added further refinements to reduce locking unecessarily

src/main.rs

@@ -364,7 +364,8 @@ fn read_join_message(stream: &mut TcpStream, client: &Arc<Client>){
     
     //join room_name
     {
-        let mut rooms = client.rooms_mutex.write().unwrap(); 
+        {
+            let rooms = client.rooms_mutex.read().unwrap(); 
             if !rooms.contains_key(&extended_room_name) { //new room, must create it
                 let map: HashMap<u32, Arc<Client>> = HashMap::new();
                 let r = Arc::new(Room {
@@ -372,26 +373,29 @@ fn read_join_message(stream: &mut TcpStream, client: &Arc<Client>){
                     clients: RwLock::new(map),
                     master_client: Arc::new(RwLock::new(client.clone())) //client is the master, since they joined first
                 });
+                let mut rooms = client.rooms_mutex.write().unwrap(); 
                 rooms.insert(String::from(&extended_room_name),r);
                 println!("New room {} created",&extended_room_name);
             }
-        
+        }
         //the room is guaranteed to exist now
-        {
+        
         { //actually add the client to the room (need a write lock)
+            let rooms = client.rooms_mutex.read().unwrap(); 
             let mut clients = rooms[&extended_room_name].clients.write().unwrap(); 
             clients.insert(client.id,client.clone());
         }
         {
             println!("Client {} joined {}",client.id,&extended_room_name);
-                {
+            
+            let rooms = client.rooms_mutex.read().unwrap(); 
             let mut room = client.room.write().unwrap(); 
             *room = Some(rooms.get(&extended_room_name).unwrap().clone()); //we create an option and assign it back to the room
-                }
-            }
             
+        }
+        {
+            let rooms = client.rooms_mutex.read().unwrap(); 
             let clients = rooms[&extended_room_name].clients.read().unwrap();  //only need a read lock now
-
             //send a join message to everyone in the room (except the client)
             for (_k,v) in clients.iter() {
                 if v.id != client.id {
@@ -405,16 +409,15 @@ fn read_join_message(stream: &mut TcpStream, client: &Arc<Client>){
                 ids_in_room.push(v.id);
                 
             }
-
-
             send_you_joined_message(client, ids_in_room, &short_room_name);
+        }
 
 
         let room = client.room.read().unwrap(); 
         //tell the client who the master is
         let master_client = room.as_ref().unwrap().master_client.read().unwrap();
         send_client_master_message(client, master_client.id);
-        }
+        
     }
     
 }