Merge pull request #479 from prometheus/grobie/fix-vet-and-lint-errors

Fix all open go lint and vet issues

collector/collector.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Exporter is a prometheus exporter using multiple Factories to collect and export system metrics.
+// Package collector includes all individual collectors to gather and export system metrics.
 package collector
 
 import (
@@ -19,15 +19,17 @@ import (
 	"github.com/prometheus/common/log"
 )
 
+// Namespace defines the common namespace to be used by all metrics.
 const Namespace = "node"
 
+// Factories contains the list of all available collectors.
 var Factories = make(map[string]func() (Collector, error))
 
 func warnDeprecated(collector string) {
 	log.Warnf("The %s collector is deprecated and will be removed in the future!", collector)
 }
 
-// Interface a collector has to implement.
+// Collector is the interface a collector has to implement.
 type Collector interface {
 	// Get new metrics and expose them via prometheus registry.
 	Update(ch chan<- prometheus.Metric) (err error)

collector/conntrack_linux.go

@@ -28,8 +28,7 @@ func init() {
 	Factories["conntrack"] = NewConntrackCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewConntrackCollector returns a new Collector exposing conntrack stats.
-// conntrack stats
 func NewConntrackCollector() (Collector, error) {
 	return &conntrackCollector{
 		current: prometheus.NewDesc(

collector/diskstats_linux.go

@@ -47,8 +47,7 @@ func init() {
 	Factories["diskstats"] = NewDiskstatsCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewDiskstatsCollector returns a new Collector exposing disk device stats.
-// disk device stats.
 func NewDiskstatsCollector() (Collector, error) {
 	var diskLabelNames = []string{"device"}
 

collector/edac_linux.go

@@ -52,8 +52,7 @@ func init() {
 	Factories["edac"] = NewEdacCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewEdacCollector returns a new Collector exposing edac stats.
-// edac stats.
 func NewEdacCollector() (Collector, error) {
 	return &edacCollector{
 		ceCount: prometheus.NewDesc(

collector/entropy_linux.go

@@ -22,18 +22,17 @@ import (
 )
 
 type entropyCollector struct {
-	entropy_avail *prometheus.Desc
+	entropyAvail *prometheus.Desc
 }
 
 func init() {
 	Factories["entropy"] = NewEntropyCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewEntropyCollector returns a new Collector exposing entropy stats.
-// entropy stats
 func NewEntropyCollector() (Collector, error) {
 	return &entropyCollector{
-		entropy_avail: prometheus.NewDesc(
+		entropyAvail: prometheus.NewDesc(
 			prometheus.BuildFQName(Namespace, "", "entropy_available_bits"),
 			"Bits of available entropy.",
 			nil, nil,
@@ -47,7 +46,7 @@ func (c *entropyCollector) Update(ch chan<- prometheus.Metric) (err error) {
 		return fmt.Errorf("couldn't get entropy_avail: %s", err)
 	}
 	ch <- prometheus.MustNewConstMetric(
-		c.entropy_avail, prometheus.GaugeValue, float64(value))
+		c.entropyAvail, prometheus.GaugeValue, float64(value))
 
 	return nil
 }

collector/filesystem_common.go

@@ -64,8 +64,7 @@ func init() {
 	Factories["filesystem"] = NewFilesystemCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewFilesystemCollector returns a new Collector exposing filesystems stats.
-// Filesystems stats.
 func NewFilesystemCollector() (Collector, error) {
 	subsystem := "filesystem"
 	mountPointPattern := regexp.MustCompile(*ignoredMountPoints)

collector/filesystem_freebsd.go

@@ -26,8 +26,8 @@ import (
 const (
 	defIgnoredMountPoints = "^/(dev)($|/)"
 	defIgnoredFSTypes     = "^devfs$"
-	MNT_RDONLY            = 0x1
+	readOnly              = 0x1 // MNT_RDONLY
-	MNT_NOWAIT            = 0x2
+	noWait                = 0x2 // MNT_NOWAIT
 )
 
