diff options
Diffstat (limited to 'absl/flags/internal/flag.h')
| -rw-r--r-- | absl/flags/internal/flag.h | 628 |
1 files changed, 588 insertions, 40 deletions
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h index 9a5d9b4b..35a148cf 100644 --- a/absl/flags/internal/flag.h +++ b/absl/flags/internal/flag.h @@ -16,45 +16,547 @@ #ifndef ABSL_FLAGS_INTERNAL_FLAG_H_ #define ABSL_FLAGS_INTERNAL_FLAG_H_ +#include <stdint.h> + +#include <atomic> +#include <cstring> +#include <memory> +#include <string> +#include <type_traits> + +#include "absl/base/call_once.h" +#include "absl/base/config.h" +#include "absl/base/thread_annotations.h" +#include "absl/flags/config.h" #include "absl/flags/internal/commandlineflag.h" #include "absl/flags/internal/registry.h" +#include "absl/memory/memory.h" +#include "absl/strings/str_cat.h" +#include "absl/strings/string_view.h" +#include "absl/synchronization/mutex.h" namespace absl { -inline namespace lts_2019_08_08 { +ABSL_NAMESPACE_BEGIN namespace flags_internal { -// This is "unspecified" implementation of absl::Flag<T> type. template <typename T> -class Flag : public flags_internal::CommandLineFlag { +class Flag; + +/////////////////////////////////////////////////////////////////////////////// +// Flag value type operations, eg., parsing, copying, etc. are provided +// by function specific to that type with a signature matching FlagOpFn. + +enum class FlagOp { + kDelete, + kClone, + kCopy, + kCopyConstruct, + kSizeof, + kStaticTypeId, + kParse, + kUnparse, +}; +using FlagOpFn = void* (*)(FlagOp, const void*, void*, void*); + +// Flag value specific operations routine. +template <typename T> +void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) { + switch (op) { + case FlagOp::kDelete: + delete static_cast<const T*>(v1); + return nullptr; + case FlagOp::kClone: + return new T(*static_cast<const T*>(v1)); + case FlagOp::kCopy: + *static_cast<T*>(v2) = *static_cast<const T*>(v1); + return nullptr; + case FlagOp::kCopyConstruct: + new (v2) T(*static_cast<const T*>(v1)); + return nullptr; + case FlagOp::kSizeof: + return reinterpret_cast<void*>(sizeof(T)); + case FlagOp::kStaticTypeId: + return reinterpret_cast<void*>(&FlagStaticTypeIdGen<T>); + case FlagOp::kParse: { + // Initialize the temporary instance of type T based on current value in + // destination (which is going to be flag's default value). + T temp(*static_cast<T*>(v2)); + if (!absl::ParseFlag<T>(*static_cast<const absl::string_view*>(v1), &temp, + static_cast<std::string*>(v3))) { + return nullptr; + } + *static_cast<T*>(v2) = std::move(temp); + return v2; + } + case FlagOp::kUnparse: + *static_cast<std::string*>(v2) = + absl::UnparseFlag<T>(*static_cast<const T*>(v1)); + return nullptr; + default: + return nullptr; + } +} + +// Deletes memory interpreting obj as flag value type pointer. +inline void Delete(FlagOpFn op, const void* obj) { + op(FlagOp::kDelete, obj, nullptr, nullptr); +} +// Makes a copy of flag value pointed by obj. +inline void* Clone(FlagOpFn op, const void* obj) { + return op(FlagOp::kClone, obj, nullptr, nullptr); +} +// Copies src to dst interpreting as flag value type pointers. +inline void Copy(FlagOpFn op, const void* src, void* dst) { + op(FlagOp::kCopy, src, dst, nullptr); +} +// Construct a copy of flag value in a location pointed by dst +// based on src - pointer to the flag's value. +inline void CopyConstruct(FlagOpFn op, const void* src, void* dst) { + op(FlagOp::kCopyConstruct, src, dst, nullptr); +} +// Returns true if parsing of input text is successfull. +inline bool Parse(FlagOpFn op, absl::string_view text, void* dst, + std::string* error) { + return op(FlagOp::kParse, &text, dst, error) != nullptr; +} +// Returns string representing supplied value. +inline std::string Unparse(FlagOpFn op, const void* val) { + std::string result; + op(FlagOp::kUnparse, val, &result, nullptr); + return result; +} +// Returns size of flag