Trait Storage

pub unsafe trait Storage {
    type Handle: StorageHandle;

    // Required methods
    unsafe fn resolve(&self, handle: Self::Handle) -> NonNull<()>;
    fn allocate(
        &self,
        layout: Layout,
    ) -> Result<(Self::Handle, usize), StorageAllocError>;
    unsafe fn deallocate(&self, layout: Layout, handle: Self::Handle);
    unsafe fn grow(
        &self,
        old_layout: Layout,
        new_layout: Layout,
        handle: Self::Handle,
    ) -> Result<(Self::Handle, usize), StorageAllocError>;
    unsafe fn shrink(
        &self,
        old_layout: Layout,
        new_layout: Layout,
        handle: Self::Handle,
    ) -> Result<(Self::Handle, usize), StorageAllocError>;
}

The trait for allocating memory in a storage

Safety

• Storage::resolve must return a valid pointer to the allocation when passed a valid Storage::Handle

Required Associated Types

type Handle: StorageHandle

The StorageHandle type that represents an allocation by this Storage

Required Methods

unsafe fn resolve(&self, handle: Self::Handle) -> NonNull<()>

Returns a pointer to the allocation represented by handle

Safety

handle must be valid

fn allocate( &self, layout: Layout, ) -> Result<(Self::Handle, usize), StorageAllocError>

Allocates memory with a layout specified by layout

Also returns the total amount of bytes actually allocated, which may be more than requested by layout

Unless Self implements MultipleStorage this will invalidate any previous allocations

unsafe fn deallocate(&self, layout: Layout, handle: Self::Handle)

Deallocates (and invalidates) a StorageHandle that was allocated with this Storage

Safety

• layout must be the same layout that was used to allocate it, though the size may by greater as long as its less than the available capacity returned by any of the allocation methods (Storage::allocate/Storage::grow/Storage::shrink)
• handle must be valid

unsafe fn grow( &self, old_layout: Layout, new_layout: Layout, handle: Self::Handle, ) -> Result<(Self::Handle, usize), StorageAllocError>

Grows (increases the size of) an allocation

Similar to Storage::allocate this method also returns the number of bytes actually allocated, which may be more than requested with new_layout

Safety

• new_layout.size() >= old_layout.size()
• handle must be valid
• if this method succeeds, handle is now invalid and cannot be used

unsafe fn shrink( &self, old_layout: Layout, new_layout: Layout, handle: Self::Handle, ) -> Result<(Self::Handle, usize), StorageAllocError>

Shrinks (decreases the size of) an allocation

Similar to Storage::allocate this method also returns the number of bytes actually allocated, which may be more than requested with new_layout

Safety

• new_layout.size() <= old_layout.size()
• handle must be valid
• if this method succeeds, handle is now invalid and cannot be used

Implementations on Foreign Types

impl<T: MultipleStorage + ?Sized> Storage for &T

type Handle = <T as Storage>::Handle

unsafe fn resolve(&self, handle: Self::Handle) -> NonNull<()>

fn allocate( &self, layout: Layout, ) -> Result<(Self::Handle, usize), StorageAllocError>

unsafe fn deallocate(&self, layout: Layout, handle: Self::Handle)

unsafe fn grow( &self, old_layout: Layout, new_layout: Layout, handle: Self::Handle, ) -> Result<(Self::Handle, usize), StorageAllocError>

unsafe fn shrink( &self, old_layout: Layout, new_layout: Layout, handle: Self::Handle, ) -> Result<(Self::Handle, usize), StorageAllocError>

impl<T: Storage + ?Sized> Storage for &mut T

type Handle = <T as Storage>::Handle

unsafe fn resolve(&self, handle: Self::Handle) -> NonNull<()>

fn allocate( &self, layout: Layout, ) -> Result<(Self::Handle, usize), StorageAllocError>

unsafe fn deallocate(&self, layout: Layout, handle: Self::Handle)

unsafe fn grow( &self, old_layout: Layout, new_layout: Layout, handle: Self::Handle, ) -> Result<(Self::Handle, usize), StorageAllocError>

unsafe fn shrink( &self, old_layout: Layout, new_layout: Layout, handle: Self::Handle, ) -> Result<(Self::Handle, usize), StorageAllocError>

Implementors

impl Storage for Global

type Handle = GlobalHandle

impl Storage for SlotStorage<'_>

type Handle = SlotStorageHandle

impl<T> Storage for InlineStorage<T>

type Handle = InlineStorageHandle