Struct bulk_allocator::UnsafeLayoutBulkAlloc

pub struct UnsafeLayoutBulkAlloc<B = System>where
    B: GlobalAlloc,{ /* private fields */ }

UnsafeLayoutBulkAlloc is an implementation of GlobalAlloc.

Each instance manages a cache for a specific layout and releases all of them on the drop at once.

Method alloc dispatches and returns a pointer from the cache, while dealloc stores the passed pointer in the cache.

See alloc and dealloc for the details.

In order to ensure effective caching, it is imperative that Layout remains consistently the same, or else panics. (This is why the term “Unsafe” is employed.) To cache effectively, Layout must be always same, or panics. Consequently, method realloc always panics.

See realloc for the details.

Safety

Instance drop releases all the memory, and all the pointers allocated via the instance will be invalid after then. Accessing such a pointer may lead to memory unsafety even if the pointer itself is not deallocated.

Implementations

impl<B> UnsafeLayoutBulkAlloc<B>where B: GlobalAlloc,

pub const fn new(backend: B) -> Self

Creates a new instance.

Trait Implementations

impl<B> Default for UnsafeLayoutBulkAlloc<B>where B: GlobalAlloc + Default,

fn default() -> Self

Returns the “default value” for a type.

impl<B> Drop for UnsafeLayoutBulkAlloc<B>where B: GlobalAlloc,

fn drop(&mut self)

Executes the destructor for this type.

impl<B> GlobalAlloc for UnsafeLayoutBulkAlloc<B>where B: GlobalAlloc,

unsafe fn alloc(&self, layout: Layout) -> *mut u8

alloc rounds up the size of layout to a multiple of the alignment of that.

This method panics if this is not the first method call and if the rounded-up layout is different from that of the first call.

If the rounded-up layout is OK, alloc allocates and caches a memory chunk via the backend if the cache is empty, and dispatches a pointer from the cache to return.

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Safety

Instance drop releases all the memory, and all the pointers allocated via the instance will be invalid after then. Accessing such a pointer may lead to memory unsafety even if the pointer itself is not deallocated.

Panics

Panics if the method call is not the first time, and if the rounded-up layout is different from that of the first call.

unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout)

delloc rounds up the size of layout to a multiple of the alignment of that.

Otherwise, dealloc stores the passed pointer into the cache. i.e. this method does not release the memory immediately. It is when the object is dropped to free the memory.

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Panics

If the rounded-up layout is different from that passed to alloc.

unsafe fn realloc(&self, _: *mut u8, _: Layout, _: usize) -> *mut u8

Panics if called.

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unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8

Behaves like alloc, but also ensures that the contents are set to zero before being returned.