From 62432038802b588ea3a8752cf4703e492cfc13f3 Mon Sep 17 00:00:00 2001
From: Thomas Roehl <Thomas.Roehl@googlemail.com>
Date: Mon, 20 Oct 2025 17:03:55 +0200
Subject: [PATCH] Fix startup error of iostat collector

---
 collectors/iostatMetric.go | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/collectors/iostatMetric.go b/collectors/iostatMetric.go
index 61ba61d..29780ba 100644
--- a/collectors/iostatMetric.go
+++ b/collectors/iostatMetric.go
@@ -20,18 +20,17 @@ import (
 	lp "github.com/ClusterCockpit/cc-lib/ccMessage"
 )
 
-// Konstante für den Pfad zu /proc/diskstats
 const IOSTATFILE = `/proc/diskstats`
 
 type IOstatCollectorConfig struct {
 	ExcludeMetrics []string `json:"exclude_metrics,omitempty"`
-	// Neues Feld zum Ausschließen von Devices per JSON-Konfiguration
 	ExcludeDevices []string `json:"exclude_devices,omitempty"`
 }
 
 type IOstatCollectorEntry struct {
-	lastValues map[string]int64
-	tags       map[string]string
+	currentValues map[string]int64
+	lastValues    map[string]int64
+	tags          map[string]string
 }
 
 type IOstatCollector struct {
@@ -105,16 +104,27 @@ func (m *IOstatCollector) Init(config json.RawMessage) error {
 		if _, skip := stringArrayContains(m.config.ExcludeDevices, device); skip {
 			continue
 		}
-		values := make(map[string]int64)
+		currentValues := make(map[string]int64)
+		lastValues := make(map[string]int64)
 		for m := range m.matches {
-			values[m] = 0
+			currentValues[m] = 0
+			lastValues[m] = 0
+		}
+		for name, idx := range m.matches {
+			if idx < len(linefields) {
+				if value, err := strconv.ParseInt(linefields[idx], 0, 64); err == nil {
+					currentValues[name] = value
+					lastValues[name] = value // Set last to current for first read
+				}
+			}
 		}
 		m.devices[device] = IOstatCollectorEntry{
 			tags: map[string]string{
 				"device": device,
 				"type":   "node",
 			},
-			lastValues: values,
+			currentValues: currentValues,
+			lastValues:    lastValues,
 		}
 	}
 	m.init = true
@@ -153,18 +163,22 @@ func (m *IOstatCollector) Read(interval time.Duration, output chan lp.CCMessage)
 		if _, ok := m.devices[device]; !ok {
 			continue
 		}
+		// Update current and last values
 		entry := m.devices[device]
 		for name, idx := range m.matches {
 			if idx < len(linefields) {
 				x, err := strconv.ParseInt(linefields[idx], 0, 64)
 				if err == nil {
-					diff := x - entry.lastValues[name]
-					y, err := lp.NewMessage(name, entry.tags, m.meta, map[string]interface{}{"value": int(diff)}, time.Now())
+					// Calculate difference using previous current and new value
+					diff := x - entry.currentValues[name]
+					y, err := lp.NewMetric(name, entry.tags, m.meta, int(diff), time.Now())
 					if err == nil {
 						output <- y
 					}
+					// Update last to previous current, and current to new value
+					entry.lastValues[name] = entry.currentValues[name]
+					entry.currentValues[name] = x
 				}
-				entry.lastValues[name] = x
 			}
 		}
 		m.devices[device] = entry