Struct std::alloc::System 1.28.0[−]
pub struct System;
The default memory allocator provided by the operating system.
This is based on malloc on Unix platforms and HeapAlloc on Windows,
plus related functions.
This type can be used in a static item
with the #[global_allocator] attribute
to force the global allocator to be the system’s one.
(The default is jemalloc for executables, on some platforms.)
use std::alloc::System; #[global_allocator] static A: System = System; fn main() { let a = Box::new(4); // Allocates from the system allocator. println!("{}", a); }Run
It can also be used directly to allocate memory independently of the standard library’s global allocator.
Trait Implementations
impl GlobalAlloc for System
impl GlobalAlloc for Systemunsafe fn alloc(&self, layout: Layout) -> *mut u8
unsafe fn alloc(&self, layout: Layout) -> *mut u8Allocate memory as described by the given layout. Read more
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8
unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8Behaves like alloc, but also ensures that the contents are set to zero before being returned. Read more
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout)
unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout)Deallocate the block of memory at the given ptr pointer with the given layout. Read more
unsafe fn realloc(
&self,
ptr: *mut u8,
layout: Layout,
new_size: usize
) -> *mut u8
unsafe fn realloc(
&self,
ptr: *mut u8,
layout: Layout,
new_size: usize
) -> *mut u8Shink or grow a block of memory to the given new_size. The block is described by the given ptr pointer and layout. Read more
impl Alloc for System
impl Alloc for Systemunsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr>
unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, AllocErr>Returns a pointer meeting the size and alignment guarantees of layout. Read more
unsafe fn alloc_zeroed(
&mut self,
layout: Layout
) -> Result<NonNull<u8>, AllocErr>
unsafe fn alloc_zeroed(
&mut self,
layout: Layout
) -> Result<NonNull<u8>, AllocErr>Behaves like alloc, but also ensures that the contents are set to zero before being returned. Read more
unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout)
unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout)Deallocate the memory referenced by ptr. Read more
unsafe fn realloc(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<NonNull<u8>, AllocErr>
unsafe fn realloc(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<NonNull<u8>, AllocErr>Returns a pointer suitable for holding data described by a new layout with layout’s alginment and a size given by new_size. To accomplish this, this may extend or shrink the allocation referenced by ptr to fit the new layout. Read more
fn usable_size(&self, layout: &Layout) -> (usize, usize)[src]
fn usable_size(&self, layout: &Layout) -> (usize, usize)Returns bounds on the guaranteed usable size of a successful allocation created with the specified layout. Read more
unsafe fn alloc_excess(&mut self, layout: Layout) -> Result<Excess, AllocErr>[src]
unsafe fn alloc_excess(&mut self, layout: Layout) -> Result<Excess, AllocErr>Behaves like alloc, but also returns the whole size of the returned block. For some layout inputs, like arrays, this may include extra storage usable for additional data. Read more
unsafe fn realloc_excess(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<Excess, AllocErr>[src]
unsafe fn realloc_excess(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<Excess, AllocErr>Behaves like realloc, but also returns the whole size of the returned block. For some layout inputs, like arrays, this may include extra storage usable for additional data. Read more
unsafe fn grow_in_place(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<(), CannotReallocInPlace>[src]
unsafe fn grow_in_place(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<(), CannotReallocInPlace>Attempts to extend the allocation referenced by ptr to fit new_size. Read more
unsafe fn shrink_in_place(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<(), CannotReallocInPlace>[src]
unsafe fn shrink_in_place(
&mut self,
ptr: NonNull<u8>,
layout: Layout,
new_size: usize
) -> Result<(), CannotReallocInPlace>Attempts to shrink the allocation referenced by ptr to fit new_size. Read more
fn alloc_one<T>(&mut self) -> Result<NonNull<T>, AllocErr>[src]
fn alloc_one<T>(&mut self) -> Result<NonNull<T>, AllocErr>Allocates a block suitable for holding an instance of T. Read more
unsafe fn dealloc_one<T>(&mut self, ptr: NonNull<T>)[src]
unsafe fn dealloc_one<T>(&mut self, ptr: NonNull<T>)Deallocates a block suitable for holding an instance of T. Read more
fn alloc_array<T>(&mut self, n: usize) -> Result<NonNull<T>, AllocErr>[src]
fn alloc_array<T>(&mut self, n: usize) -> Result<NonNull<T>, AllocErr>Allocates a block suitable for holding n instances of T. Read more
unsafe fn realloc_array<T>(
&mut self,
ptr: NonNull<T>,
n_old: usize,
n_new: usize
) -> Result<NonNull<T>, AllocErr>[src]
unsafe fn realloc_array<T>(
&mut self,
ptr: NonNull<T>,
n_old: usize,
n_new: usize
) -> Result<NonNull<T>, AllocErr>Reallocates a block previously suitable for holding n_old instances of T, returning a block suitable for holding n_new instances of T. Read more
unsafe fn dealloc_array<T>(
&mut self,
ptr: NonNull<T>,
n: usize
) -> Result<(), AllocErr>[src]
unsafe fn dealloc_array<T>(
&mut self,
ptr: NonNull<T>,
n: usize
) -> Result<(), AllocErr>Deallocates a block suitable for holding n instances of T. Read more