From 61a39b511596a7396c8aee2386f09fc99d529b9b Mon Sep 17 00:00:00 2001
From: Wan <495709+wa0x6e@users.noreply.github.com>
Date: Mon, 25 Mar 2024 16:41:45 +0800
Subject: [PATCH] chore: instrument the cache engine (#250)

---
 src/lib/cache.ts         | 9 +++++++--
 src/lib/metrics/index.ts | 6 ++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/lib/cache.ts b/src/lib/cache.ts
index 181b60f..d931b48 100644
--- a/src/lib/cache.ts
+++ b/src/lib/cache.ts
@@ -1,4 +1,5 @@
 import { IStorage } from './storage/types';
+import { cacheHitCount } from './metrics';
 
 export default class Cache {
   id: string;
@@ -17,8 +18,12 @@ export default class Cache {
     return '';
   }
 
-  getCache() {
-    return this.storage.get(this.filename);
+  async getCache() {
+    const cache = await this.storage.get(this.filename);
+
+    cacheHitCount.inc({ status: !cache ? 'MISS' : 'HIT', type: this.constructor.name });
+
+    return cache;
   }
 
   async isCacheable() {
diff --git a/src/lib/metrics/index.ts b/src/lib/metrics/index.ts
index f4a0d08..56c2f97 100644
--- a/src/lib/metrics/index.ts
+++ b/src/lib/metrics/index.ts
@@ -157,6 +157,12 @@ try {
   }
 }
 
+export const cacheHitCount = new client.Counter({
+  name: 'cache_hit_count',
+  help: 'Number of hit/miss of the cache engine',
+  labelNames: ['status', 'type']
+});
+
 const providersResponseCode = new client.Gauge({
   name: 'provider_response_code',
   help: 'Response code of each provider request',