Export of internal Abseil changes

--
f50d25c8f8491ef7031cbbcad78edd15f98c2bd1 by Abseil Team <absl-team@google.com>:

Add myriad2 to HAVE_MMAP
Remove mutex_nonprod and associated defines.

PiperOrigin-RevId: 333759830

--
25ef4c577ea983aa3fcd6cfe2af6cdc62a06f520 by Samuel Benzaquen <sbenza@google.com>:

Internal refactor.
Represent the data with a union to allow for better constexpr support in the future.

PiperOrigin-RevId: 333756733
GitOrigin-RevId: f50d25c8f8491ef7031cbbcad78edd15f98c2bd1
Change-Id: Ieecd2c47cb20de638726eb3f9fc2e5682d05dcca

2 files changed, 0 insertions, 574 deletions

diff --git a/absl/synchronization/internal/mutex_nonprod.cc b/absl/synchronization/internal/mutex_nonprod.cc
deleted file mode 100644
index 334c3bc0..00000000
--- a/absl/synchronization/internal/mutex_nonprod.cc
+++ /dev/null
@@ -1,325 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// Implementation of a small subset of Mutex and CondVar functionality
-// for platforms where the production implementation hasn't been fully
-// ported yet.
-
-#include "absl/synchronization/mutex.h"
-
-#if defined(_WIN32)
-#include <chrono>  // NOLINT(build/c++11)
-#else
-#include <sys/time.h>
-#include <time.h>
-#endif
-
-#include <algorithm>
-
-#include "absl/base/config.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/time/time.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-
-void SetMutexDeadlockDetectionMode(OnDeadlockCycle) {}
-void EnableMutexInvariantDebugging(bool) {}
-
-namespace synchronization_internal {
-
-namespace {
-
-// Return the current time plus the timeout.
-absl::Time DeadlineFromTimeout(absl::Duration timeout) {
-  return absl::Now() + timeout;
-}
-
-// Limit the deadline to a positive, 32-bit time_t value to accommodate
-// implementation restrictions.  This also deals with InfinitePast and
-// InfiniteFuture.
-absl::Time LimitedDeadline(absl::Time deadline) {
-  deadline = std::max(absl::FromTimeT(0), deadline);
-  deadline = std::min(deadline, absl::FromTimeT(0x7fffffff));
-  return deadline;
-}
-
-}  // namespace
-
-#if defined(_WIN32)
-
-MutexImpl::MutexImpl() {}
-
-MutexImpl::~MutexImpl() {
-  if (locked_) {
-    std_mutex_.unlock();
-  }
-}
-
-void MutexImpl::Lock() {
-  std_mutex_.lock();
-  locked_ = true;
-}
-
-bool MutexImpl::TryLock() {
-  bool locked = std_mutex_.try_lock();
-  if (locked) locked_ = true;
-  return locked;
-}
-
-void MutexImpl::Unlock() {
-  locked_ = false;
-  released_.SignalAll();
-  std_mutex_.unlock();
-}
-
-CondVarImpl::CondVarImpl() {}
-
-CondVarImpl::~CondVarImpl() {}
-
-void CondVarImpl::Signal() { std_cv_.notify_one(); }
-
-void CondVarImpl::SignalAll() { std_cv_.notify_all(); }
-
-void CondVarImpl::Wait(MutexImpl* mu) {
-  mu->released_.SignalAll();
-  std_cv_.wait(mu->std_mutex_);
-}
-
-bool CondVarImpl::WaitWithDeadline(MutexImpl* mu, absl::Time deadline) {
-  mu->released_.SignalAll();
-  time_t when = ToTimeT(deadline);
-  int64_t nanos = ToInt64Nanoseconds(deadline - absl::FromTimeT(when));
-  std::chrono::system_clock::time_point deadline_tp =
-      std::chrono::system_clock::from_time_t(when) +
-      std::chrono::duration_cast<std::chrono::system_clock::duration>(
-          std::chrono::nanoseconds(nanos));
-  auto deadline_since_epoch =
-      std::chrono::duration_cast<std::chrono::duration<double>>(
-          deadline_tp - std::chrono::system_clock::from_time_t(0));
-  return std_cv_.wait_until(mu->std_mutex_, deadline_tp) ==
-         std::cv_status::timeout;
-}
-
-#else  // ! _WIN32
-
-MutexImpl::MutexImpl() {
-  ABSL_RAW_CHECK(pthread_mutex_init(&pthread_mutex_, nullptr) == 0,
-                 "pthread error");
-}
-
-MutexImpl::~MutexImpl() {
-  if (locked_) {
-    ABSL_RAW_CHECK(pthread_mutex_unlock(&pthread_mutex_) == 0, "pthread error");
-  }
-  ABSL_RAW_CHECK(pthread_mutex_destroy(&pthread_mutex_) == 0, "pthread error");
-}
-
-void MutexImpl::Lock() {
-  ABSL_RAW_CHECK(pthread_mutex_lock(&pthread_mutex_) == 0, "pthread error");
-  locked_ = true;
-}
-
-bool MutexImpl::TryLock() {
-  bool locked = (0 == pthread_mutex_trylock(&pthread_mutex_));
-  if (locked) locked_ = true;
-  return locked;
-}
-
-void MutexImpl::Unlock() {
-  locked_ = false;
-  released_.SignalAll();
-  ABSL_RAW_CHECK(pthread_mutex_unlock(&pthread_mutex_) == 0, "pthread error");
-}
-
-CondVarImpl::CondVarImpl() {
-  ABSL_RAW_CHECK(pthread_cond_init(&pthread_cv_, nullptr) == 0,
-                 "pthread error");
-}
-
-CondVarImpl::~CondVarImpl() {
-  ABSL_RAW_CHECK(pthread_cond_destroy(&pthread_cv_) == 0, "pthread error");
-}
-
-void CondVarImpl::Signal() {
-  ABSL_RAW_CHECK(pthread_cond_signal(&pthread_cv_) == 0, "pthread error");
-}
-
-void CondVarImpl::SignalAll() {
-  ABSL_RAW_CHECK(pthread_cond_broadcast(&pthread_cv_) == 0, "pthread error");
-}
-
-void CondVarImpl::Wait(MutexImpl* mu) {
-  mu->released_.SignalAll();
-  ABSL_RAW_CHECK(pthread_cond_wait(&pthread_cv_, &mu->pthread_mutex_) == 0,
-                 "pthread error");
-}
-
-bool CondVarImpl::WaitWithDeadline(MutexImpl* mu, absl::Time deadline) {
-  mu->released_.SignalAll();
-  struct timespec ts = ToTimespec(deadline);
-  int rc = pthread_cond_timedwait(&pthread_cv_, &mu->pthread_mutex_, &ts);
-  if (rc == ETIMEDOUT) return true;
-  ABSL_RAW_CHECK(rc == 0, "pthread error");
-  return false;
-}
-
-#endif  // ! _WIN32
-
-void MutexImpl::Await(const Condition& cond) {
-  if (cond.Eval()) return;
-  released_.SignalAll();
-  do {
-    released_.Wait(this);
-  } while (!cond.Eval());
-}
-
-bool MutexImpl::AwaitWithDeadline(const Condition& cond, absl::Time deadline) {
-  if (cond.Eval()) return true;
-  released_.SignalAll();
-  while (true) {
-    if (released_.WaitWithDeadline(this, deadline)) return false;
-    if (cond.Eval()) return true;
-  }
-}
-
-}  // namespace synchronization_internal
-
-Mutex::Mutex() {}
-
-Mutex::~Mutex() {}
-
-void Mutex::Lock() { impl()->Lock(); }
-
-void Mutex::Unlock() { impl()->Unlock(); }
-
-bool Mutex::TryLock() { return impl()->TryLock(); }
-
-void Mutex::ReaderLock() { Lock(); }
-
-void Mutex::ReaderUnlock() { Unlock(); }
-
-void Mutex::Await(const Condition& cond) { impl()->Await(cond); }
-
-void Mutex::LockWhen(const Condition& cond) {
-  Lock();
-  Await(cond);
-}
-
-bool Mutex::AwaitWithDeadline(const Condition& cond, absl::Time deadline) {
-  return impl()->AwaitWithDeadline(
-      cond, synchronization_internal::LimitedDeadline(deadline));
-}
-
-bool Mutex::AwaitWithTimeout(const Condition& cond, absl::Duration timeout) {
-  return AwaitWithDeadline(
-      cond, synchronization_internal::DeadlineFromTimeout(timeout));
-}
-
-bool Mutex::LockWhenWithDeadline(const Condition& cond, absl::Time deadline) {
-  Lock();
-  return AwaitWithDeadline(cond, deadline);
-}
-
-bool Mutex::LockWhenWithTimeout(const Condition& cond, absl::Duration timeout) {
-  return LockWhenWithDeadline(
-      cond, synchronization_internal::DeadlineFromTimeout(timeout));
-}
-
-void Mutex::ReaderLockWhen(const Condition& cond) {
-  ReaderLock();
-  Await(cond);
-}
-
