fuck you

src/ext.rs

@@ -18,6 +18,11 @@ pub mod prelude
     pub use super::StreamGateExt as _;
     pub use super::StreamLagExt as _;
     pub use super::INodeExt as _;
+    
+    pub use super::async_write_ext::{
+	EitherWrite,
+	DeadSink,
+    };
 }
 
 pub trait INodeExt
@@ -346,3 +351,147 @@ impl fmt::Display for SoftAssertionFailedError
 	}
     };
 }
+
+mod async_write_ext {
+    use std::ops::{Deref, DerefMut};
+    use tokio::io::{
+	self,
+	AsyncWrite, AsyncRead,
+    };
+    use std::{
+	pin::Pin,
+	task::{Poll, Context},
+    };
+    use std::marker::PhantomData;
+
+    #[derive(Debug, Clone)]
+    pub enum EitherWrite<'a, T,U>
+    {
+	First(T),
+	Second(U, PhantomData<&'a mut U>),
+    }
+
+    impl<'a, T, U> Deref for EitherWrite<'a, T,U>
+    where T: AsyncWrite + Unpin + 'a,
+	  U: AsyncWrite + Unpin + 'a
+    {
+	type Target = dyn AsyncWrite + Unpin + 'a;
+
+	fn deref(&self) -> &Self::Target {
+	    match self {
+		Self::First(t) => t,
+		Self::Second(u, _) => u,
+	    }
+	}
+    }
+    
+    impl<'a, T, U> DerefMut for EitherWrite<'a, T,U>
+    where T: AsyncWrite + Unpin + 'a,
+	  U: AsyncWrite + Unpin + 'a
+    {
+	fn deref_mut(&mut self) -> &mut Self::Target {
+	    match self {
+		Self::First(t) => t,
+		Self::Second(u, _) => u,
+	    }
+	}
+    }
+
+    impl<'a, T, U> From<Result<T,U>> for EitherWrite<'a, T, U>
+    where T: AsyncWrite + Unpin + 'a,
+	  U: AsyncWrite + Unpin + 'a
+    {
+	#[inline] fn from(from: Result<T,U>) -> Self
+	{
+	    match from {
+		Ok(v) => Self::First(v),
+		Err(v) => Self::Second(v, PhantomData),
+	    }
+	}
+    }
+
+    
+
+    impl<'a, T> EitherWrite<'a, T, DeadSink>
+    {
+	#[inline] fn as_first_infallible(&mut self) -> &mut T
+	{
+	    match self {
+		Self::Second(_, _) => unsafe { core::hint::unreachable_unchecked() },
+		Self::First(t) => t
+	    }
+	}
+    }
+
+    impl<'a, U> EitherWrite<'a, DeadSink, U>
+    {
+	#[inline] fn as_second_infallible(&mut self) -> &mut U
+	{
+	    match self {
+		Self::First(_) => unsafe { core::hint::unreachable_unchecked() },
+		Self::Second(t, _) => t
+	    }
+	}
+    }
+    
+/*    impl<'a, T> AsyncWrite for EitherWrite<'a, T, DeadSink>
+    where T: AsyncWrite + Unpin + 'a
+    {
+	#[inline] fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize, io::Error>> {
+	    let this = unsafe { self.map_unchecked_mut(|x| x.as_first_infallible()) };
+	    this.poll_write(cx, buf)
+	}
+	#[inline] fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+	    let this = unsafe { self.map_unchecked_mut(|x| x.as_first_infallible()) };
+	    this.poll_flush(cx)	    
+	}
+	fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+	    let this = unsafe { self.map_unchecked_mut(|x| x.as_first_infallible()) };
+	    this.poll_shutdown(cx)
+	}
+    }*/
+    
+    impl<'a, U> AsyncWrite for EitherWrite<'a, DeadSink, U>
+    where U: AsyncWrite + Unpin + 'a
+    {
+	#[inline] fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize, io::Error>> {
+	    let this = unsafe { self.map_unchecked_mut(|x| x.as_second_infallible()) };
+	    this.poll_write(cx, buf)
+	}
+	#[inline] fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+	    let this = unsafe { self.map_unchecked_mut(|x| x.as_second_infallible()) };
+	    this.poll_flush(cx)	    
+	}
+	fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+	    let this = unsafe { self.map_unchecked_mut(|x| x.as_second_infallible()) };
+	    this.poll_shutdown(cx)
+	}
+    }
+
+
+    /// An `Infallible` type for `AsyncWrite` & `AsyncRead`
+    #[derive(Debug)]
+    pub enum DeadSink { }
+
+    impl AsyncWrite for DeadSink
+    {
+	#[inline] fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+	    unreachable!();
+	}
+	#[inline] fn poll_write(self: Pin<&mut Self>, _cx: &mut Context<'_>, _buf: &[u8]) -> Poll<Result<usize, io::Error>> {
+	    unreachable!();
+
+	}
+	#[inline] fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+	    unreachable!();
+
+	}
+    }
+
+    impl AsyncRead for DeadSink
+    {
+	#[inline] fn poll_read(self: Pin<&mut Self>, _cx: &mut Context<'_>, _buf: &mut [u8]) -> Poll<io::Result<usize>> {
+	    unreachable!();
+	}
+    }
+}

src/main.rs

@@ -1,3 +1,4 @@
+#![feature(never_type)]
 
