From d4df493fba04da602351cf55dd24b7c30791095b Mon Sep 17 00:00:00 2001
From: Holger Obermaier <40787752+ho-ob@users.noreply.github.com>
Date: Thu, 10 Mar 2022 15:28:30 +0100
Subject: [PATCH] Only compute rates with a valid previous state

---
 collectors/gpfsMetric.go       | 56 +++++++++++++++++++---------------
 collectors/infinibandMetric.go |  5 ++-
 2 files changed, 34 insertions(+), 27 deletions(-)

diff --git a/collectors/gpfsMetric.go b/collectors/gpfsMetric.go
index 98894b3..26fc723 100644
--- a/collectors/gpfsMetric.go
+++ b/collectors/gpfsMetric.go
@@ -17,11 +17,11 @@ import (
 	lp "github.com/ClusterCockpit/cc-metric-collector/internal/ccMetric"
 )
 
-const DEFAULT_GPFS_CMD = `mmpmon`
+const DEFAULT_GPFS_CMD = "mmpmon"
 
-type GpfsCollectorLastValues struct {
-	read  int64
-	write int64
+type GpfsCollectorLastState struct {
+	bytesRead    int64
+	bytesWritten int64
 }
 
 type GpfsCollector struct {
@@ -34,7 +34,7 @@ type GpfsCollector struct {
 	}
 	skipFS        map[string]struct{}
 	lastTimestamp time.Time // Store time stamp of last tick to derive bandwidths
-	lastValues    map[string]GpfsCollectorLastValues
+	lastState     map[string]GpfsCollectorLastState
 }
 
 func (m *GpfsCollector) Init(config json.RawMessage) error {
@@ -46,10 +46,9 @@ func (m *GpfsCollector) Init(config json.RawMessage) error {
 	var err error
 	m.name = "GpfsCollector"
 	m.setup()
-	m.lastTimestamp = time.Now()
 
 	// Set default mmpmon binary
-	m.config.Mmpmon = string(DEFAULT_GPFS_CMD)
+	m.config.Mmpmon = DEFAULT_GPFS_CMD
 
 	// Read JSON configuration
 	if len(config) > 0 {
@@ -98,9 +97,13 @@ func (m *GpfsCollector) Read(interval time.Duration, output chan lp.CCMetric) {
 		return
 	}
 
+	// Current time stamp
 	now := time.Now()
-	tdiff := now.Sub(m.lastTimestamp)
+	// time difference to last time stamp
+	timeDiff := now.Sub(m.lastTimestamp).Seconds()
+	// Save current timestamp
 	m.lastTimestamp = now
+
 	// mmpmon:
 	// -p: generate output that can be parsed
 	// -s: suppress the prompt on input
@@ -160,10 +163,10 @@ func (m *GpfsCollector) Read(interval time.Duration, output chan lp.CCMetric) {
 		}
 
 		m.tags["filesystem"] = filesystem
-		if _, ok := m.lastValues[filesystem]; !ok {
-			m.lastValues[filesystem] = GpfsCollectorLastValues{
-				read:  0,
-				write: 0,
+		if _, ok := m.lastState[filesystem]; !ok {
+			m.lastState[filesystem] = GpfsCollectorLastState{
+				bytesRead:    -1,
+				bytesWritten: -1,
 			}
 		}
 
@@ -210,13 +213,12 @@ func (m *GpfsCollector) Read(interval time.Duration, output chan lp.CCMetric) {
 			output <- y
 		}
 		if m.config.SendBandwidths {
-			lastVal := m.lastValues[filesystem]
-			diff := bytesRead - lastVal.read
-			lastVal.read = bytesRead
-			if y, err := lp.New("gpfs_bw_read", m.tags, m.meta, map[string]interface{}{"value": float64(diff) / tdiff.Seconds()}, timestamp); err == nil {
-				output <- y
+			if lastBytesRead := m.lastState[filesystem].bytesRead; lastBytesRead >= 0 {
+				bwRead := float64(bytesRead-lastBytesRead) / timeDiff
+				if y, err := lp.New("gpfs_bw_read", m.tags, m.meta, map[string]interface{}{"value": bwRead}, timestamp); err == nil {
+					output <- y
+				}
 			}
-			m.lastValues[filesystem] = lastVal
 		}
 
 		// bytes written
@@ -231,13 +233,19 @@ func (m *GpfsCollector) Read(interval time.Duration, output chan lp.CCMetric) {
 			output <- y
 		}
 		if m.config.SendBandwidths {
-			lastVal := m.lastValues[filesystem]
-			diff := bytesWritten - lastVal.write
-			lastVal.write = bytesWritten
-			if y, err := lp.New("gpfs_bw_write", m.tags, m.meta, map[string]interface{}{"value": float64(diff) / tdiff.Seconds()}, timestamp); err == nil {
-				output <- y
+			if lastBytesWritten := m.lastState[filesystem].bytesRead; lastBytesWritten >= 0 {
+				bwWrite := float64(bytesWritten-lastBytesWritten) / timeDiff
+				if y, err := lp.New("gpfs_bw_write", m.tags, m.meta, map[string]interface{}{"value": bwWrite}, timestamp); err == nil {
+					output <- y
+				}
+			}
+		}
+
+		if m.config.SendBandwidths {
+			m.lastState[filesystem] = GpfsCollectorLastState{
+				bytesRead:    bytesRead,
+				bytesWritten: bytesWritten,
 			}
-			m.lastValues[filesystem] = lastVal
 		}
 
 		// number of opens
diff --git a/collectors/infinibandMetric.go b/collectors/infinibandMetric.go
index 540d31d..5be095d 100644
--- a/collectors/infinibandMetric.go
+++ b/collectors/infinibandMetric.go
@@ -161,6 +161,8 @@ func (m *InfinibandCollector) Read(interval time.Duration, output chan lp.CCMetr
 	now := time.Now()
 	// time difference to last time stamp
 	timeDiff := now.Sub(m.lastTimestamp).Seconds()
+	// Save current timestamp
+	m.lastTimestamp = now
 
 	for _, info := range m.info {
 		for counterName, counterFile := range info.portCounterFiles {
@@ -205,9 +207,6 @@ func (m *InfinibandCollector) Read(interval time.Duration, output chan lp.CCMetr
 		}
 
 	}
-
-	// Save current timestamp
-	m.lastTimestamp = now
 }
 
 func (m *InfinibandCollector) Close() {