-bool Mutex::ReaderLockWhenWithTimeout(const Condition& cond,
-                                      absl::Duration timeout) {
-  return LockWhenWithTimeout(cond, timeout);
-}
-bool Mutex::ReaderLockWhenWithDeadline(const Condition& cond,
-                                       absl::Time deadline) {
-  return LockWhenWithDeadline(cond, deadline);
-}
-
-void Mutex::EnableDebugLog(const char*) {}
-void Mutex::EnableInvariantDebugging(void (*)(void*), void*) {}
-void Mutex::ForgetDeadlockInfo() {}
-void Mutex::AssertHeld() const {}
-void Mutex::AssertReaderHeld() const {}
-void Mutex::AssertNotHeld() const {}
-
-CondVar::CondVar() {}
-
-CondVar::~CondVar() {}
-
-void CondVar::Signal() { impl()->Signal(); }
-
-void CondVar::SignalAll() { impl()->SignalAll(); }
-
-void CondVar::Wait(Mutex* mu) { return impl()->Wait(mu->impl()); }
-
-bool CondVar::WaitWithDeadline(Mutex* mu, absl::Time deadline) {
-  return impl()->WaitWithDeadline(
-      mu->impl(), synchronization_internal::LimitedDeadline(deadline));
-}
-
-bool CondVar::WaitWithTimeout(Mutex* mu, absl::Duration timeout) {
-  return WaitWithDeadline(mu, absl::Now() + timeout);
-}
-
-void CondVar::EnableDebugLog(const char*) {}
-
-#ifdef ABSL_HAVE_THREAD_SANITIZER
-extern "C" void __tsan_read1(void *addr);
-#else
-#define __tsan_read1(addr)  // do nothing if TSan not enabled
-#endif
-
-// A function that just returns its argument, dereferenced
-static bool Dereference(void *arg) {
-  // ThreadSanitizer does not instrument this file for memory accesses.
-  // This function dereferences a user variable that can participate
-  // in a data race, so we need to manually tell TSan about this memory access.
-  __tsan_read1(arg);
-  return *(static_cast<bool *>(arg));
-}
-
-Condition::Condition() {}   // null constructor, used for kTrue only
-const Condition Condition::kTrue;
-
-Condition::Condition(bool (*func)(void *), void *arg)
-    : eval_(&CallVoidPtrFunction),
-      function_(func),
-      method_(nullptr),
-      arg_(arg) {}
-
-bool Condition::CallVoidPtrFunction(const Condition *c) {
-  return (*c->function_)(c->arg_);
-}
-
-Condition::Condition(const bool *cond)
-    : eval_(CallVoidPtrFunction),
-      function_(Dereference),
-      method_(nullptr),
-      // const_cast is safe since Dereference does not modify arg
-      arg_(const_cast<bool *>(cond)) {}
-
-bool Condition::Eval() const {
-  // eval_ == null for kTrue
-  return (this->eval_ == nullptr) || (*this->eval_)(this);
-}
-
-void RegisterSymbolizer(bool (*)(const void*, char*, int)) {}
-
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/absl/synchronization/internal/mutex_nonprod.inc b/absl/synchronization/internal/mutex_nonprod.inc
deleted file mode 100644
index d83bc8a9..00000000
--- a/absl/synchronization/internal/mutex_nonprod.inc
+++ /dev/null
@@ -1,249 +0,0 @@
-// Do not include.  This is an implementation detail of base/mutex.h.
-//
-// Declares three classes:
-//
-// base::internal::MutexImpl - implementation helper for Mutex
-// base::internal::CondVarImpl - implementation helper for CondVar
-// base::internal::SynchronizationStorage<T> - implementation helper for
-//                                             Mutex, CondVar
-
-#include <type_traits>
-
-#if defined(_WIN32)
-#include <condition_variable>
-#include <mutex>
-#else
-#include <pthread.h>
-#endif
-
-#include "absl/base/call_once.h"
-#include "absl/time/time.h"
-
-// Declare that Mutex::ReaderLock is actually Lock().  Intended primarily
-// for tests, and even then as a last resort.
