use std::io::{self, Cursor, Write}; use std::task::Poll; use std::{ collections::HashMap, sync::{Arc, RwLock}, }; use tonic::async_trait; use tracing::instrument; use super::{BlobReader, BlobService, BlobWriter}; use crate::{B3Digest, Error}; #[derive(Clone, Default)] pub struct MemoryBlobService { db: Arc>>>, } #[async_trait] impl BlobService for MemoryBlobService { #[instrument(skip(self, digest), fields(blob.digest=%digest))] async fn has(&self, digest: &B3Digest) -> Result { let db = self.db.read().unwrap(); Ok(db.contains_key(digest)) } async fn open_read(&self, digest: &B3Digest) -> Result>, Error> { let db = self.db.read().unwrap(); match db.get(digest).map(|x| Cursor::new(x.clone())) { Some(result) => Ok(Some(Box::new(result))), None => Ok(None), } } #[instrument(skip(self))] async fn open_write(&self) -> Box { Box::new(MemoryBlobWriter::new(self.db.clone())) } } pub struct MemoryBlobWriter { db: Arc>>>, /// Contains the buffer Vec and hasher, or None if already closed writers: Option<(Vec, blake3::Hasher)>, /// The digest that has been returned, if we successfully closed. digest: Option, } impl MemoryBlobWriter { fn new(db: Arc>>>) -> Self { Self { db, writers: Some((Vec::new(), blake3::Hasher::new())), digest: None, } } } impl tokio::io::AsyncWrite for MemoryBlobWriter { fn poll_write( mut self: std::pin::Pin<&mut Self>, _cx: &mut std::task::Context<'_>, b: &[u8], ) -> std::task::Poll> { Poll::Ready(match &mut self.writers { None => Err(io::Error::new( io::ErrorKind::NotConnected, "already closed", )), Some((ref mut buf, ref mut hasher)) => { let bytes_written = buf.write(b)?; hasher.write(&b[..bytes_written]) } }) } fn poll_flush( self: std::pin::Pin<&mut Self>, _cx: &mut std::task::Context<'_>, ) -> std::task::Poll> { Poll::Ready(match self.writers { None => Err(io::Error::new( io::ErrorKind::NotConnected, "already closed", )), Some(_) => Ok(()), }) } fn poll_shutdown( self: std::pin::Pin<&mut Self>, _cx: &mut std::task::Context<'_>, ) -> std::task::Poll> { // shutdown is "instantaneous", we only write to memory. Poll::Ready(Ok(())) } } #[async_trait] impl BlobWriter for MemoryBlobWriter { async fn close(&mut self) -> Result { if self.writers.is_none() { match &self.digest { Some(digest) => Ok(digest.clone()), None => Err(crate::Error::StorageError( "previously closed with error".to_string(), )), } } else { let (buf, hasher) = self.writers.take().unwrap(); // We know self.hasher is doing blake3 hashing, so this won't fail. let digest: B3Digest = hasher.finalize().as_bytes().into(); // Only insert if the blob doesn't already exist. let db = self.db.read()?; if !db.contains_key(&digest) { // drop the read lock, so we can open for writing. drop(db); // open the database for writing. let mut db = self.db.write()?; // and put buf in there. This will move buf out. db.insert(digest.clone(), buf); } self.digest = Some(digest.clone()); Ok(digest) } } }