From b832dce8489ef7b6231384909fd9b68d5a5ff2b7 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Tue, 25 Feb 2020 22:27:31 +0100 Subject: Creation of LTS branch "lts_2020_02_25" - 0033c9ea91a52ade7c6b725aa2ef3cbe15463421 Fix build on FreeBSD/powerpc (#616) by kgotlinux <60880393+kgotlinux@users.noreply.github.com> - 0d5ce2797eb695aee7e019e25323251ef6ffc277 Export of internal Abseil changes by Abseil Team - b69c7d880caddfc25bf348dbcfe9d45fdd8bc6e6 Export of internal Abseil changes by Abseil Team - 2a5633fc077a58528cdbfe78720f3f6bfdc6044d Merge "Export of internal Abseil changes" by Xiaoyi Zhang - f9b3d6e493c1b6ab3dbdab71c5f8fa849db4abaf Add RISCV support to GetProgramCounter() (#621) by Khem Raj - 0232c87f21c26718aa3eb2d86678070f3b498a4e Add missing ABSL_HAVE_VDSO_SUPPORT conditional (#622) by Sinan Kaya <41809318+franksinankaya@users.noreply.github.com> - 3c814105108680997d0821077694f663693b5382 Export of internal Abseil changes by Abseil Team - c44657f55692eddf5504156645d1f4ec7b3acabd Export of internal Abseil changes by Abseil Team - 98eb410c93ad059f9bba1bf43f5bb916fc92a5ea Export of internal Abseil changes by Abseil Team - bf78e977309c4cb946914b456404141ddac1c302 Export of internal Abseil changes by Abseil Team - d95d1567165d449e4c213ea31a15cbb112a9865f Export of internal Abseil changes by Abseil Team - 24713a7036a81498334807fa5c7ad3cb7c643711 Export of internal Abseil changes by Abseil Team - 72382c21fefed981b4b8a2a1b82e2d231c2c2e39 Export of internal Abseil changes by Abseil Team - 08a7e7bf972c8451855a5022f2faf3d3655db015 Export of internal Abseil changes by Abseil Team - 36bcd9599b3f48c99357ba61cf33584889306d6a Fix pointer format specifier in documentation (#614) by Andre Nguyen - 0f86336b6939ea673cc1cbe29189286cae67d63a Export of internal Abseil changes by Abseil Team - c512f118dde6ffd51cb7d8ac8804bbaf4d266c3a Export of internal Abseil changes by Abseil Team - 37dd2562ec830d547a1524bb306be313ac3f2556 Export of internal Abseil changes by Abseil Team - 44427702614d7b86b064ba06a390f5eb2f85dbf6 fix: Add support for more ARM processors detection (#608) by Andre Nguyen - 159bf2bf6d1cc8087e02468d071e94d1177d1bae Export of internal Abseil changes by Abseil Team - a2e6adecc294dc4cd98cc285a9134ce58e0f2ad0 Use https links. (#586) by nlewycky - 564001ae506a17c51fa1223684a78f05f91d3d91 Export of internal Abseil changes by Abseil Team - b3aaac8a37c467a1125c794196caa90d0957bdc3 Export of internal Abseil changes by Abseil Team - 63ee2f8877915a3565c29707dba8fe4d7822596a Export of internal Abseil changes by Abseil Team - a048203a881f11f4b7b8df5fb563aec85522f8db Export of internal Abseil changes by Abseil Team - 1de0166368e2ae67347f92099d6dca3ab3a4a496 Export of internal Abseil changes by Abseil Team - ad904b6cd3906ddf79878003d92b7bc08d7786ae Export of internal Abseil changes by Abseil Team - 29235139149790f5afc430c11cec8f1eb1677607 Export of internal Abseil changes by Abseil Team - bf86cfe165ef7d70dfe68f0b8fc0c018bc79a577 Export of internal Abseil changes by Abseil Team - 12bc53e0318d80569270a5b26ccbc62b52022b89 Export of internal Abseil changes by Abseil Team - 1e39f8626a4dadec1f56920b999dd4c3cfae333e Export of internal Abseil changes by Abseil Team - 77f87009a34c745255bd84d8f2647040d831a2b3 Export of internal Abseil changes by Abseil Team - d659fe54b35ab9b8e35c72e50a4b8814167d5a84 Export of internal Abseil changes by Abseil Team - a4b757b5d42694306a9de853cee0a5fba9c7bbe9 Export of internal Abseil changes by Abseil Team - 0514227d2547793b23e209809276375e41c76617 Export of internal Abseil changes by Abseil Team - 7f4fe64af80fe3c84db8ea938276c3690573c45e Export of internal Abseil changes by Abseil Team - 16d9fd58a51c6083234e2e9f8f50e49ed5ed02e4 Export of internal Abseil changes by Abseil Team - bcaae6009c0833b73c6fa7bdd972921d8081a724 Export of internal Abseil changes by Abseil Team - 8ba96a8244bbe334d09542e92d566673a65c1f78 Export of internal Abseil changes by Abseil Team - 2103fd9acdf58279f739860bff3f8c9f4b845605 Export of internal Abseil changes by Abseil Team - 3df7b52a6ada51a72a23796b844549a7b282f1b8 Export of internal Abseil changes by Abseil Team - fa8c75182fbfdeddb2485fc0d53baeda3f40b7a3 Export of internal Abseil changes by Abseil Team - 85092b4b648ca729c6263c4a302a41dfff28705e