value type. +inline size_t Sizeof(FlagOpFn op) { + // This sequence of casts reverses the sequence from + // `flags_internal::FlagOps()` + return static_cast<size_t>(reinterpret_cast<intptr_t>( + op(FlagOp::kSizeof, nullptr, nullptr, nullptr))); +} +// Returns static type id coresponding to the value type. +inline FlagStaticTypeId StaticTypeId(FlagOpFn op) { + return reinterpret_cast<FlagStaticTypeId>( + op(FlagOp::kStaticTypeId, nullptr, nullptr, nullptr)); +} + +/////////////////////////////////////////////////////////////////////////////// +// Persistent state of the flag data. + +template <typename T> +class FlagState : public flags_internal::FlagStateInterface { + public: + FlagState(Flag<T>* flag, T&& cur, bool modified, bool on_command_line, + int64_t counter) + : flag_(flag), + cur_value_(std::move(cur)), + modified_(modified), + on_command_line_(on_command_line), + counter_(counter) {} + + ~FlagState() override = default; + + private: + friend class Flag<T>; + + // Restores the flag to the saved state. + void Restore() const override; + + // Flag and saved flag data. + Flag<T>* flag_; + T cur_value_; + bool modified_; + bool on_command_line_; + int64_t counter_; +}; + +/////////////////////////////////////////////////////////////////////////////// +// Flag help auxiliary structs. + +// This is help argument for absl::Flag encapsulating the string literal pointer +// or pointer to function generating it as well as enum descriminating two +// cases. +using HelpGenFunc = std::string (*)(); + +union FlagHelpMsg { + constexpr explicit FlagHelpMsg(const char* help_msg) : literal(help_msg) {} + constexpr explicit FlagHelpMsg(HelpGenFunc help_gen) : gen_func(help_gen) {} + + const char* literal; + HelpGenFunc gen_func; +}; + +enum class FlagHelpKind : uint8_t { kLiteral = 0, kGenFunc = 1 }; + +struct FlagHelpArg { + FlagHelpMsg source; + FlagHelpKind kind; +}; + +extern const char kStrippedFlagHelp[]; + +// HelpConstexprWrap is used by struct AbslFlagHelpGenFor##name generated by +// ABSL_FLAG macro. It is only used to silence the compiler in the case where +// help message expression is not constexpr and does not have type const char*. +// If help message expression is indeed constexpr const char* HelpConstexprWrap +// is just a trivial identity function. +template <typename T> +const char* HelpConstexprWrap(const T&) { + return nullptr; +} +constexpr const char* HelpConstexprWrap(const char* p) { return p; } +constexpr const char* HelpConstexprWrap(char* p) { return p; } + +// These two HelpArg overloads allows us to select at compile time one of two +// way to pass Help argument to absl::Flag. We'll be passing +// AbslFlagHelpGenFor##name as T and integer 0 as a single argument to prefer +// first overload if possible. If T::Const is evaluatable on constexpr +// context (see non template int parameter below) we'll choose first overload. +// In this case the help message expression is immediately evaluated and is used +// to construct the absl::Flag. No additionl code is generated by ABSL_FLAG. +// Otherwise SFINAE kicks in and first overload is dropped from the +// consideration, in which case the second overload will be used. The second +// overload does not attempt to evaluate the help message expression +// immediately and instead delays the evaluation by returing the function +// pointer (&T::NonConst) genering the help message when necessary. This is +// evaluatable in constexpr context, but the cost is an extra function being +// generated in the ABSL_FLAG code. +template <typename T, int = (T::Const(), 1)> +constexpr FlagHelpArg HelpArg(int) { + return {FlagHelpMsg(T::Const()), FlagHelpKind::kLiteral}; +} + +template <typename T> +constexpr FlagHelpArg HelpArg(char) { + return {FlagHelpMsg(&T::NonConst), FlagHelpKind::kGenFunc}; +} + +/////////////////////////////////////////////////////////////////////////////// +// Flag default value auxiliary