Implement telegraf's own full metric type

main reasons behind this:
- make adding/removing tags cheap
- make adding/removing fields cheap
- make parsing cheaper
- make parse -> decorate -> write out bytes metric flow much faster

Refactor serializer to use byte buffer

plugins/outputs/instrumental/instrumental.go

@@ -1,6 +1,7 @@
 package instrumental
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"log"
@@ -10,11 +11,17 @@ import (
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/metric"
 	"github.com/influxdata/telegraf/plugins/outputs"
 	"github.com/influxdata/telegraf/plugins/serializers"
 	"github.com/influxdata/telegraf/plugins/serializers/graphite"
 )
 
+var (
+	ValueIncludesBadChar = regexp.MustCompile("[^[:digit:].]")
+	MetricNameReplacer   = regexp.MustCompile("[^-[:alnum:]_.]+")
+)
+
 type Instrumental struct {
 	Host       string
 	ApiToken   string
@@ -34,11 +41,6 @@ const (
 	HandshakeFormat = HelloMessage + AuthFormat
 )
 
-var (
-	ValueIncludesBadChar = regexp.MustCompile("[^[:digit:].]")
-	MetricNameReplacer   = regexp.MustCompile("[^-[:alnum:]_.]+")
-)
-
 var sampleConfig = `
   ## Project API Token (required)
   api_token = "API Token" # required
@@ -94,7 +96,7 @@ func (i *Instrumental) Write(metrics []telegraf.Metric) error {
 	var toSerialize telegraf.Metric
 	var newTags map[string]string
 
-	for _, metric := range metrics {
+	for _, m := range metrics {
 		// Pull the metric_type out of the metric's tags. We don't want the type
 		// to show up with the other tags pulled from the system, as they go in the
 		// beginning of the line instead.
@@ -106,18 +108,18 @@ func (i *Instrumental) Write(metrics []telegraf.Metric) error {
 		//
 		//  increment some_prefix.host.tag1.tag2.tag3.counter.field value timestamp
 		//
-		newTags = metric.Tags()
+		newTags = m.Tags()
 		metricType = newTags["metric_type"]
 		delete(newTags, "metric_type")
 
-		toSerialize, _ = telegraf.NewMetric(
-			metric.Name(),
+		toSerialize, _ = metric.New(
+			m.Name(),
 			newTags,
-			metric.Fields(),
-			metric.Time(),
+			m.Fields(),
+			m.Time(),
 		)
 
-		stats, err := s.Serialize(toSerialize)
+		buf, err := s.Serialize(toSerialize)
 		if err != nil {
 			log.Printf("E! Error serializing a metric to Instrumental: %s", err)
 		}
@@ -131,20 +133,25 @@ func (i *Instrumental) Write(metrics []telegraf.Metric) error {
 			metricType = "gauge"
 		}
 
-		for _, stat := range stats {
+		buffer := bytes.NewBuffer(buf)
+		for {
+			line, err := buffer.ReadBytes('\n')
+			if err != nil {
+				break
+			}
+			stat := string(line)
+
 			// decompose "metric.name value time"
 			splitStat := strings.SplitN(stat, " ", 3)
-			metric := splitStat[0]
+			name := splitStat[0]
 			value := splitStat[1]
 			time := splitStat[2]
 
 			// replace invalid components of metric name with underscore
-			clean_metric := MetricNameReplacer.ReplaceAllString(metric, "_")
+			clean_metric := MetricNameReplacer.ReplaceAllString(name, "_")
 
 			if !ValueIncludesBadChar.MatchString(value) {
 				points = append(points, fmt.Sprintf("%s %s %s %s", metricType, clean_metric, value, time))
-			} else if i.Debug {
-				log.Printf("E! Instrumental unable to send bad stat: %s", stat)
 			}
 		}
 	}
@@ -152,8 +159,6 @@ func (i *Instrumental) Write(metrics []telegraf.Metric) error {
 	allPoints := strings.Join(points, "\n") + "\n"
 	_, err = fmt.Fprintf(i.conn, allPoints)
 
-	log.Println("D! Instrumental: " + allPoints)
-
 	if err != nil {
 		if err == io.EOF {
 			i.Close()

plugins/outputs/instrumental/instrumental_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/metric"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -26,13 +27,13 @@ func TestWrite(t *testing.T) {
 	}
 
 	// Default to gauge
-	m1, _ := telegraf.NewMetric(
+	m1, _ := metric.New(
 		"mymeasurement",
 		map[string]string{"host": "192.168.0.1"},
 		map[string]interface{}{"myfield": float64(3.14)},
 		time.Date(2010, time.November, 10, 23, 0, 0, 0, time.UTC),
 	)
-	m2, _ := telegraf.NewMetric(
+	m2, _ := metric.New(
 		"mymeasurement",
 		map[string]string{"host": "192.168.0.1", "metric_type": "set"},
 		map[string]interface{}{"value": float64(3.14)},
@@ -43,27 +44,27 @@ func TestWrite(t *testing.T) {
 	i.Write(metrics)
 
 	// Counter and Histogram are increments
-	m3, _ := telegraf.NewMetric(
+	m3, _ := metric.New(
 		"my_histogram",
 		map[string]string{"host": "192.168.0.1", "metric_type": "histogram"},
 		map[string]interface{}{"value": float64(3.14)},
 		time.Date(2010, time.November, 10, 23, 0, 0, 0, time.UTC),
 	)
 	// We will modify metric names that won't be accepted by Instrumental
-	m4, _ := telegraf.NewMetric(
+	m4, _ := metric.New(
 		"bad_metric_name",
 		map[string]string{"host": "192.168.0.1:8888::123", "metric_type": "counter"},
 		map[string]interface{}{"value": 1},
 		time.Date(2010, time.November, 10, 23, 0, 0, 0, time.UTC),
 	)
 	// We will drop metric values that won't be accepted by Instrumental
-	m5, _ := telegraf.NewMetric(
+	m5, _ := metric.New(
 		"bad_values",
 		map[string]string{"host": "192.168.0.1", "metric_type": "counter"},
 		map[string]interface{}{"value": "\" 3:30\""},
 		time.Date(2010, time.November, 10, 23, 0, 0, 0, time.UTC),
 	)
-	m6, _ := telegraf.NewMetric(
+	m6, _ := metric.New(
 		"my_counter",
 		map[string]string{"host": "192.168.0.1", "metric_type": "counter"},
 		map[string]interface{}{"value": float64(3.14)},