From c44657f55692eddf5504156645d1f4ec7b3acabd Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Thu, 13 Feb 2020 06:52:24 -0800 Subject: [PATCH] Export of internal Abseil changes -- dc6d2715f0415082fcc8da8bf74e74bce69b236c by Derek Mauro : Correctly detect C++ exceptions support on Clang for Windows PiperOrigin-RevId: 294905116 -- b43c44501b4820f4a2f396e426619bd02565707e by Derek Mauro : Set CMAKE_CXX_STANDARD on the MacOS CMake build PiperOrigin-RevId: 294730418 -- 184a078649167f9738da60b0f12108256bcfd67b by Abseil Team : No need for custom spec to deal with limited platforms. PiperOrigin-RevId: 294700133 -- b437c7f659b809fc84a45eab284265fec497a3e3 by Abseil Team : Not calling sigaltstack on WatchOS and TVOS since they don't allow it. PiperOrigin-RevId: 294699951 -- 23ab8dd381ee4104125dece8455bc96b81239789 by Gennadiy Rozental : Replace use of atomic+global Mutex+bool with absl::call_once for Flag initialization. This simplifies the initialization logic and helps with upcoming work with value storage rework. PiperOrigin-RevId: 294654938 -- cee576163a2753c6138bc254e81de4800ea3307a by Gennadiy Rozental : Separate const bits from mutable bits. Since bit field is not atomic unit for reading/writing, we can't have constant bits which are not protected by data guard to share the space with mutable bits which are protected. This CL just reorder fields in class and does not make any other changes. PiperOrigin-RevId: 294501780 -- b4d0e2ab559d04f655c93f008594562234773c15 by Abseil Team : Correct the comment. PiperOrigin-RevId: 294499328 -- a788cf71af6247df033298c49939ba0414d71693 by Derek Mauro : Move the FAQ to the top level directory PiperOrigin-RevId: 294493863 GitOrigin-RevId: dc6d2715f0415082fcc8da8bf74e74bce69b236c Change-Id: I71b0d8cd401b48d41433417858ae0d69398b6602 --- absl/FAQ.md => FAQ.md | 0 absl/abseil.podspec.gen.py | 18 --------------- absl/base/config.h | 14 ++++++++---- absl/container/node_hash_set.h | 4 ++-- absl/debugging/failure_signal_handler.cc | 13 +++++++++-- absl/flags/BUILD.bazel | 1 + absl/flags/CMakeLists.txt | 1 + absl/flags/internal/flag.cc | 29 ++++-------------------- absl/flags/internal/flag.h | 19 +++++++++++----- ci/macos_xcode_cmake.sh | 1 + 10 files changed, 44 insertions(+), 56 deletions(-) rename absl/FAQ.md => FAQ.md (100%) diff --git a/absl/FAQ.md b/FAQ.md similarity index 100% rename from absl/FAQ.md rename to FAQ.md diff --git a/absl/abseil.podspec.gen.py b/absl/abseil.podspec.gen.py index 2bf153c00..6aefb794d 100755 --- a/absl/abseil.podspec.gen.py +++ b/absl/abseil.podspec.gen.py @@ -46,18 +46,6 @@ Pod::Spec.new do |s| s.watchos.deployment_target = '2.0' """ -# Limited platforms that abseil supports. -# This is mainly because of sigaltstack unavailable on watchOS. -LIMITED_SUPPORT_PLATFORMS = [ - "ios.deployment_target = '7.0'", - "osx.deployment_target = '10.9'", -] - -# Custom specification per rule. -CUSTOM_SPEC_MAP = { - "//absl/debugging:failure_signal_handler": LIMITED_SUPPORT_PLATFORMS, -} - # Rule object representing the rule of Bazel BUILD. Rule = collections.namedtuple( "Rule", "type name package srcs hdrs textual_hdrs deps visibility testonly") @@ -200,12 +188,6 @@ def write_podspec_rule(f, rule, depth): name = get_spec_name(dep.replace(":", "/")) f.write("{indent}{var}.dependency '{dep}'\n".format( indent=indent, var=spec_var, dep=name)) - # Writes custom specification. - custom_spec = CUSTOM_SPEC_MAP.get(rule.package + ":" + rule.name) - if custom_spec: - for spec in custom_spec: - f.write("{indent}{var}.