structs. + +// Signature for the function generating the initial flag value (usually +// based on default value supplied in flag's definition) +using FlagDfltGenFunc = void* (*)(); + +union FlagDefaultSrc { + constexpr explicit FlagDefaultSrc(FlagDfltGenFunc gen_func_arg) + : gen_func(gen_func_arg) {} + + void* dynamic_value; + FlagDfltGenFunc gen_func; +}; + +enum class FlagDefaultKind : uint8_t { kDynamicValue = 0, kGenFunc = 1 }; + +/////////////////////////////////////////////////////////////////////////////// +// Flag current value auxiliary structs. + +// The minimum atomic size we believe to generate lock free code, i.e. all +// trivially copyable types not bigger this size generate lock free code. +static constexpr int kMinLockFreeAtomicSize = 8; + +// The same as kMinLockFreeAtomicSize but maximum atomic size. As double words +// might use two registers, we want to dispatch the logic for them. +#if defined(ABSL_FLAGS_INTERNAL_ATOMIC_DOUBLE_WORD) +static constexpr int kMaxLockFreeAtomicSize = 16; +#else +static constexpr int kMaxLockFreeAtomicSize = 8; +#endif + +// We can use atomic in cases when it fits in the register, trivially copyable +// in order to make memcpy operations. +template <typename T> +struct IsAtomicFlagTypeTrait { + static constexpr bool value = + (sizeof(T) <= kMaxLockFreeAtomicSize && + type_traits_internal::is_trivially_copyable<T>::value); +}; + +// Clang does not always produce cmpxchg16b instruction when alignment of a 16 +// bytes type is not 16. +struct alignas(16) FlagsInternalTwoWordsType { + int64_t first; + int64_t second; +}; + +constexpr bool operator==(const FlagsInternalTwoWordsType& that, + const FlagsInternalTwoWordsType& other) { + return that.first == other.first && that.second == other.second; +} +constexpr bool operator!=(const FlagsInternalTwoWordsType& that, + const FlagsInternalTwoWordsType& other) { + return !(that == other); +} + +constexpr int64_t SmallAtomicInit() { return 0xababababababababll; } + +template <typename T, typename S = void> +struct BestAtomicType { + using type = int64_t; + static constexpr int64_t AtomicInit() { return SmallAtomicInit(); } +}; + +template <typename T> +struct BestAtomicType< + T, typename std::enable_if<(kMinLockFreeAtomicSize < sizeof(T) && + sizeof(T) <= kMaxLockFreeAtomicSize), + void>::type> { + using type = FlagsInternalTwoWordsType; + static constexpr FlagsInternalTwoWordsType AtomicInit() { + return {SmallAtomicInit(), SmallAtomicInit()}; + } +}; + +struct FlagValue { + // Heap allocated value. + void* dynamic = nullptr; + // For some types, a copy of the current value is kept in an atomically + // accessible field. + union Atomics { + // Using small atomic for small types. + std::atomic<int64_t> small_atomic; + template <typename T, + typename K = typename std::enable_if< + (sizeof(T) <= kMinLockFreeAtomicSize), void>::type> + int64_t load() const { + return small_atomic.load(std::memory_order_acquire); + } + +#if defined(ABSL_FLAGS_INTERNAL_ATOMIC_DOUBLE_WORD) + // Using big atomics for big types. + std::atomic<FlagsInternalTwoWordsType> big_atomic; + template <typename T, typename K = typename std::enable_if< + (kMinLockFreeAtomicSize < sizeof(T) && + sizeof(T) <= kMaxLockFreeAtomicSize), + void>::type> + FlagsInternalTwoWordsType load() const { + return big_atomic.load(std::memory_order_acquire); + } + constexpr Atomics() + : big_atomic{FlagsInternalTwoWordsType{SmallAtomicInit(), + SmallAtomicInit()}} {} +#else + constexpr Atomics() : small_atomic{SmallAtomicInit()} {} +#endif + }; + Atomics atomics{}; +}; + +/////////////////////////////////////////////////////////////////////////////// +// Flag callback auxiliary structs. + +// Signature for the mutation callback used by watched Flags +// The callback is noexcept. +// TODO(rogeeff): add noexcept after C++17 support is added. +using FlagCallbackFunc = void (*)(); + +struct FlagCallback { + FlagCallbackFunc