| 1 | /* |
| 2 | * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: LGPL-2.1-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #ifndef LTTNG_EVENTFD_HPP |
| 9 | #define LTTNG_EVENTFD_HPP |
| 10 | |
| 11 | #include <common/file-descriptor.hpp> |
| 12 | |
| 13 | #include <cstdint> |
| 14 | |
| 15 | namespace lttng { |
| 16 | |
| 17 | class eventfd : public file_descriptor { |
| 18 | public: |
| 19 | /* Throws a posix_error exception on failure to create the underlying resource. */ |
| 20 | eventfd(bool use_semaphore_semantics = true, std::uint64_t initial_value = 0); |
| 21 | eventfd(const eventfd&) = delete; |
| 22 | eventfd& operator=(const eventfd&) = delete; |
| 23 | eventfd(eventfd&&) = delete; |
| 24 | void operator=(eventfd&&) = delete; |
| 25 | |
| 26 | /* Throws on error. */ |
| 27 | void increment(std::uint64_t value = 1); |
| 28 | /* |
| 29 | * Note that decrement() will block if the underlying value of the eventfd is 0 when |
| 30 | * semaphore semantics are used, see EVENTFD(2). |
| 31 | * |
| 32 | * decrement() returns the new value of the underlying counter of the eventfd. |
| 33 | * |
| 34 | * Throws on error. |
| 35 | */ |
| 36 | std::uint64_t decrement(); |
| 37 | }; |
| 38 | |
| 39 | } /* namespace lttng */ |
| 40 | |
| 41 | #endif /* LTTNG_EVENTFD_HPP */ |