 func gostring(b []int8) string {
@@ -43,7 +43,7 @@ func gostring(b []int8) string {
 func (c *filesystemCollector) GetStats() (stats []filesystemStats, err error) {
 	buf := make([]unix.Statfs_t, 16)
 	for {
-		n, err := unix.Getfsstat(buf, MNT_NOWAIT)
+		n, err := unix.Getfsstat(buf, noWait)
 		if err != nil {
 			return nil, err
 		}
@@ -69,7 +69,7 @@ func (c *filesystemCollector) GetStats() (stats []filesystemStats, err error) {
 		}
 
 		var ro float64
-		if (fs.Flags & MNT_RDONLY) != 0 {
+		if (fs.Flags & readOnly) != 0 {
 			ro = 1
 		}
 

collector/filesystem_linux.go

@@ -27,10 +27,10 @@ import (
 const (
 	defIgnoredMountPoints = "^/(sys|proc|dev)($|/)"
 	defIgnoredFSTypes     = "^(sys|proc|auto)fs$"
-	ST_RDONLY             = 0x1
+	readOnly              = 0x1 // ST_RDONLY
 )
 
-// Expose filesystem fullness.
+// GetStats returns filesystem stats.
 func (c *filesystemCollector) GetStats() (stats []filesystemStats, err error) {
 	mps, err := mountPointDetails()
 	if err != nil {
@@ -57,7 +57,7 @@ func (c *filesystemCollector) GetStats() (stats []filesystemStats, err error) {
 		}
 
 		var ro float64
-		if buf.Flags&ST_RDONLY != 0 {
+		if (buf.Flags & readOnly) != 0 {
 			ro = 1
 		}
 

collector/ganglia/format.go

@@ -11,7 +11,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Types for unmarshalling gmond's XML output.
+// Package ganglia provides types for unmarshalling gmond's XML output.
 //
 // Not used elements in gmond's XML output are commented.
 // In case you want to use them, please change the names so that one
@@ -20,15 +20,18 @@ package ganglia
 
 import "encoding/xml"
 
+// ExtraElement describes EXTRA_ELEMENT elements.
 type ExtraElement struct {
 	Name string `xml:"NAME,attr"`
 	Val  string `xml:"VAL,attr"`
 }
 
+// ExtraData describes EXTRA_DATA elements.
 type ExtraData struct {
 	ExtraElements []ExtraElement `xml:"EXTRA_ELEMENT"`
 }
 
+// Metric describes METRIC elements.
 type Metric struct {
 	Name  string  `xml:"NAME,attr"`
 	Value float64 `xml:"VAL,attr"`
@@ -42,6 +45,7 @@ type Metric struct {
 	ExtraData ExtraData `xml:"EXTRA_DATA"`
 }
 
+// Host describes HOST elements.
 type Host struct {
 	Name string `xml:"NAME,attr"`
 	/*
@@ -57,6 +61,7 @@ type Host struct {
 	Metrics []Metric `xml:"METRIC"`
 }
 
+// Cluster describes CLUSTER elements.
 type Cluster struct {
 	Name string `xml:"NAME,attr"`
 	/*
@@ -68,6 +73,7 @@ type Cluster struct {
 	Hosts []Host `xml:"HOST"`
 }
 
+// Ganglia describes the top-level XML structure.
 type Ganglia struct {
 	XMLNAME  xml.Name  `xml:"GANGLIA_XML"`
 	Clusters []Cluster `xml:"CLUSTER"`

collector/gmond.go

@@ -46,7 +46,7 @@ func init() {
 
 var illegalCharsRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
 
-// Takes a prometheus registry and returns a new Collector scraping ganglia.
+// NewGmondCollector returns a new Collector scraping ganglia.
 func NewGmondCollector() (Collector, error) {
 	warnDeprecated("gmond")
 	c := gmondCollector{

collector/hwmon_linux.go

@@ -51,8 +51,8 @@ func init() {
 
 type hwMonCollector struct{}
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewHwMonCollector returns a new Collector exposing /sys/class/hwmon stats
-// /sys/class/hwmon stats (similar to lm-sensors).
+// (similar to lm-sensors).
 func NewHwMonCollector() (Collector, error) {
 	return &hwMonCollector{}, nil
 }
@@ -78,7 +78,7 @@ func addValueFile(data map[string]map[string]string, sensor string, prop string,
 	data[sensor][prop] = value
 }
 