func; + absl::Mutex guard; // Guard for concurrent callback invocations. +}; + +/////////////////////////////////////////////////////////////////////////////// +// Flag implementation, which does not depend on flag value type. +// The class encapsulates the Flag's data and access to it. + +struct DynValueDeleter { + explicit DynValueDeleter(FlagOpFn op_arg = nullptr) : op(op_arg) {} + void operator()(void* ptr) const { + if (op != nullptr) Delete(op, ptr); + } + + FlagOpFn op; +}; + +class FlagImpl { public: - constexpr Flag(const char* name, const flags_internal::HelpGenFunc help_gen, - const char* filename, - const flags_internal::FlagMarshallingOpFn marshalling_op_arg, - const flags_internal::InitialValGenFunc initial_value_gen) - : flags_internal::CommandLineFlag( - name, flags_internal::HelpText::FromFunctionPointer(help_gen), - filename, &flags_internal::FlagOps<T>, marshalling_op_arg, - initial_value_gen, - /*retired_arg=*/false, /*def_arg=*/nullptr, - /*cur_arg=*/nullptr) {} + constexpr FlagImpl(const char* name, const char* filename, FlagOpFn op, + FlagHelpArg help, FlagDfltGenFunc default_value_gen) + : name_(name), + filename_(filename), + op_(op), + help_(help.source), + help_source_kind_(static_cast<uint8_t>(help.kind)), + def_kind_(static_cast<uint8_t>(FlagDefaultKind::kGenFunc)), + modified_(false), + on_command_line_(false), + counter_(0), + callback_(nullptr), + default_value_(default_value_gen), + data_guard_{} {} + + // Constant access methods + absl::string_view Name() const; + std::string Filename() const; + std::string Help() const; + bool IsModified() const ABSL_LOCKS_EXCLUDED(*DataGuard()); + 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 ABSL_LOCKS_EXCLUDED(*DataGuard()); + + template <typename T, typename std::enable_if< + !IsAtomicFlagTypeTrait<T>::value, int>::type = 0> + void Get(T* dst) const { + AssertValidType(&flags_internal::FlagStaticTypeIdGen<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 { + // 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::FlagStaticTypeIdGen<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); + } + } + template <typename T> + void Set(const T& src) { + AssertValidType(&flags_internal::FlagStaticTypeIdGen<T>); + Write(&src); + } + + // Mutating access methods + 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()); + // If possible, updates copy of the Flag's value that is stored in an + // atomic word. + void StoreAtomic() ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()); + + // Interfaces to operate on callbacks. + void SetCallback(const FlagCallbackFunc mutation_callback) + ABSL_LOCKS_EXCLUDED(*DataGuard()); + void InvokeCallback() const ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()); + + // Interfaces to save/restore mutable flag data + template <typename T> + std::unique_ptr<FlagStateInterface> SaveState(Flag<T>* flag) const + ABSL_LOCKS_EXCLUDED(*DataGuard()) { + T&& cur_value = flag->Get(); + absl::MutexLock l(DataGuard()); + + return absl::make_unique<FlagState<T>>( + flag, std::move(cur_value), modified_, on_command_line_, counter_); + } + bool RestoreState(const void* value, bool modified, bool on_command_line, + int64_t counter) ABSL_LOCKS_EXCLUDED(*DataGuard()); + + // Value validation interfaces. + void CheckDefaultValueParsingRoundtrip() const + ABSL_LOCKS_EXCLUDED(*DataGuard()); + bool ValidateInputValue(absl::string_view value) const + ABSL_LOCKS_EXCLUDED(*DataGuard()); + + private: + // Ensures that `data_guard_` is initialized and returns it. + absl::Mutex* DataGuard() const ABSL_LOCK_RETURNED((absl::Mutex*)&data_guard_); + // Returns heap allocated value of type T initialized with default value. + std::unique_ptr<void, DynValueDeleter> MakeInitValue() const + ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()); + // Flag initialization called via absl::call_once. + void Init(); + // Attempts to parse supplied `value` std::string. If