diff options
Diffstat (limited to 'third_party/abseil-cpp/absl/flags/flag.h')
| -rw-r--r-- | third_party/abseil-cpp/absl/flags/flag.h | 242 |
1 files changed, 84 insertions, 158 deletions
diff --git a/third_party/abseil-cpp/absl/flags/flag.h b/third_party/abseil-cpp/absl/flags/flag.h index cff02c1fcb..a724ccc97d 100644 --- a/third_party/abseil-cpp/absl/flags/flag.h +++ b/third_party/abseil-cpp/absl/flags/flag.h @@ -33,14 +33,12 @@ #include <type_traits> #include "absl/base/attributes.h" -#include "absl/base/casts.h" #include "absl/base/config.h" +#include "absl/base/optimization.h" #include "absl/flags/config.h" -#include "absl/flags/declare.h" -#include "absl/flags/internal/commandlineflag.h" #include "absl/flags/internal/flag.h" #include "absl/flags/internal/registry.h" -#include "absl/flags/marshalling.h" +#include "absl/strings/string_view.h" namespace absl { ABSL_NAMESPACE_BEGIN @@ -73,98 +71,7 @@ ABSL_NAMESPACE_BEGIN template <typename T> using Flag = flags_internal::Flag<T>; #else -// MSVC debug builds do not implement initialization with constexpr constructors -// correctly. To work around this we add a level of indirection, so that the -// class `absl::Flag` contains an `internal::Flag*` (instead of being an alias -// to that class) and dynamically allocates an instance when necessary. We also -// forward all calls to internal::Flag methods via trampoline methods. In this -// setup the `absl::Flag` class does not have constructor and virtual methods, -// all the data members are public and thus MSVC is able to initialize it at -// link time. To deal with multiple threads accessing the flag for the first -// time concurrently we use an atomic boolean indicating if flag object is -// initialized. We also employ the double-checked locking pattern where the -// second level of protection is a global Mutex, so if two threads attempt to -// construct the flag concurrently only one wins. -// This solution is based on a recomendation here: -// https://developercommunity.visualstudio.com/content/problem/336946/class-with-constexpr-constructor-not-using-static.html?childToView=648454#comment-648454 - -namespace flags_internal { -absl::Mutex* GetGlobalConstructionGuard(); -} // namespace flags_internal - -template <typename T> -class Flag { - public: - // No constructor and destructor to ensure this is an aggregate type. - // Visual Studio 2015 still requires the constructor for class to be - // constexpr initializable. -#if _MSC_VER <= 1900 - constexpr Flag(const char* name, const char* filename, - const flags_internal::HelpGenFunc help_gen, - const flags_internal::FlagDfltGenFunc default_value_gen) - : name_(name), - filename_(filename), - help_gen_(help_gen), - default_value_gen_(default_value_gen), - inited_(false), - impl_(nullptr) {} -#endif - - flags_internal::Flag<T>* GetImpl() const { - if (!inited_.load(std::memory_order_acquire)) { - absl::MutexLock l(flags_internal::GetGlobalConstructionGuard()); - - if (inited_.load(std::memory_order_acquire)) { - return impl_; - } - - impl_ = - new flags_internal::Flag<T>(name_, filename_, - {flags_internal::FlagHelpMsg(help_gen_), - flags_internal::FlagHelpKind::kGenFunc}, - default_value_gen_); - inited_.store(true, std::memory_order_release); - } - - return impl_; - } - - // Public methods of `absl::Flag<T>` are NOT part of the Abseil Flags API. - // See https://abseil.io/docs/cpp/guides/flags - bool IsRetired() const { return GetImpl()->IsRetired(); } - bool IsAbseilFlag() const { return GetImpl()->IsAbseilFlag(); } - absl::string_view Name() const { return GetImpl()->Name(); } - std::string Help() const { return GetImpl()->Help(); } - bool IsModified() const { return GetImpl()->IsModified(); } - bool IsSpecifiedOnCommandLine() const { - return GetImpl()->IsSpecifiedOnCommandLine(); - } - absl::string_view Typename() const { return GetImpl()->Typename(); } - std::string Filename() const { return GetImpl()->Filename(); } - std::string DefaultValue() const { return GetImpl()->DefaultValue(); } - std::string CurrentValue() const { return GetImpl()->CurrentValue(); } - template <typename U> - inline bool IsOfType() const { - return GetImpl()->template IsOfType<U>(); - } - T Get() const { return GetImpl()->Get(); } - bool AtomicGet(T* v) const { return GetImpl()->AtomicGet(v); } - void Set(const T& v) { GetImpl()->Set(v); } - void SetCallback(const flags_internal::FlagCallbackFunc mutation_callback) { - GetImpl()->SetCallback(mutation_callback); - } - void InvokeCallback() { GetImpl()->InvokeCallback(); } - - // The data members are logically private, but