refactor: remove EventFd::defuse() and EventFd::arm() (#2452)

* fix: remove Eventfd::arm() and defuse()

* chore: changelog entry

Author: SteveLauC

changelog/2452.removed.md

@@ -0,0 +1 @@
+`EventFd::defuse()` is removed because it does nothing, `EventFd::arm()` is also removed for symmetry reasons.

src/sys/epoll.rs

@@ -88,7 +88,7 @@ impl EpollEvent {
 /// epoll.add(&eventfd, EpollEvent::new(EpollFlags::EPOLLIN,DATA))?;
 ///
 /// // Arm eventfd & Time wait
-/// eventfd.arm()?;
+/// eventfd.write(1)?;
 /// let now = Instant::now();
 ///
 /// // Wait on event

src/sys/eventfd.rs

@@ -58,20 +58,6 @@ impl EventFd {
         Self::from_value_and_flags(init_val, EfdFlags::empty())
     }
 
-    /// Arms `self`, a following call to `poll`, `select` or `epoll` will return immediately.
-    ///
-    /// [`EventFd::write`] with `1`.
-    pub fn arm(&self) -> Result<usize> {
-        self.write(1)
-    }
-
-    /// Defuses `self`, a following call to `poll`, `select` or `epoll` will block.
-    ///
-    /// [`EventFd::write`] with `0`.
-    pub fn defuse(&self) -> Result<usize> {
-        self.write(0)
-    }
-
     /// Enqueues `value` triggers, i.e., adds the integer value supplied in `value`
     /// to the counter.
     ///