From 4fb541143092395b58f85e62e23dc21eb0019945 Mon Sep 17 00:00:00 2001
From: Cosma George <georgemagic10@gmail.com>
Date: Sat, 30 Sep 2023 16:44:30 +0300
Subject: [PATCH] Reunited writer and reader so run_terminal no longer destroys
 stream.

---
 src/interfaces/serial/virtual_terminal.rs | 69 +++++++++++++----------
 1 file changed, 39 insertions(+), 30 deletions(-)

diff --git a/src/interfaces/serial/virtual_terminal.rs b/src/interfaces/serial/virtual_terminal.rs
index 1b82198..eff9898 100644
--- a/src/interfaces/serial/virtual_terminal.rs
+++ b/src/interfaces/serial/virtual_terminal.rs
@@ -9,6 +9,7 @@ use console::Term;
 use futures::stream::StreamExt;
 use futures::SinkExt;
 use std::io::Write;
+use std::sync::Arc;
 use std::{io, str};
 use tokio_util::codec::{Decoder, Encoder};
 
@@ -17,9 +18,6 @@ struct TerminalCodec;
 #[async_trait]
 impl VirtualTerminal for SerialInterface {
     // Run the virtual terminal to interact with the tock console.
-    // Warning!
-    //     Before returning, the connection is closed. You must re-open the connection for any
-    //     further operations.
     async fn run_terminal(&mut self) -> Result<(), TockloaderError> {
         if self.stream.is_none() {
             // Note: I'm using panic here because "unreachable!" doesn't feel appropriate
@@ -29,47 +27,58 @@ impl VirtualTerminal for SerialInterface {
             panic!("Stream is not initialized!")
         }
 
-        let (mut writer, mut reader) = TerminalCodec.framed(self.stream.take().unwrap()).split();
-
-        let read_handle: JoinHandle<Result<(), TockloaderError>> = tokio::spawn(async move {
-            // Q: I don't get why the decoder returns Result<Option<String>, ...> but
-            // line_result is actually Result<String, ...>.
-            // A: Because the decoded uses Ok(None) as an indicator that it needs to wait for
-            // more bytes, where we will always have a result (even if it happens to be an
-            // empty string).
-            // TODO: What does it mean if .next() return None?
-            while let Some(line_result) = reader.next().await {
-                print!("{}", line_result?);
+        let (writer, reader) = TerminalCodec.framed(self.stream.take().unwrap()).split();
+
+        let reader_arc = Arc::new(tokio::sync::Mutex::new(reader));
+        let read_handle: JoinHandle<Result<(), TockloaderError>> = tokio::spawn({
+            let reader_arc = Arc::clone(&reader_arc);
+            async move {
+                // Q: I don't get why the decoder returns Result<Option<String>, ...> but
+                // line_result is actually Result<String, ...>.
+                // A: Because the decoded uses Ok(None) as an indicator that it needs to wait for
+                // more bytes, where we will always have a result (even if it happens to be an
+                // empty string).
+                // TODO: What does it mean if .next() return None?
+                while let Some(line_result) = reader_arc.lock().await.next().await {
+                    print!("{}", line_result?);
+
+                    // We need to flush the buffer because the "tock$" prompt does not have a newline.
+                    io::stdout().flush().unwrap();
+                }
 
-                // We need to flush the buffer because the "tock$" prompt does not have a newline.
-                io::stdout().flush().unwrap();
+                Ok(())
             }
-
-            Ok(())
         });
 
-        let write_handle: JoinHandle<Result<(), TockloaderError>> = tokio::spawn(async move {
-            loop {
-                if let Some(buffer) = get_key().await? {
-                    writer.send(buffer).await?
+        let writer_arc = Arc::new(tokio::sync::Mutex::new(writer));
+        let write_handle: JoinHandle<Result<(), TockloaderError>> = tokio::spawn({
+            let writer_arc = Arc::clone(&writer_arc);
+            async move {
+                loop {
+                    if let Some(buffer) = get_key().await? {
+                        writer_arc.lock().await.send(buffer).await?
+                    }
                 }
             }
         });
 
-        // TODO: Make this work.
-        // Currently both reader and writer are moved into their async closures, thus
-        // we lose access to them here. We can't provide the closures a reference since
-        // that reference will then need to have a static lifetime.
-        // self.stream = Some(reader.reunite(writer).unwrap().into_inner());
-
-        tokio::select! {
+        let result = tokio::select! {
             join_result = read_handle => {
                 join_result?
             }
             join_result = write_handle => {
                 join_result?
             }
-        }
+        };
+
+        // Arc::into_innter will always return Mutex<SplitSink/SplitStream> because the previous select statement
+        // will always make sure all the closures are either finished or cancelled and the arc is cloned nowhere else.
+        // We can move out of the mutex for similar reasons, no one else will need this reader/writer.
+        let writer = Arc::into_inner(writer_arc).unwrap().into_inner();
+        let reader = Arc::into_inner(reader_arc).unwrap().into_inner();
+        self.stream = Some(reader.reunite(writer).unwrap().into_inner());
+
+        return result;
     }
 }