x::eventfd
is a reference to a reference-counted object that implements the
Linux kernel eventfd(2) API.
x::eventfd ev(x::eventfd::create()); // ... ev->event(1); // ... eventfd_t cnt=ev->event();
event(n) increments
the event file descriptor's event counter by
n (calling the
eventfd_write() function, as documented in the
eventfd(2)
manual page. event() calls
eventfd_read, and returns the event count.
The event file descriptor inherits from the
file descriptor object.
It is safe to use the following methods from the underlying file
descriptor object:
epoll()
(allowing the file descriptor object to be used in an
epoll set),
closeonexec(),
nonblock(), and
get_fd(). Using other methods is discouraged,
to avoid unintended side-effects.