| 1 | /* |
| 2 | * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: LGPL-2.1-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include "eventfd.hpp" |
| 9 | |
| 10 | #include <common/exception.hpp> |
| 11 | #include <common/format.hpp> |
| 12 | #include <common/readwrite.hpp> |
| 13 | |
| 14 | #include <sys/eventfd.h> |
| 15 | |
| 16 | lttng::eventfd::eventfd(bool use_semaphore_semantics, std::uint64_t initial_value) : |
| 17 | file_descriptor([use_semaphore_semantics, initial_value]() { |
| 18 | int flags = ::EFD_CLOEXEC; |
| 19 | |
| 20 | if (use_semaphore_semantics) { |
| 21 | flags |= ::EFD_SEMAPHORE; |
| 22 | } |
| 23 | |
| 24 | const auto raw_fd = ::eventfd(initial_value, flags); |
| 25 | if (raw_fd < 0) { |
| 26 | LTTNG_THROW_POSIX("Failed to create eventfd", errno); |
| 27 | } |
| 28 | |
| 29 | return raw_fd; |
| 30 | }()) |
| 31 | { |
| 32 | } |
| 33 | |
| 34 | void lttng::eventfd::increment(std::uint64_t value) |
| 35 | { |
| 36 | try { |
| 37 | write(&value, sizeof(value)); |
| 38 | } catch (const std::exception& e) { |
| 39 | LTTNG_THROW_ERROR(lttng::format("Failed to increment eventfd: {}", e.what())); |
| 40 | } |
| 41 | } |
| 42 | |
| 43 | std::uint64_t lttng::eventfd::decrement() |
| 44 | { |
| 45 | std::uint64_t value; |
| 46 | |
| 47 | try { |
| 48 | read(&value, sizeof(value)); |
| 49 | } catch (const std::exception& e) { |
| 50 | LTTNG_THROW_ERROR(lttng::format("Failed to decrement eventfd: {}", e.what())); |
| 51 | } |
| 52 | |
| 53 | return value; |
| 54 | } |