feat: added max_flows to Trace and use to restriction the creatio…

…n of new flows

src/backend.rs

@@ -19,11 +19,16 @@ pub struct Backend {
 
 impl Backend {
     /// Create a tracing `Backend`.
-    pub fn new(tracer_config: Config, channel_config: ChannelConfig, max_samples: usize) -> Self {
+    pub fn new(
+        tracer_config: Config,
+        channel_config: ChannelConfig,
+        max_samples: usize,
+        max_flows: usize,
+    ) -> Self {
         Self {
             tracer_config,
             channel_config,
-            trace: Arc::new(RwLock::new(Trace::new(max_samples))),
+            trace: Arc::new(RwLock::new(Trace::new(max_samples, max_flows))),
         }
     }
 

src/backend/trace.rs

@@ -10,7 +10,16 @@ use trippy::tracing::{Extensions, ProbeState, Round, TimeToLive, TracerRound};
 /// The state of all hops in a trace.
 #[derive(Debug, Clone)]
 pub struct Trace {
+    /// The maximum number of samples to record per hop.
+    ///
+    /// Once the maximum number of samples has been reached the oldest sample
+    /// is discarded (FIFO).
     max_samples: usize,
+    /// The maximum number of flows to record.
+    ///
+    /// Once the maximum number of flows has been reached no new flows will be
+    /// created, existing flows are updated and are never removed.
+    max_flows: usize,
     /// The flow id for the current round.
     round_flow_id: FlowId,
     /// Tracing data per registered flow id.
@@ -23,12 +32,13 @@ pub struct Trace {
 
 impl Trace {
     /// Create a new `Trace`.
-    pub fn new(max_samples: usize) -> Self {
+    pub fn new(max_samples: usize, max_flows: usize) -> Self {
         Self {
             trace_data: once((Self::default_flow_id(), TraceData::new(max_samples)))
                 .collect::<HashMap<FlowId, TraceData>>(),
             round_flow_id: Self::default_flow_id(),
             max_samples,
+            max_flows,
             registry: FlowRegistry::new(),
             error: None,
         }
@@ -105,10 +115,12 @@ impl Trace {
                 })
                 .take(usize::from(round.largest_ttl.0)),
         );
-        let flow_id = self.registry.register(flow);
-        self.round_flow_id = flow_id;
         self.update_trace_flow(Self::default_flow_id(), round);
-        self.update_trace_flow(flow_id, round);
+        if self.registry.flows().len() < self.max_flows {
+            let flow_id = self.registry.register(flow);
+            self.round_flow_id = flow_id;
+            self.update_trace_flow(flow_id, round);
+        }
     }
 
     fn update_trace_flow(&mut self, flow_id: FlowId, round: &TracerRound<'_>) {

src/frontend/tui_app.rs

@@ -54,7 +54,7 @@ impl TuiApp {
         trace_info: Vec<TraceInfo>,
     ) -> Self {
         Self {
-            selected_tracer_data: Trace::new(tui_config.max_samples),
+            selected_tracer_data: Trace::new(tui_config.max_samples, tui_config.max_flows),
             trace_info,
             tui_config,
             table_state: TableState::default(),
@@ -88,7 +88,7 @@ impl TuiApp {
 
     pub fn clear_trace_data(&mut self) {
         *self.trace_info[self.trace_selected].data.write() =
-            Trace::new(self.tui_config.max_samples);
+            Trace::new(self.tui_config.max_samples, self.tui_config.max_flows);
     }
 
     pub fn selected_hop_or_target(&self) -> &Hop {

src/main.rs

@@ -214,7 +214,12 @@ fn start_tracer(
     };
     let channel_config = make_channel_config(cfg, source_addr, target_addr);
     let tracer_config = make_tracer_config(cfg, target_addr, trace_identifier)?;
-    let backend = Backend::new(tracer_config, channel_config, cfg.tui_max_samples);
+    let backend = Backend::new(
+        tracer_config,
+        channel_config,
+        cfg.tui_max_samples,
+        cfg.tui_max_flows,
+    );
     let trace_data = backend.trace();
     thread::Builder::new()
         .name(format!("tracer-{}", tracer_config.trace_identifier.0))