 #![allow(dead_code)]
 
@@ -101,7 +102,7 @@ async fn normal(cfg: config::Config) -> eyre::Result<()>
 	// Some(path) -> prealloc
 	Some((stream_fut, None)) => {
 	    let stream = stream_fut.await?; 
-	    serial::write_async(stream, &graph).await
+	    serial::write_async(stream, &graph, serial::compress::No).await
 		.wrap_err(eyre!("Failed to serialise graph to stream"))?;
 	},
 	#[cfg(feature="prealloc")] Some((_task_fut, Some(output_file))) => {

src/serial.rs

@@ -12,16 +12,71 @@ type Decompressor<T> = BzDecoder<T>;
 
 const DEFER_DROP_SIZE_FLOOR: usize = 1024 * 1024; // 1 MB
 
+pub trait Compression
+{
+    type OutputStream: AsyncWrite + Unpin;
+    type InputStream: AsyncRead + Unpin;
+
+    fn create_output<W: AsyncWrite+ Unpin>(from: W) -> Result<Self::OutputStream, W>;
+    fn create_input<W: AsyncRead+ Unpin>(from: W) -> Result<Self::InputStream, W>;
+}
+
+pub mod compress
+{
+    
+    use super::*;
+    /// No compression.
+    #[derive(Debug)]
+    pub struct No;
+
+    impl Compression for No
+    {
+	type OutputStream = DeadSink;
+	type InputStream  = DeadSink;
+
+	fn create_input<W: AsyncRead+ Unpin>(from: W) -> Result<Self::InputStream, W> {
+	    Err(from)
+	}
+	fn create_output<W: AsyncWrite+ Unpin>(from: W) -> Result<Self::OutputStream, W> {
+	    Err(from)
+	}
+    }
+
+    #[derive(Debug)]
+    pub struct Bz;
+    
+
+    impl Compression for Bz
+    {
+	type OutputStream = Box<dyn AsyncWrite + Unpin>;
+	type InputStream  = Box<dyn AsyncRead + Unpin>;
+
+	fn create_input<W: AsyncRead+ Unpin>(from: W) -> Result<Self::InputStream, W> {
+	    panic!()
+	}
+	fn create_output<W: AsyncWrite+ Unpin>(from: W) -> Result<Self::OutputStream, W> {
+	    Ok(Box::new(super::Compressor::new(from)))
+	}
+    }
+    
+}
+
+#[inline] fn _type_name<T: ?Sized>(_val: &T) -> &'static str {
+    std::any::type_name::<T>()
+}
+
 /// Serialise this object asynchronously
 ///
 /// # Note
 /// This compresses the output stream.
 /// It cannot be used by `prealloc` read/write functions, as they do not compress.
-pub async fn write_async<T: Serialize, W>(mut to: W, item: &T) -> eyre::Result<()>
-where W: AsyncWrite + Unpin
+pub async fn write_async<Compress: Compression>(mut to: impl AsyncWrite + Unpin, item: &impl Serialize, _comp: Compress) -> eyre::Result<()>
 {
-    let sect_type_name = || std::any::type_name::<T>().header("Type trying to serialise was");
-    let sect_stream_type_name = || std::any::type_name::<W>().header("Stream type was");
+    let name_of_item = _type_name(item);
+    let name_of_stream = _type_name(&to);
+    
+    let sect_type_name = || name_of_item.header("Type trying to serialise was");
+    let sect_stream_type_name = || name_of_stream.header("Stream type was");
     
     let vec = tokio::task::block_in_place(|| serde_cbor::to_vec(item))
 	.wrap_err(eyre!("Failed to serialise item"))
@@ -29,9 +84,9 @@ where W: AsyncWrite + Unpin
         .with_section(sect_type_name.clone())?;
 
     {
-	let mut stream = Compressor::new(&mut to);
+	let mut stream: EitherWrite<_, _> = Compress::create_output(&mut to).into();//Compressor::new(&mut to);
 
-	cfg_eprintln!(Verbose; config::get_global(), "Writing {} bytes of type {:?} to stream of type {:?}", vec.len(), std::any::type_name::<T>(), std::any::type_name::<W>());
+	cfg_eprintln!(Verbose; config::get_global(), "Writing {} bytes of type {:?} to stream of type {:?}", vec.len(), name_of_item, name_of_stream);
 
 	stream.write_all(&vec[..])
 	    .await