Change to NewStreamParser to accept larger inputs from scanner (#8892)

* change to NewStreamParser to accept larger inputs from scanner

* fmt changes

plugins/common/shim/processor.go

@@ -1,14 +1,13 @@
 package shim
 
 import (
-	"bufio"
 	"fmt"
 	"sync"
 	"time"
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/agent"
-	"github.com/influxdata/telegraf/plugins/parsers"
+	"github.com/influxdata/telegraf/plugins/parsers/influx"
 	"github.com/influxdata/telegraf/plugins/processors"
 )
 
@@ -37,12 +36,7 @@ func (s *Shim) RunProcessor() error {
 	acc := agent.NewAccumulator(s, s.metricCh)
 	acc.SetPrecision(time.Nanosecond)
 
-	parser, err := parsers.NewInfluxParser()
+	err := s.Processor.Start(acc)
-	if err != nil {
-		return fmt.Errorf("Failed to create new parser: %w", err)
-	}
-
-	err = s.Processor.Start(acc)
 	if err != nil {
 		return fmt.Errorf("failed to start processor: %w", err)
 	}
@@ -54,13 +48,21 @@ func (s *Shim) RunProcessor() error {
 		wg.Done()
 	}()
 
-	scanner := bufio.NewScanner(s.stdin)
+	parser := influx.NewStreamParser(s.stdin)
-	for scanner.Scan() {
+	for {
-		m, err := parser.ParseLine(scanner.Text())
+		m, err := parser.Next()
 		if err != nil {
-			fmt.Fprintf(s.stderr, "Failed to parse metric: %s\b", err)
+			if err == influx.EOF {
+				break // stream ended
+			}
+			if parseErr, isParseError := err.(*influx.ParseError); isParseError {
+				fmt.Fprintf(s.stderr, "Failed to parse metric: %s\b", parseErr)
+				continue
+			}
+			fmt.Fprintf(s.stderr, "Failure during reading stdin: %s\b", err)
 			continue
 		}
+
 		s.Processor.Add(m, acc)
 	}
 

plugins/common/shim/processor_test.go

@@ -4,6 +4,7 @@ import (
 	"bufio"
 	"io"
 	"io/ioutil"
+	"math/rand"
 	"sync"
 	"testing"
 	"time"
@@ -16,7 +17,21 @@ import (
 )
 
 func TestProcessorShim(t *testing.T) {
-	p := &testProcessor{}
+	testSendAndRecieve(t, "f1", "fv1")
+}
+
+func TestProcessorShimWithLargerThanDefaultScannerBufferSize(t *testing.T) {
+	letters := []rune("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
+	b := make([]rune, bufio.MaxScanTokenSize*2)
+	for i := range b {
+		b[i] = letters[rand.Intn(len(letters))]
+	}
+
+	testSendAndRecieve(t, "f1", string(b))
+}
+
+func testSendAndRecieve(t *testing.T, fieldKey string, fieldValue string) {
+	p := &testProcessor{"hi", "mom"}
 
 	stdinReader, stdinWriter := io.Pipe()
 	stdoutReader, stdoutWriter := io.Pipe()
@@ -45,7 +60,8 @@ func TestProcessorShim(t *testing.T) {
 			"a": "b",
 		},
 		map[string]interface{}{
-			"v": 1,
+			"v":      1,
+			fieldKey: fieldValue,
 		},
 		time.Now(),
 	)
@@ -62,19 +78,24 @@ func TestProcessorShim(t *testing.T) {
 	mOut, err := parser.ParseLine(out)
 	require.NoError(t, err)
 
-	val, ok := mOut.GetTag("hi")
+	val, ok := mOut.GetTag(p.tagName)
 	require.True(t, ok)
-	require.Equal(t, "mom", val)
+	require.Equal(t, p.tagValue, val)
-
+	val2, ok := mOut.Fields()[fieldKey]
+	require.True(t, ok)
+	require.Equal(t, fieldValue, val2)
 	go ioutil.ReadAll(r)
 	wg.Wait()
 }
 
-type testProcessor struct{}
+type testProcessor struct {
+	tagName  string
+	tagValue string
+}
 
 func (p *testProcessor) Apply(in ...telegraf.Metric) []telegraf.Metric {
 	for _, metric := range in {
-		metric.AddTag("hi", "mom")
+		metric.AddTag(p.tagName, p.tagValue)
 	}
 	return in
 }