Export of internal Abseil changes

--
693f81830b9f9cc8b24a1f38492b8dfcdd1d0e24 by Abseil Team <absl-team@google.com>:

Check that absl::int128 works as a std::chrono::duration::rep.

In particular, validate that ...
  std::chrono::time_point<std::chrono::system_clock,
                          std::chrono::duration<absl::int128,
                                                std::atto>>
is a superset (range and resolution) of absl::Time.

PiperOrigin-RevId: 283370280

--
df6073b686bd44223c6f9070fcceec918c728871 by Gennadiy Rozental <rogeeff@google.com>:

Changes thread annotations to use DataGuard() function instead of a specific Mutex.
Remove unused declaration of InvokeCallback.

PiperOrigin-RevId: 283361188

--
b49eb2dd2ee1a0b4c8a7bb1a94e368b81ce5f861 by Abseil Team <absl-team@google.com>:

Rewrite GetNominalCPUFrequency to use advapi32 instead of shlwapi

Using shlwapi.dll means that gdi32.dll is loaded which then makes process destruction more expensive, which is unacceptable for some uses. There may be other places that pull in gdi32.dll - this just fixes the one.

PiperOrigin-RevId: 282960698

--
b5508afec5099a0fdbb55e39a7cd2993259ed860 by Abseil Team <absl-team@google.com>:

Small typo fix in comments: initiazliation -> initialization

PiperOrigin-RevId: 282891800

--
4319cc419584e91ee74f6ae1a32d88a412fc5c01 by Abseil Team <absl-team@google.com>:

Update c_find_first_of() comment to remove the mention of an ordered container.

PiperOrigin-RevId: 282836540

--
5fcabc0a834dff39a505d5a5fc5403ddeb96028e by Derek Mauro <dmauro@google.com>:

Fix NaCl build, where format checking is broken

PiperOrigin-RevId: 282826202

--
aaf9ad3274c056a2f68e9b8ccada45c9802e2f1e by Derek Mauro <dmauro@google.com>:

Fix more -Wundef warnings

PiperOrigin-RevId: 282799820

--
1fb06150a70ffe98bf4b2d42b2a39d083bf44f8c by Derek Mauro <dmauro@google.com>:

Release support for additional platforms

PiperOrigin-RevId: 282793384

--
fa947fc28624a316fa872d7045b3838b88a0d69b by Derek Mauro <dmauro@google.com>:

Cleanup inconsistent usage of __has_attribute

PiperOrigin-RevId: 282793296

--
990030ad282263d6303c83b780a55fdec8e90d43 by Gennadiy Rozental <rogeeff@google.com>:

Eliminate the pointer in absl::Flag, which points to n space where we were storing flag's default value. We also eliminate additional (now unnecessary) allocation for flag's default value.
Instead we'll initialize the flags value directly from the value specified in ABSL_FLAG.
If the default value is updated via the call to SetCommandLineOptionWithMode we are replacing pointer to initialization routine to pointer to new default value.

PiperOrigin-RevId: 282637616
GitOrigin-RevId: 693f81830b9f9cc8b24a1f38492b8dfcdd1d0e24
Change-Id: I6f2edd8ef844de09aa2c182a7ca3133a22364792

2 files changed, 99 insertions, 63 deletions

diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index d087f79e891c..435cc362478f 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -49,12 +49,11 @@ void FlagImpl::Init() {
 
   absl::MutexLock lock(&locks_->primary_mu);
 
-  if (def_ != nullptr) {
+  if (cur_ != nullptr) {
     inited_.store(true, std::memory_order_release);
   } else {
-    // Need to initialize def and cur fields.
-    def_ = (*initial_value_gen_)();
-    cur_ = Clone(op_, def_);
+    // Need to initialize cur field.
+    cur_ = MakeInitValue().release();
     StoreAtomic();
     inited_.store(true, std::memory_order_release);
     InvokeCallback();
@@ -63,8 +62,7 @@ void FlagImpl::Init() {
 
 // Ensures that the lazily initialized data is initialized,
 // and returns pointer to the mutex guarding flags data.
-absl::Mutex* FlagImpl::DataGuard() const
-    ABSL_LOCK_RETURNED(locks_->primary_mu) {
+absl::Mutex* FlagImpl::DataGuard() const {
   if (ABSL_PREDICT_FALSE(!inited_.load(std::memory_order_acquire))) {
     const_cast<FlagImpl*>(this)->Init();
   }
@@ -79,12 +77,23 @@ void FlagImpl::Destroy() const {
 
