Struct capnp::message::HeapAllocator

pub struct HeapAllocator { /* private fields */ }

Standard segment allocator. Allocates each segment via alloc::alloc::alloc_zeroed().

Implementations

impl HeapAllocator

pub fn new() -> Self

pub fn first_segment_words(self, value: u32) -> Self

Sets the size of the initial segment in words, where 1 word = 8 bytes.

pub fn allocation_strategy(self, value: AllocationStrategy) -> Self

Sets the allocation strategy for segments after the first one.

pub fn max_segment_words(self, value: u32) -> Self

Sets the maximum number of words allowed in a single allocation.

Trait Implementations

impl Allocator for HeapAllocator

fn allocate_segment(&mut self, minimum_size: u32) -> (*mut u8, u32)

Allocates zeroed memory for a new segment, returning a pointer to the start of the segment and a u32 indicating the length of the segment in words. The allocated segment must be at least minimum_size words long (minimum_size * 8 bytes long). Allocator implementations commonly allocate much more than the minimum, to reduce the total number of segments needed. A reasonable strategy is to allocate the maximum of minimum_size and twice the size of the previous segment.

unsafe fn deallocate_segment(
    &mut self,
    ptr: *mut u8,
    word_size: u32,
    _words_used: u32
)

Indicates that a segment, previously allocated via allocate_segment(), is no longer in use. word_size is the length of the segment in words, as returned from allocate_segment(). words_used is always less than or equal to word_size, and indicates how many words (contiguous from the start of the segment) were possibly written with non-zero values.

impl Debug for HeapAllocator

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for HeapAllocator

fn default() -> Self

Returns the “default value” for a type.