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Diffstat (limited to 'absl/synchronization/internal/sem_waiter.h')
-rw-r--r-- | absl/synchronization/internal/sem_waiter.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/absl/synchronization/internal/sem_waiter.h b/absl/synchronization/internal/sem_waiter.h new file mode 100644 index 00000000..c22746f9 --- /dev/null +++ b/absl/synchronization/internal/sem_waiter.h @@ -0,0 +1,65 @@ +// 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_ |