     // Values are heap allocated for Abseil Flags.
     if (cur_) Delete(op_, cur_);
-    if (def_) Delete(op_, def_);
+    if (def_kind_ == FlagDefaultSrcKind::kDynamicValue)
+      Delete(op_, default_src_.dynamic_value);
   }
 
   delete locks_;
 }
 
+std::unique_ptr<void, DynValueDeleter> FlagImpl::MakeInitValue() const {
+  void* res = nullptr;
+  if (def_kind_ == FlagDefaultSrcKind::kDynamicValue) {
+    res = Clone(op_, default_src_.dynamic_value);
+  } else {
+    res = (*default_src_.gen_func)();
+  }
+  return {res, DynValueDeleter{op_}};
+}
+
 std::string FlagImpl::Help() const {
   return help_source_kind_ == FlagHelpSrcKind::kLiteral ? help_.literal
                                                         : help_.gen_func();
@@ -103,7 +112,8 @@ bool FlagImpl::IsSpecifiedOnCommandLine() const {
 std::string FlagImpl::DefaultValue() const {
   absl::MutexLock l(DataGuard());
 
-  return Unparse(marshalling_op_, def_);
+  auto obj = MakeInitValue();
+  return Unparse(marshalling_op_, obj.get());
 }
 
 std::string FlagImpl::CurrentValue() const {
@@ -121,8 +131,7 @@ void FlagImpl::SetCallback(
   InvokeCallback();
 }
 
-void FlagImpl::InvokeCallback() const
-    ABSL_EXCLUSIVE_LOCKS_REQUIRED(locks_->primary_mu) {
+void FlagImpl::InvokeCallback() const {
   if (!callback_) return;
 
   // If the flag has a mutation callback this function invokes it. While the
@@ -172,23 +181,20 @@ bool FlagImpl::RestoreState(const CommandLineFlag& flag, const void* value,
 // 'dst' assuming it is a pointer to the flag's value type. In case if any error
 // is encountered in either step, the error message is stored in 'err'
 bool FlagImpl::TryParse(const CommandLineFlag& flag, void* dst,
-                        absl::string_view value, std::string* err) const
-    ABSL_EXCLUSIVE_LOCKS_REQUIRED(locks_->primary_mu) {
-  void* tentative_value = Clone(op_, def_);
+                        absl::string_view value, std::string* err) const {
+  auto tentative_value = MakeInitValue();
   std::string parse_err;
-  if (!Parse(marshalling_op_, value, tentative_value, &parse_err)) {
+  if (!Parse(marshalling_op_, value, tentative_value.get(), &parse_err)) {
     auto type_name = flag.Typename();
     absl::string_view err_sep = parse_err.empty() ? "" : "; ";
     absl::string_view typename_sep = type_name.empty() ? "" : " ";
     *err = absl::StrCat("Illegal value '", value, "' specified for",
                         typename_sep, type_name, " flag '", flag.Name(), "'",
                         err_sep, parse_err);
-    Delete(op_, tentative_value);
     return false;
   }
 
-  Copy(op_, tentative_value, dst);
-  Delete(op_, tentative_value);
+  Copy(op_, tentative_value.get(), dst);
   return true;
 }
 
@@ -208,7 +214,7 @@ void FlagImpl::Read(const CommandLineFlag& flag, void* dst,
   CopyConstruct(op_, cur_, dst);
 }
 
-void FlagImpl::StoreAtomic() ABSL_EXCLUSIVE_LOCKS_REQUIRED(locks_->primary_mu) {
+void FlagImpl::StoreAtomic() {
   size_t data_size = Sizeof(op_);
 
   if (data_size <= sizeof(int64_t)) {
@@ -299,12 +305,22 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
       break;
     }
     case SET_FLAGS_DEFAULT: {
-      // modify the flag's default-value
-      if (!TryParse(flag, def_, value, err)) return false;
+      // Flag's new default-value.
+      auto new_default_value = MakeInitValue();
+
+      if (!TryParse(flag, new_default_value.get(), value, err)) return false;
+
+      if (def_kind_ == FlagDefaultSrcKind::kDynamicValue) {
+        // Release old default value.
+        Delete(op_, default_src_.dynamic_value);
+      }
+
+      default_src_.dynamic_value = new_default_value.release();
+      def_kind_ = FlagDefaultSrcKind::kDynamicValue;
 
       if (!modified_) {
         // Need to set both default value *and* current, in this case
-        Copy(op_, def_, cur_);
+        Copy(op_, default_src_.dynamic_value, cur_);
         StoreAtomic();
         InvokeCallback();
       }
@@ -321,9 +337,9 @@ void FlagImpl::CheckDefaultValueParsingRoundtrip(
 
   absl::MutexLock lock(DataGuard());
 
