Remove number of sent messages in sendmmsg, because it can be easily retrieved from Vec len. Improve docs

Author: Gleb Pomykalov

src/sys/socket/mod.rs

@@ -811,9 +811,9 @@ pub struct SendMmsgData<'a, I, C>
     pub _lt: std::marker::PhantomData<&'a I>,
 }
 
-/// An extension of [`sendmsg`] that allows the caller to transmit multiple
-/// messages on a socket using a single system call.  (This has performance
-/// benefits for some applications.).
+/// An extension of `sendmsg` that allows the caller to transmit multiple
+/// messages on a socket using a single system call. This has performance
+/// benefits for some applications.
 ///
 /// Allocations are performed for cmsgs and to build `msghdr` buffer
 ///
@@ -823,11 +823,11 @@ pub struct SendMmsgData<'a, I, C>
 /// * `data`:           Struct that implements `IntoIterator` with `SendMmsgData` items
 /// * `flags`:          Optional flags passed directly to the operating system.
 ///
-/// Returns tuple, where the first value is number of sent messages, and the second one
-/// it a `Vec` with numbers of bytes sent on each appropriate message.
+/// # Returns
+/// `Vec` with numbers of sent bytes on each sent message.
 ///
-///# References
-/// [`sendmmsg`](fn.sendmsg.html)
+/// # References
+/// [`sendmsg`](fn.sendmsg.html)
 #[cfg(any(
     target_os = "linux",
     target_os = "android",
@@ -839,7 +839,7 @@ pub fn sendmmsg<'a, I, C>(
     fd: RawFd,
     data: impl std::iter::IntoIterator<Item=&'a SendMmsgData<'a, I, C>>,
     flags: MsgFlags
-) -> Result<(usize, Vec<usize>)>
+) -> Result<Vec<usize>>
     where
         I: AsRef<[IoVec<&'a [u8]>]> + 'a,
         C: AsRef<[ControlMessage<'a>]> + 'a,
@@ -888,7 +888,7 @@ pub fn sendmmsg<'a, I, C>(
         sent_bytes[i] = initialized_data[i].msg_len as usize;
     }
 
-    Ok((sent_messages, sent_bytes))
+    Ok(sent_bytes)
 }
 
 
@@ -902,11 +902,11 @@ pub struct RecvMmsgData<'a, I>
     pub cmsg_buffer: Option<&'a mut Vec<u8>>,
 }
 
-/// An extension of [`recvmsg`] that allows the caller to receive multiple
-/// messages from a socket using a single system call.  (This has
-/// performance benefits for some applications.)
+/// An extension of `recvmsg` that allows the caller to receive multiple
+/// messages from a socket using a single system call. This has
+/// performance benefits for some applications.
 ///
-/// `iov` and `cmsg_buffer` should be constucted similarly to recvmsg
+/// `iov` and `cmsg_buffer` should be constructed similarly to `recvmsg`
 ///
 /// Multiple allocations are performed
 ///
@@ -922,8 +922,12 @@ pub struct RecvMmsgData<'a, I>
 /// * `cmsg_buffer`:    Space to receive ancillary data.  Should be created by
 ///                     [`cmsg_space!`](macro.cmsg_space.html)
 ///
+/// # Returns
+/// A `Vec` with multiple `RecvMsg`, one per received message
+///
 /// # References
-/// [`recvmsg`](fn.recvmsg.html)
+/// - [`recvmsg`](fn.recvmsg.html)
+/// - [`RecvMsg`](struct.RecvMsg.html)
 #[cfg(any(
     target_os = "linux",
     target_os = "android",

test/sys/test_socket.rs

@@ -282,13 +282,12 @@ mod recvfrom {
                 );
             }
             sendmmsg(s, msgs.iter(), flags)
-                .map(move |(sent_messages, sent_bytes)| {
-                    assert!(sent_messages >= 1);
-                    assert_eq!(sent_bytes.len(), sent_messages);
+                .map(move |sent_bytes| {
+                    assert!(sent_bytes.len() >= 1);
                     for sent in &sent_bytes {
                         assert_eq!(*sent, m.len());
                     }
-                    sent_messages
+                    sent_bytes.len()
                 })
         });
         // UDP sockets should set the from address