From a01a4da9b5bd2d87d209c6c22395212b69a9c520 Mon Sep 17 00:00:00 2001
From: Lukasz Raczylo <lukasz@raczylo.com>
Date: Tue, 11 Jun 2024 00:03:05 +0100
Subject: [PATCH] Add metrics for cached queries + cache hit/miss

---
 monitoring/defaults.go | 3 +++
 monitoring/structs.go  | 4 ++++
 server.go              | 3 +++
 3 files changed, 10 insertions(+)

diff --git a/monitoring/defaults.go b/monitoring/defaults.go
index cb17744..f0e7ee7 100644
--- a/monitoring/defaults.go
+++ b/monitoring/defaults.go
@@ -5,6 +5,9 @@ func (ms *MetricsSetup) RegisterDefaultMetrics() {
 	ms.RegisterMetricsCounter(MetricsFailed, nil)
 	ms.RegisterMetricsCounter(MetricsSkipped, nil)
 	ms.RegisterMetricsHistogram(MetricsDuration, nil)
+	ms.RegisterMetricsCounter(MetricsCacheHit, nil)
+	ms.RegisterMetricsCounter(MetricsCacheMiss, nil)
+	ms.RegisterMetricsCounter(MetricsQueriesCached, nil)
 }
 
 func (ms *MetricsSetup) RegisterGoMetrics() {
diff --git a/monitoring/structs.go b/monitoring/structs.go
index fe1cd5e..1f99194 100644
--- a/monitoring/structs.go
+++ b/monitoring/structs.go
@@ -7,4 +7,8 @@ const (
 	MetricsSkipped       = "requests_skipped"
 	MetricsExecutedQuery = "executed_query"
 	MetricsTimedQuery    = "timed_query"
+
+	MetricsCacheHit      = "cache_hit"
+	MetricsCacheMiss     = "cache_miss"
+	MetricsQueriesCached = "cached_queries"
 )
diff --git a/server.go b/server.go
index 5763711..516f2dc 100644
--- a/server.go
+++ b/server.go
@@ -152,11 +152,13 @@ func processGraphQLRequest(c *fiber.Ctx) error {
 		queryCacheHash = calculateHash(c)
 
 		if cachedResponse := cacheLookup(queryCacheHash); cachedResponse != nil {
+			cfg.Monitoring.Increment(libpack_monitoring.MetricsCacheHit, nil)
 			cfg.Logger.Debug("Cache hit", map[string]interface{}{"hash": queryCacheHash, "user_id": extractedUserID, "request_uuid": c.Locals("request_uuid")})
 			c.Request().Header.Add("X-Cache-Hit", "true")
 			c.Send(cachedResponse)
 			wasCached = true
 		} else {
+			cfg.Monitoring.Increment(libpack_monitoring.MetricsCacheMiss, nil)
 			cfg.Logger.Debug("Cache miss", map[string]interface{}{"hash": queryCacheHash, "user_id": extractedUserID, "request_uuid": c.Locals("request_uuid")})
 			proxyAndCacheTheRequest(c, queryCacheHash, parsedResult.cacheTime, parsedResult.activeEndpoint)
 		}
@@ -182,6 +184,7 @@ func proxyAndCacheTheRequest(c *fiber.Ctx, queryCacheHash string, cacheTime int,
 		return
 	}
 	cfg.Cache.CacheClient.Set(queryCacheHash, c.Response().Body(), time.Duration(cacheTime)*time.Second)
+	cfg.Monitoring.Increment(libpack_monitoring.MetricsQueriesCached, nil)
 	c.Send(c.Response().Body())
 }