[lttng-tools.git] / src / common / eventfd.hpp

/*
 * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 */

#ifndef LTTNG_EVENTFD_HPP
#define LTTNG_EVENTFD_HPP

#include <common/file-descriptor.hpp>

#include <cstdint>

namespace lttng {

class eventfd : public file_descriptor {
public:
	/* Throws a posix_error exception on failure to create the underlying resource. */
	explicit eventfd(bool use_semaphore_semantics = true, std::uint64_t initial_value = 0);
	eventfd(const eventfd&) = delete;
	eventfd& operator=(const eventfd&) = delete;
	eventfd(eventfd&&) = delete;
	void operator=(eventfd&&) = delete;
	~eventfd() = default;

	/* Throws on error. */
	void increment(std::uint64_t value = 1);
	/*
	 * Note that decrement() will block if the underlying value of the eventfd is 0 when
	 * semaphore semantics are used, see EVENTFD(2).
	 *
	 * decrement() returns the new value of the underlying counter of the eventfd.
	 *
	 * Throws on error.
	 */
	std::uint64_t decrement();
};

} /* namespace lttng */

#endif /* LTTNG_EVENTFD_HPP */
Commit	Line	Data
20c734f5 JG	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. */
b4853cf4	20	explicit eventfd(bool use_semaphore_semantics = true, std::uint64_t initial_value = 0);
20c734f5 JG	21	eventfd(const eventfd&) = delete;
	22	eventfd& operator=(const eventfd&) = delete;
	23	eventfd(eventfd&&) = delete;
	24	void operator=(eventfd&&) = delete;
b4853cf4	25	~eventfd() = default;
20c734f5 JG	26
	27	/* Throws on error. */
	28	void increment(std::uint64_t value = 1);
	29	/*
	30	* Note that decrement() will block if the underlying value of the eventfd is 0 when
	31	* semaphore semantics are used, see EVENTFD(2).
	32	*
	33	* decrement() returns the new value of the underlying counter of the eventfd.
	34	*
	35	* Throws on error.
	36	*/
	37	std::uint64_t decrement();
	38	};
	39
	40	} /* namespace lttng */
	41
	42	#endif /* LTTNG_EVENTFD_HPP */