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|
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;
#[derive(Clone, Default)]
pub struct MemoryBlobService {
db: Arc<RwLock<HashMap<B3Digest, Vec<u8>>>>,
}
#[async_trait]
impl BlobService for MemoryBlobService {
#[instrument(skip_all, ret, err, fields(blob.digest=%digest))]
async fn has(&self, digest: &B3Digest) -> io::Result<bool> {
let db = self.db.read().unwrap();
Ok(db.contains_key(digest))
}
#[instrument(skip_all, err, fields(blob.digest=%digest))]
async fn open_read(&self, digest: &B3Digest) -> io::Result<Option<Box<dyn BlobReader>>> {
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_all)]
async fn open_write(&self) -> Box<dyn BlobWriter> {
Box::new(MemoryBlobWriter::new(self.db.clone()))
}
}
pub struct MemoryBlobWriter {
db: Arc<RwLock<HashMap<B3Digest, Vec<u8>>>>,
/// Contains the buffer Vec and hasher, or None if already closed
writers: Option<(Vec<u8>, blake3::Hasher)>,
/// The digest that has been returned, if we successfully closed.
digest: Option<B3Digest>,
}
impl MemoryBlobWriter {
fn new(db: Arc<RwLock<HashMap<B3Digest, Vec<u8>>>>) -> 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<Result<usize, io::Error>> {
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<Result<(), io::Error>> {
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<Result<(), io::Error>> {
// shutdown is "instantaneous", we only write to memory.
Poll::Ready(Ok(()))
}
}
#[async_trait]
impl BlobWriter for MemoryBlobWriter {
async fn close(&mut self) -> io::Result<B3Digest> {
if self.writers.is_none() {
match &self.digest {
Some(digest) => Ok(digest.clone()),
None => Err(io::Error::new(io::ErrorKind::BrokenPipe, "already closed")),
}
} 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().map_err(|e| {
io::Error::new(io::ErrorKind::BrokenPipe, format!("RwLock poisoned: {}", e))
})?;
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().map_err(|e| {
io::Error::new(io::ErrorKind::BrokenPipe, format!("RwLock poisoned: {}", e))
})?;
// and put buf in there. This will move buf out.
db.insert(digest.clone(), buf);
}
self.digest = Some(digest.clone());
Ok(digest)
}
}
}
|