-// Split a sensor name into <type><num>_<property>
+// explodeSensorFilename splits a sensor name into <type><num>_<property>.
 func explodeSensorFilename(filename string) (ok bool, sensorType string, sensorNum int, sensorProperty string) {
 	matches := hwmonFilenameFormat.FindStringSubmatch(filename)
 	if len(matches) == 0 {
@@ -164,7 +164,7 @@ func (c *hwMonCollector) updateHwmon(ch chan<- prometheus.Metric, dir string) (e
 		)
 	}
 
-	// format all sensors
+	// Format all sensors.
 	for sensor, sensorData := range data {
 
 		_, sensorType, _, _ := explodeSensorFilename(sensor)

collector/infiniband_linux.go

@@ -45,6 +45,7 @@ func init() {
 	Factories["infiniband"] = NewInfiniBandCollector
 }
 
+// NewInfiniBandCollector returns a new Collector exposing InfiniBand stats.
 func NewInfiniBandCollector() (Collector, error) {
 	var i infinibandCollector
 

collector/infiniband_linux_test.go

@@ -24,7 +24,7 @@ func TestInfiniBandDevices(t *testing.T) {
 	}
 
 	if l := len(devices); l != 1 {
-		t.Fatal("Retrieved an unexpected number of InfiniBand devices: %d", l)
+		t.Fatalf("Retrieved an unexpected number of InfiniBand devices: %d", l)
 	}
 }
 
@@ -35,6 +35,6 @@ func TestInfiniBandPorts(t *testing.T) {
 	}
 
 	if l := len(ports); l != 2 {
-		t.Fatal("Retrieved an unexpected number of InfiniBand ports: %d", l)
+		t.Fatalf("Retrieved an unexpected number of InfiniBand ports: %d", l)
 	}
 }

collector/interrupts_common.go

@@ -26,8 +26,7 @@ func init() {
 	Factories["interrupts"] = NewInterruptsCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewInterruptsCollector returns a new Collector exposing interrupts stats.
-// interrupts stats
 func NewInterruptsCollector() (Collector, error) {
 	return &interruptsCollector{
 		desc: typedDesc{prometheus.NewDesc(

collector/ksmd_linux.go

@@ -46,8 +46,7 @@ func getCanonicalMetricName(filename string) string {
 	}
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewKsmdCollector returns a new Collector exposing kernel/system statistics.
-// kernel/system statistics.
 func NewKsmdCollector() (Collector, error) {
 	subsystem := "ksmd"
 	descs := make(map[string]*prometheus.Desc)
@@ -60,7 +59,7 @@ func NewKsmdCollector() (Collector, error) {
 	return &ksmdCollector{descs}, nil
 }
 
-// Expose kernel and system statistics.
+// Update implements Collector and exposes kernel and system statistics.
 func (c *ksmdCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	for _, n := range ksmdFiles {
 		val, err := readUintFromFile(sysFilePath(path.Join("kernel/mm/ksm", n)))

collector/loadavg.go

@@ -31,7 +31,7 @@ func init() {
 	Factories["loadavg"] = NewLoadavgCollector
 }
 
-// Take a prometheus registry and return a new Collector exposing load average.
+// NewLoadavgCollector returns a new Collector exposing load average stats.
 func NewLoadavgCollector() (Collector, error) {
 	return &loadavgCollector{
 		metric: []typedDesc{

collector/logind_linux.go

@@ -65,15 +65,15 @@ type logindSession struct {
 
 // Struct elements must be public for the reflection magic of godbus to work.
 type logindSessionEntry struct {
-	SessionId         string
+	SessionID         string
-	UserId            uint32
+	UserID            uint32
 	UserName          string
-	SeatId            string
+	SeatID            string
 	SessionObjectPath dbus.ObjectPath
 }
 
 type logindSeatEntry struct {
-	SeatId         string
+	SeatID         string
 	SeatObjectPath dbus.ObjectPath
 }
 
