[BUGFIX] use available memory for usage estimation

Fix memory usage estimation following this commit:
https://github.com/freifunk-gluon/gluon/pull/1517

data/statistics.go

@@ -84,10 +84,11 @@ type DHCP struct {
 
 // Memory struct
 type Memory struct {
-	Cached  int64 `json:"cached"`
-	Total   int64 `json:"total"`
-	Buffers int64 `json:"buffers"`
-	Free    int64 `json:"free"`
+	Cached    int64 `json:"cached"`
+	Total     int64 `json:"total"`
+	Buffers   int64 `json:"buffers"`
+	Free      int64 `json:"free,omitempty"`
+	Available int64 `json:"available,omitempty"`
 }
 
 // SwitchPort struct

database/graphite/node.go

@@ -104,6 +104,7 @@ func (c *Connection) InsertNode(node *runtime.Node) {
 	addField("memory.cached", stats.Memory.Cached)
 	addField("memory.free", stats.Memory.Free)
 	addField("memory.total", stats.Memory.Total)
+	addField("memory.available", stats.Memory.Available)
 
 	c.addPoint(fields)
 }

database/influxdb/node.go

@@ -33,18 +33,19 @@ func (conn *Connection) InsertNode(node *runtime.Node) {
 	tags.SetString("nodeid", stats.NodeID)
 
 	fields := models.Fields{
-		"load":           stats.LoadAverage,
-		"time.up":        int64(stats.Uptime),
-		"time.idle":      int64(stats.Idletime),
-		"proc.running":   stats.Processes.Running,
-		"clients.wifi":   stats.Clients.Wifi,
-		"clients.wifi24": stats.Clients.Wifi24,
-		"clients.wifi5":  stats.Clients.Wifi5,
-		"clients.total":  stats.Clients.Total,
-		"memory.buffers": stats.Memory.Buffers,
-		"memory.cached":  stats.Memory.Cached,
-		"memory.free":    stats.Memory.Free,
-		"memory.total":   stats.Memory.Total,
+		"load":             stats.LoadAverage,
+		"time.up":          int64(stats.Uptime),
+		"time.idle":        int64(stats.Idletime),
+		"proc.running":     stats.Processes.Running,
+		"clients.wifi":     stats.Clients.Wifi,
+		"clients.wifi24":   stats.Clients.Wifi24,
+		"clients.wifi5":    stats.Clients.Wifi5,
+		"clients.total":    stats.Clients.Total,
+		"memory.buffers":   stats.Memory.Buffers,
+		"memory.cached":    stats.Memory.Cached,
+		"memory.free":      stats.Memory.Free,
+		"memory.total":     stats.Memory.Total,
+		"memory.available": stats.Memory.Available,
 	}
 
 	if nodeinfo := node.Nodeinfo; nodeinfo != nil {

output/meshviewer-ffrgb/struct.go

@@ -126,10 +126,16 @@ func NewNode(nodes *runtime.Nodes, n *runtime.Node) *Node {
 		/* The Meshviewer could not handle absolute memory output
 		 * calc the used memory as a float which 100% equal 1.0
 		 * calc is coppied from node statuspage (look discussion:
-		 * https://github.com/FreifunkBremen/yanic/issues/35)
+		 * https://github.com/FreifunkBremen/yanic/issues/35 and
+		 * https://github.com/freifunk-gluon/gluon/pull/1517)
 		 */
 		if statistic.Memory.Total > 0 {
-			usage := 1 - (float64(statistic.Memory.Free)+float64(statistic.Memory.Buffers)+float64(statistic.Memory.Cached))/float64(statistic.Memory.Total)
+			usage := 0.0
+			if statistic.Memory.Available > 0 {
+				usage = 1 - float64(statistic.Memory.Available)/float64(statistic.Memory.Total)
+			} else {
+				usage = 1 - (float64(statistic.Memory.Free)+float64(statistic.Memory.Buffers)+float64(statistic.Memory.Cached))/float64(statistic.Memory.Total)
+			}
 			node.MemoryUsage = &usage
 		}
 

output/meshviewer/node.go

@@ -71,10 +71,16 @@ func NewStatistics(stats *data.Statistics, isOnline bool) *Statistics {
 	/* The Meshviewer could not handle absolute memory output
 	 * calc the used memory as a float which 100% equal 1.0
 	 * calc is coppied from node statuspage (look discussion:
-	 * https://github.com/FreifunkBremen/yanic/issues/35)
+	 * https://github.com/FreifunkBremen/yanic/issues/35 and
+	 * https://github.com/freifunk-gluon/gluon/pull/1517)
 	 */
 	if stats.Memory.Total > 0 {
-		usage := 1 - (float64(stats.Memory.Free)+float64(stats.Memory.Buffers)+float64(stats.Memory.Cached))/float64(stats.Memory.Total)
+		usage := 0.0
+		if stats.Memory.Available > 0 {
+			usage = 1 - float64(stats.Memory.Available)/float64(stats.Memory.Total)
+		} else {
+			usage = 1 - (float64(stats.Memory.Free)+float64(stats.Memory.Buffers)+float64(stats.Memory.Cached))/float64(stats.Memory.Total)
+		}
 		output.MemoryUsage = &usage
 	}