parsing is successful, + // returns new value. Otherwise returns nullptr. + std::unique_ptr<void, DynValueDeleter> TryParse(absl::string_view value, + std::string* err) const + ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()); + // Stores the flag value based on the pointer to the source. + void StoreValue(const void* src) ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard()); + + FlagHelpKind HelpSourceKind() const { + return static_cast<FlagHelpKind>(help_source_kind_); + } + FlagDefaultKind DefaultKind() const + 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(FlagStaticTypeId type_id) const; + + // Immutable flag's state. + + // Flags name passed to ABSL_FLAG as second arg. + const char* const name_; + // The file name where ABSL_FLAG resides. + const char* const filename_; + // Type-specific operations "vtable". + const FlagOpFn op_; + // Help message literal or function to generate it. + const FlagHelpMsg help_; + // Indicates if help message was supplied as literal or generator func. + const uint8_t help_source_kind_ : 1; + + // ------------------------------------------------------------------------ + // The bytes containing the const bitfields must not be shared with bytes + // containing the mutable bitfields. + // ------------------------------------------------------------------------ + + // Unique tag for absl::call_once call to initialize this flag. + // + // The placement of this variable between the immutable and mutable bitfields + // is important as prevents them from occupying the same byte. If you remove + // this variable, make sure to maintain this property. + absl::once_flag init_control_; + + // Mutable flag's state (guarded by `data_guard_`). + + // If def_kind_ == kDynamicValue, default_value_ holds a dynamically allocated + // value. + uint8_t def_kind_ : 1 ABSL_GUARDED_BY(*DataGuard()); + // Has this flag's value been modified? + bool modified_ : 1 ABSL_GUARDED_BY(*DataGuard()); + // Has this flag been specified on command line. + bool on_command_line_ : 1 ABSL_GUARDED_BY(*DataGuard()); + + // Mutation counter + int64_t counter_ ABSL_GUARDED_BY(*DataGuard()); + // Optional flag's callback and absl::Mutex to guard the invocations. + FlagCallback* callback_ ABSL_GUARDED_BY(*DataGuard()); + // Either a pointer to the function generating the default value based on the + // value specified in ABSL_FLAG or pointer to the dynamically set default + // value via SetCommandLineOptionWithMode. def_kind_ is used to distinguish + // these two cases. + FlagDefaultSrc default_value_ ABSL_GUARDED_BY(*DataGuard()); + // Current Flag Value + FlagValue value_; + + // This is reserved space for an absl::Mutex to guard flag data. It will be + // initialized in FlagImpl::Init via placement new. + // We can't use "absl::Mutex data_guard_", since this class is not literal. + // We do not want to use "absl::Mutex* data_guard_", since this would require + // heap allocation during initialization, which is both slows program startup + // and can fail. Using reserved space + placement new allows us to avoid both + // problems. + alignas(absl::Mutex) mutable char data_guard_[sizeof(absl::Mutex)]; +}; + +/////////////////////////////////////////////////////////////////////////////// +// The Flag object parameterized by the flag's value type. This class implements +// flag reflection handle interface. + +template <typename T> +class Flag final : public flags_internal::CommandLineFlag { + public: + constexpr Flag(const char* name, const char* filename, const FlagHelpArg help, + const FlagDfltGenFunc default_value_gen) + : impl_(name, filename, &FlagOps<T>, help, default_value_gen) {} T Get() const { - // Implementation notes: - // - // We are wrapping a union around the value of `T` to serve three purposes: - // - // 1. `U.value` has correct size and alignment for a value of type `T` - // 2. The `U.value` constructor is not invoked since