@@ -81,8 +81,7 @@ func init() {
 	Factories["logind"] = NewLogindCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewLogindCollector returns a new Collector exposing logind statistics.
-// logind statistics.
 func NewLogindCollector() (Collector, error) {
 	return &logindCollector{}, nil
 }
@@ -197,7 +196,7 @@ func (c *logindDbus) listSeats() ([]string, error) {
 
 	ret := make([]string, len(seats)+1)
 	for i := range seats {
-		ret[i] = seats[i].SeatId
+		ret[i] = seats[i].SeatID
 	}
 	// Always add the empty seat, which is used for remote sessions like SSH
 	ret[len(seats)] = ""
@@ -260,7 +259,7 @@ func (c *logindDbus) getSession(session logindSessionEntry) *logindSession {
 	}
 
 	return &logindSession{
-		seat:        session.SeatId,
+		seat:        session.SeatID,
 		remote:      remote.String(),
 		sessionType: knownStringOrOther(sessionTypeStr, attrTypeValues),
 		class:       knownStringOrOther(classStr, attrClassValues),

collector/logind_linux_test.go

@@ -31,17 +31,17 @@ func (c *testLogindInterface) listSeats() ([]string, error) {
 func (c *testLogindInterface) listSessions() ([]logindSessionEntry, error) {
 	return []logindSessionEntry{
 		{
-			SessionId:         "1",
+			SessionID:         "1",
-			UserId:            0,
+			UserID:            0,
 			UserName:          "",
-			SeatId:            "",
+			SeatID:            "",
 			SessionObjectPath: dbus.ObjectPath("/org/freedesktop/login1/session/1"),
 		},
 		{
-			SessionId:         "2",
+			SessionID:         "2",
-			UserId:            0,
+			UserID:            0,
 			UserName:          "",
-			SeatId:            "seat0",
+			SeatID:            "seat0",
 			SessionObjectPath: dbus.ObjectPath("/org/freedesktop/login1/session/2"),
 		},
 	}, nil
@@ -50,13 +50,13 @@ func (c *testLogindInterface) listSessions() ([]logindSessionEntry, error) {
 func (c *testLogindInterface) getSession(session logindSessionEntry) *logindSession {
 	sessions := map[dbus.ObjectPath]*logindSession{
 		dbus.ObjectPath("/org/freedesktop/login1/session/1"): {
-			seat:        session.SeatId,
+			seat:        session.SeatID,
 			remote:      "true",
 			sessionType: knownStringOrOther("tty", attrTypeValues),
 			class:       knownStringOrOther("user", attrClassValues),
 		},
 		dbus.ObjectPath("/org/freedesktop/login1/session/2"): {
-			seat:        session.SeatId,
+			seat:        session.SeatID,
 			remote:      "false",
 			sessionType: knownStringOrOther("x11", attrTypeValues),
 			class:       knownStringOrOther("greeter", attrClassValues),

collector/mdadm_linux.go

@@ -56,10 +56,8 @@ func evalStatusline(statusline string) (active, total, size int64, err error) {
 	// +1 to make it more obvious that the whole string containing the info is also returned as matches[0].
 	if len(matches) < 3+1 {
 		return 0, 0, 0, fmt.Errorf("too few matches found in statusline: %s", statusline)
-	} else {
+	} else if len(matches) > 3+1 {
-		if len(matches) > 3+1 {
+		return 0, 0, 0, fmt.Errorf("too many matches found in statusline: %s", statusline)
-			return 0, 0, 0, fmt.Errorf("too many matches found in statusline: %s", statusline)
-		}
 	}
 
 	size, err = strconv.ParseInt(matches[1], 10, 64)
@@ -109,7 +107,7 @@ func evalUnknownPersonalitylineRE(statusline string) (size int64, err error) {
 	return size, nil
 }
 
