From b7ca43be33ee447ba78653a3801dd9062c9bc709 Mon Sep 17 00:00:00 2001
From: Artlef <artlef@localhost>
Date: Sat, 7 Mar 2020 22:46:40 +0100
Subject: [PATCH] Use channel for server messages in client threads

---
 src/bin/client.rs | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/src/bin/client.rs b/src/bin/client.rs
index dce6d04..714c06b 100644
--- a/src/bin/client.rs
+++ b/src/bin/client.rs
@@ -7,6 +7,7 @@ use shakmaty::{Chess, Color, Outcome, Position, Setup};
 use std::io;
 use std::os::unix::net::UnixStream;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::mpsc::{channel, Receiver, TryRecvError};
 use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time;
@@ -16,7 +17,7 @@ struct Client {
     side: Color,
     running: Arc<AtomicBool>,
     input_buffer: Arc<Mutex<String>>,
-    server_message: Arc<Mutex<String>>,
+    server_message_recv: Receiver<String>,
 }
 
 fn main() {
@@ -38,7 +39,7 @@ fn main() {
     clichess::write_to_stream(&mut stream, username_pubkey_json.to_string()).unwrap();
     let input_buffer = setup_input_buffer();
     //start a thread to listen to server messages
-    let server_message = setup_server_message_recv(&stream).unwrap();
+    let server_message_recv = setup_server_message_recv(&stream).unwrap();
 
     let mut client = Client {
         player: clichess::Player {
@@ -49,7 +50,7 @@ fn main() {
         side: Color::White,
         running: running.clone(),
         input_buffer: input_buffer.clone(),
-        server_message: server_message.clone(),
+        server_message_recv,
     };
 
     match prompt_user_for_role(&client, &mut stream) {
@@ -139,9 +140,9 @@ fn setupctrlc() -> Arc<AtomicBool> {
     running
 }
 
-fn setup_server_message_recv(stream: &UnixStream) -> io::Result<Arc<Mutex<String>>> {
+fn setup_server_message_recv(stream: &UnixStream) -> io::Result<Receiver<String>> {
     let buf = Arc::new(Mutex::new(String::new()));
-    let buf2 = buf.clone();
+    let (sender, receiver) = channel();
     let thread_stream = stream.try_clone()?;
 
     thread::spawn(move || {
@@ -149,17 +150,10 @@ fn setup_server_message_recv(stream: &UnixStream) -> io::Result<Arc<Mutex<String
             //wait for server message
             let buffer =
                 clichess::read_line_from_stream(&thread_stream).expect("Error message from server");
-            {
-                let mut server_message = buf2.lock().unwrap();
-                if server_message.is_empty() {
-                    *server_message = buffer;
-                } else {
-                    println!("Warning: server tried to send a message while the current one has not been computed yet.");
-                }
-            }
+            sender.send(buffer).unwrap();
         }
     });
-    Ok(buf)
+    Ok(receiver)
 }
 
 fn read_user_input(client: &Client) -> String {
@@ -203,13 +197,14 @@ fn fetch_message_from_server(client: &Client) -> String {
     while client.running.load(Ordering::SeqCst) {
         thread::sleep(time::Duration::from_millis(10));
         {
-            let mut server_response = client.server_message.lock().unwrap();
-            if server_response.is_empty() {
-                continue;
-            } else {
-                response = server_response.clone();
-                server_response.clear();
-                break;
+            let server_response_recv = &client.server_message_recv;
+            match server_response_recv.try_recv() {
+                Ok(msg) => {
+                    response = msg;
+                    break;
+                }
+                Err(TryRecvError::Disconnected) => println!("Error: server disconnected."),
+                Err(TryRecvError::Empty) => continue,
             }
         }
     }