initial port of crossbeam-channel

library/std/src/sync/mpmc/error.rs

@@ -0,0 +1,46 @@
+use crate::error;
+use crate::fmt;
+
+pub use crate::sync::mpsc::{RecvError, RecvTimeoutError, SendError, TryRecvError, TrySendError};
+
+/// An error returned from the [`send_timeout`] method.
+///
+/// The error contains the message being sent so it can be recovered.
+///
+/// [`send_timeout`]: super::Sender::send_timeout
+#[derive(PartialEq, Eq, Clone, Copy)]
+pub enum SendTimeoutError<T> {
+    /// The message could not be sent because the channel is full and the operation timed out.
+    ///
+    /// If this is a zero-capacity channel, then the error indicates that there was no receiver
+    /// available to receive the message and the operation timed out.
+    Timeout(T),
+
+    /// The message could not be sent because the channel is disconnected.
+    Disconnected(T),
+}
+
+impl<T> fmt::Debug for SendTimeoutError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        "SendTimeoutError(..)".fmt(f)
+    }
+}
+
+impl<T> fmt::Display for SendTimeoutError<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match *self {
+            SendTimeoutError::Timeout(..) => "timed out waiting on send operation".fmt(f),
+            SendTimeoutError::Disconnected(..) => "sending on a disconnected channel".fmt(f),
+        }
+    }
+}
+
+impl<T: Send> error::Error for SendTimeoutError<T> {}
+
+impl<T> From<SendError<T>> for SendTimeoutError<T> {
+    fn from(err: SendError<T>) -> SendTimeoutError<T> {
+        match err {
+            SendError(e) => SendTimeoutError::Disconnected(e),
+        }
+    }
+}