fail if no metric is found for a series

waybar-collectd/src/err.rs

@@ -0,0 +1,22 @@
+use std::fmt;
+
+use protocol::ProtocolError;
+
+#[derive(PartialEq, Debug)]
+pub enum WaybarCollectdError {
+    ProtocolError(ProtocolError),
+    NoMatchingMetricFound(String),
+}
+
+impl fmt::Display for WaybarCollectdError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let message = match self {
+            Self::ProtocolError(val) => format!("Collectd integration failed: {val}"),
+            Self::NoMatchingMetricFound(name) => {
+                format!("No matching metric found for {}", name)
+            }
+        };
+
+        f.write_str(&message)
+    }
+}

waybar-collectd/src/main.rs

@@ -1,4 +1,5 @@
 mod config;
+mod err;
 mod observables;
 mod runner;
 

waybar-collectd/src/observables.rs

@@ -1,7 +1,7 @@
 use protocol::{Protocol, ProtocolError};
 use regex::Regex;
 
-use crate::config::MetricSpecification;
+use crate::{config::MetricSpecification, err::WaybarCollectdError};
 
 pub struct Observable {
     pub name: String,
@@ -23,8 +23,10 @@ impl Observable {
         proto: &mut Protocol,
         name: &str,
         includes: &Vec<MetricSpecification>,
-    ) -> Result<Observable, ProtocolError> {
-        let all_values = proto.list()?;
+    ) -> Result<Observable, WaybarCollectdError> {
+        let all_values = proto
+            .list()
+            .map_err(|e| WaybarCollectdError::ProtocolError(e))?;
         let regexes: Vec<MetricRegex> = includes
             .iter()
             .map(|i| MetricRegex {
@@ -32,7 +34,7 @@ impl Observable {
                 value: i.value.to_string(),
             })
             .collect();
-        let filtered_values = all_values
+        let filtered_values: Vec<Metric> = all_values
             .into_iter()
             .filter_map(|v| {
                 for r in regexes.iter() {
@@ -48,11 +50,15 @@ impl Observable {
             })
             .collect();
 
+        if filtered_values.len() == 0 {
+            Err(WaybarCollectdError::NoMatchingMetricFound(name.to_string()))
+        } else {
             Ok(Observable {
                 name: name.to_string(),
                 metrics: filtered_values,
             })
         }
+    }
 
     pub fn sample(&self, proto: &mut Protocol) -> Result<f32, ProtocolError> {
         let results = self

waybar-collectd/src/runner.rs

@@ -1,10 +1,11 @@
 use core::fmt;
 
 use draw::{StackedConfig, StackedSeries, StackedSeriesConfig, stacked};
-use protocol::{Protocol, ProtocolError};
+use protocol::Protocol;
 
 use crate::{
     config::GraphConfig,
+    err::WaybarCollectdError,
     observables::{Observable, ObservableCollection},
 };
 
@@ -33,7 +34,7 @@ impl Graph {
                 .series
                 .iter()
                 .map(|s| Observable::discover(proto, &s.name, &s.metrics))
-                .collect::<Result<Vec<Observable>, ProtocolError>>()
+                .collect::<Result<Vec<Observable>, WaybarCollectdError>>()
                 .expect("Could not discover required metrics"),
         );