From f3840bc5e33ce4932e35986cf3718450c6f02af2 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Thu, 18 Jul 2019 15:07:49 -0700 Subject: Export of internal Abseil changes. -- dcff7cc4eb3837d39d1e083cbf1d4f082054cbf6 by Laramie Leavitt : Add default and fallback modes for SaltedSeedSeq::generate(). SeedSeq::generate will often be called with contiguous ranges of uint32_t. Detect this case and use the currently direct code paths to handle it. Otherwise use a fallback mechanism which does an additional copy. PiperOrigin-RevId: 258853656 -- 59ec88845ac2ee6567c493021b54385940d66762 by Gennadiy Rozental : Internal change PiperOrigin-RevId: 258822137 -- eb2d1ab21f6f94c24c51c1cd3719846be259e8e7 by Abseil Team : Add iOS version 11 to the mix of Apple OS versions that have various C++17 header files but do not support them. PiperOrigin-RevId: 258820405 -- 452cea3e13b29797b2c385d7c6da7613d36bdc45 by Gennadiy Rozental : Internal change PiperOrigin-RevId: 258802436 GitOrigin-RevId: dcff7cc4eb3837d39d1e083cbf1d4f082054cbf6 Change-Id: I2261cb58e142eb15017ef646a56710dd64f06496 --- absl/base/config.h | 22 ++++++---- absl/flags/flag.h | 21 +++++---- absl/flags/internal/registry.cc | 80 +++------------------------------- absl/flags/internal/registry.h | 3 +- absl/random/internal/salted_seed_seq.h | 63 +++++++++++++++----------- 5 files changed, 67 insertions(+), 122 deletions(-) diff --git a/absl/base/config.h b/absl/base/config.h index 406a931f..692738e3 100644 --- a/absl/base/config.h +++ b/absl/base/config.h @@ -370,16 +370,20 @@ #error "absl endian detection needs to be set up for your compiler" #endif -// MacOS 10.13 doesn't let you use , , or even though -// the headers exist and are publicly noted to work. See +// MacOS 10.13 and iOS 10.11 don't let you use , , or +// even though the headers exist and are publicly noted to work. See // https://github.com/abseil/abseil-cpp/issues/207 and // https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes +// libc++ spells out the availability requirements in the file +// llvm-project/libcxx/include/__config. #if defined(__APPLE__) && defined(_LIBCPP_VERSION) && \ - defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && \ - __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101400 -#define ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE 1 + ((defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && \ + __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 101400) || \ + (defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__) && \ + __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ < 101200)) +#define ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE 1 #else -#define ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE 0 +#define ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE 0 #endif // ABSL_HAVE_STD_ANY @@ -391,7 +395,7 @@ #ifdef __has_include #if __has_include() && __cplusplus >= 201703L && \ - !ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE + !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE #define ABSL_HAVE_STD_ANY 1 #endif #endif @@ -405,7 +409,7 @@ #ifdef __has_include #if __has_include() && __cplusplus >= 201703L && \ - !ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE + !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE #define ABSL_HAVE_STD_OPTIONAL 1 #endif #endif @@ -419,7 +423,7 @@ #ifdef __has_include #if __has_include() && __cplusplus >= 201703L && \ - !ABSL_INTERNAL_MACOS_CXX17_TYPES_UNAVAILABLE + !ABSL_INTERNAL_APPLE_CXX17_TYPES_UNAVAILABLE #define ABSL_HAVE_STD_VARIANT 1 #endif #endif diff --git a/absl/flags/flag.h b/absl/flags/flag.h index c70023ab..6c9f4876 100644 --- a/absl/flags/flag.h +++ b/absl/flags/flag.h @@ -216,17 +216,16 @@ 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. -#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ - namespace absl {} \ - ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \ - ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help) \ - absl::Flag FLAGS_##name( \ - ABSL_FLAG_IMPL_FLAGNAME(#name), \ - &AbslFlagsWrapHelp##name, \ - ABSL_FLAG_IMPL_FILENAME(), \ - &absl::flags_internal::FlagMarshallingOps, \ - &AbslFlagsInitFlag##name); \ - extern bool FLAGS_no##name; \ +#define ABSL_FLAG_IMPL(Type, name, default_value, help) \ + namespace absl {} \ + 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); \ + extern bool FLAGS_no##name; \ bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name) // ABSL_RETIRED_FLAG diff --git a/absl/flags/internal/registry.cc b/absl/flags/internal/registry.cc index f37871c9..4e5d1106 100644 --- a/absl/flags/internal/registry.cc +++ b/absl/flags/internal/registry.cc @@ -54,53 +54,6 @@ void DestroyFlag(CommandLineFlag* flag) NO_THREAD_SAFETY_ANALYSIS { // the function