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
150
151
152
153
154
155
156
157
158
159
160
161
162
163
use std::any::Any;
use std::fmt;
use std::io;
use std::sync::Mutex;
doc_rt_core! {
/// Task failed to execute to completion.
pub struct JoinError {
repr: Repr,
}
}
enum Repr {
Cancelled,
Panic(Mutex<Box<dyn Any + Send + 'static>>),
}
impl JoinError {
#[doc(hidden)]
#[deprecated]
pub fn cancelled() -> JoinError {
Self::cancelled2()
}
pub(crate) fn cancelled2() -> JoinError {
JoinError {
repr: Repr::Cancelled,
}
}
#[doc(hidden)]
#[deprecated]
pub fn panic(err: Box<dyn Any + Send + 'static>) -> JoinError {
Self::panic2(err)
}
pub(crate) fn panic2(err: Box<dyn Any + Send + 'static>) -> JoinError {
JoinError {
repr: Repr::Panic(Mutex::new(err)),
}
}
/// Returns true if the error was caused by the task being cancelled
pub fn is_cancelled(&self) -> bool {
match &self.repr {
Repr::Cancelled => true,
_ => false,
}
}
/// Returns true if the error was caused by the task panicking
///
/// # Examples
///
/// ```
/// use std::panic;
///
/// #[tokio::main]
/// async fn main() {
/// let err = tokio::spawn(async {
/// panic!("boom");
/// }).await.unwrap_err();
///
/// assert!(err.is_panic());
/// }
/// ```
pub fn is_panic(&self) -> bool {
match &self.repr {
Repr::Panic(_) => true,
_ => false,
}
}
/// Consumes the join error, returning the object with which the task panicked.
///
/// # Panics
///
/// `into_panic()` panics if the `Error` does not represent the underlying
/// task terminating with a panic. Use `is_panic` to check the error reason
/// or `try_into_panic` for a variant that does not panic.
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// #[tokio::main]
/// async fn main() {
/// let err = tokio::spawn(async {
/// panic!("boom");
/// }).await.unwrap_err();
///
/// if err.is_panic() {
/// // Resume the panic on the main task
/// panic::resume_unwind(err.into_panic());
/// }
/// }
/// ```
pub fn into_panic(self) -> Box<dyn Any + Send + 'static> {
self.try_into_panic()
.expect("`JoinError` reason is not a panic.")
}
/// Consumes the join error, returning the object with which the task
/// panicked if the task terminated due to a panic. Otherwise, `self` is
/// returned.
///
/// # Examples
///
/// ```should_panic
/// use std::panic;
///
/// #[tokio::main]
/// async fn main() {
/// let err = tokio::spawn(async {
/// panic!("boom");
/// }).await.unwrap_err();
///
/// if let Ok(reason) = err.try_into_panic() {
/// // Resume the panic on the main task
/// panic::resume_unwind(reason);
/// }
/// }
/// ```
pub fn try_into_panic(self) -> Result<Box<dyn Any + Send + 'static>, JoinError> {
match self.repr {
Repr::Panic(p) => Ok(p.into_inner().expect("Extracting panic from mutex")),
_ => Err(self),
}
}
}
impl fmt::Display for JoinError {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self.repr {
Repr::Cancelled => write!(fmt, "cancelled"),
Repr::Panic(_) => write!(fmt, "panic"),
}
}
}
impl fmt::Debug for JoinError {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self.repr {
Repr::Cancelled => write!(fmt, "JoinError::Cancelled"),
Repr::Panic(_) => write!(fmt, "JoinError::Panic(...)"),
}
}
}
impl std::error::Error for JoinError {}
impl From<JoinError> for io::Error {
fn from(src: JoinError) -> io::Error {
io::Error::new(
io::ErrorKind::Other,
match src.repr {
Repr::Cancelled => "task was cancelled",
Repr::Panic(_) => "task panicked",
},
)
}
}