial value and a testable operation have been provided.
*/
template <
typename LazyOperation = Operation,
typename = EnableIfTestable<sizeof...(Contracts), Factory, LazyOperation>>
testing::AssertionResult Test() const {
return Test(operation_);
}
private:
template <typename, typename, typename...>
friend class ExceptionSafetyTestBuilder;
friend ExceptionSafetyTestBuilder<> testing::MakeExceptionSafetyTester();
ExceptionSafetyTestBuilder() {}
ExceptionSafetyTestBuilder(const Factory& f, const Operation& o,
const std::tuple<Contracts...>& i)
: factory_(f), operation_(o), contracts_(i) {}
template <typename SelectedOperation, size_t... Indices>
testing::AssertionResult TestImpl(SelectedOperation selected_operation,
absl::index_sequence<Indices...>) const {
return ExceptionSafetyTest<FactoryElementType<Factory>>(
factory_, selected_operation, std::get<Indices>(contracts_)...)
.Test();
}
Factory factory_;
Operation operation_;
std::tuple<Contracts...> contracts_;
};
} // namespace exceptions_internal
} // namespace testing
#endif // ABSL_HAVE_EXCEPTIONS
#endif // ABSL_BASE_INTERNAL_EXCEPTION_SAFETY_TESTING_H_
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