-  void* dst = Clone(op_, def_);
+  auto dst = MakeInitValue();
   std::string error;
-  if (!flags_internal::Parse(marshalling_op_, v, dst, &error)) {
+  if (!flags_internal::Parse(marshalling_op_, v, dst.get(), &error)) {
     ABSL_INTERNAL_LOG(
         FATAL,
         absl::StrCat("Flag ", flag.Name(), " (from ", flag.Filename(),
@@ -333,18 +349,15 @@ void FlagImpl::CheckDefaultValueParsingRoundtrip(
 
   // We do not compare dst to def since parsing/unparsing may make
   // small changes, e.g., precision loss for floating point types.
-  Delete(op_, dst);
 }
 
 bool FlagImpl::ValidateInputValue(absl::string_view value) const {
   absl::MutexLock l(DataGuard());
 
-  void* obj = Clone(op_, def_);
+  auto obj = MakeInitValue();
   std::string ignored_error;
-  const bool result =
-      flags_internal::Parse(marshalling_op_, value, obj, &ignored_error);
-  Delete(op_, obj);
-  return result;
+  return flags_internal::Parse(marshalling_op_, value, obj.get(),
+                               &ignored_error);
 }
 
 }  // namespace flags_internal
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index d79902543a22..947a8cadaf2d 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -119,47 +119,61 @@ constexpr flags_internal::HelpInitArg HelpArg(char) {
           flags_internal::FlagHelpSrcKind::kGenFunc};
 }
 
-// Signature for the function generating the initial flag value based (usually
+// Signature for the function generating the initial flag value (usually
 // based on default value supplied in flag's definition)
-using InitialValGenFunc = void* (*)();
+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 FlagDefaultSrcKind : int8_t { kDynamicValue, kGenFunc };
 
 // Signature for the mutation callback used by watched Flags
 // The callback is noexcept.
 // TODO(rogeeff): add noexcept after C++17 support is added.
 using FlagCallback = void (*)();
 
-void InvokeCallback(absl::Mutex* primary_mu, absl::Mutex* callback_mu,
-                    FlagCallback cb) ABSL_EXCLUSIVE_LOCKS_REQUIRED(primary_mu);
+struct DynValueDeleter {
+  void operator()(void* ptr) const { Delete(op, ptr); }
+
+  const FlagOpFn op;
+};
 
 // The class encapsulates the Flag's data and safe access to it.
 class FlagImpl {
  public:
   constexpr FlagImpl(const flags_internal::FlagOpFn op,
                      const flags_internal::FlagMarshallingOpFn marshalling_op,
-                     const flags_internal::InitialValGenFunc initial_value_gen,
+                     const flags_internal::FlagDfltGenFunc default_value_gen,
                      const HelpInitArg help)
       : op_(op),
         marshalling_op_(marshalling_op),
-        initial_value_gen_(initial_value_gen),
         help_(help.source),
-        help_source_kind_(help.kind) {}
+        help_source_kind_(help.kind),
+        def_kind_(flags_internal::FlagDefaultSrcKind::kGenFunc),
+        default_src_(default_value_gen) {}
 
   // Forces destruction of the Flag's data.
   void Destroy() const;
 
   // Constant access methods
   std::string Help() const;
-  bool IsModified() const ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
-  bool IsSpecifiedOnCommandLine() const ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
-  std::string DefaultValue() const ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
-  std::string CurrentValue() const ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+  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(const CommandLineFlag& flag, void* dst,
             const flags_internal::FlagOpFn dst_op) const
-      ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
   // Attempts to parse supplied `value` std::string.
   bool TryParse(const CommandLineFlag& flag, void* dst, absl::string_view value,
                 std::string* err) const
-      ABSL_EXCLUSIVE_LOCKS_REQUIRED(locks_->primary_mu);
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
   template <typename T>
   bool AtomicGet(T* v) const {
     const int64_t r = atomic_.load(std::memory_order_acquire);
@@ -174,23 +188,23 @@ class FlagImpl {
   // Mutating access methods
   void Write(const CommandLineFlag& flag, const void* src,
              const flags_internal::FlagOpFn src_op)
-      ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
   bool SetFromString(const CommandLineFlag& flag, absl::string_view value,
                      FlagSettingMode set_mode, ValueSource source,
-                     std::string* err) ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+                     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(locks_->primary_mu);
+  void StoreAtomic() ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
   // Interfaces to operate on callbacks.
   void SetCallback(const flags_internal::FlagCallback mutation_callback)
-      ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
-  void InvokeCallback() const ABSL_EXCLUSIVE_LOCKS_REQUIRED(locks_->primary_mu);
+      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<flags_internal::FlagStateInterface> SaveState(
-      Flag<T>* flag) const ABSL_LOCKS_EXCLUDED(locks_->primary_mu) {
+      Flag<T>* flag) const ABSL_LOCKS_EXCLUDED(*DataGuard()) {
     T&& cur_value = flag->Get();
     absl::MutexLock l(DataGuard());
 
