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|
use std::io::{self, Cursor};
use std::{
collections::HashMap,
sync::{Arc, RwLock},
};
use tracing::{instrument, warn};
use super::{BlobService, BlobWriter};
use crate::{B3Digest, Error};
#[derive(Clone, Default)]
pub struct MemoryBlobService {
db: Arc<RwLock<HashMap<B3Digest, Vec<u8>>>>,
}
impl BlobService for MemoryBlobService {
#[instrument(skip(self, digest), fields(blob.digest=%digest))]
fn has(&self, digest: &B3Digest) -> Result<bool, Error> {
let db = self.db.read().unwrap();
Ok(db.contains_key(digest))
}
fn open_read(&self, digest: &B3Digest) -> Result<Option<Box<dyn io::Read + Send>>, 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))]
fn open_write(&self) -> Result<Box<dyn BlobWriter>, Error> {
Ok(Box::new(MemoryBlobWriter::new(self.db.clone())))
}
}
pub struct MemoryBlobWriter {
db: Arc<RwLock<HashMap<B3Digest, Vec<u8>>>>,
/// Contains the 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 std::io::Write for MemoryBlobWriter {
fn write(&mut self, b: &[u8]) -> std::io::Result<usize> {
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(&buf[..bytes_written])
}
}
}
fn flush(&mut self) -> std::io::Result<()> {
match &mut self.writers {
None => Err(io::Error::new(
io::ErrorKind::NotConnected,
"already closed",
)),
Some(_) => Ok(()),
}
}
}
impl BlobWriter for MemoryBlobWriter {
fn close(&mut self) -> Result<B3Digest, Error> {
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::from_vec(hasher.finalize().as_bytes().to_vec()).unwrap();
// 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)
}
}
}
|
