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|
use std::{
io,
path::{Path, PathBuf},
pin::pin,
task::Poll,
};
use bytes::Buf;
use data_encoding::HEXLOWER;
use pin_project_lite::pin_project;
use tokio::io::AsyncWriteExt;
use tonic::async_trait;
use tracing::instrument;
use crate::B3Digest;
use super::{BlobReader, BlobService, BlobWriter};
/// Connects to a tvix-store BlobService on an existing path backed by a POSIX-compliant
/// filesystem.
///
/// It takes an existing path, builds a `tmp` directory and a `blobs` directory inside of it. All
/// blobs received are staged in that `tmp` directory, then they are moved **atomically** into
/// `blobs/B3DIGEST[:2]/B3DIGEST[2:]` in a sharding style, e.g. `abcdef` gets turned into `ab/cdef`
///
/// **Disclaimer** : This very simple implementation is subject to change and does not give any
/// final guarantees on the on-disk format.
#[derive(Clone)]
pub struct SimpleFilesystemBlobService {
/// Where the blobs are located on a filesystem already mounted.
path: PathBuf,
}
impl SimpleFilesystemBlobService {
pub async fn new(path: PathBuf) -> std::io::Result<Self> {
tokio::fs::create_dir_all(&path).await?;
tokio::fs::create_dir_all(path.join("tmp")).await?;
tokio::fs::create_dir_all(path.join("blobs")).await?;
Ok(Self { path })
}
}
fn derive_path(root: &Path, digest: &B3Digest) -> PathBuf {
let prefix = HEXLOWER.encode(&digest.as_slice()[..2]);
let pathname = HEXLOWER.encode(digest.as_slice());
root.join("blobs").join(prefix).join(pathname)
}
#[async_trait]
impl BlobService for SimpleFilesystemBlobService {
#[instrument(skip_all, ret, err, fields(blob.digest=%digest))]
async fn has(&self, digest: &B3Digest) -> io::Result<bool> {
Ok(tokio::fs::try_exists(derive_path(&self.path, digest)).await?)
}
#[instrument(skip_all, err, fields(blob.digest=%digest))]
async fn open_read(&self, digest: &B3Digest) -> io::Result<Option<Box<dyn BlobReader>>> {
let dst_path = derive_path(&self.path, digest);
let reader = match tokio::fs::File::open(dst_path).await {
Ok(file) => {
let reader: Box<dyn BlobReader> = Box::new(file);
Ok(Some(reader))
}
Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(None),
Err(e) => Err(e),
};
Ok(reader?)
}
#[instrument(skip_all)]
async fn open_write(&self) -> Box<dyn BlobWriter> {
let file = match async_tempfile::TempFile::new_in(self.path.join("tmp")).await {
Ok(file) => Ok(file),
Err(e) => match e {
async_tempfile::Error::Io(io_error) => Err(io_error),
async_tempfile::Error::InvalidFile => Err(std::io::Error::new(
std::io::ErrorKind::NotFound,
"invalid or missing file specified",
)),
async_tempfile::Error::InvalidDirectory => Err(std::io::Error::new(
std::io::ErrorKind::NotFound,
"invalid or missing directory specified",
)),
},
};
Box::new(SimpleFilesystemBlobWriter {
root: self.path.clone(),
file,
digester: blake3::Hasher::new(),
})
}
}
pin_project! {
struct SimpleFilesystemBlobWriter {
root: PathBuf,
file: std::io::Result<async_tempfile::TempFile>,
digester: blake3::Hasher
}
}
impl tokio::io::AsyncWrite for SimpleFilesystemBlobWriter {
fn poll_write(
mut self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
buf: &[u8],
) -> std::task::Poll<Result<usize, std::io::Error>> {
if let Err(e) = self.file.as_mut() {
return Poll::Ready(Err(std::mem::replace(
e,
std::io::Error::new(
std::io::ErrorKind::NotConnected,
"this file is already closed",
),
)));
}
let writer = self.file.as_mut().unwrap();
match pin!(writer).poll_write(cx, buf) {
Poll::Ready(Ok(n)) => {
let this = self.project();
this.digester.update(buf.take(n).into_inner());
Poll::Ready(Ok(n))
}
Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
Poll::Pending => Poll::Pending,
}
}
fn poll_flush(
mut self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Result<(), std::io::Error>> {
if let Err(e) = self.file.as_mut() {
return Poll::Ready(Err(std::mem::replace(
e,
std::io::Error::new(
std::io::ErrorKind::NotConnected,
"this file is already closed",
),
)));
}
let writer = self.file.as_mut().unwrap();
pin!(writer).poll_flush(cx)
}
fn poll_shutdown(
mut self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Result<(), std::io::Error>> {
if let Err(e) = self.file.as_mut() {
return Poll::Ready(Err(std::mem::replace(
e,
std::io::Error::new(
std::io::ErrorKind::NotConnected,
"this file is already closed",
),
)));
}
let writer = self.file.as_mut().unwrap();
pin!(writer).poll_shutdown(cx)
}
}
#[async_trait]
impl BlobWriter for SimpleFilesystemBlobWriter {
async fn close(&mut self) -> io::Result<B3Digest> {
if let Err(e) = self.file.as_mut() {
return Err(std::mem::replace(
e,
std::io::Error::new(
std::io::ErrorKind::NotConnected,
"this file is already closed",
),
));
}
let writer = self.file.as_mut().unwrap();
writer.sync_all().await?;
writer.flush().await?;
let digest: B3Digest = self.digester.finalize().as_bytes().into();
let dst_path = derive_path(&self.root, &digest);
tokio::fs::create_dir_all(dst_path.parent().unwrap()).await?;
tokio::fs::rename(writer.file_path(), dst_path).await?;
Ok(digest)
}
}
|
