[go: up one dir, main page]

mimalloc 0.1.11

Performance and security oriented drop-in allocator
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

// Copyright 2019 Octavian Oncescu

#![no_std]

//! A drop-in global allocator wrapper around the [mimalloc](https://github.com/microsoft/mimalloc) allocator.
//! Mimalloc is a general purpose, performance oriented allocator built by Microsoft.
//!
//! ## Usage
//! ```rust,ignore
//! use mimalloc::MiMalloc;
//!
//! #[global_allocator]
//! static GLOBAL: MiMalloc = MiMalloc;
//! ```
//!
//! ## Usage without secure mode
//! By default this library builds mimalloc in secure mode. This means that
//! heap allocations are encrypted, but this results in a 3% increase in overhead.
//!
//! To disable secure mode, in `Cargo.toml`:
//! ```rust,ignore
//! [dependencies]
//! mimalloc = { version = "*", default-features = false }
//! ```

extern crate libmimalloc_sys as ffi;

use core::alloc::{GlobalAlloc, Layout};
use ffi::*;
use libc::c_void;

// Copied from https://github.com/rust-lang/rust/blob/master/src/libstd/sys_common/alloc.rs
#[cfg(all(any(
    target_arch = "x86",
    target_arch = "arm",
    target_arch = "mips",
    target_arch = "powerpc",
    target_arch = "powerpc64",
    target_arch = "asmjs",
    target_arch = "wasm32"
)))]
const MIN_ALIGN: usize = 8;

#[cfg(all(any(
    target_arch = "x86_64",
    target_arch = "aarch64",
    target_arch = "mips64",
    target_arch = "s390x",
    target_arch = "sparc64"
)))]
const MIN_ALIGN: usize = 16;

/// Drop-in mimalloc global allocator.
///
/// ## Usage
/// ```rust,ignore
/// use mimalloc::MiMalloc;
///
/// #[global_allocator]
/// static GLOBAL: MiMalloc = MiMalloc;
/// ```
pub struct MiMalloc;

unsafe impl GlobalAlloc for MiMalloc {
    #[inline]
    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
            mi_malloc(layout.size()) as *mut u8
        } else {
            if cfg!(target_os = "macos") {
                if layout.align() > (1 << 31) {
                    return core::ptr::null_mut();
                }
            }

            mi_malloc_aligned(layout.size(), layout.align()) as *mut u8
        }
    }

    #[inline]
    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
            mi_zalloc(layout.size()) as *mut u8
        } else {
            if cfg!(target_os = "macos") {
                if layout.align() > (1 << 31) {
                    return core::ptr::null_mut();
                }
            }

            mi_zalloc_aligned(layout.size(), layout.align()) as *mut u8
        }
    }

    #[inline]
    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
        mi_free(ptr as *const c_void);
    }

    #[inline]
    unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 {
        if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() {
            mi_realloc(ptr as *const c_void, new_size) as *mut u8
        } else {
            mi_realloc_aligned(ptr as *const c_void, new_size, layout.align()) as *mut u8
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn it_frees_allocated_memory() {
        unsafe {
            let layout = Layout::from_size_align(8, 8).unwrap();
            let alloc = MiMalloc;

            let ptr = alloc.alloc(layout.clone());
            alloc.dealloc(ptr, layout);
        }
    }

    #[test]
    fn it_frees_zero_allocated_memory() {
        unsafe {
            let layout = Layout::from_size_align(8, 8).unwrap();
            let alloc = MiMalloc;

            let ptr = alloc.alloc_zeroed(layout.clone());
            alloc.dealloc(ptr, layout);
        }
    }

    #[test]
    fn it_frees_reallocated_memory() {
        unsafe {
            let layout = Layout::from_size_align(8, 8).unwrap();
            let alloc = MiMalloc;

            let ptr = alloc.alloc(layout.clone());
            let ptr = alloc.realloc(ptr, layout.clone(), 16);
            alloc.dealloc(ptr, layout);
        }
    }
}