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#![deny(rust_2018_idioms, unused, unused_import_braces, unused_qualifications, warnings)]
use {
std::{
fmt,
fs::File as SyncFile,
io::{
self,
Read as _,
Write as _
},
mem::forget,
num::ParseIntError,
path::{
Path,
PathBuf
},
thread,
time::Duration
},
async_std::{
fs::{
self,
File
},
io::prelude::*,
task::{
block_on,
sleep
}
},
derive_more::From,
heim::process::pid_exists
};
#[must_use = "must call the drop_async method to unlock"]
pub struct DirLock<'a>(&'a Path);
#[derive(Debug, From)]
pub enum Error {
#[from(ignore)]
Cloned(String, String),
HeimProcess(heim::process::ProcessError),
#[from(ignore)]
Io(io::Error, Option<PathBuf>),
ParseInt(ParseIntError)
}
impl Clone for Error {
fn clone(&self) -> Error {
match *self {
Error::Cloned(ref display, ref debug) => Error::Cloned(display.clone(), debug.clone()),
Error::HeimProcess(ref e) => Error::Cloned(format!("heim process error: {}", e), format!("{:?}", e)),
Error::Io(ref e, Some(ref path)) => Error::Cloned(format!("I/O error at {}: {}", path.display(), e), format!("{:?}", e)),
Error::Io(ref e, None) => Error::Cloned(format!("I/O error: {}", e), format!("{:?}", e)),
Error::ParseInt(ref e) => Error::ParseInt(e.clone())
}
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Error::Cloned(display, _) => display.fmt(f),
Error::HeimProcess(e) => write!(f, "heim process error: {}", e),
Error::Io(e, Some(path)) => write!(f, "I/O error at {}: {}", path.display(), e),
Error::Io(e, None) => write!(f, "I/O error: {}", e),
Error::ParseInt(e) => e.fmt(f)
}
}
}
trait IoResultExt {
type T;
fn at(self, path: impl AsRef<Path>) -> Self::T;
}
impl IoResultExt for io::Error {
type T = Error;
fn at(self, path: impl AsRef<Path>) -> Error {
Error::Io(self, Some(path.as_ref().to_owned()))
}
}
impl<T, E: IoResultExt> IoResultExt for Result<T, E> {
type T = Result<T, E::T>;
fn at(self, path: impl AsRef<Path>) -> Result<T, E::T> {
self.map_err(|e| e.at(path))
}
}
impl DirLock<'_> {
pub async fn new(path: &impl AsRef<Path>) -> Result<DirLock<'_>, Error> {
let path = path.as_ref();
loop {
match fs::create_dir(path).await {
Ok(()) => {
let pidfile = path.join("pid");
writeln!(SyncFile::create(&pidfile).at(&pidfile)?, "{}", std::process::id()).at(pidfile)?;
return Ok(DirLock(path));
}
Err(e) => match e.kind() {
io::ErrorKind::AlreadyExists => {
if match File::open(path.join("pid")).await {
Ok(mut f) => {
let mut buf = String::default();
f.read_to_string(&mut buf).await.at(path.join("pid"))?;
!buf.is_empty()
&& !pid_exists(buf.trim().parse()?).await?
}
Err(e) => if e.kind() == io::ErrorKind::NotFound {
false
} else {
return Err(e.at(path.join("pid")));
}
} {
DirLock(path).clean_up().await?;
}
sleep(Duration::from_secs(1)).await;
continue;
}
_ => { return Err(e.at(path)); }
}
}
}
}
pub fn new_sync(path: &impl AsRef<Path>) -> Result<DirLock<'_>, Error> {
let path = path.as_ref();
loop {
match std::fs::create_dir(path) {
Ok(()) => {
let pidfile = path.join("pid");
writeln!(SyncFile::create(&pidfile).at(&pidfile)?, "{}", std::process::id()).at(pidfile)?;
return Ok(DirLock(path));
}
Err(e) => match e.kind() {
io::ErrorKind::AlreadyExists => {
if match SyncFile::open(path.join("pid")) {
Ok(mut f) => {
let mut buf = String::default();
f.read_to_string(&mut buf).at(path.join("pid"))?;
!buf.is_empty()
&& !block_on(pid_exists(buf.trim().parse()?))?
}
Err(e) => if e.kind() == io::ErrorKind::NotFound {
false
} else {
return Err(e.at(path.join("pid")));
}
} {
DirLock(path).clean_up_sync()?;
}
thread::sleep(Duration::from_secs(1));
continue;
}
_ => { return Err(e.at(path)); }
}
}
}
}
pub async fn drop_async(self) -> Result<(), Error> {
self.clean_up().await?;
forget(self);
Ok(())
}
async fn clean_up(&self) -> Result<(), Error> {
if let Err(e) = fs::remove_file(self.0.join("pid")).await {
if e.kind() != io::ErrorKind::NotFound {
return Err(e.at(self.0.join("pid")));
}
}
if let Err(e) = fs::remove_dir(self.0).await {
if e.kind() != io::ErrorKind::NotFound {
return Err(e.at(self.0));
}
}
Ok(())
}
fn clean_up_sync(&self) -> Result<(), Error> {
if let Err(e) = std::fs::remove_file(self.0.join("pid")) {
if e.kind() != io::ErrorKind::NotFound {
return Err(e.at(self.0.join("pid")));
}
}
if let Err(e) = std::fs::remove_dir(self.0) {
if e.kind() != io::ErrorKind::NotFound {
return Err(e.at(self.0));
}
}
Ok(())
}
}
impl Drop for DirLock<'_> {
fn drop(&mut self) {
self.clean_up_sync().expect("failed to clean up dir lock");
}
}