1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149

//! Channel error types.

use std::error::Error;
use std::fmt;

/// Error returned by the `Sender`.
#[derive(PartialEq, Eq, Clone, Copy)]
pub struct SendError<T>(pub T);

impl<T> fmt::Debug for SendError<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("SendError").finish_non_exhaustive()
    }
}

impl<T> fmt::Display for SendError<T> {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(fmt, "channel closed")
    }
}

impl<T> Error for SendError<T> {}

// ===== TrySendError =====

/// This enumeration is the list of the possible error outcomes for the
/// [`try_send`](super::Sender::try_send) method.
#[derive(PartialEq, Eq, Clone, Copy)]
pub enum TrySendError<T> {
    /// The data could not be sent on the channel because the channel is
    /// currently full and sending would require blocking.
    Full(T),

    /// The receive half of the channel was explicitly closed or has been
    /// dropped.
    Closed(T),
}

impl<T> fmt::Debug for TrySendError<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            TrySendError::Full(..) => "Full(..)".fmt(f),
            TrySendError::Closed(..) => "Closed(..)".fmt(f),
        }
    }
}

impl<T> fmt::Display for TrySendError<T> {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(
            fmt,
            "{}",
            match self {
                TrySendError::Full(..) => "no available capacity",
                TrySendError::Closed(..) => "channel closed",
            }
        )
    }
}

impl<T> Error for TrySendError<T> {}

impl<T> From<SendError<T>> for TrySendError<T> {
    fn from(src: SendError<T>) -> TrySendError<T> {
        TrySendError::Closed(src.0)
    }
}

// ===== TryRecvError =====

/// Error returned by `try_recv`.
#[derive(PartialEq, Eq, Clone, Copy, Debug)]
pub enum TryRecvError {
    /// This **channel** is currently empty, but the **Sender**(s) have not yet
    /// disconnected, so data may yet become available.
    Empty,
    /// The **channel**'s sending half has become disconnected, and there will
    /// never be any more data received on it.
    Disconnected,
}

impl fmt::Display for TryRecvError {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        match *self {
            TryRecvError::Empty => "receiving on an empty channel".fmt(fmt),
            TryRecvError::Disconnected => "receiving on a closed channel".fmt(fmt),
        }
    }
}

impl Error for TryRecvError {}

// ===== RecvError =====

/// Error returned by `Receiver`.
#[derive(Debug, Clone)]
#[doc(hidden)]
#[deprecated(note = "This type is unused because recv returns an Option.")]
pub struct RecvError(());

#[allow(deprecated)]
impl fmt::Display for RecvError {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(fmt, "channel closed")
    }
}

#[allow(deprecated)]
impl Error for RecvError {}

cfg_time! {
    // ===== SendTimeoutError =====

    #[derive(PartialEq, Eq, Clone, Copy)]
    /// Error returned by [`Sender::send_timeout`](super::Sender::send_timeout)].
    pub enum SendTimeoutError<T> {
        /// The data could not be sent on the channel because the channel is
        /// full, and the timeout to send has elapsed.
        Timeout(T),

        /// The receive half of the channel was explicitly closed or has been
        /// dropped.
        Closed(T),
    }

    impl<T> fmt::Debug for SendTimeoutError<T> {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            match *self {
                SendTimeoutError::Timeout(..) => "Timeout(..)".fmt(f),
                SendTimeoutError::Closed(..) => "Closed(..)".fmt(f),
            }
        }
    }

    impl<T> fmt::Display for SendTimeoutError<T> {
        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
            write!(
                fmt,
                "{}",
                match self {
                    SendTimeoutError::Timeout(..) => "timed out waiting on send operation",
                    SendTimeoutError::Closed(..) => "channel closed",
                }
            )
        }
    }

    impl<T> Error for SendTimeoutError<T> {}
}