From f8eb4fc79cb90eeb6f9e71af0b5fff59ec8b792e Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Thu, 6 Mar 2025 22:55:23 -0600
Subject: [PATCH] Add a metric for active author subscriptions

---
 packages/ditto/storages/DittoRelayStore.ts | 3 +++
 packages/metrics/metrics.ts                | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/packages/ditto/storages/DittoRelayStore.ts b/packages/ditto/storages/DittoRelayStore.ts
index 9fb232ac..7a0935e1 100644
--- a/packages/ditto/storages/DittoRelayStore.ts
+++ b/packages/ditto/storages/DittoRelayStore.ts
@@ -1,6 +1,7 @@
 import { DittoConf } from '@ditto/conf';
 import { DittoDB, DittoTables } from '@ditto/db';
 import {
+  activeAuthorSubscriptionsGauge,
   cachedFaviconsSizeGauge,
   cachedNip05sSizeGauge,
   pipelineEventsCounter,
@@ -185,6 +186,7 @@ export class DittoRelayStore implements NRelay {
     // Try to fetch a kind 0 for the user if we don't have one yet.
     // TODO: Create a more elaborate system to refresh all replaceable events by addr.
     if (event.kind !== 0 && !event.author?.sig && !this.authorEncounters.get(event.pubkey)) {
+      activeAuthorSubscriptionsGauge.inc();
       this.authorEncounters.set(event.pubkey, true);
 
       const [author] = await pool.query(
@@ -196,6 +198,7 @@ export class DittoRelayStore implements NRelay {
         // await because it's important to have the kind 0 before the policy filter.
         await this.event(author, { signal });
       }
+      activeAuthorSubscriptionsGauge.dec();
     }
 
     // Ensure the event doesn't violate the policy.
diff --git a/packages/metrics/metrics.ts b/packages/metrics/metrics.ts
index 716582d4..9e131951 100644
--- a/packages/metrics/metrics.ts
+++ b/packages/metrics/metrics.ts
@@ -149,3 +149,8 @@ export const webPushNotificationsCounter: Counter<'type'> = new Counter({
   help: 'Total number of Web Push notifications sent',
   labelNames: ['type'],
 });
+
+export const activeAuthorSubscriptionsGauge: Gauge = new Gauge({
+  name: `${prefix}_active_author_subscriptions`,
+  help: "Number of active REQ's to find kind 0 events from the pool",
+});