they need to be public for - // this to be an aggregate type. - const char* name_; - const char* filename_; - const flags_internal::HelpGenFunc help_gen_; - const flags_internal::FlagDfltGenFunc default_value_gen_; - - mutable std::atomic<bool> inited_; - mutable flags_internal::Flag<T>* impl_; -}; +#include "absl/flags/internal/flag_msvc.inc" #endif // GetFlag() @@ -185,7 +92,7 @@ class Flag { // std::string first_name = absl::GetFlag(FLAGS_firstname); template <typename T> ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) { - return flag.Get(); + return flags_internal::FlagImplPeer::InvokeGet<T>(flag); } // SetFlag() @@ -197,7 +104,7 @@ ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag<T>& flag) { // but especially within performance-critical code. template <typename T> void SetFlag(absl::Flag<T>* flag, const T& v) { - flag->Set(v); + flags_internal::FlagImplPeer::InvokeSet(*flag, v); } // Overload of `SetFlag()` to allow callers to pass in a value that is @@ -206,7 +113,22 @@ void SetFlag(absl::Flag<T>* flag, const T& v) { template <typename T, typename V> void SetFlag(absl::Flag<T>* flag, const V& v) { T value(v); - flag->Set(value); + flags_internal::FlagImplPeer::InvokeSet(*flag, value); +} + +// GetFlagReflectionHandle() +// +// Returns the reflection handle corresponding to specified Abseil Flag +// instance. Use this handle to access flag's reflection information, like name, +// location, default value etc. +// +// Example: +// +// std::string = absl::GetFlagReflectionHandle(FLAGS_count).DefaultValue(); + +template <typename T> +const CommandLineFlag& GetFlagReflectionHandle(const absl::Flag<T>& f) { + return flags_internal::FlagImplPeer::InvokeReflect(f); } ABSL_NAMESPACE_END @@ -249,6 +171,8 @@ ABSL_NAMESPACE_END // // ABSL_FLAG(T, name, default_value, help).OnUpdate(callback); // +// `callback` should be convertible to `void (*)()`. +// // After any setting of the flag value, the callback will be called at least // once. A rapid sequence of changes may be merged together into the same // callback. No concurrent calls to the callback will be made for the same @@ -263,33 +187,36 @@ ABSL_NAMESPACE_END // Note: ABSL_FLAG.OnUpdate() does not have a public definition. Hence, this // comment serves as its API documentation. - // ----------------------------------------------------------------------------- // Implementation details below this section // ----------------------------------------------------------------------------- // ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_NAMES +#if !defined(_MSC_VER) || defined(__clang__) +#define ABSL_FLAG_IMPL_FLAG_PTR(flag) flag +#define ABSL_FLAG_IMPL_HELP_ARG(name) \ + absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>( \ + FLAGS_help_storage_##name) +#define ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name) \ + absl::flags_internal::DefaultArg<Type, AbslFlagDefaultGenFor##name>(0) +#else +#define ABSL_FLAG_IMPL_FLAG_PTR(flag) flag.GetImpl() +#define ABSL_FLAG_IMPL_HELP_ARG(name) &AbslFlagHelpGenFor##name::NonConst +#define ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name) &AbslFlagDefaultGenFor##name::Gen +#endif #if ABSL_FLAGS_STRIP_NAMES #define ABSL_FLAG_IMPL_FLAGNAME(txt) "" #define ABSL_FLAG_IMPL_FILENAME() "" -#if !defined(_MSC_VER) || defined(__clang__) -#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ - absl::flags_internal::FlagRegistrar<T, false>(&flag) -#else -#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ - absl::flags_internal::FlagRegistrar<T, false>(flag.GetImpl()) -#endif +#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ + absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \ + nullptr) #else #define ABSL_FLAG_IMPL_FLAGNAME(txt) txt #define ABSL_FLAG_IMPL_FILENAME() __FILE__ -#if !defined(_MSC_VER) || defined(__clang__) -#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ - absl::flags_internal::FlagRegistrar<T, true>(&flag) -#else -#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ - absl::flags_internal::FlagRegistrar<T, true>(flag.GetImpl()) -#endif +#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ + absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \ + __FILE__) #endif // ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_HELP @@ -305,50 +232,48 @@ ABSL_NAMESPACE_END // between the two via the call to HelpArg in absl::Flag instantiation below. // If help message expression is constexpr evaluable compiler will optimize // away this whole struct. -#define ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, txt) \ - struct AbslFlagHelpGenFor##name { \ - template <typename T = void> \ - static constexpr const char* Const() { \ - return absl::flags_internal::HelpConstexprWrap( \ - ABSL_FLAG_IMPL_FLAGHELP(txt)); \ - } \ - static std::string NonConst() { return ABSL_FLAG_IMPL_FLAGHELP(txt); } \ - } - -#define ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - static void* AbslFlagsInitFlag##name() { \ - return absl::flags_internal::MakeFromDefaultValue<Type>(default_value); \ - } +// TODO(rogeeff): place these generated structs into local namespace and apply +// ABSL_INTERNAL_UNIQUE_SHORT_NAME. +// TODO(rogeeff): Apply __attribute__((nodebug)) to FLAGS_help_storage_##name +#define ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, txt) \ + struct AbslFlagHelpGenFor##name { \ + /* The expression is run in the caller as part of the */ \ + /* default value argument. That keeps temporaries alive */ \ + /* long enough for NonConst to work correctly. */ \ + static constexpr absl::string_view Value( \ + absl::string_view absl_flag_help = ABSL_FLAG_IMPL_FLAGHELP(txt)) { \ + return absl_flag_help; \ + } \ + static std::string NonConst() { return std::string(Value()); } \ + }; \ + constexpr auto FLAGS_help_storage_##name ABSL_INTERNAL_UNIQUE_SMALL_NAME() \ + ABSL_ATTRIBUTE_SECTION_VARIABLE(flags_help_cold) = \ + absl::flags_internal::HelpStringAsArray<AbslFlagHelpGenFor##name>( \ + 0); + +#define ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ + struct AbslFlagDefaultGenFor##name { \ + Type value = absl::flags_internal::InitDefaultValue<Type>(default_value); \ + static void Gen(void* absl_flag_default_loc) { \ + new (absl_flag_default_loc) Type(AbslFlagDefaultGenFor##name{}.value); \ + } \ + }; // ABSL_FLAG_IMPL // // Note: Name of registrar object is not arbitrary. It is used to "grab" // global name for FLAGS_no<flag_name> symbol, thus preventing the possibility // of defining two flags with names foo and nofoo. -#if !defined(_MSC_VER) || defined(__clang__) -#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ - namespace absl /* block flags in namespaces */ {} \ - ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help); \ - ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{ \ - ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(), \ - absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>(0), \ - &AbslFlagsInitFlag##name}; \ - extern bool FLAGS_no##name; \ - bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) -#else -// MSVC version uses aggregate initialization. We also do not try to -// optimize away help wrapper. -#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ - namespace absl /* block flags in namespaces */ {} \ - ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help); \ - ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{ \ - ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(), \ - &AbslFlagHelpGenFor##name::NonConst, &AbslFlagsInitFlag##name}; \ - extern bool FLAGS_no##name; \ - bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) -#endif +#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ + namespace absl /* block flags in namespaces */ {} \ + ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ + ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \ + ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{ \ + ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(), \ + ABSL_FLAG_IMPL_HELP_ARG(name), ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name)}; \ + extern absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name; \ + absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name = \ + ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) // ABSL_RETIRED_FLAG // @@ -369,11 +294,12 @@ ABSL_NAMESPACE_END // // `default_value` is only used as a double check on the type. `explanation` is // unused. -// TODO(rogeeff): Return an anonymous struct instead of bool, and place it into -// the unnamed namespace. -#define ABSL_RETIRED_FLAG(type, flagname, default_value, explanation) \ - ABSL_ATTRIBUTE_UNUSED static const bool ignored_##flagname = \ - ([] { return type(default_value); }, \ - absl::flags_internal::RetiredFlag<type>(#flagname)) +// TODO(rogeeff): replace RETIRED_FLAGS with FLAGS once forward declarations of +// retired flags are cleaned up. +#define ABSL_RETIRED_FLAG(type, name, default_value, explanation) \ + static absl::flags_internal::RetiredFlag<type> RETIRED_FLAGS_##name; \ + ABSL_ATTRIBUTE_UNUSED static const auto RETIRED_FLAGS_REG_##name = \ + (RETIRED_FLAGS_##name.Retire(#name), \ + ::absl::flags_internal::FlagRegistrarEmpty{}) #endif // ABSL_FLAGS_FLAG_H_ |