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
/// Wait on multiple concurrent branches, returning when **all** branches
/// complete.
///
/// The `join!` macro must be used inside of async functions, closures, and
/// blocks.
///
/// The `join!` macro takes a list of async expressions and evaluates them
/// concurrently on the same task. Each async expression evaluates to a future
/// and the futures from each expression are multiplexed on the current task.
///
/// When working with async expressions returning `Result`, `join!` will wait
/// for **all** branches complete regardless if any complete with `Err`. Use
/// [`try_join!`] to return early when `Err` is encountered.
///
/// [`try_join!`]: macro@try_join
///
/// # Notes
///
/// The supplied futures are stored inline and does not require allocating a
/// `Vec`.
///
/// ### Runtime characteristics
///
/// By running all async expressions on the current task, the expressions are
/// able to run **concurrently** but not in **parallel**. This means all
/// expressions are run on the same thread and if one branch blocks the thread,
/// all other expressions will be unable to continue. If parallelism is
/// required, spawn each async expression using [`tokio::spawn`] and pass the
/// join handle to `join!`.
///
/// [`tokio::spawn`]: crate::spawn
///
/// # Examples
///
/// Basic join with two branches
///
/// ```
/// async fn do_stuff_async() {
/// // async work
/// }
///
/// async fn more_async_work() {
/// // more here
/// }
///
/// #[tokio::main]
/// async fn main() {
/// let (first, second) = tokio::join!(
/// do_stuff_async(),
/// more_async_work());
///
/// // do something with the values
/// }
/// ```
) => ;
// ===== Normalize =====
=> ;
// ===== Entry point =====
=> ;
}