split code in separate modules

src/cli_args.rs

@@ -0,0 +1,22 @@
+use std::path::PathBuf;
+use clap::Parser;
+
+//------------------------------------------------------------------------------
+
+/// MQTT to Statsd bridge.
+#[derive(Parser, Debug)]
+#[clap( name = "mqtt2statsd", version = clap::crate_version!())]
+pub struct Args {
+    /// Log MQTT & statsd messages on the console
+    #[arg(short, long)]
+    pub verbose: bool,
+
+    /// Configuration file
+    pub configuration: PathBuf
+}
+
+//------------------------------------------------------------------------------
+
+pub fn parse() -> Args {
+    Args::parse()
+}

src/config.rs

@@ -0,0 +1,68 @@
+use std::error::Error;
+use std::fs;
+use std::path::PathBuf;
+
+use serde::Deserialize;
+
+// =============================================================================
+// Structs
+// =============================================================================
+
+#[derive(Debug, Deserialize)]
+pub struct Config {
+    pub mqtt: MqttConfig,
+    pub statsd: StatsdConfig,
+    pub topics: Vec<Topic>
+}
+
+//------------------------------------------------------------------------------
+
+#[derive(Debug, Deserialize)]
+pub struct MqttConfig {
+    pub hostname: String,
+
+    #[serde(default = "default_mqtt_port") ]
+    pub port: u32
+}
+
+//------------------------------------------------------------------------------
+
+
+#[derive(Debug, Deserialize)]
+pub struct StatsdConfig {
+    pub hostname: String,
+
+    #[serde(default = "default_statsd_port")]
+    pub port: u32
+}
+
+//------------------------------------------------------------------------------
+
+#[derive(Debug, Deserialize)]
+pub struct Topic {
+    pub mqtt_topic: String,
+    pub statsd_topic: String
+}
+
+// =============================================================================
+// Public Functions
+// =============================================================================
+
+pub fn from_file( path: &PathBuf ) -> Result<Config, Box<dyn Error>> {
+    let config_str = fs::read_to_string(path)?;
+    Ok( toml::from_str(&config_str)? )
+}
+
+// =============================================================================
+// Private Functions
+// =============================================================================
+
+fn default_mqtt_port() -> u32 {
+    1883
+}
+
+//------------------------------------------------------------------------------
+
+fn default_statsd_port() -> u32 {
+    8125
+}

src/main.rs

@@ -1,108 +1,18 @@
-use std::path::PathBuf;
-use std::fs;
+use std::error::Error;
 
-use clap::Parser;
-use serde::Deserialize;
+mod cli_args;
+mod config;
+mod mqtt;
 
-extern crate paho_mqtt as mqtt;
-
-// =============================================================================
-// CLI arguments
-// =============================================================================
-
-/// MQTT to Statsd bridge.
-#[derive(Parser, Debug)]
-#[clap( name = "mqtt2statsd", version = clap::crate_version!())]
-struct Args {
-    /// Log MQTT & statsd messages on the console
-    #[arg(short, long)]
-    verbose: bool,
-
-    /// Configuration file
-    configuration: PathBuf
-}
-
-// =============================================================================
-// Configuration file structure
-// =============================================================================
-
-#[derive(Debug, Deserialize)]
-struct Config {
-    mqtt: MqttConfig,
-    statsd: StatsdConfig,
-    topics: Vec<Topic>
-}
-
-//------------------------------------------------------------------------------
-
-fn default_mqtt_port() -> u32 { 1883 }
-
-#[derive(Debug, Deserialize)]
-struct MqttConfig {
-    hostname: String,
-
-    #[serde(default = "default_mqtt_port") ]
-    port: u32
-}
-
-//------------------------------------------------------------------------------
-
-fn default_statsd_port() -> u32 { 8125 }
-
-#[derive(Debug, Deserialize)]
-struct StatsdConfig {
-    hostname: String,
-
-    #[serde(default = "default_statsd_port")]
-    port: u32
-}
-
-//------------------------------------------------------------------------------
-
-#[derive(Debug, Deserialize)]
-struct Topic {
-    mqtt_topic: String,
-    statsd_topic: String
-}
-
-// =============================================================================
-// Main code
-// =============================================================================
-
-fn main() {
-    let args = Args::parse();
-
-    let config_str = fs::read_to_string(args.configuration)
-        .expect("Failed to read configuration file");
-    let config: Config = toml::from_str(&config_str)
-        .expect("Error in configuration file");
+fn main() -> Result<(), Box<dyn Error>> {
+    let args = cli_args::parse();
+    let config = config::from_file(&args.configuration)?;
 
     println!("{:#?}", config); //TODO: remove
 
-    let mqtt_opts = mqtt::CreateOptionsBuilder::new()
-        .server_uri(config.mqtt.hostname)
-        .finalize();
-
-    let mqtt = mqtt::Client::new(mqtt_opts)
-        .expect("Cannot create mqtt client");
-
+    let mqtt = mqtt::create( &config.mqtt )?;
     let rx = mqtt.start_consuming();
-
-    let conn_opts = mqtt::ConnectOptionsBuilder::new()
-        .keep_alive_interval(std::time::Duration::from_secs(20))
-        .finalize();
-
-    mqtt.connect(conn_opts)
-        .expect( "Cannot connect" );
-
-    for topic in config.topics {
-        let e = mqtt.subscribe(topic.mqtt_topic.as_str(), 1);
-        if e.is_ok() {
-            println!( "Subscribed to {}", topic.mqtt_topic );
-        } else if args.verbose {
-            println!( "Cannot subscribe to {} (error: {e:?})", topic.mqtt_topic );
-        }
-    }
+    mqtt::subscribe( &mqtt, &config.topics, args.verbose );
 
     for msg in rx.iter() {
         if let Some(msg) = msg {
@@ -117,4 +27,6 @@ fn main() {
         println!("Disconnecting");
         //mqtt.unsubscribe_many(topics)
     }
+
+    Ok(())
 }

src/mqtt.rs

@@ -0,0 +1,38 @@
+extern crate paho_mqtt as paho;
+
+use crate::config::MqttConfig;
+use crate::config::Topic;
+
+// =============================================================================
+// Public Functions
+// =============================================================================
+
+pub fn create( config: &MqttConfig ) -> Result<paho::Client, paho::Error> {
+    let client_opts = paho::CreateOptionsBuilder::new()
+        .server_uri(&config.hostname)
+        .finalize();
+
+    let ret = paho::Client::new(client_opts)?;
+
+    let conn_opts = paho::ConnectOptionsBuilder::new()
+        .keep_alive_interval(std::time::Duration::from_secs(20))
+        .finalize();
+
+    ret.connect(conn_opts)?;
+
+    Ok(ret)
+}
+
+//------------------------------------------------------------------------------
+
+pub fn subscribe( mqtt: &paho::Client, topics: &Vec<Topic>, verbose: bool ) {
+
+    for topic in topics {
+        let e = mqtt.subscribe(topic.mqtt_topic.as_str(), 1);
+        if e.is_ok() {
+            println!( "Subscribed to {}", topic.mqtt_topic );
+        } else if verbose {
+            println!( "Cannot subscribe to {} (error: {e:?})", topic.mqtt_topic );
+        }
+    }
+}