Store connection handler in a map db

src/main.rs

@@ -1,7 +1,7 @@
 use rumqttc::{self, AsyncClient, Event, Incoming, LastWill, MqttOptions, Publish, QoS};
 use serde::{Deserialize, Serialize};
 use serde_json::json;
-use std::time::Duration;
+use std::{collections::HashMap, time::Duration};
 use tokio::sync::mpsc;
 use tokio_modbus::prelude::*;
 
@@ -281,22 +281,39 @@ enum RegistryCommand {
     Disconnect(ConnectionId),
 }
 
+type RegistryDb = HashMap<ConnectionId, tokio::task::JoinHandle<()>>;
+
 async fn connection_registry(
     prefix: String,
     dispatcher: mpsc::Sender<DispatchCommand>,
     mut rx: mpsc::Receiver<RegistryCommand>,
 ) {
     println!("Starting connection registry...");
+    let mut db: RegistryDb = HashMap::new();
+
     while let Some(command) = rx.recv().await {
         use RegistryCommand::*;
         match command {
+            Disconnect(id) => {
+                if let Some(handle) = db.remove(&id) {
+                    handle.abort();
+                }
+            }
             Connect { id, details } => {
                 println!("Connection {}: {:?}", id, &details);
                 let prefix = prefix.clone();
                 let dispatcher = dispatcher.clone();
-                tokio::spawn(async move {
-                    handle_connect(dispatcher, id, prefix, details).await;
-                });
+
+                if let Some(handle) = db.remove(&id) {
+                    handle.abort();
+                }
+
+                db.insert(
+                    id.clone(),
+                    tokio::spawn(async move {
+                        handle_connect(dispatcher, id, prefix, details).await;
+                    }),
+                );
             }
             _ => println!("unimplemented"),
         }
@@ -315,25 +332,21 @@ async fn handle_connect(
             let slave = Slave(connect.slave);
             // println!("{:?}", connect);
 
-            let status = match connect.settings {
+            let mut modbus = match connect.settings {
                 ModbusProto::Tcp { ref host, port } => {
                     let socket_addr = format!("{}:{}", host, port).parse().unwrap();
-                    let mut modbus = tcp::connect_slave(socket_addr, slave).await.unwrap();
-                    ConnectStatus {
-                        connect: connect,
-                        status: ConnectState::Connected,
-                    }
+                    tcp::connect_slave(socket_addr, slave).await.unwrap()
                 }
                 ModbusProto::Rtu { ref tty, baud_rate } => {
                     let builder = tokio_serial::new(tty, baud_rate);
                     let port = tokio_serial::SerialStream::open(&builder).unwrap();
-                    let mut modbus = rtu::connect_slave(port, slave).await.unwrap();
-                    ConnectStatus {
-                        connect: connect,
-                        status: ConnectState::Connected,
-                    }
+                    rtu::connect_slave(port, slave).await.unwrap()
                 }
             };
+            let status = ConnectStatus {
+                connect: connect,
+                status: ConnectState::Connected,
+            };
             dispatcher
                 .send(DispatchCommand::Publish {
                     topic: format!("{}/status/{}", topic_prefix, id),