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Diffstat (limited to 'third_party/abseil_cpp/absl/synchronization/internal/waiter.h')
-rw-r--r-- | third_party/abseil_cpp/absl/synchronization/internal/waiter.h | 155 |
1 files changed, 0 insertions, 155 deletions
diff --git a/third_party/abseil_cpp/absl/synchronization/internal/waiter.h b/third_party/abseil_cpp/absl/synchronization/internal/waiter.h deleted file mode 100644 index be3df180d4e2..000000000000 --- a/third_party/abseil_cpp/absl/synchronization/internal/waiter.h +++ /dev/null @@ -1,155 +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. -// - -#ifndef ABSL_SYNCHRONIZATION_INTERNAL_WAITER_H_ -#define ABSL_SYNCHRONIZATION_INTERNAL_WAITER_H_ - -#include "absl/base/config.h" - -#ifdef _WIN32 -#include <sdkddkver.h> -#else -#include <pthread.h> -#endif - -#ifdef __linux__ -#include <linux/futex.h> -#endif - -#ifdef ABSL_HAVE_SEMAPHORE_H -#include <semaphore.h> -#endif - -#include <atomic> -#include <cstdint> - -#include "absl/base/internal/thread_identity.h" -#include "absl/synchronization/internal/futex.h" -#include "absl/synchronization/internal/kernel_timeout.h" - -// May be chosen at compile time via -DABSL_FORCE_WAITER_MODE=<index> -#define ABSL_WAITER_MODE_FUTEX 0 -#define ABSL_WAITER_MODE_SEM 1 -#define ABSL_WAITER_MODE_CONDVAR 2 -#define ABSL_WAITER_MODE_WIN32 3 - -#if defined(ABSL_FORCE_WAITER_MODE) -#define ABSL_WAITER_MODE ABSL_FORCE_WAITER_MODE -#elif defined(_WIN32) && _WIN32_WINNT >= _WIN32_WINNT_VISTA -#define ABSL_WAITER_MODE ABSL_WAITER_MODE_WIN32 -#elif defined(ABSL_INTERNAL_HAVE_FUTEX) -#define ABSL_WAITER_MODE ABSL_WAITER_MODE_FUTEX -#elif defined(ABSL_HAVE_SEMAPHORE_H) -#define ABSL_WAITER_MODE ABSL_WAITER_MODE_SEM -#else -#define ABSL_WAITER_MODE ABSL_WAITER_MODE_CONDVAR -#endif - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace synchronization_internal { - -// Waiter is an OS-specific semaphore. -class Waiter { - public: - // Prepare any data to track waits. - Waiter(); - - // Not copyable or movable - Waiter(const Waiter&) = delete; - Waiter& operator=(const Waiter&) = delete; - - // Destroy any data to track waits. - ~Waiter(); - - // Blocks the calling thread until a matching call to `Post()` or - // `t` has passed. Returns `true` if woken (`Post()` called), - // `false` on timeout. - bool Wait(KernelTimeout t); - - // Restart the caller of `Wait()` as with a normal semaphore. - void Post(); - - // If anyone is waiting, wake them up temporarily and cause them to - // call `MaybeBecomeIdle()`. They will then return to waiting for a - // `Post()` or timeout. - void Poke(); - - // Returns the Waiter associated with the identity. - static Waiter* GetWaiter(base_internal::ThreadIdentity* identity) { - static_assert( - sizeof(Waiter) <= sizeof(base_internal::ThreadIdentity::WaiterState), - "Insufficient space for Waiter"); - return reinterpret_cast<Waiter*>(identity->waiter_state.data); - } - - // How many periods to remain idle before releasing resources -#ifndef ABSL_HAVE_THREAD_SANITIZER - static constexpr int kIdlePeriods = 60; -#else - // Memory consumption under ThreadSanitizer is a serious concern, - // so we release resources sooner. The value of 1 leads to 1 to 2 second - // delay before marking a thread as idle. - static const int kIdlePeriods = 1; -#endif - - private: -#if ABSL_WAITER_MODE == ABSL_WAITER_MODE_FUTEX - // Futexes are defined by specification to be 32-bits. - // Thus std::atomic<int32_t> must be just an int32_t with lockfree methods. - std::atomic<int32_t> futex_; - static_assert(sizeof(int32_t) == sizeof(futex_), "Wrong size for futex"); - -#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_CONDVAR - // REQUIRES: mu_ must be held. - void InternalCondVarPoke(); - - pthread_mutex_t mu_; - pthread_cond_t cv_; - int waiter_count_; - int wakeup_count_; // Unclaimed wakeups. - -#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_SEM - sem_t sem_; - // This seems superfluous, but for Poke() we need to cause spurious - // wakeups on the semaphore. Hence we can't actually use the - // semaphore's count. - std::atomic<int> wakeups_; - -#elif ABSL_WAITER_MODE == ABSL_WAITER_MODE_WIN32 - // WinHelper - Used to define utilities for accessing the lock and - // condition variable storage once the types are complete. - class WinHelper; - - // REQUIRES: WinHelper::GetLock(this) must be held. - void InternalCondVarPoke(); - - // We can't include Windows.h in our headers, so we use aligned charachter - // buffers to define the storage of SRWLOCK and CONDITION_VARIABLE. - alignas(void*) unsigned char mu_storage_[sizeof(void*)]; - alignas(void*) unsigned char cv_storage_[sizeof(void*)]; - int waiter_count_; - int wakeup_count_; - -#else - #error Unknown ABSL_WAITER_MODE -#endif -}; - -} // namespace synchronization_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_SYNCHRONIZATION_INTERNAL_WAITER_H_ |