1.28.0[−][src]Module std::alloc
Memory allocation APIs
In a given program, the standard library has one “global” memory allocator
that is used for example by Box<T>
and Vec<T>
.
Currently the default global allocator is unspecified. Libraries, however,
like cdylib
s and staticlib
s are guaranteed to use the System
by
default.
The #[global_allocator]
attribute
This attribute allows configuring the choice of global allocator. You can use this to implement a completely custom global allocator to route all default allocation requests to a custom object.
use std::alloc::{GlobalAlloc, System, Layout}; struct MyAllocator; unsafe impl GlobalAlloc for MyAllocator { unsafe fn alloc(&self, layout: Layout) -> *mut u8 { System.alloc(layout) } unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { System.dealloc(ptr, layout) } } #[global_allocator] static GLOBAL: MyAllocator = MyAllocator; fn main() { // This `Vec` will allocate memory through `GLOBAL` above let mut v = Vec::new(); v.push(1); }Run
The attribute is used on a static
item whose type implements the
GlobalAlloc
trait. This type can be provided by an external library:
extern crate jemallocator; use jemallocator::Jemalloc; #[global_allocator] static GLOBAL: Jemalloc = Jemalloc; fn main() {}Run
The #[global_allocator]
can only be used once in a crate
or its recursive dependencies.
Structs
Layout | Layout of a block of memory. |
LayoutErr | The parameters given to |
System | The default memory allocator provided by the operating system. |
AllocErr | Experimental The |
CannotReallocInPlace | Experimental The |
Excess | Experimental Represents the combination of a starting address and a total capacity of the returned block. |
Global | Experimental The global memory allocator. |
Traits
GlobalAlloc | A memory allocator that can be registered as the standard library’s default
though the |
Alloc | Experimental An implementation of |
Functions
alloc⚠ | Allocate memory with the global allocator. |
alloc_zeroed⚠ | Allocate zero-initialized memory with the global allocator. |
dealloc⚠ | Deallocate memory with the global allocator. |
handle_alloc_error | Abort on memory allocation error or failure. |
realloc⚠ | Reallocate memory with the global allocator. |
set_alloc_error_hook | Experimental Registers a custom allocation error hook, replacing any that was previously registered. |
take_alloc_error_hook | Experimental Unregisters the current allocation error hook, returning it. |