-// Gets the size that has already been synced out of the sync-line.
+// evalBuildline gets the size that has already been synced out of the sync-line.
 func evalBuildline(buildline string) (int64, error) {
 	matches := buildlineRE.FindStringSubmatch(buildline)
 
@@ -131,7 +129,7 @@ func evalBuildline(buildline string) (int64, error) {
 	return syncedSize, nil
 }
 
-// Parses an mdstat-file and returns a struct with the relevant infos.
+// parseMdstat parses an mdstat-file and returns a struct with the relevant infos.
 func parseMdstat(mdStatusFilePath string) ([]mdStatus, error) {
 	content, err := ioutil.ReadFile(mdStatusFilePath)
 	if err != nil {
@@ -234,7 +232,7 @@ func parseMdstat(mdStatusFilePath string) ([]mdStatus, error) {
 	return mdStates, nil
 }
 
-// Just returns the pointer to an empty struct as we only use throwaway-metrics.
+// NewMdadmCollector returns a new Collector exposing raid statistics.
 func NewMdadmCollector() (Collector, error) {
 	return &mdadmCollector{}, nil
 }

collector/megacli.go

@@ -47,8 +47,8 @@ func init() {
 	Factories["megacli"] = NewMegaCliCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewMegaCliCollector returns a new Collector exposing RAID status through
-// RAID status through megacli.
+// megacli.
 func NewMegaCliCollector() (Collector, error) {
 	warnDeprecated("megacli")
 	return &megaCliCollector{

collector/meminfo_numa_linux.go

@@ -50,8 +50,7 @@ func init() {
 	Factories["meminfo_numa"] = NewMeminfoNumaCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewMeminfoNumaCollector returns a new Collector exposing memory stats.
-// memory stats.
 func NewMeminfoNumaCollector() (Collector, error) {
 	return &meminfoNumaCollector{
 		metricDescs: map[string]*prometheus.Desc{},

collector/mountstats_linux.go

@@ -93,6 +93,7 @@ func init() {
 	Factories["mountstats"] = NewMountStatsCollector
 }
 
+// NewMountStatsCollector returns a new Collector exposing NFS statistics.
 func NewMountStatsCollector() (Collector, error) {
 	fs, err := procfs.NewFS(*procPath)
 	if err != nil {
@@ -105,7 +106,7 @@ func NewMountStatsCollector() (Collector, error) {
 	}
 
 	const (
-		// For the time being, only NFS statistics are available via this mechanism
+		// For the time being, only NFS statistics are available via this mechanism.
 		subsystem = "mountstats_nfs"
 	)
 

collector/nfs_linux.go

@@ -78,19 +78,19 @@ var (
 		nil,
 	)
 
-	nfsRpcOperationsDesc = prometheus.NewDesc(
+	nfsRPCOperationsDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(Namespace, "nfs", "rpc_operations"),
 		"Number of RPCs performed.",
 		nil,
 		nil,
 	)
-	nfsRpcRetransmissionsDesc = prometheus.NewDesc(
+	nfsRPCRetransmissionsDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(Namespace, "nfs", "rpc_retransmissions"),
 		"Number of RPC transmissions performed.",
 		nil,
 		nil,
 	)
-	nfsRpcAuthenticationRefreshesDesc = prometheus.NewDesc(
+	nfsRPCAuthenticationRefreshesDesc = prometheus.NewDesc(
 		prometheus.BuildFQName(Namespace, "nfs", "rpc_authentication_refreshes"),
 		"Number of RPC authentication refreshes performed.",
 		nil,
@@ -111,6 +111,7 @@ func init() {
 	Factories["nfs"] = NewNfsCollector
 }
 
