Add the lttng::eventfd class

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

diff --git a/src/common/eventfd.cpp b/src/common/eventfd.cpp
new file mode 100644 (file)
index 0000000..6858526
--- /dev/null
+++ b/src/common/eventfd.cpp
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#include "eventfd.hpp"
+
+#include <common/exception.hpp>
+#include <common/format.hpp>
+#include <common/readwrite.hpp>
+
+#include <sys/eventfd.h>
+
+lttng::eventfd::eventfd(bool use_semaphore_semantics, std::uint64_t initial_value) :
+       file_descriptor([use_semaphore_semantics, initial_value]() {
+               int flags = ::EFD_CLOEXEC;
+
+               if (use_semaphore_semantics) {
+                       flags |= ::EFD_SEMAPHORE;
+               }
+
+               const auto raw_fd = ::eventfd(initial_value, flags);
+               if (raw_fd < 0) {
+                       LTTNG_THROW_POSIX("Failed to create eventfd", errno);
+               }
+
+               return raw_fd;
+       }())
+{
+}
+
+void lttng::eventfd::increment(std::uint64_t value)
+{
+       try {
+               write(&value, sizeof(value));
+       } catch (const std::exception& e) {
+               LTTNG_THROW_ERROR(fmt::format("Failed to increment eventfd: {}", e.what()));
+       }
+}
+
+std::uint64_t lttng::eventfd::decrement()
+{
+       std::uint64_t value;
+
+       try {
+               read(&value, sizeof(value));
+       } catch (const std::exception& e) {
+               LTTNG_THROW_ERROR(fmt::format("Failed to decrement eventfd: {}", e.what()));
+       }
+
+       return value;
+}