chore: update gateway pressure observability

crates/aether-testkit/src/metrics.rs

@@ -85,22 +85,69 @@ fn parse_prometheus_line(line: &str) -> Option<PrometheusSample> {
 
 fn parse_labels(raw: &str) -> BTreeMap<String, String> {
     let mut labels = BTreeMap::new();
-    for pair in raw.split(',').filter(|pair| !pair.is_empty()) {
+    for pair in split_label_pairs(raw) {
         if let Some((key, value)) = pair.split_once('=') {
             labels.insert(
                 key.trim().to_string(),
-                value
-                    .trim()
-                    .trim_matches('"')
-                    .replace("\\\"", "\"")
-                    .replace("\\n", "\n")
-                    .replace("\\\\", "\\"),
+                unescape_label_value(value.trim().trim_matches('"')),
             );
         }
     }
     labels
 }
 
+fn split_label_pairs(raw: &str) -> Vec<&str> {
+    let mut pairs = Vec::new();
+    let mut start = 0;
+    let mut in_string = false;
+    let mut escaped = false;
+    for (index, ch) in raw.char_indices() {
+        if escaped {
+            escaped = false;
+            continue;
+        }
+        match ch {
+            '\\' if in_string => escaped = true,
+            '"' => in_string = !in_string,
+            ',' if !in_string => {
+                let pair = raw[start..index].trim();
+                if !pair.is_empty() {
+                    pairs.push(pair);
+                }
+                start = index + ch.len_utf8();
+            }
+            _ => {}
+        }
+    }
+    let pair = raw[start..].trim();
+    if !pair.is_empty() {
+        pairs.push(pair);
+    }
+    pairs
+}
+
+fn unescape_label_value(value: &str) -> String {
+    let mut output = String::with_capacity(value.len());
+    let mut chars = value.chars();
+    while let Some(ch) = chars.next() {
+        if ch != '\\' {
+            output.push(ch);
+            continue;
+        }
+        match chars.next() {
+            Some('n') => output.push('\n'),
+            Some('\\') => output.push('\\'),
+            Some('"') => output.push('"'),
+            Some(next) => {
+                output.push('\\');
+                output.push(next);
+            }
+            None => output.push('\\'),
+        }
+    }
+    output
+}
+
 #[cfg(test)]
 mod tests {
     use super::{find_metric_value_u64, parse_prometheus_samples};
@@ -133,4 +180,38 @@ aether_gateway_concurrency_rejected_total{gate="gateway_requests"} 12
             Some(12)
         );
     }
+
+    #[test]
+    fn parses_quoted_label_values_containing_commas() {
+        let samples = parse_prometheus_samples(
+            r#"
+metric_with_sql{rank="1",query_prefix="SELECT id, name, created_at FROM request_candidates",state="active"} 2
+"#,
+        );
+
+        assert_eq!(samples.len(), 1);
+        assert_eq!(samples[0].labels.get("rank").map(String::as_str), Some("1"));
+        assert_eq!(
+            samples[0].labels.get("query_prefix").map(String::as_str),
+            Some("SELECT id, name, created_at FROM request_candidates")
+        );
+        assert_eq!(
+            samples[0].labels.get("state").map(String::as_str),
+            Some("active")
+        );
+    }
+
+    #[test]
+    fn unescapes_quoted_label_values() {
+        let samples = parse_prometheus_samples(
+            r#"
+metric_with_escape{message="bad\"line\nx\\y"} 1
+"#,
+        );
+
+        assert_eq!(
+            samples[0].labels.get("message").map(String::as_str),
+            Some("bad\"line\nx\\y")
+        );
+    }
 }