-#ifdef ABSL_MUTEX_READER_LOCK_IS_EXCLUSIVE
-#error ABSL_MUTEX_READER_LOCK_IS_EXCLUSIVE cannot be directly set
-#else
-#define ABSL_MUTEX_READER_LOCK_IS_EXCLUSIVE 1
-#endif
-
-// Declare that Mutex::EnableInvariantDebugging is not implemented.
-// Intended primarily for tests, and even then as a last resort.
-#ifdef ABSL_MUTEX_ENABLE_INVARIANT_DEBUGGING_NOT_IMPLEMENTED
-#error ABSL_MUTEX_ENABLE_INVARIANT_DEBUGGING_NOT_IMPLEMENTED cannot be directly set
-#else
-#define ABSL_MUTEX_ENABLE_INVARIANT_DEBUGGING_NOT_IMPLEMENTED 1
-#endif
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-class Condition;
-
-namespace synchronization_internal {
-
-class MutexImpl;
-
-// Do not use this implementation detail of CondVar. Provides most of the
-// implementation, but should not be placed directly in static storage
-// because it will not linker initialize properly. See
-// SynchronizationStorage<T> below for what we mean by linker
-// initialization.
-class CondVarImpl {
- public:
-  CondVarImpl();
-  CondVarImpl(const CondVarImpl&) = delete;
-  CondVarImpl& operator=(const CondVarImpl&) = delete;
-  ~CondVarImpl();
-
-  void Signal();
-  void SignalAll();
-  void Wait(MutexImpl* mutex);
-  bool WaitWithDeadline(MutexImpl* mutex, absl::Time deadline);
-
- private:
-#if defined(_WIN32)
-  std::condition_variable_any std_cv_;
-#else
-  pthread_cond_t pthread_cv_;
-#endif
-};
-
-// Do not use this implementation detail of Mutex. Provides most of the
-// implementation, but should not be placed directly in static storage
-// because it will not linker initialize properly. See
-// SynchronizationStorage<T> below for what we mean by linker
-// initialization.
-class MutexImpl {
- public:
-  MutexImpl();
-  MutexImpl(const MutexImpl&) = delete;
-  MutexImpl& operator=(const MutexImpl&) = delete;
-  ~MutexImpl();
-
-  void Lock();
-  bool TryLock();
-  void Unlock();
-  void Await(const Condition& cond);
-  bool AwaitWithDeadline(const Condition& cond, absl::Time deadline);
-
- private:
-  friend class CondVarImpl;
-
-#if defined(_WIN32)
-  std::mutex std_mutex_;
-#else
-  pthread_mutex_t pthread_mutex_;
-#endif
-
-  // True if the underlying mutex is locked.  If the destructor is entered
-  // while locked_, the underlying mutex is unlocked.  Mutex supports
-  // destruction while locked, but the same is undefined behavior for both
-  // pthread_mutex_t and std::mutex.
-  bool locked_ = false;
-
-  // Signaled before releasing the lock, in support of Await.
-  CondVarImpl released_;
-};
-
-// Do not use this implementation detail of CondVar and Mutex.  A storage
-// space for T that supports a LinkerInitialized constructor. T must
-// have a default constructor, which is called by the first call to
-// get(). T's destructor is never called if the LinkerInitialized
-// constructor is called.
-//
-// Objects constructed with the default constructor are constructed and
-// destructed like any other object, and should never be allocated in
-// static storage.
-//
-// Objects constructed with the LinkerInitialized constructor should
-// always be in static storage. For such objects, calls to get() are always
-// valid, except from signal handlers.
-//
-// Note that this implementation relies on undefined language behavior that
-// are known to hold for the set of supported compilers. An analysis
-// follows.
-//
-// From the C++11 standard:
-//
-// [basic.life] says an object has non-trivial initialization if it is of
-// class type and it is initialized by a constructor other than a trivial
-// default constructor.  (the LinkerInitialized constructor is
-// non-trivial)
-//
-// [basic.life] says the lifetime of an object with a non-trivial
-// constructor begins when the call to the constructor is complete.
-//
-// [basic.life] says the lifetime of an object with non-trivial destructor
-// ends when the call to the destructor begins.
