0 on success, or -1 with errno set on failure (e.g., EAGAIN
if the counter would overflow).
Write to an eventfd to trigger a wakeup notification.
Increments the eventfd counter by 1, making it readable and triggering any epoll/io_uring watcher on the handle.
handle | The eventfd handle to write to. |
0 on success, or -1 with errno set on failure (e.g., EAGAIN
if the counter would overflow).