Fix Conan builds (#400) by Adrian Ostrowski - e96ae2203b80d5ae2e0b7abe0c77b722b224b16d Export of internal Abseil changes by Abseil Team - 20de2db748ca0471cfb61cb53e813dd12938c12b Export of internal Abseil changes by Abseil Team - 846e5dbedac123d12455adcfe6f53c8b5dcbfeef Export of internal Abseil changes by Abseil Team - 8207907f4f7fbaeeaa2b7340c76875e06fd345ba Export of internal Abseil changes by Abseil Team - 078b89b3c046d230ef3ad39494e5852184eb528b Export of internal Abseil changes by Abseil Team - 19b021cb3ff23048dfbe236a4e611925d8930831 Export of internal Abseil changes by Abseil Team - ecc0033b54847f6c9ee37dbb0be8aa17e5b6d37b Always enable proper symbolize implementation on Windows ... by Loo Rong Jie - 2796d500aea5a31d26b8b24a33fab7a1c8fa2f32 Export of internal Abseil changes by Abseil Team - e4c8d0eb8ef4acb5d7a4252b3b87feb391ef7e41 Export of internal Abseil changes by Abseil Team - a15364ce4d88534ae2295127e5d8e32aefb6b446 Export of internal Abseil changes by Abseil Team - ab3552a18964e7063c8324f45b3896a6a20b08a8 Export of internal Abseil changes by Abseil Team - e9f9000c7c80993cb589d011616b7a8016e42f4a Fix ABSL_WAITER_MODE detection for mingw (#342) by Joe Sylve - abea769b551f7a100f540967cb95debdb0080df8 Fix ABSL_HAVE_ALARM check on mingw (#341) by Joe Sylve - 25597bdfc148e91e27678ec30efa52f4fc8c164f Export of internal Abseil changes by Abseil Team - aad33fefaa8f744d71ce747a53717b835bdf8e84 Export of internal Abseil changes by Abseil Team - 8fe7214fe2d7a45ecc4d85f6a524c6b1532426de Export of internal Abseil changes by Abseil Team - debac94cfb5a0fa75d1d97c399682bd1c72e3191 Export of internal Abseil changes by Abseil Team - 882b3501a31eb0e4ae4213afb91a0e43feda7d5f Fix spelling errors (#384) by Sungmann Cho <55860394+chosungmann@users.noreply.github.com> - 502efe6d7841bff82b1aeef5500491fe9a48c635 Export of internal Abseil changes by Abseil Team - ccdd1d57b6386ebc26fb0c7d99b604672437c124 Export of internal Abseil changes by Abseil Team - ddf8e52a2918dd0ccec75d3e2426125fa3926724 Export of internal Abseil changes by Abseil Team - 6ec136281086b71da32b5fb068bd6e46b78a5c79 Export of internal Abseil changes by Abseil Team - ac78ffc3bc0a8b295cab9a03817760fd460df2a1 Export of internal Abseil changes by Abseil Team - 5374c56e5196320681993869e3126b51edac2a43 Export of internal Abseil changes by Abseil Team - 97c1664b4bbab5f78fac2b151ab02656268fb34b Export of internal Abseil changes by Abseil Team - 325fd7b042ff4ec34f7dd32e602cd81ad0e24b22 Export of internal Abseil changes by Abseil Team - 83c1d65c90a92aa49632b9ac5a793214bb0768bc Export of internal Abseil changes by Abseil Team - eb6b7bd23bc0815bfd784e1a74021ce166765280 Export of internal Abseil changes by Abseil Team - 9ddac555b7861dc178d0dbe758a1cfbed718784b Export of internal Abseil changes by Abseil Team - 1948f6f967e34db9793cfa8b4bcbaf370d039fd8 Export of internal Abseil changes by Abseil Team - a0d1e098c2f99694fa399b175a7ccf920762030e Export of internal Abseil changes by Abseil Team - 2d2d7fbc283315b676159716376e739d3d23ed94 Export of internal Abseil changes by Abseil Team - 0302d1e5fa4fcdd1763b7d1bb3212943b1ae911d supppress unused variable warning for gcc (#372) by Martin - 262d74ba81b1fc4d71f459555cde8ecb39786d68 Export of internal Abseil changes by Abseil Team - f0afae0d49af3e15a7169e019634d7719143d94d Export of internal Abseil changes by Abseil Team - 0e7afdcbd24c7e5b7cab4e0217d8886f1525b520 Export of internal Abseil changes by Abseil Team - 9a41ffdd3a0ccbcdd29c4e3886b28e06f2cd9c66 Export of internal Abseil changes by Abseil Team - 36910d3d7e9fccadd6603f232d0c4f54dcd47c7e [bazel] Add fixes for --incompatible_load_cc_rules_from_b... by Yannic - aae8143cf9aa611f70d7ea9b95b8b8b383b2271a Export of internal Abseil changes by Abseil Team - d9aa92d7fb324314f9df487ac23d32a25650b742 Export of internal Abseil changes by Abseil Team - 321ab5303023c86cd15d9ddc5740fb4b4fde32e1 Export of internal Abseil changes by Abseil Team - 4ef574064e75b86f115549e9eb4c7e806781b3ab Export of internal Abseil changes by Abseil Team GitOrigin-RevId: 0033c9ea91a52ade7c6b725aa2ef3cbe15463421 Change-Id: I8a2b70063cb3ab40c6943a6db0fe40cae71ed8d7 --- absl/flags/flag.h | 170 ++++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 145 insertions(+), 25 deletions(-) (limited to 'absl/flags/flag.h') diff --git a/absl/flags/flag.h b/absl/flags/flag.h index 28925927..cff02c1f 100644 --- a/absl/flags/flag.h +++ b/absl/flags/flag.h @@ -29,16 +29,21 @@ #ifndef ABSL_FLAGS_FLAG_H_ #define ABSL_FLAGS_FLAG_H_ +#include +#include + #include "absl/base/attributes.h" #include "absl/base/casts.h" +#include "absl/base/config.