haz_alloc_core/
backend.rs

1use core::cell::Cell;
2use core::ptr;
3
4pub struct TlsCallback {
5    pub func: Cell<Option<fn()>>,
6    pub next: Cell<*const TlsCallback>,
7}
8
9impl TlsCallback {
10    pub const fn new() -> Self {
11        Self {
12            func: Cell::new(None),
13            next: Cell::new(ptr::null()),
14        }
15    }
16}
17
18/// This trait contains external functions that are provided by the user
19/// in order for the library to perform system actions such as
20/// page allocation.
21///
22/// # Safety
23///
24/// The implementation must make sure the functions in the trait behave
25/// properly.
26pub unsafe trait Backend {
27    type Mutex: Mutex;
28
29    /// Reserve the block of memory starting at `ptr` if `ptr` is not null and
30    /// with `size`.
31    ///
32    /// If `ptr` is null, the block of memory can start at an offset determined
33    /// by the system.
34    ///
35    /// If the function fails null is returned.
36    fn mreserve(ptr: *mut u8, size: usize) -> *mut u8;
37
38    /// Commit memory starting at `ptr` with size `size`.
39    ///
40    /// If the function fails null is returned.
41    ///
42    /// # Safety
43    ///
44    /// The memory must be reserved.
45    unsafe fn mcommit(ptr: *mut u8, size: usize) -> bool;
46
47    /// Decommit memory starting at `ptr` with size `size`.
48    ///
49    /// # Safety
50    ///
51    /// The memory must be commited.
52    unsafe fn mdecommit(ptr: *mut u8, size: usize);
53
54    /// Unreserve memory starting at `ptr` with size `size`.
55    ///
56    /// # Safety
57    ///
58    /// The memory must be reserved.
59    ///
60    /// The size must be equals to the same size used for reserving.
61    unsafe fn munreserve(ptr: *mut u8, size: usize);
62
63    /// Returns the page size.
64    ///
65    /// It is a good idea to cache before returning.
66    fn pagesize() -> usize;
67
68    /// Attach the given callback to this thread, running it when the thread
69    /// is destroyed.
70    ///
71    /// # Safety
72    ///
73    /// The callback must be #[thread_local].
74    unsafe fn tls_attach(callback: *const TlsCallback);
75}
76
77/// # Safety
78///
79/// The implementation must make sure the functions in the trait behave
80/// properly.
81pub unsafe trait Mutex: 'static + Sync + Send {
82    type Guard<'a>;
83
84    /// Creates a mutex.
85    ///
86    /// # Safety
87    /// 
88    /// The mutex must not be moved until dropped.
89    /// The mutex must not be initialized.
90    unsafe fn new(ptr: *mut Self);
91
92    /// Lock a mutex.
93    /// 
94    /// # Safety
95    /// 
96    /// The mutex must not be moved until dropped.
97    /// The mutex must be initialized.
98    #[must_use]
99    unsafe fn lock(&self) -> Self::Guard<'_>;
100}
haz_alloc_core/backend.rs

haz_alloc_core/
backend.rs
