lazily 0.54.0

Lazy reactive signals with dependency tracking and cache invalidation
Documentation 
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

use std::cell::Cell;
use std::time::{Duration, Instant};

use lazily::stdlib::{Timeout, TimeoutOperation, TimeoutOutcome, TimeoutPoll};

#[test]
fn completion_before_deadline_is_latched() {
    let start = Instant::now();
    let mut timeout = Timeout::at(start + Duration::from_secs(5));
    let operation_calls = Cell::new(0);

    assert_eq!(
        timeout.poll_at(
            start,
            || {
                operation_calls.set(operation_calls.get() + 1);
                TimeoutOperation::Completed("ready")
            },
            || false,
        ),
        TimeoutPoll::Completed(&"ready")
    );
    assert_eq!(timeout.outcome(), Some(&TimeoutOutcome::Completed("ready")));
    assert!(timeout.is_terminal());

    assert_eq!(
        timeout.poll_at(
            start + Duration::from_secs(10),
            || panic!("terminal timeout polled the operation again"),
            || panic!("terminal timeout polled cancellation again"),
        ),
        TimeoutPoll::Completed(&"ready")
    );
    assert_eq!(operation_calls.get(), 1);
}

#[test]
fn pending_operation_times_out_at_the_deadline() {
    let start = Instant::now();
    let deadline = start + Duration::from_secs(3);
    let mut timeout = Timeout::<()>::at(deadline);

    assert_eq!(
        timeout.poll_at(start, || TimeoutOperation::Pending, || false),
        TimeoutPoll::Pending {
            remaining: Duration::from_secs(3)
        }
    );
    assert_eq!(
        timeout.poll_at(deadline, || TimeoutOperation::Pending, || false),
        TimeoutPoll::TimedOut
    );
    assert_eq!(timeout.outcome(), Some(&TimeoutOutcome::TimedOut));

    assert_eq!(
        timeout.poll_at(
            deadline + Duration::from_secs(1),
            || panic!("terminal timeout polled the operation again"),
            || panic!("terminal timeout polled cancellation again"),
        ),
        TimeoutPoll::TimedOut
    );
}

#[test]
fn completion_wins_a_pre_deadline_cancellation_race() {
    let start = Instant::now();
    let mut completed = Timeout::at(start + Duration::from_secs(1));

    assert_eq!(
        completed.poll_at(start, || TimeoutOperation::Completed(42), || true,),
        TimeoutPoll::Completed(&42)
    );

    let mut cancelled = Timeout::<()>::at(start + Duration::from_secs(1));
    assert_eq!(
        cancelled.poll_at(start, || TimeoutOperation::Pending, || true),
        TimeoutPoll::Cancelled
    );
    assert_eq!(cancelled.outcome(), Some(&TimeoutOutcome::Cancelled));
}

#[test]
fn zero_duration_is_immediately_timed_out() {
    let now = Instant::now();
    let mut timeout = Timeout::<()>::at(now);

    assert_eq!(
        timeout.poll_at(
            now,
            || panic!("zero-duration timeout polled the operation"),
            || panic!("zero-duration timeout polled cancellation"),
        ),
        TimeoutPoll::TimedOut
    );
}

#[test]
fn unavailable_operation_is_a_latched_terminal_outcome() {
    let start = Instant::now();
    let mut timeout = Timeout::<()>::at(start + Duration::from_secs(1));

    assert_eq!(
        timeout.poll_at(start, || TimeoutOperation::Unavailable, || false),
        TimeoutPoll::Unavailable
    );
    assert_eq!(timeout.outcome(), Some(&TimeoutOutcome::Unavailable));
    assert_eq!(
        timeout.poll_at(
            start,
            || panic!("terminal timeout polled the operation again"),
            || panic!("terminal timeout polled cancellation again"),
        ),
        TimeoutPoll::Unavailable
    );
}

#[test]
fn wait_with_exposes_deterministic_clock_and_wait_seams() {
    let start = Instant::now();
    let clock = Cell::new(start);
    let ready = Cell::new(false);
    let wait_calls = Cell::new(0);
    let mut timeout = Timeout::at(start + Duration::from_secs(5));

    let outcome = timeout.wait_with(
        || {
            if ready.get() {
                TimeoutOperation::Completed("done")
            } else {
                TimeoutOperation::Pending
            }
        },
        || false,
        || clock.get(),
        |remaining| {
            assert_eq!(remaining, Duration::from_secs(5));
            wait_calls.set(wait_calls.get() + 1);
            ready.set(true);
            clock.set(start + Duration::from_secs(1));
        },
    );

    assert_eq!(outcome, &TimeoutOutcome::Completed("done"));
    assert_eq!(wait_calls.get(), 1);
}