feat(irtt): make IRTT measurement optional and refine engine behavior

Conditionally compile IRTT functionality behind the `irtt` feature flag to allow building smaller binaries without IRTT dependencies. Enhance IRTT engine shutdown, configuration, and clarify ICMP protocol names.

src/controller.rs

@@ -8,10 +8,11 @@ use std::{
 use flume::{Receiver, SendError, Sender};
 use thiserror::Error;
 
+#[cfg(feature = "irtt")]
+use crate::measurement::irtt::IrttBinding;
 use crate::{
     measurement::{
         icmp::IcmpBinding,
-        irtt::IrttBinding,
         model::{MeasurementSource, MeasurementStream, MeasurementStreamId, ProbeSchedule},
     },
     settings::ReflectorDefinition,
@@ -21,6 +22,7 @@ use crate::{
 pub enum ControllerError {
     #[error("ICMP channel error")]
     IcmpChannelError(#[from] SendError<Vec<IcmpBinding>>),
+    #[cfg(feature = "irtt")]
     #[error("IRTT channel error")]
     IrttChannelError(#[from] SendError<Vec<IrttBinding>>),
 }
@@ -28,6 +30,7 @@ pub enum ControllerError {
 pub struct Controller {
     reflector_rx: Receiver<Vec<SocketAddr>>,
     icmp_binding_tx: Sender<Vec<IcmpBinding>>,
+    #[cfg(feature = "irtt")]
     irtt_binding_tx: Sender<Vec<IrttBinding>>,
     reflectors: HashMap<SocketAddr, ReflectorDefinition>,
     active_streams: Arc<RwLock<Vec<MeasurementStream>>>,
@@ -42,7 +45,7 @@ impl Controller {
     pub fn new(
         reflector_rx: Receiver<Vec<SocketAddr>>,
         icmp_binding_tx: Sender<Vec<IcmpBinding>>,
-        irtt_binding_tx: Sender<Vec<IrttBinding>>,
+        #[cfg(feature = "irtt")] irtt_binding_tx: Sender<Vec<IrttBinding>>,
         reflectors: HashMap<SocketAddr, ReflectorDefinition>,
         active_streams: Arc<RwLock<Vec<MeasurementStream>>>,
         endpoint_streams: Arc<RwLock<HashMap<SocketAddr, MeasurementStream>>>,
@@ -51,6 +54,7 @@ impl Controller {
         Self {
             reflector_rx,
             icmp_binding_tx,
+            #[cfg(feature = "irtt")]
             irtt_binding_tx,
             reflectors,
             active_streams,
@@ -90,18 +94,21 @@ impl Controller {
     ) -> Result<(), ControllerError> {
         let count = endpoints.len();
         let mut icmp = Vec::new();
+        #[cfg(feature = "irtt")]
         let mut irtt = Vec::new();
         let mut streams = Vec::with_capacity(count);
         let mut endpoint_streams = HashMap::new();
         for (index, endpoint) in endpoints.into_iter().enumerate() {
-            let Some((port, hmac)) = self.reflectors.get(&endpoint).map(|definition| {
-                (
-                    definition.irtt_port.unwrap_or(2112),
-                    definition.irtt_hmac.clone(),
-                )
-            }) else {
+            let Some(_definition) = self.reflectors.get(&endpoint) else {
                 continue;
             };
+            #[cfg(feature = "irtt")]
+            let (port, hmac) = {
+                (
+                    _definition.irtt_port.unwrap_or(2112),
+                    _definition.irtt_hmac.clone(),
+                )
+            };
             let stream = self.stream_for(endpoint);
             let schedule = ProbeSchedule {
                 period: self.period,
@@ -111,9 +118,12 @@ impl Controller {
                 MeasurementSource::IcmpEcho | MeasurementSource::IcmpTimestamp => {
                     icmp.push(IcmpBinding::new(stream, schedule))
                 }
+                #[cfg(feature = "irtt")]
                 MeasurementSource::Irtt => {
                     irtt.push(IrttBinding::new(stream, schedule, port, hmac))
                 }
+                #[cfg(not(feature = "irtt"))]
+                MeasurementSource::Irtt => unreachable!("IRTT feature is checked before startup"),
                 _ => unreachable!("unsupported reflector measurement source"),
             }
             streams.push(stream);
@@ -128,6 +138,7 @@ impl Controller {
             .write()
             .expect("endpoint stream lock poisoned") = endpoint_streams;
         self.icmp_binding_tx.send_async(icmp).await?;
+        #[cfg(feature = "irtt")]
         self.irtt_binding_tx.send_async(irtt).await?;
         Ok(())
     }