From 9677a0faabe7491dc6e11d3fd55067720a5efa3b Mon Sep 17 00:00:00 2001
From: Philip O'Toole <philip@influxdb.com>
Date: Tue, 8 Sep 2015 19:06:19 -0700
Subject: [PATCH] Add collectd stats

---
 CHANGELOG.md                 |  1 +
 services/collectd/service.go | 39 +++++++++++++++++++++++++++++++-----
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2991bdb5d54..879368b3e24 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 With this release InfluxDB is moving to Go 1.5.
 
 ### Features
+- [#4050](https://github.com/influxdb/influxdb/pull/4050): Add stats to collectd
 - [#3771](https://github.com/influxdb/influxdb/pull/3771): Close idle Graphite TCP connections
 - [#3755](https://github.com/influxdb/influxdb/issues/3755): Add option to build script. Thanks @fg2it
 - [#3863](https://github.com/influxdb/influxdb/pull/3863): Move to Go 1.5
diff --git a/services/collectd/service.go b/services/collectd/service.go
index b0fee0bc49b..7d8e65f820c 100644
--- a/services/collectd/service.go
+++ b/services/collectd/service.go
@@ -1,13 +1,16 @@
 package collectd
 
 import (
+	"expvar"
 	"fmt"
 	"log"
 	"net"
 	"os"
+	"strings"
 	"sync"
 	"time"
 
+	"github.com/influxdb/influxdb"
 	"github.com/influxdb/influxdb/cluster"
 	"github.com/influxdb/influxdb/meta"
 	"github.com/influxdb/influxdb/tsdb"
@@ -16,6 +19,17 @@ import (
 
 const leaderWaitTimeout = 30 * time.Second
 
+// statistics gathered by the collectd service.
+const (
+	statPointsReceived      = "points_rx"
+	statBytesReceived       = "bytes_rx"
+	statPointsParseFail     = "points_parse_fail"
+	statReadFail            = "read_fail"
+	statBatchesTrasmitted   = "batches_tx"
+	statPointsTransmitted   = "points_tx"
+	statBatchesTransmitFail = "batches_tx_fail"
+)
+
 // pointsWriter is an internal interface to make testing easier.
 type pointsWriter interface {
 	WritePoints(p *cluster.WritePointsRequest) error
@@ -42,6 +56,9 @@ type Service struct {
 	batcher *tsdb.PointBatcher
 	typesdb gollectd.Types
 	addr    net.Addr
+
+	// expvar-based stats.
+	statMap *expvar.Map
 }
 
 // NewService returns a new instance of the collectd service.
@@ -59,6 +76,12 @@ func NewService(c Config) *Service {
 func (s *Service) Open() error {
 	s.Logger.Printf("Starting collectd service")
 
+	// Configure expvar monitoring. It's OK to do this even if the service fails to open and
+	// should be done before any data could arrive for the service.
+	key := strings.Join([]string{"collectd", s.Config.BindAddress}, ":")
+	tags := map[string]string{"bind": s.Config.BindAddress}
+	s.statMap = influxdb.NewStatistics(key, "collectd", tags)
+
 	if s.Config.BindAddress == "" {
 		return fmt.Errorf("bind address is blank")
 	} else if s.Config.Database == "" {
@@ -182,10 +205,12 @@ func (s *Service) serve() {
 
 		n, _, err := s.ln.ReadFromUDP(buffer)
 		if err != nil {
+			s.statMap.Add(statReadFail, 1)
 			s.Logger.Printf("collectd ReadFromUDP error: %s", err)
 			continue
 		}
 		if n > 0 {
+			s.statMap.Add(statBytesReceived, int64(n))
 			s.handleMessage(buffer[:n])
 		}
 	}
@@ -194,6 +219,7 @@ func (s *Service) serve() {
 func (s *Service) handleMessage(buffer []byte) {
 	packets, err := gollectd.Packets(buffer, s.typesdb)
 	if err != nil {
+		s.statMap.Add(statPointsParseFail, 1)
 		s.Logger.Printf("Collectd parse error: %s", err)
 		return
 	}
@@ -202,6 +228,7 @@ func (s *Service) handleMessage(buffer []byte) {
 		for _, p := range points {
 			s.batcher.In() <- p
 		}
+		s.statMap.Add(statPointsReceived, int64(len(points)))
 	}
 }
 
@@ -213,15 +240,17 @@ func (s *Service) writePoints() {
 		case <-s.stop:
 			return
 		case batch := <-s.batcher.Out():
-			req := &cluster.WritePointsRequest{
+			if err := s.PointsWriter.WritePoints(&cluster.WritePointsRequest{
 				Database:         s.Config.Database,
 				RetentionPolicy:  s.Config.RetentionPolicy,
 				ConsistencyLevel: cluster.ConsistencyLevelAny,
 				Points:           batch,
-			}
-			if err := s.PointsWriter.WritePoints(req); err != nil {
-				s.Logger.Printf("failed to write batch: %s", err)
-				continue
+			}); err == nil {
+				s.statMap.Add(statBatchesTrasmitted, 1)
+				s.statMap.Add(statPointsTransmitted, int64(len(batch)))
+			} else {
+				s.Logger.Printf("failed to write point batch to database %q: %s", s.Config.Database, err)
+				s.statMap.Add(statBatchesTransmitFail, 1)
 			}
 		}
 	}