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
|
use rand::distributions::Uniform;
use rand::{thread_rng, Rng};
use rayon::prelude::*;
use std::cell::Cell;
use std::cmp::{self, Ordering};
use std::panic;
use std::sync::atomic::AtomicUsize;
use std::sync::atomic::Ordering::Relaxed;
use std::thread;
static VERSIONS: AtomicUsize = AtomicUsize::new(0);
lazy_static::lazy_static! {
static ref DROP_COUNTS: Vec<AtomicUsize> = (0..20_000).map(|_| AtomicUsize::new(0)).collect();
}
#[derive(Clone, Eq)]
struct DropCounter {
x: u32,
id: usize,
version: Cell<usize>,
}
impl PartialEq for DropCounter {
fn eq(&self, other: &Self) -> bool {
self.partial_cmp(other) == Some(Ordering::Equal)
}
}
impl PartialOrd for DropCounter {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
self.version.set(self.version.get() + 1);
other.version.set(other.version.get() + 1);
VERSIONS.fetch_add(2, Relaxed);
self.x.partial_cmp(&other.x)
}
}
impl Ord for DropCounter {
fn cmp(&self, other: &Self) -> Ordering {
self.partial_cmp(other).unwrap()
}
}
impl Drop for DropCounter {
fn drop(&mut self) {
DROP_COUNTS[self.id].fetch_add(1, Relaxed);
VERSIONS.fetch_sub(self.version.get(), Relaxed);
}
}
macro_rules! test {
($input:ident, $func:ident) => {
let len = $input.len();
// Work out the total number of comparisons required to sort
// this array...
let count = AtomicUsize::new(0);
$input.to_owned().$func(|a, b| {
count.fetch_add(1, Relaxed);
a.cmp(b)
});
let mut panic_countdown = count.load(Relaxed);
let step = if len <= 100 {
1
} else {
cmp::max(1, panic_countdown / 10)
};
// ... and then panic after each `step` comparisons.
loop {
// Refresh the counters.
VERSIONS.store(0, Relaxed);
for i in 0..len {
DROP_COUNTS[i].store(0, Relaxed);
}
let v = $input.to_owned();
let _ = thread::spawn(move || {
let mut v = v;
let panic_countdown = AtomicUsize::new(panic_countdown);
v.$func(|a, b| {
if panic_countdown.fetch_sub(1, Relaxed) == 1 {
SILENCE_PANIC.with(|s| s.set(true));
panic!();
}
a.cmp(b)
})
})
.join();
// Check that the number of things dropped is exactly
// what we expect (i.e. the contents of `v`).
for (i, c) in DROP_COUNTS.iter().enumerate().take(len) {
let count = c.load(Relaxed);
assert!(
count == 1,
"found drop count == {} for i == {}, len == {}",
count,
i,
len
);
}
// Check that the most recent versions of values were dropped.
assert_eq!(VERSIONS.load(Relaxed), 0);
if panic_countdown < step {
break;
}
panic_countdown -= step;
}
};
}
thread_local!(static SILENCE_PANIC: Cell<bool> = Cell::new(false));
#[test]
fn sort_panic_safe() {
let prev = panic::take_hook();
panic::set_hook(Box::new(move |info| {
if !SILENCE_PANIC.with(Cell::get) {
prev(info);
}
}));
for &len in &[1, 2, 3, 4, 5, 10, 20, 100, 500, 5_000, 20_000] {
let len_dist = Uniform::new(0, len);
for &modulus in &[5, 30, 1_000, 20_000] {
for &has_runs in &[false, true] {
let mut rng = thread_rng();
let mut input = (0..len)
.map(|id| DropCounter {
x: rng.gen_range(0..modulus),
id,
version: Cell::new(0),
})
.collect::<Vec<_>>();
if has_runs {
for c in &mut input {
c.x = c.id as u32;
}
for _ in 0..5 {
let a = rng.sample(&len_dist);
let b = rng.sample(&len_dist);
if a < b {
input[a..b].reverse();
} else {
input.swap(a, b);
}
}
}
test!(input, par_sort_by);
test!(input, par_sort_unstable_by);
}
}
}
}
|
