Change extension key tablev1.0.1

Remove gauges for extensions which no longer appear after a filesystem
scan. This removes the Prometheus metric labels for extensions that have
been removed from the filesystem, instead of leaving them at their last
known value indefinitely.

1 files changed, 24 insertions, 15 deletions

diff --git a/main.go b/main.go
index 2e3a136..6408877 100644
--- a/main.go
+++ b/main.go
@@ -23,7 +23,8 @@ var (
 	path      string
 	subsystem string
 
-	gauges map[string]*prometheus.GaugeVec
+	extensionKeys map[string]bool
+	gauges        map[string]*prometheus.GaugeVec
 )
 
 func main() {
@@ -71,6 +72,8 @@ func main() {
 	)
 
 	// Start the update process
+	extensionKeys = make(map[string]bool)
+
 	update()
 	go updateLoop()
 
@@ -89,10 +92,8 @@ func main() {
 }
 
 func update() {
-	keys := make(map[string]bool)
-
-	sizes := make(map[string]int64)
-	counts := make(map[string]int64)
+	sizes := make(map[string]float64)
+	counts := make(map[string]float64)
 
 	slog.Debug("Scanning filesystem for updates")
 	err := filepath.Walk(path, func(path string, info fs.FileInfo, err error) error {
@@ -111,10 +112,10 @@ func update() {
 			ext = ext[1:]
 		}
 
-		keys[ext] = true
+		extensionKeys[ext] = true
 
 		counts[ext]++
-		sizes[ext] += info.Size()
+		sizes[ext] += float64(info.Size())
 
 		return nil
 	})
@@ -126,14 +127,22 @@ func update() {
 
 	// Loop over all keys and set the respective gauge values
 	slog.Debug("Writing new values to metrics")
-	for key, _ := range keys {
-		gauges["count"].With(prometheus.Labels{
-			"extension": key,
-		}).Set(float64(counts[key]))
-
-		gauges["size"].With(prometheus.Labels{
-			"extension": key,
-		}).Set(float64(sizes[key]))
+	for key, _ := range extensionKeys {
+		if _, ok := counts[key]; ok {
+			gauges["count"].With(prometheus.Labels{
+				"extension": key,
+			}).Set(counts[key])
+			gauges["size"].With(prometheus.Labels{
+				"extension": key,
+			}).Set(sizes[key])
+
+			continue
+		}
+
+		// Clean up extension which no longer exists in the directory
+		gauges["count"].Delete(prometheus.Labels{"extension": key})
+		gauges["size"].Delete(prometheus.Labels{"extension": key})
+		delete(extensionKeys, key)
 	}
 }