Add metric for new enqueued URLs

quickpeep_raker/src/raking/rakemetrics.rs

@@ -18,4 +18,10 @@ pub fn describe_raking_metrics() {
         Unit::Bytes,
         "Number of content bytes raked."
     );
+
+    describe_counter!(
+        "qprake_queue_new_url",
+        Unit::Count,
+        "Number of new URLs enqueued"
+    );
 }

quickpeep_raker/src/raking/task.rs

@@ -10,6 +10,7 @@ use chrono::Utc;
 use cylon::Cylon;
 use log::{error, warn};
 use lru::LruCache;
+use metrics::increment_counter;
 use quickpeep_structs::rake_entries::{
     IconEntry, RakedPageEntry, RakedReference, RakedReferrerEntry, ReferenceKind,
 };
@@ -537,11 +538,14 @@ impl EventProcessor<'_> {
                         .map(|record: AllowedDomainRecord| record.applies_to_url(&ref_url))
                         .unwrap_or(false);
                     if allowed {
-                        txn.enqueue_url(
+                        let is_fresh = txn.enqueue_url(
                             &reference.target,
                             reference.last_mod,
                             reference.kind.into(),
                         )?;
+                        if is_fresh {
+                            increment_counter!("qprake_queue_new_url");
+                        }
                         continue;
                     }