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feat: atomic writing (#1673)

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* feat: atomic writing

* Apply suggestions from code review

* clean up temp files on error

Co-authored-by: Aiden McClelland <me@drbonez.dev>
This commit is contained in:
J M
2022-07-22 14:08:49 -06:00
committed by GitHub
parent 15af827cbc
commit c22c80d3b0
12 changed files with 357 additions and 122 deletions
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98
backend/src/util/mod.rs
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@@ -11,8 +11,7 @@ use async_trait::async_trait;
use clap::ArgMatches;
use color_eyre::eyre::{self, eyre};
use fd_lock_rs::FdLock;
use futures::future::BoxFuture;
use futures::FutureExt;
use helpers::canonicalize;
pub use helpers::NonDetachingJoinHandle;
use lazy_static::lazy_static;
pub use models::Version;
@@ -23,7 +22,7 @@ use tokio::sync::{Mutex, OwnedMutexGuard, RwLock};
use tracing::instrument;
use crate::shutdown::Shutdown;
use crate::{Error, ResultExt as _};
use crate::{Error, ErrorKind, ResultExt as _};
pub mod config;
pub mod io;
pub mod logger;
@@ -273,40 +272,6 @@ impl<F: FnOnce() -> T, T> Drop for GeneralGuard<F, T> {
}
}
pub async fn canonicalize(
path: impl AsRef<Path> + Send + Sync,
create_parent: bool,
) -> Result<PathBuf, Error> {
fn create_canonical_folder<'a>(
path: impl AsRef<Path> + Send + Sync + 'a,
) -> BoxFuture<'a, Result<PathBuf, Error>> {
async move {
let path = canonicalize(path, true).await?;
tokio::fs::create_dir(&path)
.await
.with_ctx(|_| (crate::ErrorKind::Filesystem, path.display().to_string()))?;
Ok(path)
}
.boxed()
}
let path = path.as_ref();
if tokio::fs::metadata(path).await.is_err() {
if let (Some(parent), Some(file_name)) = (path.parent(), path.file_name()) {
if create_parent && tokio::fs::metadata(parent).await.is_err() {
return Ok(create_canonical_folder(parent).await?.join(file_name));
} else {
return Ok(tokio::fs::canonicalize(parent)
.await
.with_ctx(|_| (crate::ErrorKind::Filesystem, parent.display().to_string()))?
.join(file_name));
}
}
}
tokio::fs::canonicalize(&path)
.await
.with_ctx(|_| (crate::ErrorKind::Filesystem, path.display().to_string()))
}
pub struct FileLock(OwnedMutexGuard<()>, Option<FdLock<File>>);
impl Drop for FileLock {
fn drop(&mut self) {
@@ -322,7 +287,9 @@ impl FileLock {
static ref INTERNAL_LOCKS: Mutex<BTreeMap<PathBuf, Arc<Mutex<()>>>> =
Mutex::new(BTreeMap::new());
}
let path = canonicalize(path.as_ref(), true).await?;
let path = canonicalize(path.as_ref(), true)
.await
.with_kind(ErrorKind::Filesystem)?;
let mut internal_locks = INTERNAL_LOCKS.lock().await;
if !internal_locks.contains_key(&path) {
internal_locks.insert(path.clone(), Arc::new(Mutex::new(())));
@@ -362,58 +329,3 @@ impl FileLock {
Ok(())
}
}
pub struct AtomicFile {
tmp_path: PathBuf,
path: PathBuf,
file: File,
}
impl AtomicFile {
pub async fn new(path: impl AsRef<Path> + Send + Sync) -> Result<Self, Error> {
let path = canonicalize(&path, true).await?;
let tmp_path = if let (Some(parent), Some(file_name)) =
(path.parent(), path.file_name().and_then(|f| f.to_str()))
{
parent.join(format!(".{}.tmp", file_name))
} else {
return Err(Error::new(
eyre!("invalid path: {}", path.display()),
crate::ErrorKind::Filesystem,
));
};
let file = File::create(&tmp_path)
.await
.with_ctx(|_| (crate::ErrorKind::Filesystem, tmp_path.display().to_string()))?;
Ok(Self {
tmp_path,
path,
file,
})
}
pub async fn save(mut self) -> Result<(), Error> {
use tokio::io::AsyncWriteExt;
self.file.flush().await?;
self.file.shutdown().await?;
self.file.sync_all().await?;
tokio::fs::rename(&self.tmp_path, &self.path)
.await
.with_ctx(|_| {
(
crate::ErrorKind::Filesystem,
format!("mv {} -> {}", self.tmp_path.display(), self.path.display()),
)
})
}
}
impl std::ops::Deref for AtomicFile {
type Target = File;
fn deref(&self) -> &Self::Target {
&self.file
}
}
impl std::ops::DerefMut for AtomicFile {
fn deref_mut(&mut self) -> &mut Self::Target {
&mut self.file
}
}