maurice/snix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Export of internal Abseil changes

Browse source 
--
803abc2dcad8b2354c988e9bf58dac4a17683832 by Gennadiy Rozental <rogeeff@google.com>:

Avoid warning when RTTI is not enabled.

PiperOrigin-RevId: 294247546

--
5a7b0b4d07d1d6e56fbb0b0ffbf4f8fcab772dbf by Derek Mauro <dmauro@google.com>:

Add a public Abseil FAQ

PiperOrigin-RevId: 294226960

--
6945c4a6df7d7679711fea31aacf4fba6ac7baa1 by Gennadiy Rozental <rogeeff@google.com>:

Re-enable type mismatch check, which works in all the cases including shared libraries.

We will use RTTI in case when our hand written approximation of it reports a type mismatch. This way we can ensure that if a flag is defined in one shared object and referenced in another we do not report spurious errors.

PiperOrigin-RevId: 293905563
GitOrigin-RevId: 803abc2dcad8b2354c988e9bf58dac4a17683832
Change-Id: I1a23776d227ed2734c2e7183323786b7a95c3cc7
This commit is contained in:
Abseil Team 2020-02-10 10:18:03 -08:00 • committed by Mark Barolak
parent d95d156716
commit bf78e97730
9 changed files with 229 additions and 71 deletions
Download patch file Download diff file Expand all files Collapse all files

48
absl/flags/internal/flag.h
View file

@ -301,41 +301,44 @@ class FlagImpl {
bool IsSpecifiedOnCommandLine() const ABSL_LOCKS_EXCLUDED(*DataGuard());
std::string DefaultValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
std::string CurrentValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
void Read(void* dst, const FlagOpFn dst_op) const
ABSL_LOCKS_EXCLUDED(*DataGuard());
void Read(void* dst) const ABSL_LOCKS_EXCLUDED(*DataGuard());
// Attempts to parse supplied `value` std::string. If parsing is successful, then
// it replaces `dst` with the new value.
bool TryParse(void** dst, absl::string_view value, std::string* err) const
ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
#ifndef NDEBUG
template <typename T>
void Get(T* dst) const {
Read(dst, &FlagOps<T>);
}
#else
template <typename T, typename std::enable_if<
!IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
void Get(T* dst) const {
Read(dst, &FlagOps<T>);
AssertValidType(&flags_internal::FlagOps<T>);
Read(dst);
}
// Overload for `GetFlag()` for types that support lock-free reads.
template <typename T, typename std::enable_if<IsAtomicFlagTypeTrait<T>::value,
int>::type = 0>
void Get(T* dst) const {
using U = BestAtomicType<T>;
const typename U::type r = value_.atomics.template load<T>();
// For flags of types which can be accessed "atomically" we want to avoid
// slowing down flag value access due to type validation. That's why
// this validation is hidden behind !NDEBUG
#ifndef NDEBUG
AssertValidType(&flags_internal::FlagOps<T>);
#endif
using U = flags_internal::BestAtomicType<T>;
typename U::type r = value_.atomics.template load<T>();
if (r != U::AtomicInit()) {
std::memcpy(static_cast<void*>(dst), &r, sizeof(T));
} else {
Read(dst, &FlagOps<T>);
Read(dst);
}
}
#endif
template <typename T>
void Set(const T& src) {
AssertValidType(&flags_internal::FlagOps<T>);
Write(&src);
}
// Mutating access methods
void Write(const void* src, const FlagOpFn src_op)
ABSL_LOCKS_EXCLUDED(*DataGuard());
void Write(const void* src) ABSL_LOCKS_EXCLUDED(*DataGuard());
bool SetFromString(absl::string_view value, FlagSettingMode set_mode,
ValueSource source, std::string* err)
ABSL_LOCKS_EXCLUDED(*DataGuard());
@ -383,6 +386,13 @@ class FlagImpl {
ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()) {
return static_cast<FlagDefaultKind>(def_kind_);
}
// Used in read/write operations to validate source/target has correct type.
// For example if flag is declared as absl::Flag<int> FLAGS_foo, a call to
// absl::GetFlag(FLAGS_foo) validates that the type of FLAGS_foo is indeed
// int. To do that we pass the "assumed" type id (which is deduced from type
// int) as an argument `op`, which is in turn is validated against the type id
// stored in flag object by flag definition statement.
void AssertValidType(const flags_internal::FlagOpFn op) const;
// Immutable flag's state.
@ -461,9 +471,7 @@ class Flag final : public flags_internal::CommandLineFlag {
impl_.Get(&u.value);
return std::move(u.value);
}
void Set(const T& v) { impl_.Write(&v, &FlagOps<T>); }
void Set(const T& v) { impl_.Set(v); }
void SetCallback(const FlagCallbackFunc mutation_callback) {
impl_.SetCallback(mutation_callback);
}
@ -509,10 +517,10 @@ class Flag final : public flags_internal::CommandLineFlag {
void Destroy() override { impl_.Destroy(); }
void Read(void* dst) const override { impl_.Read(dst, &FlagOps<T>); }
void Read(void* dst) const override { impl_.Read(dst); }
FlagOpFn TypeId() const override { return &FlagOps<T>; }
// Flag's implementation with value type abstracted out.
// Flag's data
FlagImpl impl_;
};