Struct PagedPool 

pub struct PagedPool { /* private fields */ }

A pool of reusable fixed-size buffers allocated in large pages.

This type implements MemoryPool and can be configured as a custom memory pool for a S3CrtClient. It can also return mutable buffers (PoolBufferMut) to use in other scenarios, such as reading cache blocks from disk or buffering incremental uploads.

The pool is configured by providing a set of sizes for the buffers, e.g. read and write part sizes, cache block size. For each of these sizes, the pool will maintain a [SizePool] instance, which will allocate “pages” of BUFFERS_PER_PAGE (16) buffers on demand.

When a buffer of a given size is requested, the pool will return a buffer from one of 2 logical areas: primary and secondary:

• primary: the [SizePool] with the smallest buffer size large enough to contain the requested size is selected. If any of its existing pages has a free buffer, it is marked as reserved and returned, otherwise a new page is allocated.
• secondary: if the requested size is larger than the maximum buffer size in [SizePool]s, a buffer of the exact size is allocated and returned.

When a primary buffer is dropped, it will automatically be released back to the pool, so it can be reused. Secondary buffers will also notify the pool on drop, but only for tracking.

The trim method can be invoked to free all empty pages, i.e. with no currently reserved buffers, across [SizePool]s.

When reserving a buffer, a BufferKind parameter is required to keep track of the usage. Requests through the MemoryPool interface will map the originating MetaRequestType to BufferKind.

Implementations

impl PagedPool

pub const MAX_BUFFER_SIZE: usize

Maximum size for a primary buffer.

Buffers larger than this size will be allocated from secondary memory.

pub const DEFAULT_BUFFER_SIZE: usize

Default size for a primary buffer.

Used when no other valid buffer size is provided when creating the pool.

pub fn new_with_candidate_sizes(buffer_sizes: impl Into<Vec<usize>>) -> Self

Create a new pool, configuring primary memory with the given set of buffer sizes, if valid.

Ignores invalid (0 or greater than MAX_BUFFER_SIZE) or duplicate values for buffer sizes. If no valid value is provided, uses DEFAULT_BUFFER_SIZE.

pub fn trim(&self) -> bool

Trim empty pages in the pool.

pub fn schedule_trim(&self, recurring_time: Duration)

Schedule recurring calls to trim.

pub fn reserved_bytes(&self, kind: BufferKind) -> usize

Return the reserved memory in bytes for the given kind of buffer.

pub fn get_buffer_mut(&self, capacity: usize, kind: BufferKind) -> PoolBufferMut

Get a new empty mutable buffer from the pool with the requested capacity.

Trait Implementations

impl Clone for PagedPool

fn clone(&self) -> PagedPool

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PagedPool

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

Formats the value using the given formatter.

impl MemoryPool for PagedPool

type Buffer = PoolBuffer

Associated buffer type.

fn get_buffer( &self, size: usize, meta_request_type: MetaRequestType, ) -> Self::Buffer

Get a buffer of at least the requested size.

fn trim(&self) -> bool

Trim the pool.