mqtt: Add MqttClient::connect method

Separating the `connect` call out of the `MqttClient::new` function
makes is such that we do not have to create a new object for each
iteration of the initial connection loop.  Instead, we just create one
object and repeatedly call its `connect` method until it succeeds

src/mqtt.rs

@@ -3,20 +3,21 @@ use std::time::Duration;
 pub use paho_mqtt::Error;
 use paho_mqtt::{
     AsyncClient, AsyncReceiver, ConnectOptions, ConnectOptionsBuilder,
-    CreateOptionsBuilder, Message, SslOptionsBuilder,
+    CreateOptionsBuilder, Message, ServerResponse, SslOptionsBuilder,
 };
 use tokio_stream::StreamExt;
 use tracing::{info, trace};
 
 use crate::config::Configuration;
 
-pub struct MqttClient {
+pub struct MqttClient<'a> {
+    config: &'a Configuration,
     client: AsyncClient,
     stream: AsyncReceiver<Option<Message>>,
 }
 
-impl MqttClient {
-    pub async fn new(config: &Configuration) -> Result<MqttClient, Error> {
+impl<'a> MqttClient<'a> {
+    pub fn new(config: &'a Configuration) -> Result<Self, Error> {
         let uri = format!(
             "{}://{}:{}",
             if config.mqtt.tls { "ssl" } else { "tcp" },
@@ -28,10 +29,13 @@ impl MqttClient {
             CreateOptionsBuilder::new().server_uri(uri).finalize();
         let mut client = AsyncClient::new(client_opts)?;
         let stream = client.get_stream(10);
-        client.connect(Self::conn_opts(config)?).await?;
-        info!("Successfully connected to MQTT broker");
+        Ok(Self { config, client, stream })
+    }
 
-        Ok(Self { client, stream })
+    pub async fn connect(&mut self) -> Result<ServerResponse, Error> {
+        let res = self.client.connect(self.conn_opts()?).await?;
+        info!("Successfully connected to MQTT broker");
+        Ok(res)
     }
 
     pub async fn run(mut self) {
@@ -41,20 +45,20 @@ impl MqttClient {
         }
     }
 
-    fn conn_opts(config: &Configuration) -> Result<ConnectOptions, Error> {
+    fn conn_opts(&self) -> Result<ConnectOptions, Error> {
         let mut conn_opts = ConnectOptionsBuilder::new();
         conn_opts.automatic_reconnect(
             Duration::from_millis(500),
             Duration::from_secs(30),
         );
-        if config.mqtt.tls {
+        if self.config.mqtt.tls {
             let ssl_opts = SslOptionsBuilder::new()
-                .trust_store(&config.mqtt.ca_file)?
+                .trust_store(&self.config.mqtt.ca_file)?
                 .finalize();
             conn_opts.ssl_options(ssl_opts);
         }
         if let [Some(username), Some(password)] =
-            [&config.mqtt.username, &config.mqtt.password]
+            [&self.config.mqtt.username, &self.config.mqtt.password]
         {
             conn_opts.user_name(username).password(password);
         }

src/session.rs

@@ -2,11 +2,11 @@ use std::time::Duration;
 
 use tracing::{debug, info, warn};
 
-use crate::mqtt::MqttClient;
 use crate::browser::{Browser, BrowserError};
 use crate::config::Configuration;
 use crate::marionette::error::ConnectionError;
 use crate::marionette::Marionette;
+use crate::mqtt::MqttClient;
 
 #[derive(Debug)]
 pub enum SessionError {
@@ -84,13 +84,10 @@ impl Session {
     }
 
     pub async fn run(&self) {
-        let client;
+        let mut client = MqttClient::new(&self.config).unwrap();
         loop {
-            match MqttClient::new(&self.config).await {
-                Ok(c) => {
-                    client = c;
-                    break;
-                }
+            match client.connect().await {
+                Ok(_) => break,
                 Err(e) => warn!("Failed to connect to MQTT server: {}", e),
             }
             tokio::time::sleep(Duration::from_secs(1)).await;