Module std::alloc 1.28.0[−][src]
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.
The compiler may link to a version of jemalloc on some platforms,
but this is not guaranteed.
Libraries, however, like cdylibs and staticlibs 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. |