@@ -199,13 +213,13 @@ class FlagImpl {
   }
   bool RestoreState(const CommandLineFlag& flag, const void* value,
                     bool modified, bool on_command_line, int64_t counter)
-      ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
 
   // Value validation interfaces.
   void CheckDefaultValueParsingRoundtrip(const CommandLineFlag& flag) const
-      ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
   bool ValidateInputValue(absl::string_view value) const
-      ABSL_LOCKS_EXCLUDED(locks_->primary_mu);
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
 
  private:
   // Lazy initialization of the Flag's data.
@@ -214,27 +228,36 @@ class FlagImpl {
   // and returns pointer to the mutex guarding flags data.
   absl::Mutex* DataGuard() const ABSL_LOCK_RETURNED(locks_->primary_mu);
 
+  // Returns heap allocated value of type T initialized with default value.
+  std::unique_ptr<void, DynValueDeleter> MakeInitValue() const
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
+
   // Immutable Flag's data.
-  const FlagOpFn op_;                          // Type-specific handler.
-  const FlagMarshallingOpFn marshalling_op_;   // Marshalling ops handler.
-  const InitialValGenFunc initial_value_gen_;  // Makes flag's initial value.
+  const FlagOpFn op_;                         // Type-specific handler.
+  const FlagMarshallingOpFn marshalling_op_;  // Marshalling ops handler.
   const FlagHelpSrc help_;  // Help message literal or function to generate it.
   // Indicates if help message was supplied as literal or generator func.
   const FlagHelpSrcKind help_source_kind_;
 
-  // Mutable Flag's data. (guarded by locks_->primary_mu).
-  // Indicates that locks_, cur_ and def_ fields have been lazily initialized.
+  // Mutable Flag's data. (guarded by DataGuard()).
+  // Indicates that locks_ and cur_ fields have been lazily initialized.
   std::atomic<bool> inited_{false};
   // Has flag value been modified?
-  bool modified_ ABSL_GUARDED_BY(locks_->primary_mu) = false;
+  bool modified_ ABSL_GUARDED_BY(*DataGuard()) = false;
   // Specified on command line.
-  bool on_command_line_ ABSL_GUARDED_BY(locks_->primary_mu) = false;
-  // Lazily initialized pointer to default value
-  void* def_ ABSL_GUARDED_BY(locks_->primary_mu) = nullptr;
+  bool on_command_line_ ABSL_GUARDED_BY(*DataGuard()) = false;
+  // If def_kind_ == kDynamicValue, default_src_ holds a dynamically allocated
+  // value.
+  FlagDefaultSrcKind def_kind_ 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_src_ ABSL_GUARDED_BY(*DataGuard());
   // Lazily initialized pointer to current value
-  void* cur_ ABSL_GUARDED_BY(locks_->primary_mu) = nullptr;
+  void* cur_ ABSL_GUARDED_BY(*DataGuard()) = nullptr;
   // Mutation counter
-  int64_t counter_ ABSL_GUARDED_BY(locks_->primary_mu) = 0;
+  int64_t counter_ ABSL_GUARDED_BY(*DataGuard()) = 0;
   // For some types, a copy of the current value is kept in an atomically
   // accessible field.
   std::atomic<int64_t> atomic_{flags_internal::AtomicInit()};
@@ -263,7 +286,7 @@ class Flag final : public flags_internal::CommandLineFlag {
   constexpr Flag(const char* name, const flags_internal::HelpInitArg help,
                  const char* filename,
                  const flags_internal::FlagMarshallingOpFn marshalling_op,
-                 const flags_internal::InitialValGenFunc initial_value_gen)
+                 const flags_internal::FlagDfltGenFunc initial_value_gen)
       : flags_internal::CommandLineFlag(name, filename),
         impl_(&flags_internal::FlagOps<T>, marshalling_op, initial_value_gen,
               help) {}