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//! Inter process signalling library used by `kvarnctl` to communicate with Kvarn.
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
#![cfg_attr(docsrs, feature(doc_cfg))]
#![deny(clippy::all, clippy::pedantic)]
#![allow(clippy::missing_panics_doc)]
#[cfg(unix)]
pub mod unix {
use log::{debug, error, info, warn};
use notify::Watcher;
use std::future::Future;
use std::io;
use std::ops::Deref;
use std::path::Path;
use std::pin::Pin;
use std::sync::Arc;
#[cfg(not(feature = "uring"))]
use tokio::{
io::{AsyncReadExt, AsyncWriteExt},
net::{UnixListener, UnixStream},
};
#[cfg(feature = "uring")]
use tokio_uring::net::{UnixListener, UnixStream};
#[cfg(feature = "uring")]
fn spawn<T: 'static>(f: impl Future<Output = T> + 'static) -> impl Future<Output = T> {
let handle = tokio_uring::spawn(f);
async move { handle.await.unwrap() }
}
#[cfg(not(feature = "uring"))]
fn spawn<T: 'static + Send>(
f: impl Future<Output = T> + 'static + Send,
) -> impl Future<Output = T> {
let handle = tokio::spawn(f);
async move { handle.await.unwrap() }
}
pub enum Response<T> {
/// The socket wasn't found, or had no listener.
NotFound,
/// An error occurred in reading or writing.
Error,
/// Successful transmission.
Data(T),
}
impl<D: ?Sized, T: Deref<Target = D>> Response<T> {
/// Turns `&UnixResponse<T>` to `UnixResponse<&D>`
/// where `T: Deref<Target = D>`.
/// For example, `UnixResponse<Vec<u8>>.as_deref() == &UnixResponse<&[u8]>`
pub fn as_deref(&self) -> Response<&D> {
match self {
Self::NotFound => Response::NotFound,
Self::Error => Response::Error,
Self::Data(t) => Response::Data(&**t),
}
}
}
pub struct HandlerResponse {
/// The response body.
pub data: Vec<u8>,
/// If the communication should be closed.
pub close: bool,
/// A function to run after sending the response.
pub post_send: Option<Box<dyn FnOnce() + Send + Sync>>,
}
/// Sends `data` to a [`UnixListener`] at `path`.
pub async fn send_to(data: impl Into<Vec<u8>>, path: impl AsRef<Path>) -> Response<Vec<u8>> {
let path = path.as_ref();
match UnixStream::connect(path).await {
Err(err) => match err.kind() {
io::ErrorKind::NotFound | io::ErrorKind::ConnectionRefused => Response::NotFound,
_ => Response::Error,
},
#[allow(unused_mut)]
Ok(mut connection) => {
debug!("Connected to {path:?}");
#[cfg(feature = "uring")]
let (r, mut buf): (_, Vec<u8>) = connection.write_all(data.into()).await;
#[cfg(not(feature = "uring"))]
let r = connection.write_all(&data.into()).await;
#[cfg(not(feature = "uring"))]
// flush
let r = connection.shutdown().await.and(r);
if let Err(err) = r {
error!("Failed to send message! {:?}", err);
Response::Error
} else {
debug!("Wrote to {path:?}");
#[cfg(feature = "uring")]
{
// max 2 kiB size
buf.reserve(1024 * 2);
#[allow(clippy::uninit_vec)] // we set beck the length after
unsafe {
buf.set_len(buf.capacity());
}
}
#[cfg(not(feature = "uring"))]
let mut buf = vec![];
debug!("Try to read from {path:?}");
#[cfg(not(feature = "uring"))]
let r = connection.read_to_end(&mut buf).await;
#[cfg(feature = "uring")]
let (r, mut buf) = connection.read(buf).await;
match r {
Err(err) => {
error!("Failed to receive message. {:?}", err);
Response::Error
}
#[cfg(feature = "uring")]
Ok(len) => {
unsafe { buf.set_len(len) };
debug!("Read from {path:?}");
Response::Data(buf)
}
#[cfg(not(feature = "uring"))]
Ok(_) => {
debug!("Read from {path:?}");
Response::Data(buf)
}
}
}
}
}
}
/// Starts an [`UnixListener`] at `path` with `handler` receiving messages.
///
/// This starts a new task, and so the future resolves quickly.
///
/// The `handler` gets the data from the request, and should return whether to close the
/// listener and the data to send back.
///
/// `handler` is guaranteed to be inside an async Tokio context - you can use e.g. [`tokio::spawn`].
///
/// # Return value
///
/// Returns `true` if we removed an existing socket, `false` otherwise.
/// The removed socket might be live or a leftover from a previous call to this (or any other
/// UNIX socket creation).
