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// Copyright 2023 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_SEM_WAITER_H_
#define ABSL_SYNCHRONIZATION_INTERNAL_SEM_WAITER_H_
#include "absl/base/config.h"
#ifdef ABSL_HAVE_SEMAPHORE_H
#include <semaphore.h>
#include <atomic>
#include <cstdint>
#include "absl/base/internal/thread_identity.h"
#include "absl/synchronization/internal/futex.h"
#include "absl/synchronization/internal/kernel_timeout.h"
#include "absl/synchronization/internal/waiter_base.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace synchronization_internal {
#define ABSL_INTERNAL_HAVE_SEM_WAITER 1
class SemWaiter : public WaiterCrtp<SemWaiter> {
public:
SemWaiter();
bool Wait(KernelTimeout t);
void Post();
void Poke();
static constexpr char kName[] = "SemWaiter";
private:
int TimedWait(KernelTimeout t);
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_;
};
} // namespace synchronization_internal
ABSL_NAMESPACE_END
} // namespace absl
#endif // ABSL_HAVE_SEMAPHORE_H
#endif // ABSL_SYNCHRONIZATION_INTERNAL_SEM_WAITER_H_
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