FIrst attempt at buffering stream... Doesn"t seem to be working well...

Fortune for rsh's current commit: Small blessing − 小吉

src/sock/buffered.rs

@@ -32,11 +32,58 @@ pub struct Buffered<T: ?Sized, const SIZE: usize>
     #[pin] stream: T
 }
 
-impl<T: ?Sized + AsyncWrite, const SIZE: usize> AsyncWrite for Buffered<T, SIZE>
+#[inline] fn div_mod<V>(a: V, b: V) -> (V, <V as std::ops::Div>::Output, <V as std::ops::Rem>::Output)
+where V: std::ops::Div + std::ops::Rem + Clone
+{
+    (a.clone(), a.clone() / b.clone(), a % b)
+}
+
+impl<T: ?Sized, const SIZE: usize> AsyncWrite for Buffered<T, SIZE>
+where T: AsyncWrite
 {
     fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize, io::Error>> {
+
+	let this = self.project();
+	let w = if buf.len() + this.buffer.len() > SIZE {
+	    // `buf` cannot fit into buffer, push the bytes that can fit.
+	    let buf = &buf[..(this.buffer.len()-SIZE)];
+	    this.buffer.extend_from_slice(buf);
+	    buf.len()
+	} else {
+	    // `buf` can fit into buffer.
+	    this.buffer.extend_from_slice(&buf[..]);
+	    buf.len()
+	};
+
+	// Push `SIZE` bytes from buffer,
+	loop {
+	    if this.buffer.len() >= SIZE {
+		use futures::ready;
+		
+		match ready!(this.stream.poll_write(cx, &this.buffer[..SIZE])) {
+		    Ok(n) => {
+			this.buffer.drain(0..n);
+		    },
+		    x => return Poll::Ready(x),
+		    //TODO: How to break after this?
+		}
+	    } else {
+		// TODO: How to re-queue for polling?
+		todo!()
+	    }
+	}
+	
+	Poll::Ready(Ok(w))
+	/*
+	    match div_mod(buf.len(), SIZE) {
+	// Buffer is equal to `SIZE`
+	    (sz, _, _) if sz == SIZE => (),
+	// Buffer is smaller than `SIZE`
+	    (sz, 0, x) => (),
+	// Buffer is a multiple of SIZE,
+	    (sz, x, 0) => (),
+    }*/
 	// TODO: Push `buf` into `self.buffer`. When `self.buffer` is full, write to `self.stream` and clear what's been written.
-	todo!()
     }
     fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
 	todo!("Flush any remaining bytes in the buffer to `stream`")
@@ -53,4 +100,4 @@ impl<T: ?Sized + AsyncWrite, const SIZE: usize> AsyncWrite for Buffered<T, SIZE>
 	todo!("How to do the above?")
     }
 }
-    
+