+// NewNfsCollector returns a new Collector exposing NFS statistics.
 func NewNfsCollector() (Collector, error) {
 	return &nfsCollector{}, nil
 }
@@ -145,17 +146,17 @@ func (c *nfsCollector) Update(ch chan<- prometheus.Metric) (err error) {
 		} else if fields := rpcLineRE.FindStringSubmatch(line); fields != nil {
 			value, _ := strconv.ParseFloat(fields[1], 64)
 			ch <- prometheus.MustNewConstMetric(
-				nfsRpcOperationsDesc,
+				nfsRPCOperationsDesc,
 				prometheus.CounterValue, value)
 
 			value, _ = strconv.ParseFloat(fields[2], 64)
 			ch <- prometheus.MustNewConstMetric(
-				nfsRpcRetransmissionsDesc,
+				nfsRPCRetransmissionsDesc,
 				prometheus.CounterValue, value)
 
 			value, _ = strconv.ParseFloat(fields[3], 64)
 			ch <- prometheus.MustNewConstMetric(
-				nfsRpcAuthenticationRefreshesDesc,
+				nfsRPCAuthenticationRefreshesDesc,
 				prometheus.CounterValue, value)
 		} else if fields := procLineRE.FindStringSubmatch(line); fields != nil {
 			version := fields[1]

collector/ntp.go

@@ -37,8 +37,8 @@ func init() {
 	Factories["ntp"] = NewNtpCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewNtpCollector returns a new Collector exposing the offset between ntp and
-// the offset between ntp and the current system time.
+// the current system time.
 func NewNtpCollector() (Collector, error) {
 	warnDeprecated("ntp")
 	if *ntpServer == "" {

collector/runit.go

@@ -36,6 +36,7 @@ func init() {
 	Factories["runit"] = NewRunitCollector
 }
 
+// NewRunitCollector returns a new Collector exposing runit statistics.
 func NewRunitCollector() (Collector, error) {
 	var (
 		subsystem   = "service"

collector/stat_linux.go

@@ -42,8 +42,7 @@ func init() {
 	Factories["stat"] = NewStatCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewStatCollector returns a new Collector exposing kernel/system statistics.
-// kernel/system statistics.
 func NewStatCollector() (Collector, error) {
 	return &statCollector{
 		cpu: prometheus.NewDesc(

collector/supervisord.go

@@ -39,6 +39,7 @@ func init() {
 	Factories["supervisord"] = NewSupervisordCollector
 }
 
+// NewSupervisordCollector returns a new Collector exposing supervisord statistics.
 func NewSupervisordCollector() (Collector, error) {
 	client, err := xmlrpc.NewClient(*supervisordURL, nil)
 	if err != nil {

collector/systemd_linux.go

@@ -51,8 +51,7 @@ func init() {
 	Factories["systemd"] = NewSystemdCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewSystemdCollector returns a new Collector exposing systemd statistics.
-// systemd statistics.
 func NewSystemdCollector() (Collector, error) {
 	const subsystem = "systemd"
 

collector/tcpstat_linux.go

@@ -26,20 +26,31 @@ import (
 	"github.com/prometheus/client_golang/prometheus"
 )
 
-type TCPConnectionState int
+type tcpConnectionState int
 
 const (
-	TCP_ESTABLISHED TCPConnectionState = iota + 1
+	// TCP_ESTABLISHED
-	TCP_SYN_SENT
+	tcpEstablished tcpConnectionState = iota + 1
-	TCP_SYN_RECV
+	// TCP_SYN_SENT
-	TCP_FIN_WAIT1
+	tcpSynSent
-	TCP_FIN_WAIT2
+	// TCP_SYN_RECV
-	TCP_TIME_WAIT
+	tcpSynRecv
-	TCP_CLOSE
+	// TCP_FIN_WAIT1
-	TCP_CLOSE_WAIT
+	tcpFinWait1
-	TCP_LAST_ACK
+	// TCP_FIN_WAIT2
-	TCP_LISTEN
+	tcpFinWait2
-	TCP_CLOSING
+	// TCP_TIME_WAIT
+	tcpTimeWait
+	// TCP_CLOSE
+	tcpClose
+	// TCP_CLOSE_WAIT
+	tcpCloseWait
+	// TCP_LAST_ACK
+	tcpLastAck
+	// TCP_LISTEN
+	tcpListen
+	// TCP_CLOSING
+	tcpClosing
 )
 
 type tcpStatCollector struct {
@@ -84,10 +95,10 @@ func (c *tcpStatCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	for st, value := range tcpStats {
 		ch <- c.desc.mustNewConstMetric(value, st.String())
 	}
-	return err
+	return nil
 }
 
