Create public models for telegraf metrics, accumlator, plugins

This will basically make the root directory a place for storing the
major telegraf interfaces, which will make telegraf's godoc looks quite
a bit nicer. And make it easier for contributors to lookup the few data
types that they actually care about.

closes #564

accumulator.go

@@ -1,188 +1,21 @@
 package telegraf
 
-import (
-	"fmt"
-	"log"
-	"math"
-	"sync"
-	"time"
-
-	"github.com/influxdata/telegraf/internal/models"
-
-	"github.com/influxdata/influxdb/client/v2"
-)
+import "time"
 
 type Accumulator interface {
-	Add(measurement string, value interface{},
-		tags map[string]string, t ...time.Time)
-	AddFields(measurement string, fields map[string]interface{},
-		tags map[string]string, t ...time.Time)
+	// Create a point with a value, decorating it with tags
+	// NOTE: tags is expected to be owned by the caller, don't mutate
+	// it after passing to Add.
+	Add(measurement string,
+		value interface{},
+		tags map[string]string,
+		t ...time.Time)
 
-	SetDefaultTags(tags map[string]string)
-	AddDefaultTag(key, value string)
-
-	Prefix() string
-	SetPrefix(prefix string)
+	AddFields(measurement string,
+		fields map[string]interface{},
+		tags map[string]string,
+		t ...time.Time)
 
 	Debug() bool
 	SetDebug(enabled bool)
 }
-
-func NewAccumulator(
-	inputConfig *models.InputConfig,
-	points chan *client.Point,
-) Accumulator {
-	acc := accumulator{}
-	acc.points = points
-	acc.inputConfig = inputConfig
-	return &acc
-}
-
-type accumulator struct {
-	sync.Mutex
-
-	points chan *client.Point
-
-	defaultTags map[string]string
-
-	debug bool
-
-	inputConfig *models.InputConfig
-
-	prefix string
-}
-
-func (ac *accumulator) Add(
-	measurement string,
-	value interface{},
-	tags map[string]string,
-	t ...time.Time,
-) {
-	fields := make(map[string]interface{})
-	fields["value"] = value
-	ac.AddFields(measurement, fields, tags, t...)
-}
-
-func (ac *accumulator) AddFields(
-	measurement string,
-	fields map[string]interface{},
-	tags map[string]string,
-	t ...time.Time,
-) {
-	if len(fields) == 0 || len(measurement) == 0 {
-		return
-	}
-
-	if !ac.inputConfig.Filter.ShouldTagsPass(tags) {
-		return
-	}
-
-	// Override measurement name if set
-	if len(ac.inputConfig.NameOverride) != 0 {
-		measurement = ac.inputConfig.NameOverride
-	}
-	// Apply measurement prefix and suffix if set
-	if len(ac.inputConfig.MeasurementPrefix) != 0 {
-		measurement = ac.inputConfig.MeasurementPrefix + measurement
-	}
-	if len(ac.inputConfig.MeasurementSuffix) != 0 {
-		measurement = measurement + ac.inputConfig.MeasurementSuffix
-	}
-
-	if tags == nil {
-		tags = make(map[string]string)
-	}
-	// Apply plugin-wide tags if set
-	for k, v := range ac.inputConfig.Tags {
-		if _, ok := tags[k]; !ok {
-			tags[k] = v
-		}
-	}
-	// Apply daemon-wide tags if set
-	for k, v := range ac.defaultTags {
-		if _, ok := tags[k]; !ok {
-			tags[k] = v
-		}
-	}
-
-	result := make(map[string]interface{})
-	for k, v := range fields {
-		// Filter out any filtered fields
-		if ac.inputConfig != nil {
-			if !ac.inputConfig.Filter.ShouldPass(k) {
-				continue
-			}
-		}
-		result[k] = v
-
-		// Validate uint64 and float64 fields
-		switch val := v.(type) {
-		case uint64:
-			// InfluxDB does not support writing uint64
-			if val < uint64(9223372036854775808) {
-				result[k] = int64(val)
-			} else {
-				result[k] = int64(9223372036854775807)
-			}
-		case float64:
-			// NaNs are invalid values in influxdb, skip measurement
-			if math.IsNaN(val) || math.IsInf(val, 0) {
-				if ac.debug {
-					log.Printf("Measurement [%s] field [%s] has a NaN or Inf "+
-						"field, skipping",
-						measurement, k)
-				}
-				continue
-			}
-		}
-	}
-	fields = nil
-	if len(result) == 0 {
-		return
-	}
-
-	var timestamp time.Time
-	if len(t) > 0 {
-		timestamp = t[0]
-	} else {
-		timestamp = time.Now()
-	}
-
-	if ac.prefix != "" {
-		measurement = ac.prefix + measurement
-	}
-
-	pt, err := client.NewPoint(measurement, tags, result, timestamp)
-	if err != nil {
-		log.Printf("Error adding point [%s]: %s\n", measurement, err.Error())
-		return
-	}
-	if ac.debug {
-		fmt.Println("> " + pt.String())
-	}
-	ac.points <- pt
-}
-
-func (ac *accumulator) SetDefaultTags(tags map[string]string) {
-	ac.defaultTags = tags
-}
-
-func (ac *accumulator) AddDefaultTag(key, value string) {
-	ac.defaultTags[key] = value
-}
-
-func (ac *accumulator) Prefix() string {
-	return ac.prefix
-}
-
-func (ac *accumulator) SetPrefix(prefix string) {
-	ac.prefix = prefix
-}
-
-func (ac *accumulator) Debug() bool {
-	return ac.debug
-}
-
-func (ac *accumulator) SetDebug(debug bool) {
-	ac.debug = debug
-}