Trait Allocator 

pub unsafe trait Allocator:
    Debug
    + Default
    + Clone {
    type SpecificAllocationError: Into<AllocationError> + Debug;

    // Required methods
    fn allocate(
        &self,
        layout: Layout,
    ) -> Result<NonNull<u8>, Self::SpecificAllocationError>;
    unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout);

    // Provided method
    unsafe fn resize(
        &self,
        ptr: NonNull<u8>,
        old_layout: Layout,
        new_layout: Layout,
    ) -> Result<NonNull<u8>, Self::SpecificAllocationError> { ... }
}

Represents an Allocator.

Safety

This trait is inherently unsafe, since it depends on well managed raw pointers. For example it is possible to call Allocator::deallocate twice on the same pointer, which is an Undefined Behaviour.

Required Associated Types

type SpecificAllocationError: Into<AllocationError> + Debug

A specific Allocator error. Implementor can add additional information to the error, not only generic “allocation failed”.

Required Methods

fn allocate( &self, layout: Layout, ) -> Result<NonNull<u8>, Self::SpecificAllocationError>

Allocates new piece of memory. This is the only safe function here. The returned ptr is guaranteed to satisfy layout requirements (although the implementation is free to overallocate and strengthen alignment).

Errors

An error typically means out-of-memory error. But the implemtation is allowed to provide additional info.

unsafe fn deallocate(&self, ptr: NonNull<u8>, layout: Layout)

Deallocates memory.

Safety

Passed ptr has to be created with previous call to Allocator::allocate or Allocator::resize. Layouts have to match. Using the passed ptr after the call to this function is an Undefined Behaviour.

Provided Methods

unsafe fn resize( &self, ptr: NonNull<u8>, old_layout: Layout, new_layout: Layout, ) -> Result<NonNull<u8>, Self::SpecificAllocationError>

Resizes given ptr to the new layout.

Errors

An error typically means out-of-memory error. But the implemtation is allowed to provide additional info.

Safety

ptr has to be a valid pointer created with previous call to Allocator::allocate or Allocator::resize. old_layout has to match the pointers layout. Using the passed ptr after the call to this function is an Undefined Behaviour. Use the return value instead.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors