o3 0.38.2

shared-nothing primitives
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
147
148
149
150
151
152
153
154
155
156
157
158
159
160

//! Observes the layouts and fallible allocation paths implemented by o3.

use std::{
    alloc::{GlobalAlloc, Layout, System},
    array,
    cell::Cell,
    ptr,
};

use o3::base::marker::ThreadBound;

thread_local! {
    static COUNTS: Cell<[usize; 4]> = const { Cell::new([0; 4]) };
    static REALLOCATIONS: Cell<usize> = const { Cell::new(0) };
    static FAIL: Cell<Option<usize>> = const { Cell::new(None) };
}

pub struct Tracker;

#[derive(Debug, Default, PartialEq)]
pub struct Activity {
    pub allocations: usize,
    pub allocated_bytes: usize,
    pub deallocations: usize,
    pub deallocated_bytes: usize,
}

pub struct Measurement([usize; 4], ThreadBound);

impl Measurement {
    pub fn finish(self) -> Activity {
        let [a, ab, d, db] = self.delta();
        Activity {
            allocations: a,
            allocated_bytes: ab,
            deallocations: d,
            deallocated_bytes: db,
        }
    }

    fn delta(self) -> [usize; 4] {
        COUNTS
            .with(|counts| array::from_fn(|index| counts.get()[index].wrapping_sub(self.0[index])))
    }
}

impl Tracker {
    pub fn begin() -> Measurement {
        Measurement(COUNTS.with(Cell::get), ThreadBound::NEW)
    }

    pub fn measure<T>(run: impl FnOnce() -> T) -> (T, [usize; 4]) {
        let before = Self::begin();
        (run(), before.delta())
    }

    pub fn activity<T>(run: impl FnOnce() -> T) -> (T, Activity) {
        let before = Self::begin();
        (run(), before.finish())
    }

    pub fn count<T>(run: impl FnOnce() -> T) -> (T, usize) {
        let (value, counts) = Self::measure(run);
        (value, counts[0])
    }

    pub fn counts<T>(run: impl FnOnce() -> T) -> (T, [usize; 2]) {
        let (value, counts) = Self::measure(run);
        (value, [counts[0], counts[2]])
    }

    pub fn usage<T>(run: impl FnOnce() -> T) -> (T, (usize, usize)) {
        let (value, counts) = Self::measure(run);
        (value, (counts[0], counts[1]))
    }

    pub fn resizes<T>(run: impl FnOnce() -> T) -> (T, usize) {
        let before = REALLOCATIONS.with(Cell::get);
        let value = run();
        let count = REALLOCATIONS.with(Cell::get).wrapping_sub(before);
        (value, count)
    }

    pub fn fail_after<T>(allowed: usize, run: impl FnOnce() -> T) -> T {
        let previous = FAIL.with(|fail| fail.replace(Some(allowed)));
        let value = run();
        FAIL.with(|fail| fail.set(previous));
        value
    }

    fn is_rejected() -> bool {
        FAIL.with(|fail| match fail.get() {
            Some(0) => {
                fail.set(None);
                true
            }
            Some(left) => {
                fail.set(Some(left - 1));
                false
            }
            None => false,
        })
    }

    fn record(new: Option<usize>, old: Option<usize>) {
        COUNTS.with(|counts| {
            let mut values = counts.get();
            for (offset, bytes) in [(0, new), (2, old)] {
                if let Some(bytes) = bytes {
                    values[offset] = values[offset].wrapping_add(1);
                    values[offset + 1] = values[offset + 1].wrapping_add(bytes);
                }
            }
            counts.set(values);
        });
    }
}

// SAFETY: requests and pointers are forwarded unchanged to System. Thread-local
// observation never touches allocated memory.
unsafe impl GlobalAlloc for Tracker {
    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
        if Self::is_rejected() {
            return ptr::null_mut();
        }
        let pointer = unsafe { System.alloc(layout) };
        if !pointer.is_null() {
            Self::record(Some(layout.size()), None);
        }
        pointer
    }

    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
        if Self::is_rejected() {
            return ptr::null_mut();
        }
        let pointer = unsafe { System.alloc_zeroed(layout) };
        if !pointer.is_null() {
            Self::record(Some(layout.size()), None);
        }
        pointer
    }

    unsafe fn dealloc(&self, pointer: *mut u8, layout: Layout) {
        unsafe { System.dealloc(pointer, layout) };
        Self::record(None, Some(layout.size()));
    }

    unsafe fn realloc(&self, pointer: *mut u8, layout: Layout, size: usize) -> *mut u8 {
        if Self::is_rejected() {
            return ptr::null_mut();
        }
        let resized = unsafe { System.realloc(pointer, layout, size) };
        if !resized.is_null() {
            REALLOCATIONS.with(|count| count.set(count.get().wrapping_add(1)));
            Self::record(Some(size), Some(layout.size()));
        }
        resized
    }
}