captool: add series value dumping capability (#997)

* Add series value dumping capability

* Add fetch index to dump output

Author: GeorgeHahn

lading/src/bin/captool.rs

@@ -22,6 +22,10 @@ struct Args {
     #[clap(short, long)]
     metric: Option<String>,
 
+    /// dump a metric's values. Requires --metric.
+    #[clap(short, long)]
+    dump_values: bool,
+
     /// Path to line-delimited capture file
     capture_path: String,
 }
@@ -88,7 +92,7 @@ async fn main() -> Result<(), Error> {
         return Ok(());
     }
 
-    if let Some(metric) = args.metric {
+    if let Some(metric) = &args.metric {
         // key is hash of the metric name and all the sorted, concatenated labels
         // value is a tuple of
         // - hashset of "key:value" strings (aka, concatenated labels)
@@ -100,7 +104,7 @@ async fn main() -> Result<(), Error> {
         // Use a BTreeSet to ensure that the tags are sorted
         lines
             .iter()
-            .filter(|line| line.metric_name == metric)
+            .filter(|line| &line.metric_name == metric)
             .for_each(|line| {
                 let mut sorted_labels: BTreeSet<String> = BTreeSet::new();
                 for (key, value) in line.labels.iter() {
@@ -133,6 +137,20 @@ async fn main() -> Result<(), Error> {
         }
     }
 
+    if args.dump_values {
+        if let Some(metric) = &args.metric {
+            lines
+                .iter()
+                .filter(|line| &line.metric_name == metric)
+                .for_each(|line| {
+                    println!("{}: {}", line.fetch_index, line.value);
+                });
+        } else {
+            error!("--dump-values requires --metric");
+            return Err(Error::InvalidArgs);
+        }
+    }
+
     info!("Bye. :)");
     Ok(())
 }

lading_capture/src/json.rs

@@ -38,6 +38,15 @@ impl LineValue {
     }
 }
 
+impl std::fmt::Display for LineValue {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            LineValue::Int(int) => write!(f, "{int}"),
+            LineValue::Float(float) => write!(f, "{float}"),
+        }
+    }
+}
+
 #[derive(Debug, Serialize, Deserialize)]
 /// The structure of a capture file line.
 pub struct Line<'a> {