servo-allocator 0.1.0-rc1

A component of the servo web-engine.
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

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

//! Selecting the default global allocator for Servo, and exposing common
//! allocator introspection APIs for memory profiling.

use std::os::raw::c_void;

#[cfg(not(feature = "allocation-tracking"))]
#[global_allocator]
static ALLOC: Allocator = Allocator;

#[cfg(feature = "allocation-tracking")]
#[global_allocator]
static ALLOC: crate::tracking::AccountingAlloc<Allocator> =
    crate::tracking::AccountingAlloc::with_allocator(Allocator);

#[cfg(feature = "allocation-tracking")]
mod tracking;

pub fn is_tracking_unmeasured() -> bool {
    cfg!(feature = "allocation-tracking")
}

pub fn dump_unmeasured(_writer: impl std::io::Write) {
    #[cfg(feature = "allocation-tracking")]
    ALLOC.dump_unmeasured_allocations(_writer);
}

pub use crate::platform::*;

type EnclosingSizeFn = unsafe extern "C" fn(*const c_void) -> usize;

/// # Safety
/// No restrictions. The passed pointer is never dereferenced.
/// This function is only marked unsafe because the MallocSizeOfOps APIs
/// requires an unsafe function pointer.
#[cfg(feature = "allocation-tracking")]
unsafe extern "C" fn enclosing_size_impl(ptr: *const c_void) -> usize {
    let (adjusted, size) = crate::ALLOC.enclosing_size(ptr);
    if size != 0 {
        crate::ALLOC.note_allocation(adjusted, size);
    }
    size
}

#[expect(non_upper_case_globals)]
#[cfg(feature = "allocation-tracking")]
pub static enclosing_size: Option<EnclosingSizeFn> = Some(crate::enclosing_size_impl);

#[expect(non_upper_case_globals)]
#[cfg(not(feature = "allocation-tracking"))]
pub static enclosing_size: Option<EnclosingSizeFn> = None;

#[cfg(not(any(windows, feature = "use-system-allocator", target_env = "ohos")))]
mod platform {
    use std::os::raw::c_void;

    pub use tikv_jemallocator::Jemalloc as Allocator;

    /// Get the size of a heap block.
    ///
    /// # Safety
    ///
    /// Passing a non-heap allocated pointer to this function results in undefined behavior.
    pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
        let size = unsafe { tikv_jemallocator::usable_size(ptr) };
        #[cfg(feature = "allocation-tracking")]
        crate::ALLOC.note_allocation(ptr, size);
        size
    }

    /// Memory allocation APIs compatible with libc
    pub mod libc_compat {
        pub use tikv_jemalloc_sys::{free, malloc, realloc};
    }
}

#[cfg(all(
    not(windows),
    any(feature = "use-system-allocator", target_env = "ohos")
))]
mod platform {
    pub use std::alloc::System as Allocator;
    use std::os::raw::c_void;

    /// Get the size of a heap block.
    ///
    /// # Safety
    ///
    /// Passing a non-heap allocated pointer to this function results in undefined behavior.
    pub unsafe extern "C" fn usable_size(ptr: *const c_void) -> usize {
        #[cfg(target_vendor = "apple")]
        unsafe {
            let size = libc::malloc_size(ptr);
            #[cfg(feature = "allocation-tracking")]
            crate::ALLOC.note_allocation(ptr, size);
            size
        }

        #[cfg(not(target_vendor = "apple"))]
        unsafe {
            let size = libc::malloc_usable_size(ptr as *mut _);
            #[cfg(feature = "allocation-tracking")]
            crate::ALLOC.note_allocation(ptr, size);
            size
        }
    }

    pub mod libc_compat {
        pub use libc::{free, malloc, realloc};
    }
}

#[cfg(windows)]
mod platform {
    pub use std::alloc::System as Allocator;
    use std::os::raw::c_void;

    use windows_sys::Win32::Foundation::FALSE;
    use windows_sys::Win32::System::Memory::{GetProcessHeap, HeapSize, HeapValidate};

    /// Get the size of a heap block.
    ///
    /// # Safety
    ///
    /// Passing a non-heap allocated pointer to this function results in undefined behavior.
    pub unsafe extern "C" fn usable_size(mut ptr: *const c_void) -> usize {
        unsafe {
            let heap = GetProcessHeap();

            if HeapValidate(heap, 0, ptr) == FALSE {
                ptr = *(ptr as *const *const c_void).offset(-1)
            }

            let size = HeapSize(heap, 0, ptr) as usize;
            #[cfg(feature = "allocation-tracking")]
            crate::ALLOC.note_allocation(ptr, size);
            size
        }
    }
}