Lint: Fix linter errors, improve error handling

Signed-off-by: Knut Ahlers <knut@ahlers.me>

influx.go

@@ -21,7 +21,7 @@ type metricsSender struct {
 	influxDB string
 }
 
-func NewMetricsSender(influxHost, influxUser, influxPass, influxDatabase string) (*metricsSender, error) {
+func newMetricsSender(influxHost, influxUser, influxPass, influxDatabase string) (*metricsSender, error) {
 	out := &metricsSender{
 		errs:     make(chan error, 10),
 		influxDB: influxDatabase,
@@ -40,7 +40,7 @@ func (m *metricsSender) ForceTransmit() error {
 func (m *metricsSender) RecordPoint(name string, tags map[string]string, fields map[string]interface{}) error {
 	pt, err := influx.NewPoint(name, tags, fields, time.Now())
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Unable to create point")
 	}
 
 	m.batchLock.Lock()
@@ -56,7 +56,7 @@ func (m *metricsSender) resetBatch() error {
 	})
 
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Unable to create new points batch")
 	}
 
 	m.batch = b
@@ -80,9 +80,7 @@ func (m *metricsSender) transmit() error {
 	if err := m.client.Write(m.batch); err != nil {
 		return errors.Wrap(err, "Unable to write recorded points")
 	}
-	m.resetBatch()
-
-	return nil
+	return errors.Wrap(m.resetBatch(), "Unable to reset batch")
 }
 
 func (m *metricsSender) initialize(influxHost, influxUser, influxPass string) error {
@@ -94,12 +92,12 @@ func (m *metricsSender) initialize(influxHost, influxUser, influxPass string) er
 	})
 
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Unable to create InfluxDB HTTP client")
 	}
 
 	m.client = influxClient
 	if err := m.resetBatch(); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to reset batch")
 	}
 	go m.sendLoop()
 

main.go

@@ -53,7 +53,7 @@ func main() {
 	var err error
 
 	if cfg.InfluxDB != "" {
-		if metrics, err = NewMetricsSender(cfg.InfluxHost, cfg.InfluxUser, cfg.InfluxPass, cfg.InfluxDB); err != nil {
+		if metrics, err = newMetricsSender(cfg.InfluxHost, cfg.InfluxUser, cfg.InfluxPass, cfg.InfluxDB); err != nil {
 			log.WithError(err).Fatalf("Unable to initialize InfluxDB sender")
 		}
 	}

ping.go

@@ -4,6 +4,8 @@ import (
 	"math"
 	"sort"
 	"time"
+
+	"github.com/pkg/errors"
 )
 
 type pingHistory []int64
@@ -12,18 +14,20 @@ func (s *sparkClient) ExecutePingTest(t *testResult) error {
 	ph := pingHistory{}
 
 	if err := s.connect(); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to connect")
 	}
 
 	if err := s.writeCommand("ECO"); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to send ECO command")
 	}
 
 	buf := make([]byte, 1)
 
 	for i := 0; i < numPings; i++ {
 		start := time.Now()
-		s.conn.Write([]byte{46})
+		if _, err := s.conn.Write([]byte{46}); err != nil {
+			return err
+		}
 
 		if _, err := s.conn.Read(buf); err != nil {
 			return err

spark.go

@@ -7,6 +7,7 @@ import (
 	"net"
 	"strings"
 
+	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
 )
 
@@ -74,7 +75,7 @@ func newSparkClient(hostname string, port int) *sparkClient {
 func (s *sparkClient) dial() error {
 	c, err := net.Dial("tcp", s.remote)
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Unable to dial")
 	}
 	s.conn = c
 