will acquire it itself if needed. // -------------------------------------------------------------------- -// A map from flag pointer to CommandLineFlag*. Used when registering -// validators. -class FlagPtrMap { - public: - void Register(CommandLineFlag* flag) { - auto& vec = buckets_[BucketForFlag(flag->cur)]; - if (vec.size() == vec.capacity()) { - // Bypass default 2x growth factor with 1.25 so we have fuller vectors. - // This saves 4% memory compared to default growth. - vec.reserve(vec.size() * 1.25 + 0.5); - } - vec.push_back(flag); - } - - CommandLineFlag* FindByPtr(const void* flag_ptr) { - const auto& flag_vector = buckets_[BucketForFlag(flag_ptr)]; - for (CommandLineFlag* entry : flag_vector) { - if (entry->cur == flag_ptr) { - return entry; - } - } - return nullptr; - } - - private: - // Instead of std::map, we use a custom hash table where each bucket stores - // flags in a vector. This reduces memory usage 40% of the memory that would - // have been used by std::map. - // - // kNumBuckets was picked as a large enough prime. As of writing this code, a - // typical large binary has ~8k (old-style) flags, and this would gives - // buckets with roughly 50 elements each. - // - // Note that reads to this hash table are rare: exactly as many as we have - // flags with validators. As of writing, a typical binary only registers 52 - // validated flags. - static constexpr size_t kNumBuckets = 163; - std::vector buckets_[kNumBuckets]; - - static int BucketForFlag(const void* ptr) { - // Modulo a prime is good enough here. On a real program, bucket size stddev - // after registering 8k flags is ~5 (mean size at 51). - return reinterpret_cast(ptr) % kNumBuckets; - } -}; -constexpr size_t FlagPtrMap::kNumBuckets; - class FlagRegistry { public: FlagRegistry() = default; @@ -111,9 +64,7 @@ class FlagRegistry { } // Store a flag in this registry. Takes ownership of *flag. - // If ptr is non-null, the flag can later be found by calling - // FindFlagViaPtrLocked(ptr). - void RegisterFlag(CommandLineFlag* flag, const void* ptr); + void RegisterFlag(CommandLineFlag* flag); void Lock() EXCLUSIVE_LOCK_FUNCTION(lock_) { lock_.Lock(); } void Unlock() UNLOCK_FUNCTION(lock_) { lock_.Unlock(); } @@ -126,9 +77,6 @@ class FlagRegistry { // found or not retired. Does not emit a warning. CommandLineFlag* FindRetiredFlagLocked(absl::string_view name); - // Returns the flag object whose current-value is stored at flag_ptr. - CommandLineFlag* FindFlagViaPtrLocked(const void* flag_ptr); - static FlagRegistry* GlobalRegistry(); // returns a singleton registry private: @@ -142,8 +90,6 @@ class FlagRegistry { using FlagConstIterator = FlagMap::const_iterator; FlagMap flags_; - FlagPtrMap flag_ptr_map_; - absl::Mutex lock_; // Disallow @@ -169,7 +115,7 @@ class FlagRegistryLock { } // namespace -void FlagRegistry::RegisterFlag(CommandLineFlag* flag, const void* ptr) { +void FlagRegistry::RegisterFlag(CommandLineFlag* flag) { FlagRegistryLock registry_lock(this); std::pair ins = flags_.insert(FlagMap::value_type(flag->Name(), flag)); @@ -217,11 +163,6 @@ void FlagRegistry::RegisterFlag(CommandLineFlag* flag, const void* ptr) { // All cases above are fatal, except for the retired flags. std::exit(1); } - - if (ptr != nullptr) { - // This must be the first time we're seeing this flag. - flag_ptr_map_.Register(flag); - } } CommandLineFlag* FlagRegistry::FindFlagLocked(absl::string_view name) { @@ -247,10 +188,6 @@ CommandLineFlag* FlagRegistry::FindRetiredFlagLocked(absl::string_view name) { return i->second; } -CommandLineFlag* FlagRegistry::FindFlagViaPtrLocked(const void* flag_ptr) { - return flag_ptr_map_.FindByPtr(flag_ptr); -} - // -------------------------------------------------------------------- // FlagSaver // FlagSaverImpl @@ -430,13 +367,6 @@ CommandLineFlag* FindCommandLineFlag(absl::string_view name) { return registry->FindFlagLocked(name); } -CommandLineFlag* FindCommandLineV1Flag(const void* flag_ptr) { - FlagRegistry* const registry = FlagRegistry::GlobalRegistry(); - FlagRegistryLock frl(registry); - - return registry->FindFlagViaPtrLocked(flag_ptr); -} - CommandLineFlag* FindRetiredFlag(absl::string_view name) { FlagRegistry* const registry = FlagRegistry::GlobalRegistry(); FlagRegistryLock frl(registry); @@ -477,8 +407,8 @@ void GetAllFlags(std::vector* OUTPUT) { // -------------------------------------------------------------------- -bool RegisterCommandLineFlag(CommandLineFlag* flag, const void* ptr) { - FlagRegistry::GlobalRegistry()->RegisterFlag(flag, ptr); +bool RegisterCommandLineFlag(CommandLineFlag* flag) { + FlagRegistry::GlobalRegistry()->RegisterFlag(flag); return true; } @@ -492,7 +422,7 @@ bool Retire(FlagOpFn ops, FlagMarshallingOpFn