On io error, `file_handler()` now sends both the path and the error to output channel, instead of ignoring failed attempts.

Fortune for lazy-rebuild's current commit: Half blessing − 半吉

src/handle.rs

@@ -37,7 +37,7 @@ where F: FnMut(&[u8]) -> io::Result<()>
     Ok(read)
 }
 
-fn file_handler(mut recv: mpsc::Receiver<PathBuf>, backpressure: usize) -> impl Stream<Item = (PathBuf, sha256::Sha256Hash)>
+fn file_handler(mut recv: mpsc::Receiver<PathBuf>, backpressure: usize) -> impl Stream<Item = (PathBuf, io::Result<sha256::Sha256Hash>)>
 {
     
     let (r_tx, r_rx) = mpsc::channel(backpressure);
@@ -51,32 +51,38 @@ fn file_handler(mut recv: mpsc::Receiver<PathBuf>, backpressure: usize) -> impl
 			.read(true)
 			.open(&path).await.unwrap();
 		    let mut hasher = Sha256::new();
-		    match uring_read(&mut file, |buffer| {
+		    let ring_res = uring_read(&mut file, |buffer| {
 			if ret.is_closed() {
 			    return Err(io::Error::new(io::ErrorKind::ConnectionAborted, "return channel dropped, stopping operation"));
 			}
 			hasher.update(buffer);
 			Ok(())
-		    }).await {
-			Ok(_n) => {
-			    eprintln!("Proc {} bytes from {:?}", _n, path);
-			    let _ = ret.send((path, hasher.into())).await;
-			},
-			Err(e) => {
-			    eprintln!("Proc for {:?} failed: {}", path, e);
+		    }).await;
+		    let _ = tokio::join![
+			file.close(), // We are in a unique task per file, so awaiting this here concurrently with the returning async block is fine.
+			async move {
+			    match ring_res {
+				Ok(_n) => {
+				    eprintln!("Proc {} bytes from {:?}", _n, path);
+				    let _ = ret.send((path, Ok(hasher.into()))).await;
+				},
+				Err(e) => {
+				    eprintln!("Proc for {:?} failed: {}", path, e);
+				    match ret.try_send((path, Err(e))) {
+					Ok(_) => (),
+					Err(mpsc::error::TrySendError::Full(val)) => { tokio_uring::spawn(async move { let _ = ret.send(val).await; }); },
+					_ => return,
+				    }
+				}
+			    }
 			}
-		    }
-		    // Close the file.
-		    // We are in a unique task per file, so awaiting this here is fine.
-		    let _ = file.close().await;
-		    
+		    ];
 		});
 	    }
 	    // Drop sender that we're cloning from
 	    drop(r_tx);
 	});
     });
-    //TODO: Change stream item to io::Result<(path, hash)>
     ReceiverStream::new(r_rx)
 }
 //TODO: Higher-level wrapper around `file_handler()`