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" namespace absl { -inline namespace lts_2019_08_08 { +ABSL_NAMESPACE_BEGIN // Flag // @@ -64,8 +69,103 @@ inline namespace lts_2019_08_08 { // ABSL_FLAG(int, count, 0, "Count of items to process"); // // No public methods of `absl::Flag` are part of the Abseil Flags API. +#if !defined(_MSC_VER) || defined(__clang__) template using Flag = flags_internal::Flag; +#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 +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* 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(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` 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 + inline bool IsOfType() const { + return GetImpl()->template IsOfType(); + } + 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 inited_; + mutable flags_internal::Flag* impl_; +}; +#endif // GetFlag() // @@ -84,23 +184,10 @@ using Flag = flags_internal::Flag; // // FLAGS_firstname is a Flag of type `std::string` // std::string first_name = absl::GetFlag(FLAGS_firstname); template -T GetFlag(const absl::Flag& flag) { -#define ABSL_FLAGS_INTERNAL_LOCK_FREE_VALIDATE(BIT) \ - static_assert( \ - !std::is_same::value, \ - "Do not specify explicit template parameters to absl::GetFlag"); - ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(ABSL_FLAGS_INTERNAL_LOCK_FREE_VALIDATE) -#undef ABSL_FLAGS_INTERNAL_LOCK_FREE_VALIDATE - +ABSL_MUST_USE_RESULT T GetFlag(const absl::Flag& flag) { return flag.Get(); } -// Overload for `GetFlag()` for types that support lock-free reads. -#define ABSL_FLAGS_INTERNAL_LOCK_FREE_EXPORT(T) \ - extern T GetFlag(const absl::Flag& flag); -ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(ABSL_FLAGS_INTERNAL_LOCK_FREE_EXPORT) -#undef ABSL_FLAGS_INTERNAL_LOCK_FREE_EXPORT - // SetFlag() // // Sets the value of an `absl::Flag` to the value `v`. Do not construct an @@ -122,7 +209,7 @@ void SetFlag(absl::Flag* flag, const V& v) { flag->Set(value); } -} // inline namespace lts_2019_08_08 +ABSL_NAMESPACE_END } // namespace absl @@ -186,13 +273,23 @@ void SetFlag(absl::Flag* flag, const V& v) { #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(&flag) #else +#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ + absl::flags_internal::FlagRegistrar(flag.GetImpl()) +#endif +#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(&flag) +#else +#define ABSL_FLAG_IMPL_REGISTRAR(T, flag) \ + absl::flags_internal::FlagRegistrar(flag.GetImpl()) +#endif #endif // ABSL_FLAG_IMPL macro definition conditional on ABSL_FLAGS_STRIP_HELP @@ -203,9 +300,19 @@ void SetFlag(absl::Flag* flag, const V& v) { #define ABSL_FLAG_IMPL_FLAGHELP(txt) txt #endif -#define ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, txt) \ - static std::string AbslFlagsWrapHelp##name() { \ - return ABSL_FLAG_IMPL_FLAGHELP(txt); \ +// AbslFlagHelpGenFor##name is used to encapsulate both immediate (method Const) +// and lazy (method NonConst) evaluation of help message expression. We choose +// 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 \ + 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) \ @@ -218,17 +325,30 @@ void SetFlag(absl::Flag* flag, const V& v) { // Note: Name of registrar object is not arbitrary. It is used to "grab" // global name for FLAGS_no 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 FLAGS_##name( \ - ABSL_FLAG_IMPL_FLAGNAME(#name), &AbslFlagsWrapHelp##name, \ - ABSL_FLAG_IMPL_FILENAME(), \ - &absl::flags_internal::FlagMarshallingOps, \ - &AbslFlagsInitFlag##name); \ + ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help); \ + ABSL_CONST_INIT absl::Flag FLAGS_##name{ \ + ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(), \ + absl::flags_internal::HelpArg(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 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 // ABSL_RETIRED_FLAG // -- cgit v1.2.3