Struct Cache 

pub struct Cache<BN, BF>
where
    BN: Clone,
    BF: Clone,
{
    instance_name: String,
    near: BN,
    far: BF,
}

Cache for a BlobService, using a “near” and “far” blobservice. Requests are tried in (and returned from) the near store first, only if things are not present there, the far BlobService is queried. In case the near blobservice doesn’t have the blob, we ask the remote blobservice for chunks, and try to read each of these chunks from the near blobservice again, before falling back to the far one. While doing so, the full blob is written to the near blobservice. The far BlobService is never written to.

Fields

instance_name: String

near: BN

far: BF

Implementations

impl<BN, BF> Cache<BN, BF>

where BN: Clone, BF: Clone,

pub fn new(instance_name: String, near: BN, far: BF) -> Self

Trait Implementations

impl<BN, BF> BlobService for Cache<BN, BF>

where BN: BlobService + Clone + 'static, BF: BlobService + Clone + 'static,

fn has<'life0, 'life1, 'async_trait>( &'life0 self, digest: &'life1 B3Digest, ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Check if the service has the blob, by its content hash. On implementations returning chunks, this must also work for chunks.

fn open_read<'life0, 'life1, 'async_trait>( &'life0 self, digest: &'life1 B3Digest, ) -> Pin<Box<dyn Future<Output = Result<Option<Box<dyn BlobReader>>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Request a blob from the store, by its content hash. On implementations returning chunks, this must also work for chunks.

fn open_write<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Box<dyn BlobWriter>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Insert a new blob into the store. Returns a BlobWriter, which implements tokio::io::AsyncWrite and a BlobWriter::close to finalize the blob and get its digest.

fn chunks<'life0, 'life1, 'async_trait>( &'life0 self, digest: &'life1 B3Digest, ) -> Pin<Box<dyn Future<Output = Result<Option<Vec<ChunkMeta>>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Return a list of chunks for a given blob. There’s a distinction between returning Ok(None) and Ok(Some(vec![])). The former return value is sent in case the blob is not present at all, while the second one is sent in case there’s no more granular chunks (or the backend does not support chunking). A default implementation checking for existence and then returning it does not have more granular chunks available is provided.

impl<BN, BF> Clone for Cache<BN, BF>

where BN: Clone + Clone, BF: Clone + Clone,

fn clone(&self) -> Cache<BN, BF>

Returns a duplicate of the value.

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

Performs copy-assignment from source.