{spec}\n".format( - indent=indent, var=spec_var, spec=spec)) def write_indented_list(f, leading, values): diff --git a/absl/base/config.h b/absl/base/config.h index eac5d268e..ee99f9462 100644 --- a/absl/base/config.h +++ b/absl/base/config.h @@ -316,13 +316,19 @@ static_assert(ABSL_INTERNAL_INLINE_NAMESPACE_STR[0] != 'h' || #error ABSL_HAVE_EXCEPTIONS cannot be directly set. #elif defined(__clang__) -// TODO(calabrese) -// Switch to using __cpp_exceptions when we no longer support versions < 3.6. -// For details on this check, see: -// http://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-exceptions-macro + +#if __clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 6) +// Clang >= 3.6 +#if __has_feature(cxx_exceptions) +#define ABSL_HAVE_EXCEPTIONS 1 +#endif // __has_feature(cxx_exceptions) +#else +// Clang < 3.6 +// http://releases.llvm.org/3.6.0/tools/clang/docs/ReleaseNotes.html#the-exceptions-macro #if defined(__EXCEPTIONS) && __has_feature(cxx_exceptions) #define ABSL_HAVE_EXCEPTIONS 1 #endif // defined(__EXCEPTIONS) && __has_feature(cxx_exceptions) +#endif // __clang_major__ > 3 || (__clang_major__ == 3 && __clang_minor__ >= 6) // Handle remaining special cases and default to exceptions being supported. #elif !(defined(__GNUC__) && (__GNUC__ < 5) && !defined(__EXCEPTIONS)) && \ diff --git a/absl/container/node_hash_set.h b/absl/container/node_hash_set.h index 0e2dee54a..ad54b6dcc 100644 --- a/absl/container/node_hash_set.h +++ b/absl/container/node_hash_set.h @@ -77,7 +77,7 @@ struct NodeHashSetPolicy; // // // Create a node hash set of three strings // absl::node_hash_map ducks = -// {"huey", "dewey"}, "louie"}; +// {"huey", "dewey", "louie"}; // // // Insert a new element into the node hash map // ducks.insert("donald"}; @@ -111,7 +111,7 @@ class node_hash_set // * Initializer List constructor // // absl::node_hash_set set2 = - // {{"huey"}, {"dewey"}, {"louie"},}; + // {{"huey"}, {"dewey"}, {"louie"}}; // // * Copy constructor // diff --git a/absl/debugging/failure_signal_handler.cc b/absl/debugging/failure_signal_handler.cc index 470d67681..cd141ecf5 100644 --- a/absl/debugging/failure_signal_handler.cc +++ b/absl/debugging/failure_signal_handler.cc @@ -24,6 +24,10 @@ #include #endif +#ifdef __APPLE__ +#include +#endif + #ifdef ABSL_HAVE_MMAP #include #endif @@ -44,6 +48,11 @@ #ifndef _WIN32 #define ABSL_HAVE_SIGACTION +// Apple WatchOS and TVOS don't allow sigaltstack +#if !(defined(TARGET_OS_WATCH) && TARGET_OS_WATCH) && \ + !(defined(TARGET_OS_TV) && TARGET_OS_TV) +#define ABSL_HAVE_SIGALTSTACK +#endif #endif namespace absl { @@ -117,7 +126,7 @@ const char* FailureSignalToString(int signo) { } // namespace debugging_internal -#ifndef _WIN32 +#ifdef ABSL_HAVE_SIGALTSTACK static bool SetupAlternateStackOnce() { #if defined(__wasm__) || defined (__asjms__) @@ -169,7 +178,7 @@ static bool SetupAlternateStackOnce() { // Returns the appropriate flag for sig_action.sa_flags // if the system supports using an alternate stack. static int MaybeSetupAlternateStack() { -#ifndef _WIN32 +#ifdef ABSL_HAVE_SIGALTSTACK ABSL_ATTRIBUTE_UNUSED static const bool kOnce = SetupAlternateStackOnce(); return SA_ONSTACK; #else diff --git a/absl/flags/BUILD.bazel b/absl/flags/BUILD.bazel index d2ca5c6f8..cdb4e7e8f 100644 --- a/absl/flags/BUILD.bazel +++ b/absl/flags/BUILD.bazel @@ -41,6 +41,7 @@ cc_library( ":config", ":handle", ":registry", + "//absl/base", "//absl/base:config", "//absl/base:core_headers", "//absl/memory", diff --git a/absl/flags/CMakeLists.txt b/absl/flags/CMakeLists.txt index 20e66825a..1d25f0ded 100644 --- a/absl/flags/CMakeLists.txt +++ b/absl/flags/CMakeLists.txt @@ -27,6 +27,7 @@ absl_cc_library( LINKOPTS ${ABSL_DEFAULT_LINKOPTS} DEPS + absl::base absl::config absl::flags_config absl::flags_handle diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc index ba70da91a..721e411e0 100644 --- a/absl/flags/internal/flag.cc +++ b/absl/flags/internal/flag.cc @@ -80,41 +80,22 @@ class MutexRelock { absl::Mutex* mu_; }; -// This global lock guards the initialization and destruction of data_guard_, -// which is used to guard the other Flag data. -ABSL_CONST_INIT static absl::Mutex flag_mutex_lifetime_guard(absl::kConstInit); - } // namespace void FlagImpl::Init() { - { - absl::MutexLock lock(&flag_mutex_lifetime_guard); - - // Must initialize data guard for this flag. - if (!is_data_guard_inited_) { - new (&data_guard_) absl::Mutex; - is_data_guard_inited_ = true; - } - } + new (&data_guard_) absl::Mutex; absl::MutexLock lock(reinterpret_cast(&data_guard_)); - if (value_.dynamic != nullptr) { - inited_.store(true, std::memory_order_release); - } else { - // Need to initialize cur field. - value_.dynamic = MakeInitValue().release(); - StoreAtomic(); - inited_.store(true, std::memory_order_release); - } + value_.dynamic = MakeInitValue().release(); + StoreAtomic(); } // Ensures that the lazily initialized data is initialized, // and returns pointer to the mutex guarding flags data. absl::Mutex* FlagImpl::DataGuard() const { - if (ABSL_PREDICT_FALSE(!inited_.load(std::memory_order_acquire))) { - const_cast(this)->Init(); - } + absl::call_once(const_cast(this)->init_control_, &FlagImpl::Init, + const_cast(this)); // data_guard_ is initialized. return reinterpret_cast(&data_guard_); diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h index ef30a22f5..b426ccb57 100644 --- a/absl/flags/internal/flag.h +++ b/absl/flags/internal/flag.h @@ -24,6 +24,7 @@ #include #include +#include "absl/base/call_once.h" #include "absl/base/config.h" #include "absl/base/thread_annotations.h" #include "absl/flags/config.h" @@ -281,10 +282,8 @@ class FlagImpl { help_(help.source), help_source_kind_(static_cast(help.kind)), def_kind_(static_cast(FlagDefaultKind::kGenFunc)), - is_data_guard_inited_(false), modified_(false), on_command_line_(false), - inited_(false), counter_(0), callback_(nullptr), default_src_(default_value_gen), @@ -406,20 +405,28 @@ class FlagImpl { // 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_src_ holds a dynamically allocated // value. uint8_t def_kind_ : 1 ABSL_GUARDED_BY(*DataGuard()); - // Protects against multiple concurrent constructions of `data_guard_`. - bool is_data_guard_inited_ : 1; // 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()); - // Indicates that the flag state is initialized. - std::atomic inited_; // Mutation counter int64_t counter_ ABSL_GUARDED_BY(*DataGuard()); // Optional flag's callback and absl::Mutex to guard the invocations. diff --git a/ci/macos_xcode_cmake.sh b/ci/macos_xcode_cmake.sh index 75b0f2d19..a1f4a857b 100755 --- a/ci/macos_xcode_cmake.sh +++ b/ci/macos_xcode_cmake.sh @@ -36,6 +36,7 @@ for compilation_mode in ${ABSL_CMAKE_BUILD_TYPES}; do time cmake ${ABSEIL_ROOT} \ -GXcode \ -DCMAKE_BUILD_TYPE=${compilation_mode} \ + -DCMAKE_CXX_STANDARD=11 \ -DABSL_USE_GOOGLETEST_HEAD=ON \ -DABSL_RUN_TESTS=ON time cmake --build .