marshalling_ops, /*filename_arg=*/"RETIRED", ops, marshalling_ops, /*initial_value_gen=*/nullptr, /*retired_arg=*/true, nullptr, nullptr); - FlagRegistry::GlobalRegistry()->RegisterFlag(flag, nullptr); + FlagRegistry::GlobalRegistry()->RegisterFlag(flag); return true; } diff --git a/absl/flags/internal/registry.h b/absl/flags/internal/registry.h index bd141e1e..27566fbf 100644 --- a/absl/flags/internal/registry.h +++ b/absl/flags/internal/registry.h @@ -57,7 +57,6 @@ void FillCommandLineFlagInfo(CommandLineFlag* flag, //----------------------------------------------------------------------------- CommandLineFlag* FindCommandLineFlag(absl::string_view name); -CommandLineFlag* FindCommandLineV1Flag(const void* flag_ptr); CommandLineFlag* FindRetiredFlag(absl::string_view name); // Executes specified visitor for each non-retired flag in the registry. @@ -74,7 +73,7 @@ void GetAllFlags(std::vector* OUTPUT); //----------------------------------------------------------------------------- -bool RegisterCommandLineFlag(CommandLineFlag*, const void* ptr = nullptr); +bool RegisterCommandLineFlag(CommandLineFlag*); //----------------------------------------------------------------------------- // Retired registrations: diff --git a/absl/random/internal/salted_seed_seq.h b/absl/random/internal/salted_seed_seq.h index 3d16cf97..e160f79e 100644 --- a/absl/random/internal/salted_seed_seq.h +++ b/absl/random/internal/salted_seed_seq.h @@ -64,10 +64,15 @@ class SaltedSeedSeq { template void generate(RandomAccessIterator begin, RandomAccessIterator end) { + // The common case is that generate is called with ContiguousIterators + // to uint arrays. Such contiguous memory regions may be optimized, + // which we detect here. + using tag = absl::conditional_t< + (std::is_pointer::value && + std::is_same, uint32_t>::value), + ContiguousAndUint32Tag, DefaultTag>; if (begin != end) { - generate_impl( - std::integral_constant{}, - begin, end); + generate_impl(begin, end, tag{}); } } @@ -79,19 +84,12 @@ class SaltedSeedSeq { size_t size() const { return seq_->size(); } private: - // The common case for generate is that it is called with iterators over a - // 32-bit value buffer. These can be reinterpreted to a uint32_t and we can - // operate on them as such. - template - void generate_impl(std::integral_constant /*is_32bit*/, - RandomAccessIterator begin, RandomAccessIterator end) { - seq_->generate(begin, end); - const uint32_t salt = absl::random_internal::GetSaltMaterial().value_or(0); - auto buffer = absl::MakeSpan(begin, end); - MixIntoSeedMaterial( - absl::MakeConstSpan(&salt, 1), - absl::MakeSpan(reinterpret_cast(buffer.data()), - buffer.size())); + struct ContiguousAndUint32Tag {}; + struct DefaultTag {}; + + // Generate which requires the iterators are contiguous pointers to uint32_t. + void generate_impl(uint32_t* begin, uint32_t* end, ContiguousAndUint32Tag) { + generate_contiguous(absl::MakeSpan(begin, end)); } // The uncommon case for generate is that it is called with iterators over @@ -99,17 +97,32 @@ class SaltedSeedSeq { // case we allocate a temporary 32-bit buffer and then copy-assign back // to the initial inputs. template - void generate_impl(std::integral_constant /*is_32bit*/, - RandomAccessIterator begin, RandomAccessIterator end) { - // Allocate a temporary buffer, seed, and then copy. - absl::InlinedVector data(std::distance(begin, end), 0); - generate_impl(std::integral_constant{}, data.begin(), - data.end()); - std::copy(data.begin(), data.end(), begin); + void generate_impl(RandomAccessIterator begin, RandomAccessIterator end, + DefaultTag) { + return generate_and_copy(std::distance(begin, end), begin); + } + + // Fills the initial seed buffer the underlying SSeq::generate() call, + // mixing in the salt material. + void generate_contiguous(absl::Span buffer) { + seq_->generate(buffer.begin(), buffer.end()); + const uint32_t salt = absl::random_internal::GetSaltMaterial().value_or(0); + MixIntoSeedMaterial(absl::MakeConstSpan(&salt, 1), buffer); + } + + // Allocates a seed buffer of `n` elements, generates the seed, then + // copies the result into the `out` iterator. + template + void generate_and_copy(size_t n, Iterator out) { + // Allocate a temporary buffer, generate, and then copy. + absl::InlinedVector data(n, 0); + generate_contiguous(absl::MakeSpan(data.data(), data.size())); + std::copy(data.begin(), data.end(), out); } - // Because [rand.req.seedseq] is not copy-constructible, copy-assignable nor - // movable so we wrap it with unique pointer to be able to move SaltedSeedSeq. + // Because [rand.req.seedseq] is not required to be copy-constructible, + // copy-assignable nor movable, we wrap it with unique pointer to be able + // to move SaltedSeedSeq. std::unique_ptr seq_; }; -- cgit v1.2.3