use std::io; use tonic::async_trait; use crate::proto::stat_blob_response::ChunkMeta; use crate::B3Digest; mod chunked_reader; mod combinator; mod from_addr; mod grpc; mod memory; mod naive_seeker; mod object_store; mod simplefs; mod sled; #[cfg(test)] mod tests; pub use self::chunked_reader::ChunkedReader; pub use self::combinator::CombinedBlobService; pub use self::from_addr::from_addr; pub use self::grpc::GRPCBlobService; pub use self::memory::MemoryBlobService; pub use self::object_store::ObjectStoreBlobService; pub use self::simplefs::SimpleFilesystemBlobService; pub use self::sled::SledBlobService; /// The base trait all BlobService services need to implement. /// It provides functions to check whether a given blob exists, /// a way to read (and seek) a blob, and a method to create a blobwriter handle, /// which will implement a writer interface, and also provides a close funtion, /// to finalize a blob and get its digest. #[async_trait] pub trait BlobService: Send + Sync { /// Check if the service has the blob, by its content hash. /// On implementations returning chunks, this must also work for chunks. async fn has(&self, digest: &B3Digest) -> io::Result<bool>; /// Request a blob from the store, by its content hash. /// On implementations returning chunks, this must also work for chunks. async fn open_read(&self, digest: &B3Digest) -> io::Result<Option<Box<dyn BlobReader>>>; /// 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. async fn open_write(&self) -> Box<dyn BlobWriter>; /// 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. async fn chunks(&self, digest: &B3Digest) -> io::Result<Option<Vec<ChunkMeta>>> { if !self.has(digest).await? { return Ok(None); } else { // default implementation, signalling the backend does not have more // granular chunks available. return Ok(Some(vec![])); } } } /// A [tokio::io::AsyncWrite] that the user needs to close() afterwards for persist. /// On success, it returns the digest of the written blob. #[async_trait] pub trait BlobWriter: tokio::io::AsyncWrite + Send + Unpin { /// Signal there's no more data to be written, and return the digest of the /// contents written. /// /// Closing a already-closed BlobWriter is a no-op. async fn close(&mut self) -> io::Result<B3Digest>; } /// BlobReader is a [tokio::io::AsyncRead] that also allows seeking. pub trait BlobReader: tokio::io::AsyncRead + tokio::io::AsyncSeek + Send + Unpin + 'static {} /// A [`io::Cursor<Vec<u8>>`] can be used as a BlobReader. impl BlobReader for io::Cursor<&'static [u8]> {} impl BlobReader for io::Cursor<&'static [u8; 0]> {} impl BlobReader for io::Cursor<Vec<u8>> {} impl BlobReader for io::Cursor<bytes::Bytes> {} impl BlobReader for tokio::fs::File {}