@@ -83,13 +84,13 @@ func (s *sparkClient) dial() error {
 
 func (s *sparkClient) connect() error {
 	if err := s.dial(); err != nil {
-		return fmt.Errorf("Unable to connect to sparkyfish-server %q: %s", s.remote, err)
+		return errors.Wrapf(err, "Unable to connect to sparkyfish-server %q", s.remote)
 	}
 
 	s.reader = bufio.NewReader(s.conn)
 
 	if err := s.writeCommand(fmt.Sprintf("HELO%d", protocolVersion)); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to send HELO command")
 	}
 
 	return s.readGreeting()
@@ -97,19 +98,19 @@ func (s *sparkClient) connect() error {
 
 func (s *sparkClient) writeCommand(command string) error {
 	if _, err := fmt.Fprintf(s.conn, "%s\r\n", command); err != nil {
-		return fmt.Errorf("Unable to send command %q: %s", command, err)
+		return errors.Wrapf(err, "Unable to send command %q", command)
 	}
 	return nil
 }
 
 func (s *sparkClient) readGreeting() error {
 	if helo, err := s.reader.ReadString('\n'); err != nil || strings.TrimSpace(helo) != "HELO" {
-		return fmt.Errorf("Unexpected response to greeting")
+		return errors.New("Unexpected response to greeting")
 	}
 
 	cn, err := s.reader.ReadString('\n')
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Unable to read string")
 	}
 
 	cn = strings.TrimSpace(cn)
@@ -119,11 +120,14 @@ func (s *sparkClient) readGreeting() error {
 
 	loc, err := s.reader.ReadString('\n')
 	if err != nil {
-		return err
+		return errors.Wrap(err, "Unable to read string")
 	}
 
 	loc = strings.TrimSpace(loc)
 
-	log.Debugf("Connected to %q in location %q", cn, loc)
+	log.WithFields(log.Fields{
+		"cn":       cn,
+		"location": loc,
+	}).Debug("Connected to server")
 	return nil
 }

throughput.go

@@ -3,36 +3,37 @@ package main
 import (
 	"bytes"
 	"crypto/rand"
-	"fmt"
 	"io"
 	"io/ioutil"
 	"log"
 	"net"
 	"syscall"
 	"time"
+
+	"github.com/pkg/errors"
 )
 
 func (s *sparkClient) ExecuteThroughputTest(t *testResult) error {
 	if err := s.runSendTest(t); err != nil {
-		return err
+		return errors.Wrap(err, "Send-test failed")
 	}
-	return s.runRecvTest(t)
+	return errors.Wrap(s.runRecvTest(t), "Recv-test failed")
 }
 
 func (s *sparkClient) runSendTest(t *testResult) error {
 	data := make([]byte, 1024*blockSize)
 	if _, err := rand.Read(data); err != nil {
-		return fmt.Errorf("Was unable to gather random data: %s", err)
+		return errors.Wrap(err, "Unable to gather random data")
 	}
 	dataReader := bytes.NewReader(data)
 
 	if err := s.connect(); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to connect")
 	}
 	defer s.conn.Close()
 
 	if err := s.writeCommand("RCV"); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to send RCV command")
 	}
 
 	var (
@@ -57,7 +58,7 @@ func (s *sparkClient) runSendTest(t *testResult) error {
 				break
 			}
 
-			return fmt.Errorf("Error copying: %s", err)
+			return errors.Wrap(err, "Unable to copy data")
 		}
 
 		bps := float64(1024*blockSize*8) / (float64(time.Since(start).Nanoseconds()) / float64(time.Second.Nanoseconds()))
@@ -69,7 +70,9 @@ func (s *sparkClient) runSendTest(t *testResult) error {
 		}
 		blockCount++
 
-		dataReader.Seek(0, 0)
+		if _, err := dataReader.Seek(0, 0); err != nil {
+			return errors.Wrap(err, "Unable to seek")
+		}
 
 		if time.Since(totalStart) > time.Duration(throughputTestLength)*time.Second {
 			break
@@ -84,12 +87,12 @@ func (s *sparkClient) runSendTest(t *testResult) error {
 
 func (s *sparkClient) runRecvTest(t *testResult) error {
 	if err := s.connect(); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to connect")
 	}
 	defer s.conn.Close()
 
 	if err := s.writeCommand("SND"); err != nil {
-		return err
+		return errors.Wrap(err, "Unable to send SND command")
 	}
 
 	var (
@@ -111,7 +114,7 @@ func (s *sparkClient) runRecvTest(t *testResult) error {
 				break
 			}
 
-			return fmt.Errorf("Error copying: %s", err)
+			return errors.Wrap(err, "Unable to copy data")
 		}
 
 		bps := float64(1024*blockSize*8) / (float64(time.Since(start).Nanoseconds()) / float64(time.Second.Nanoseconds()))