Client::poll_ready and send_request may return Connection Errors (#132)

Closes #131

src/proto/error.rs

@@ -1,4 +1,4 @@
-use codec::RecvError;
+use codec::{RecvError, SendError};
 use frame::Reason;
 
 use std::io;
@@ -11,12 +11,13 @@ pub enum Error {
 }
 
 impl Error {
-    pub fn into_connection_recv_error(self) -> RecvError {
-        use self::Error::*;
-
-        match self {
-            Proto(reason) => RecvError::Connection(reason),
-            Io(e) => RecvError::Io(e),
+    /// Clone the error for internal purposes.
+    ///
+    /// `io::Error` is not `Clone`, so we only copy the `ErrorKind`.
+    pub(super) fn shallow_clone(&self) -> Error {
+        match *self {
+            Error::Proto(reason) => Error::Proto(reason),
+            Error::Io(ref io) => Error::Io(io::Error::from(io.kind())),
         }
     }
 }
@@ -32,3 +33,21 @@ impl From<io::Error> for Error {
         Error::Io(src)
     }
 }
+
+impl From<Error> for RecvError {
+    fn from(src: Error) -> RecvError {
+        match src {
+            Error::Proto(reason) => RecvError::Connection(reason),
+            Error::Io(e) => RecvError::Io(e),
+        }
+    }
+}
+
+impl From<Error> for SendError {
+    fn from(src: Error) -> SendError {
+        match src {
+            Error::Proto(reason) => SendError::Connection(reason),
+            Error::Io(e) => SendError::Io(e),
+        }
+    }
+}