-//
-// [basic.life] p5 specifies undefined behavior when accessing non-static
-// members of an instance outside its
-// lifetime. (SynchronizationStorage::get() access non-static members)
-//
-// So, LinkerInitialized object of SynchronizationStorage uses a
-// non-trivial constructor, which is called at some point during dynamic
-// initialization, and is therefore subject to order of dynamic
-// initialization bugs, where get() is called before the object's
-// constructor is, resulting in undefined behavior.
-//
-// Similarly, a LinkerInitialized SynchronizationStorage object has a
-// non-trivial destructor, and so its lifetime ends at some point during
-// destruction of objects with static storage duration [basic.start.term]
-// p4. There is a window where other exit code could call get() after this
-// occurs, resulting in undefined behavior.
-//
-// Combined, these statements imply that LinkerInitialized instances
-// of SynchronizationStorage<T> rely on undefined behavior.
-//
-// However, in practice, the implementation works on all supported
-// compilers. Specifically, we rely on:
-//
-// a) zero-initialization being sufficient to initialize
-// LinkerInitialized instances for the purposes of calling
-// get(), regardless of when the constructor is called. This is
-// because the is_dynamic_ boolean is correctly zero-initialized to
-// false.
-//
-// b) the LinkerInitialized constructor is a NOP, and immaterial to
-// even to concurrent calls to get().
-//
-// c) the destructor being a NOP for LinkerInitialized objects
-// (guaranteed by a check for !is_dynamic_), and so any concurrent and
-// subsequent calls to get() functioning as if the destructor were not
-// called, by virtue of the instances' storage remaining valid after the
-// destructor runs.
-//
-// d) That a-c apply transitively when SynchronizationStorage<T> is the
-// only member of a class allocated in static storage.
-//
-// Nothing in the language standard guarantees that a-d hold.  In practice,
-// these hold in all supported compilers.
-//
-// Future direction:
-//
-// Ideally, we would simply use std::mutex or a similar class, which when
-// allocated statically would support use immediately after static
-// initialization up until static storage is reclaimed (i.e. the properties
-// we require of all "linker initialized" instances).
-//
-// Regarding construction in static storage, std::mutex is required to
-// provide a constexpr default constructor [thread.mutex.class], which
-// ensures the instance's lifetime begins with static initialization
-// [basic.start.init], and so is immune to any problems caused by the order
-// of dynamic initialization. However, as of this writing Microsoft's
-// Visual Studio does not provide a constexpr constructor for std::mutex.
-// See
-// https://blogs.msdn.microsoft.com/vcblog/2015/06/02/constexpr-complete-for-vs-2015-rtm-c11-compiler-c17-stl/
-//
-// Regarding destruction of instances in static storage, [basic.life] does
-// say an object ends when storage in which the occupies is released, in
-// the case of non-trivial destructor. However, std::mutex is not specified
-// to have a trivial destructor.
-//
-// So, we would need a class with a constexpr default constructor and a
-// trivial destructor. Today, we can achieve neither desired property using
-// std::mutex directly.
-template <typename T>
-class SynchronizationStorage {
- public:
-  // Instances allocated on the heap or on the stack should use the default
-  // constructor.
-  SynchronizationStorage()
-      : destruct_(true), once_() {}
-
-  constexpr explicit SynchronizationStorage(absl::ConstInitType)
-      : destruct_(false), once_(), space_{{0}} {}
-
-  SynchronizationStorage(SynchronizationStorage&) = delete;
-  SynchronizationStorage& operator=(SynchronizationStorage&) = delete;
-
-  ~SynchronizationStorage() {
-    if (destruct_) {
-      get()->~T();
-    }
-  }
-
-  // Retrieve the object in storage. This is fast and thread safe, but does
-  // incur the cost of absl::call_once().
-  T* get() {
-    absl::call_once(once_, SynchronizationStorage::Construct, this);
-    return reinterpret_cast<T*>(&space_);
-  }
-
- private:
-  static void Construct(SynchronizationStorage<T>* self) {
-    new (&self->space_) T();
-  }
-
-  // When true, T's destructor is run when this is destructed.
-  const bool destruct_;
-
-  absl::once_flag once_;
-
-  // An aligned space for the T.
-  alignas(T) unsigned char space_[sizeof(T)];
-};
-
-}  // namespace synchronization_internal
-ABSL_NAMESPACE_END
-}  // namespace absl