added metric for queue lengths

backend/src/utils/prometheus.ts

@@ -277,3 +277,17 @@ const collectionSize = new Gauge({
 export function setCollectionSize(collection: string, size: number): void {
   collectionSize.set({ collection }, size);
 }
+
+const queueLength = new Gauge({
+  name: "queue_length",
+  help: "Length of the queues",
+  labelNames: ["queueName", "countType"],
+});
+
+export function setQueueLength(
+  queueName: string,
+  countType: string,
+  length: number
+): void {
+  queueLength.set({ queueName, countType }, length);
+}