Struct MmapAllocator

pub struct MmapAllocator;

Implementation of std::alloc::GlobalAlloc whose backend is mmap(2)

Implementations

impl MmapAllocator

pub const fn new() -> Self

Creates a new instance.

Trait Implementations

impl Clone for MmapAllocator

fn clone(&self) -> MmapAllocator

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MmapAllocator

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for MmapAllocator

fn default() -> Self

Returns the “default value” for a type.

impl GlobalAlloc for MmapAllocator

Portability

alloc() calls mmap() with flag MAP_ANONYMOUS. Many systems support the flag, however, it is not specified in POSIX.

Safety

All functions are thread safe.

Error

Each function don’t cause panic but set OS errno on error.

Note that it is not an error to deallocate pointer which is not allocated. This is the spec of munmap(2). See man 2 munmap for details.

unsafe fn alloc(&self, layout: Layout) -> *mut u8

Panics

This method may panic if the align of layout is greater than the kernel page align. (Basically, kernel page align is always greater than the align of layout that rust generates unless the programer dares to build such a layout on purpose.)

unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8

Panics

This method can panic if the align of layout is greater than the kernel page align.

unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout)

Deallocates the block of memory at the given ptr pointer with the given layout.

unsafe fn realloc( &self, ptr: *mut u8, layout: Layout, new_size: usize, ) -> *mut u8

Shrinks or grows a block of memory to the given new_size in bytes. The block is described by the given ptr pointer and layout.

impl Copy for MmapAllocator