-func getTCPStats(statsFile string) (map[TCPConnectionState]float64, error) {
+func getTCPStats(statsFile string) (map[tcpConnectionState]float64, error) {
 	file, err := os.Open(statsFile)
 	if err != nil {
 		return nil, err
@@ -97,9 +108,9 @@ func getTCPStats(statsFile string) (map[TCPConnectionState]float64, error) {
 	return parseTCPStats(file)
 }
 
-func parseTCPStats(r io.Reader) (map[TCPConnectionState]float64, error) {
+func parseTCPStats(r io.Reader) (map[tcpConnectionState]float64, error) {
 	var (
-		tcpStats = map[TCPConnectionState]float64{}
+		tcpStats = map[tcpConnectionState]float64{}
 		scanner  = bufio.NewScanner(r)
 	)
 
@@ -116,35 +127,35 @@ func parseTCPStats(r io.Reader) (map[TCPConnectionState]float64, error) {
 			return nil, err
 		}
 
-		tcpStats[TCPConnectionState(st)]++
+		tcpStats[tcpConnectionState(st)]++
 	}
 
 	return tcpStats, nil
 }
 
-func (st TCPConnectionState) String() string {
+func (st tcpConnectionState) String() string {
 	switch st {
-	case TCP_ESTABLISHED:
+	case tcpEstablished:
 		return "established"
-	case TCP_SYN_SENT:
+	case tcpSynSent:
 		return "syn_sent"
-	case TCP_SYN_RECV:
+	case tcpSynRecv:
 		return "syn_recv"
-	case TCP_FIN_WAIT1:
+	case tcpFinWait1:
 		return "fin_wait1"
-	case TCP_FIN_WAIT2:
+	case tcpFinWait2:
 		return "fin_wait2"
-	case TCP_TIME_WAIT:
+	case tcpTimeWait:
 		return "time_wait"
-	case TCP_CLOSE:
+	case tcpClose:
 		return "close"
-	case TCP_CLOSE_WAIT:
+	case tcpCloseWait:
 		return "close_wait"
-	case TCP_LAST_ACK:
+	case tcpLastAck:
 		return "last_ack"
-	case TCP_LISTEN:
+	case tcpListen:
 		return "listen"
-	case TCP_CLOSING:
+	case tcpClosing:
 		return "closing"
 	default:
 		return "unknown"

collector/tcpstat_linux_test.go

@@ -30,11 +30,11 @@ func TestTCPStat(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if want, got := 1, int(tcpStats[TCP_ESTABLISHED]); want != got {
+	if want, got := 1, int(tcpStats[tcpEstablished]); want != got {
 		t.Errorf("want tcpstat number of established state %d, got %d", want, got)
 	}
 
-	if want, got := 1, int(tcpStats[TCP_LISTEN]); want != got {
+	if want, got := 1, int(tcpStats[tcpListen]); want != got {
 		t.Errorf("want tcpstat number of listen state %d, got %d", want, got)
 	}
 }

collector/textfile.go

@@ -44,8 +44,8 @@ func init() {
 	Factories["textfile"] = NewTextFileCollector
 }
 
-// Takes a registers a
+// NewTextFileCollector returns a new Collector exposing metrics read from files
-// SetMetricFamilyInjectionHook.
+// in the given textfile directory.
 func NewTextFileCollector() (Collector, error) {
 	c := &textFileCollector{
 		path: *textFileDirectory,
@@ -65,7 +65,7 @@ func NewTextFileCollector() (Collector, error) {
 	return c, nil
 }
 