///
/// The sender can be used to signal we need to close (if `true` is sent)
#[allow(clippy::too_many_lines)]
pub async fn start_at(
#[cfg(feature = "uring")] handler: impl Fn(Vec<u8>) -> Pin<Box<dyn Future<Output = HandlerResponse>>>
+ 'static,
#[cfg(not(feature = "uring"))] handler: impl Fn(Vec<u8>) -> Pin<Box<dyn Future<Output = HandlerResponse> + Send + Sync>>
+ Send
+ Sync
+ 'static,
path: impl AsRef<Path> + Send + Sync + 'static,
) -> (bool, tokio::sync::mpsc::UnboundedSender<bool>) {
#[cfg(feature = "uring")]
let overridden = tokio_uring::fs::remove_file(path.as_ref()).await.is_ok();
#[cfg(not(feature = "uring"))]
let overridden = tokio::fs::remove_file(path.as_ref()).await.is_ok();
let (sender, mut receiver) = tokio::sync::mpsc::unbounded_channel();
let returned_sender = sender.clone();
let _task = spawn(async move {
let path = path.as_ref();
let sender = Arc::new(sender);
let handler = Arc::new(handler);
let reload_sender = Arc::clone(&sender);
let watcher_path = path.to_path_buf();
let mut watcher =
notify::recommended_watcher(move |ev: Result<notify::Event, notify::Error>| {
if let Ok(ev) = ev {
// for some reason, a metadata event is triggered when the actual file is
// deleted. A Delete event is triggered when all file descriptors are
// dropped (when we stop listening to the socket)
std::thread::sleep(std::time::Duration::from_millis(100));
if let notify::EventKind::Modify(notify::event::ModifyKind::Metadata(_)) =
ev.kind
{
let meta = std::fs::metadata(&watcher_path);
if meta.is_err() {
let _ = reload_sender.send(false);
}
}
}
})
.ok();
if watcher.is_none() {
warn!("Failed to watch socket for deletion");
}
// loop to not recurse function & recurse Arc<handler>
'outer: loop {
match UnixListener::bind(path) {
Err(err) => {
error!("Failed to bind signal socket: {err}");
return;
}
Ok(listener) => {
if let Some(watcher) = &mut watcher {
if watcher
.watch(path, notify::RecursiveMode::NonRecursive)
.is_err()
{
warn!("Failed to watch socket for deletion");
}
}
debug!("Bound");
debug!("In tokio task");
// use a sender to poll both the listen loop and the receiver, which receives
// when the listen loop wants to break.
let sender = Arc::clone(&sender);
let handler = Arc::clone(&handler);
loop {
let r = tokio::select! {
r = listener.accept() => r,
Some(close) = receiver.recv() => if close
{break 'outer}
else
{
// just being explicit
// this causes a Delete event at `path`
drop(listener);
warn!("Re-listening because socket file got deleted");
tokio::time::sleep(std::time::Duration::from_millis(100)).await;
while let Ok(close) = receiver.try_recv() {
if close {
break 'outer;
}
}
continue 'outer;
},
else => {
error!("Stopping because close stream was closed!");
break 'outer;
},
};
match r {
Ok(connection) => {
#[cfg(not(feature = "uring"))]
let (mut connection, _addr) = connection;
let handler = Arc::clone(&handler);
let sender = sender.clone();
debug!("accepted connection");
// spawn here so the listening isn't blocked.
let _task = spawn(async move {
debug!("In tokio task, handling message");
let mut data = Vec::with_capacity(4 * 1024);
#[allow(clippy::uninit_vec)] // we set back the length after
#[cfg(feature = "uring")]
unsafe {
data.set_len(data.capacity());
}
#[cfg(not(feature = "uring"))]
let r = connection.read_to_end(&mut data).await;
#[cfg(feature = "uring")]
let (r, mut data) = connection.read(data).await;
match r {
Err(err) => {
warn!("Failed on reading request: {err:?}");
return;
}
#[cfg(feature = "uring")]
Ok(len) => unsafe { data.set_len(len) },
#[cfg(not(feature = "uring"))]
Ok(_) => {}
}
debug!(
"Read {} from remote",
String::from_utf8_lossy(&data)
);
let handler = Arc::clone(&handler);
let HandlerResponse {
data,
close,
post_send,
} = handler(data).await;
if close {
info!("Closing");
let _ = sender.send(true);
debug!("Closed");
}
debug!("Write response");
#[cfg(feature = "uring")]
if let (Err(err), _) = connection.write_all(data).await {
warn!("Failed to write response: {err:?}");
return;
}
#[cfg(not(feature = "uring"))]
if let Err(err) = connection.write_all(&data).await {
warn!("Failed to write response: {err:?}");
return;
}
debug!("Wrote response");
if let Some(post_send) = post_send {
(post_send)();
}
debug!("Handled post send");
});
}
Err(err) => {
warn!("Signal listener got an error: {err:?}");
break;
}
}
}
}
}
}
});
(overridden, returned_sender)
}
}