Reduce the cpu/memory used by the graphite parser (influxdata#5841)

plugins/parsers/graphite/parser.go

@@ -1,10 +1,9 @@
 package graphite
 
 import (
- "bufio"
  "bytes"
+ "errors"
  "fmt"
- "io"
  "math"
  "strconv"
  "strings"
@@ -63,42 +62,36 @@ func NewGraphiteParser(
 
 func (p *GraphiteParser) Parse(buf []byte) ([]telegraf.Metric, error) {
  // parse even if the buffer begins with a newline
- buf = bytes.TrimPrefix(buf, []byte("\n"))
- // add newline to end if not exists:
- if len(buf) > 0 && !bytes.HasSuffix(buf, []byte("\n")) {
- buf = append(buf, []byte("\n")...)
+ if len(buf) != 0 && buf[0] == '\n' {
+ buf = buf[1:]
  }
 
- metrics := make([]telegraf.Metric, 0)
+ var metrics []telegraf.Metric
+ var errs []string
 
- var errStr string
- buffer := bytes.NewBuffer(buf)
- reader := bufio.NewReader(buffer)
  for {
- // Read up to the next newline.
- buf, err := reader.ReadBytes('\n')
- if err == io.EOF {
- break
- }
- if err != nil && err != io.EOF {
- return metrics, err
+ n := bytes.IndexByte(buf, '\n')
+ var line []byte
+ if n >= 0 {
+ line = bytes.TrimSpace(buf[:n:n])
+ } else {
+ line = bytes.TrimSpace(buf) // last line
  }
-
- // Trim the buffer, even though there should be no padding
- line := strings.TrimSpace(string(buf))
- if line == "" {
- continue
+ if len(line) != 0 {
+ metric, err := p.ParseLine(string(line))
+ if err == nil {
+ metrics = append(metrics, metric)
+ } else {
+ errs = append(errs, err.Error())
+ }
  }
- metric, err := p.ParseLine(line)
- if err == nil {
- metrics = append(metrics, metric)
- } else {
- errStr += err.Error() + "\n"
+ if n < 0 {
+ break
  }
+ buf = buf[n+1:]
  }
-
- if errStr != "" {
- return metrics, fmt.Errorf(strings.TrimSpace(errStr))
+ if len(errs) != 0 {
+ return metrics, errors.New(strings.Join(errs, "\n"))
  }
  return metrics, nil
 }