U's constructor does - // not - // do it explicitly. - // 3. The `U.value` destructor is invoked since U's destructor does it - // explicitly. This makes `U` a kind of RAII wrapper around non default - // constructible value of T, which is destructed when we leave the - // scope. We do need to destroy U.value, which is constructed by - // CommandLineFlag::Read even though we left it in a moved-from state - // after std::move. - // - // All of this serves to avoid requiring `T` being default constructible. + // See implementation notes in CommandLineFlag::Get(). union U { T value; U() {} @@ -62,23 +564,69 @@ class Flag : public flags_internal::CommandLineFlag { }; U u; - this->Read(&u.value, &flags_internal::FlagOps<T>); + impl_.Get(&u.value); return std::move(u.value); } + void Set(const T& v) { impl_.Set(v); } + void SetCallback(const FlagCallbackFunc mutation_callback) { + impl_.SetCallback(mutation_callback); + } - bool AtomicGet(T* v) const { - const int64_t r = this->atomic.load(std::memory_order_acquire); - if (r != flags_internal::CommandLineFlag::kAtomicInit) { - memcpy(v, &r, sizeof(T)); - return true; - } + // CommandLineFlag interface + absl::string_view Name() const override { return impl_.Name(); } + std::string Filename() const override { return impl_.Filename(); } + absl::string_view Typename() const override { return ""; } + std::string Help() const override { return impl_.Help(); } + bool IsModified() const override { return impl_.IsModified(); } + bool IsSpecifiedOnCommandLine() const override { + return impl_.IsSpecifiedOnCommandLine(); + } + std::string DefaultValue() const override { return impl_.DefaultValue(); } + std::string CurrentValue() const override { return impl_.CurrentValue(); } + bool ValidateInputValue(absl::string_view value) const override { + return impl_.ValidateInputValue(value); + } + + // Interfaces to save and restore flags to/from persistent state. + // Returns current flag state or nullptr if flag does not support + // saving and restoring a state. + std::unique_ptr<FlagStateInterface> SaveState() override { + return impl_.SaveState(this); + } - return false; + // Restores the flag state to the supplied state object. If there is + // nothing to restore returns false. Otherwise returns true. + bool RestoreState(const FlagState<T>& flag_state) { + return impl_.RestoreState(&flag_state.cur_value_, flag_state.modified_, + flag_state.on_command_line_, flag_state.counter_); + } + bool SetFromString(absl::string_view value, FlagSettingMode set_mode, + ValueSource source, std::string* error) override { + return impl_.SetFromString(value, set_mode, source, error); } + void CheckDefaultValueParsingRoundtrip() const override { + impl_.CheckDefaultValueParsingRoundtrip(); + } + + private: + friend class FlagState<T>; + + void Read(void* dst) const override { impl_.Read(dst); } + FlagStaticTypeId TypeId() const override { return &FlagStaticTypeIdGen<T>; } - void Set(const T& v) { this->Write(&v, &flags_internal::FlagOps<T>); } + // Flag's data + FlagImpl impl_; }; +template <typename T> +inline void FlagState<T>::Restore() const { + if (flag_->RestoreState(*this)) { + ABSL_INTERNAL_LOG(INFO, + absl::StrCat("Restore saved value of ", flag_->Name(), + " to: ", flag_->CurrentValue())); + } +} + // This class facilitates Flag object registration and tail expression-based // flag definition, for example: // ABSL_FLAG(int, foo, 42, "Foo help").OnUpdate(NotifyFooWatcher); @@ -89,7 +637,7 @@ class FlagRegistrar { if (do_register) flags_internal::RegisterCommandLineFlag(flag_); } - FlagRegistrar& OnUpdate(flags_internal::FlagCallback cb) && { + FlagRegistrar& OnUpdate(FlagCallbackFunc cb) && { flag_->SetCallback(cb); return *this; } @@ -117,7 +665,7 @@ T* MakeFromDefaultValue(EmptyBraces) { } } // namespace flags_internal -} // inline namespace lts_2019_08_08 +ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_FLAGS_INTERNAL_FLAG_H_ |