-// textFile collector works via SetMetricFamilyInjectionHook in parseTextFiles.
+// Update implements the Collector interface.
 func (c *textFileCollector) Update(ch chan<- prometheus.Metric) (err error) {
 	return nil
 }

collector/time.go

@@ -30,8 +30,8 @@ func init() {
 	Factories["time"] = NewTimeCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewTimeCollector returns a new Collector exposing the current system time in
-// the current system time in seconds since epoch.
+// seconds since epoch.
 func NewTimeCollector() (Collector, error) {
 	return &timeCollector{
 		desc: prometheus.NewDesc(

collector/vmstat_linux.go

@@ -35,8 +35,7 @@ func init() {
 	Factories["vmstat"] = NewvmStatCollector
 }
 
-// Takes a prometheus registry and returns a new Collector exposing
+// NewvmStatCollector returns a new Collector exposing vmstat stats.
-// vmstat stats.
 func NewvmStatCollector() (Collector, error) {
 	return &vmStatCollector{}, nil
 }

collector/wifi_linux.go

@@ -56,6 +56,7 @@ type wifiStater interface {
 	StationInfo(ifi *wifi.Interface) (*wifi.StationInfo, error)
 }
 
+// NewWifiCollector returns a new Collector exposing Wifi statistics.
 func NewWifiCollector() (Collector, error) {
 	const (
 		subsystem = "wifi"

collector/zfs.go

@@ -24,20 +24,16 @@ import (
 	"github.com/prometheus/common/log"
 )
 
-var zfsNotAvailableError = errors.New("ZFS / ZFS statistics are not available")
+var errZFSNotAvailable = errors.New("ZFS / ZFS statistics are not available")
 
 type zfsSysctl string
 
-// Metrics
-
 type zfsMetric struct {
 	subsystem string    // The Prometheus subsystem name.
 	name      string    // The Prometheus name of the metric.
 	sysctl    zfsSysctl // The sysctl of the ZFS metric.
 }
 
-// Collector
-
 func init() {
 	Factories["zfs"] = NewZFSCollector
 }
@@ -49,6 +45,7 @@ type zfsCollector struct {
 	linuxPathMap      map[string]string
 }
 
+// NewZFSCollector returns a new Collector exposing ZFS statistics.
 func NewZFSCollector() (Collector, error) {
 	var z zfsCollector
 	z.linuxProcpathBase = "spl/kstat/zfs"
@@ -65,14 +62,13 @@ func NewZFSCollector() (Collector, error) {
 	return &z, nil
 }
 
-func (c *zfsCollector) Update(ch chan<- prometheus.Metric) (err error) {
+func (c *zfsCollector) Update(ch chan<- prometheus.Metric) error {
 	for subsystem := range c.linuxPathMap {
-		err = c.updateZfsStats(subsystem, ch)
+		if err := c.updateZfsStats(subsystem, ch); err != nil {
-		switch {
+			if err == errZFSNotAvailable {
-		case err == zfsNotAvailableError:
+				log.Debug(err)
-			log.Debug(err)
+				return nil
-			return nil
+			}
-		case err != nil:
 			return err
 		}
 	}

collector/zfs_linux.go

@@ -30,7 +30,7 @@ func (c *zfsCollector) openProcFile(path string) (file *os.File, err error) {
 	file, err = os.Open(procFilePath(path))
 	if err != nil {
 		log.Debugf("Cannot open %q for reading. Is the kernel module loaded?", procFilePath(path))
-		err = zfsNotAvailableError
+		err = errZFSNotAvailable
 	}
 	return
 }
@@ -61,7 +61,7 @@ func (c *zfsCollector) updatePoolStats(ch chan<- prometheus.Metric) (err error)
 		file, err := os.Open(zpoolPath)
 		if err != nil {
 			log.Debugf("Cannot open %q for reading. Is the kernel module loaded?", zpoolPath)
-			return zfsNotAvailableError
+			return errZFSNotAvailable
 		}
 
 		err = c.parsePoolProcfsFile(file, zpoolPath, func(poolName string, s zfsSysctl, v int) {

node_exporter.go

@@ -72,7 +72,7 @@ func (n NodeCollector) Collect(ch chan<- prometheus.Metric) {
 }
 
 func filterAvailableCollectors(collectors string) string {
-	availableCollectors := make([]string, 0)
+	var availableCollectors []string
 	for _, c := range strings.Split(collectors, ",") {
 		_, ok := collector.Factories[c]
 		if ok {