Add cache metrics

api/cache/cache.go

@@ -1,14 +1,16 @@
 package cache
 
 import (
+	"github.com/eko/gocache/lib/v4/metrics"
+	"github.com/prometheus/client_golang/prometheus"
 	"time"
 
 	"github.com/eko/gocache/lib/v4/cache"
 	"github.com/eko/gocache/lib/v4/marshaler"
 	"github.com/eko/gocache/lib/v4/store"
 	gocacheStore "github.com/eko/gocache/store/go_cache/v4"
 	redis_store "github.com/eko/gocache/store/redis/v4"
 	gocache "github.com/patrickmn/go-cache"
 	"github.com/redis/go-redis/v9"
 
 	"github.com/spacemeshos/go-spacemesh/log"
@@ -18,21 +20,37 @@
 	RedisAddress                  = ""
 	Expiration      time.Duration = 0
 	ShortExpiration               = 5 * time.Minute
+	promMetrics                   = metrics.NewPrometheus("explorer_cache")
+	LastUpdated                   = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "explorer_cache_last_updated",
+			Help: "The last time the cache was updated, labeled by endpoint and id",
+		},
+		[]string{"endpoint"},
+	)
 )
 
 func New() *marshaler.Marshaler {
-	var manager *cache.Cache[any]
+	prometheus.MustRegister(LastUpdated)
+	var manager *cache.MetricCache[any]
 	if RedisAddress != "" {
 		log.Info("using redis cache")
 		redisStore := redis_store.NewRedis(redis.NewClient(&redis.Options{
 			Addr: RedisAddress,
 		}), store.WithExpiration(Expiration))
-		manager = cache.New[any](redisStore)
+		manager = cache.NewMetric[any](
+			promMetrics,
+			cache.New[any](redisStore),
+		)
 	} else {
 		log.Info("using memory cahe")
 		client := gocache.New(Expiration, 6*time.Hour)
 		s := gocacheStore.NewGoCache(client)
-		manager = cache.New[any](s)
+		manager = cache.NewMetric[any](
+			promMetrics,
+			cache.New[any](s),
+		)
 	}
+
 	return marshaler.New(manager)
 }

api/handler/account.go

@@ -39,6 +39,7 @@ func Account(c echo.Context) error {
 		log.Warning("failed to cache account stats: %v", err)
 		return c.NoContent(http.StatusInternalServerError)
 	}
+	cache.LastUpdated.WithLabelValues("/account/" + address).SetToCurrentTime()
 
 	return c.JSON(http.StatusOK, accountStats)
 }

api/handler/circulation.go

@@ -2,9 +2,10 @@
 
 import (
 	"context"
+	"github.com/spacemeshos/explorer-backend/api/cache"
 	"net/http"
 
 	"github.com/labstack/echo/v4"
 	"github.com/spacemeshos/explorer-backend/api/storage"
 
 	"github.com/spacemeshos/go-spacemesh/log"
@@ -27,6 +28,7 @@
 		log.Warning("failed to cache circulation: %v", err)
 		return c.NoContent(http.StatusInternalServerError)
 	}
+	cache.LastUpdated.WithLabelValues("/circulation").SetToCurrentTime()
 
 	return c.JSON(http.StatusOK, circulation)
 }
@@ -47,6 +49,7 @@
 		}
 
 		log.Info("circulation refreshed")
+		cache.LastUpdated.WithLabelValues("/refresh/circulation").SetToCurrentTime()
 	}()
 
 	return c.NoContent(http.StatusOK)

api/handler/epoch.go

@@ -2,10 +2,12 @@
 
 import (
 	"context"
+	"fmt"
+	"github.com/spacemeshos/explorer-backend/api/cache"
 	"net/http"
 	"strconv"
 
 	"github.com/labstack/echo/v4"
 	"github.com/spacemeshos/explorer-backend/api/storage"
 
 	"github.com/spacemeshos/go-spacemesh/log"
@@ -34,6 +36,8 @@
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues("/epoch/" + c.Param("id")).SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, epochStats)
 }
 
@@ -57,6 +61,7 @@
 		}
 
 		log.Info("epoch %d refreshed", id)
+		cache.LastUpdated.WithLabelValues("/refresh/epoch/" + c.Param("id")).SetToCurrentTime()
 	}()
 
 	return c.NoContent(http.StatusOK)
@@ -85,6 +90,8 @@
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues(fmt.Sprintf("/epoch/%s/decentral", c.Param("id"))).SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, epochStats)
 }
 
@@ -107,7 +114,8 @@
 			return
 		}
 
-		log.Info("epoch decentral refreshed")
+		log.Info("epoch %d decentral refreshed", id)
+		cache.LastUpdated.WithLabelValues(fmt.Sprintf("/refresh/epoch/%s/decentral", c.Param("id"))).SetToCurrentTime()
 	}()
 
 	return c.NoContent(http.StatusOK)

api/handler/layer.go

@@ -37,5 +37,7 @@ func Layer(c echo.Context) error {
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues("/layer/" + c.Param("id")).SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, layerStats)
 }

api/handler/overview.go

@@ -2,9 +2,10 @@
 
 import (
 	"context"
+	"github.com/spacemeshos/explorer-backend/api/cache"
 	"net/http"
 
 	"github.com/labstack/echo/v4"
 	"github.com/spacemeshos/explorer-backend/api/storage"
 
 	"github.com/spacemeshos/go-spacemesh/log"
@@ -28,6 +29,8 @@
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues("/overview").SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, overview)
 }
 
@@ -47,6 +50,7 @@
 		}
 
 		log.Info("overview refreshed")
+		cache.LastUpdated.WithLabelValues("/refresh/overview").SetToCurrentTime()
 	}()
 
 	return c.NoContent(http.StatusOK)

api/handler/smesher.go

@@ -35,6 +35,8 @@ func Smeshers(c echo.Context) error {
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues(fmt.Sprintf("/smeshers?limit=%d&offset=%d", limit, offset)).SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, smeshers)
 }
 
@@ -58,6 +60,7 @@ func SmeshersRefresh(c echo.Context) error {
 		}
 
 		log.Info("smeshers refreshed")
+		cache.LastUpdated.WithLabelValues("/refresh/smeshers").SetToCurrentTime()
 	}()
 
 	return c.NoContent(http.StatusOK)
@@ -90,6 +93,9 @@ func SmeshersByEpoch(c echo.Context) error {
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues(
+		fmt.Sprintf("/smeshers/%s?limit=%d&offset=%d", c.Param("epoch"), limit, offset)).SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, smeshers)
 }
 
@@ -119,6 +125,7 @@ func SmeshersByEpochRefresh(c echo.Context) error {
 		}
 
 		log.Info("smeshers by epoch %d refreshed", epochId)
+		cache.LastUpdated.WithLabelValues("/refresh/smeshers/" + c.Param("epoch")).SetToCurrentTime()
 	}()
 
 	return c.NoContent(http.StatusOK)
@@ -150,5 +157,7 @@ func Smesher(c echo.Context) error {
 		return c.NoContent(http.StatusInternalServerError)
 	}
 
+	cache.LastUpdated.WithLabelValues("/smesher/" + smesherId).SetToCurrentTime()
+
 	return c.JSON(http.StatusOK, smesher)
 }