Refactor InfluxDB listener (#6974)

Use streaming parser in InfluxDB listener

plugins/parsers/influx/parser.go

@@ -3,8 +3,10 @@ package influx
 import (
 	"errors"
 	"fmt"
+	"io"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/influxdata/telegraf"
 )
@@ -17,6 +19,9 @@ var (
 	ErrNoMetric = errors.New("no metric in line")
 )
 
+type TimeFunc func() time.Time
+
+// ParseError indicates a error in the parsing of the text.
 type ParseError struct {
 	Offset     int
 	LineOffset int
@@ -38,6 +43,8 @@ func (e *ParseError) Error() string {
 	return fmt.Sprintf("metric parse error: %s at %d:%d: %q", e.msg, e.LineNumber, e.Column, buffer)
 }
 
+// Parser is an InfluxDB Line Protocol parser that implements the
+// parsers.Parser interface.
 type Parser struct {
 	DefaultTags map[string]string
 
@@ -62,6 +69,10 @@ func NewSeriesParser(handler *MetricHandler) *Parser {
 	}
 }
 
+func (h *Parser) SetTimeFunc(f TimeFunc) {
+	h.handler.SetTimeFunc(f)
+}
+
 func (p *Parser) Parse(input []byte) ([]telegraf.Metric, error) {
 	p.Lock()
 	defer p.Unlock()
@@ -75,7 +86,6 @@ func (p *Parser) Parse(input []byte) ([]telegraf.Metric, error) {
 		}
 
 		if err != nil {
-			p.handler.Reset()
 			return nil, &ParseError{
 				Offset:     p.machine.Position(),
 				LineOffset: p.machine.LineOffset(),
@@ -88,7 +98,6 @@ func (p *Parser) Parse(input []byte) ([]telegraf.Metric, error) {
 
 		metric, err := p.handler.Metric()
 		if err != nil {
-			p.handler.Reset()
 			return nil, err
 		}
 
@@ -126,10 +135,93 @@ func (p *Parser) applyDefaultTags(metrics []telegraf.Metric) {
 	}
 
 	for _, m := range metrics {
-		for k, v := range p.DefaultTags {
-			if !m.HasTag(k) {
-				m.AddTag(k, v)
-			}
+		p.applyDefaultTagsSingle(m)
+	}
+}
+
+func (p *Parser) applyDefaultTagsSingle(metric telegraf.Metric) {
+	for k, v := range p.DefaultTags {
+		if !metric.HasTag(k) {
+			metric.AddTag(k, v)
 		}
 	}
 }
+
+// StreamParser is an InfluxDB Line Protocol parser.  It is not safe for
+// concurrent use in multiple goroutines.
+type StreamParser struct {
+	machine *streamMachine
+	handler *MetricHandler
+}
+
+func NewStreamParser(r io.Reader) *StreamParser {
+	handler := NewMetricHandler()
+	return &StreamParser{
+		machine: NewStreamMachine(r, handler),
+		handler: handler,
+	}
+}
+
+// SetTimeFunc changes the function used to determine the time of metrics
+// without a timestamp.  The default TimeFunc is time.Now.  Useful mostly for
+// testing, or perhaps if you want all metrics to have the same timestamp.
+func (h *StreamParser) SetTimeFunc(f TimeFunc) {
+	h.handler.SetTimeFunc(f)
+}
+
+func (h *StreamParser) SetTimePrecision(u time.Duration) {
+	h.handler.SetTimePrecision(u)
+}
+
+// Next parses the next item from the stream.  You can repeat calls to this
+// function until it returns EOF.
+func (p *StreamParser) Next() (telegraf.Metric, error) {
+	err := p.machine.Next()
+	if err == EOF {
+		return nil, EOF
+	}
+
+	if err != nil {
+		return nil, &ParseError{
+			Offset:     p.machine.Position(),
+			LineOffset: p.machine.LineOffset(),
+			LineNumber: p.machine.LineNumber(),
+			Column:     p.machine.Column(),
+			msg:        err.Error(),
+			buf:        p.machine.LineText(),
+		}
+	}
+
+	metric, err := p.handler.Metric()
+	if err != nil {
+		return nil, err
+	}
+
+	return metric, nil
+}
+
+// Position returns the current byte offset into the data.
+func (p *StreamParser) Position() int {
+	return p.machine.Position()
+}
+
+// LineOffset returns the byte offset of the current line.
+func (p *StreamParser) LineOffset() int {
+	return p.machine.LineOffset()
+}
+
+// LineNumber returns the current line number.  Lines are counted based on the
+// regular expression `\r?\n`.
+func (p *StreamParser) LineNumber() int {
+	return p.machine.LineNumber()
+}
+
+// Column returns the current column.
+func (p *StreamParser) Column() int {
+	return p.machine.Column()
+}
+
+// LineText returns the text of the current line that has been parsed so far.
+func (p *StreamParser) LineText() string {
+	return p.machine.LineText()
+}