Struct BufferAllocator 

pub struct BufferAllocator { /* private fields */ }

BufferAllocator creates Buffer objects to be used for block device I/O requests.

This is implemented through a simple buddy allocation scheme. Allocations always prioritize the lowest available offset (first-fit), packing allocations toward the beginning of the memory pool and reusing recently freed lower offsets.

Implementations

impl BufferAllocator

pub fn new(block_size: usize, source: BufferSource) -> Self

pub fn vmo(&self) -> Option<Arc<Vmo>>

Returns the underlying VMO if the allocator is untrusted.

Returns None if is_trusted() is true, because exposing the VMO would allow external modification of memory that is assumed to be unshared.

pub fn is_trusted(&self) -> bool

pub fn block_size(&self) -> usize

pub fn buffer_source(&self) -> &BufferSource

pub fn take_buffer_source(self) -> BufferSource

Takes the buffer source from the allocator and consumes the allocator.

pub fn identifier(&self) -> usize

Returns an identifier for this allocator based on its memory address.

pub fn allocate_buffer(&self, size: usize) -> BufferFuture<'_>

Allocates a Buffer with capacity for size bytes. Blocks until there are enough bytes available to satisfy the request.

The allocated buffer will be block-aligned and the padding up to block alignment can also be used by the buffer.

Allocation is O(lg(N) + M), where N = size and M = number of allocations.

Panics

Panics if size exceeds the pool size (self.buffer_source().size()).

pub fn allocate_buffer_sync(&self, size: usize) -> Buffer<'_>

Allocates a Buffer with capacity for size bytes synchronously. Blocks the current thread until enough memory is available.

Panics

Panics if size exceeds the pool size (self.buffer_source().size()).

pub fn allocate_buffer_sync_owned(self: &Arc<Self>, size: usize) -> OwnedBuffer

Allocates an OwnedBuffer with capacity for size bytes synchronously. Blocks the current thread until enough memory is available.

Panics

Panics if size exceeds the pool size (self.buffer_source().size()).

pub fn try_allocate_buffer_owned( self: &Arc<Self>, size: usize, ) -> Result<OwnedBuffer, EventListener>

Allocates an OwnedBuffer non-blockingly, returning an EventListener if memory is unavailable.

Panics

Panics if size exceeds the pool size (self.buffer_source().size()).

pub fn try_allocate_buffer( &self, size: usize, ) -> Result<Buffer<'_>, EventListener>

Like allocate_buffer, but returns an EventListener if the allocation cannot be satisfied. The listener will signal when the caller should try again.

Panics

Panics if size exceeds the pool size (self.buffer_source().size()).

impl BufferAllocator

pub fn clean_transfer_buffer(&self)

Zeroes out all unnallocated ranges in the transfer buffer.

Trait Implementations

impl BufferAllocator for BufferAllocator

fn free_buffer(&self, range: Range<usize>)

Frees or reclaims the specified memory range.

fn is_trusted(&self) -> bool

Returns true if buffers produced by this allocator are trusted (unshared).

fn vmo(&self) -> Option<Arc<Vmo>>

Returns the underlying VMO if backed by a VMO and untrusted.

fn identifier(&self) -> usize

Returns an identifier for this allocator based on its memory address.

fn paddrs(&self, _range: &Range<usize>) -> Option<(&[zx_paddr_t], u64)>

Returns the physical addresses for range if pinned, along with the contiguity.

impl Debug for BufferAllocator

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

Formats the value using the given formatter.

impl<'a> TryAllocateBuffer<'a> for BufferAllocator

type Buffer = BufferImpl<'a, &'a BufferAllocator, BufferAllocator>

fn try_allocate_buffer( &'a self, size: usize, ) -> Result<Buffer<'a>, EventListener>

Attempts to allocate a buffer of size bytes. Returns an EventListener to wait on if memory is temporarily unavailable.

fn allocate_buffer_sync(&'a self, size: usize) -> Self::Buffer

Allocates a buffer synchronously, blocking the current thread until memory is available.