perf(inputs/influxdb_listener): benchmark serving writes (#6673)

* perf(inputs/influxdb_listener): benchmark serving writes

* chore(inputs/influxdb_listener): remove stray comment

plugins/inputs/influxdb_listener/influxdb_listener_test.go

@@ -0,0 +1,114 @@
+package http_listener
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/influxdata/telegraf/internal"
+	"github.com/influxdata/telegraf/plugins/parsers/influx"
+	"github.com/influxdata/telegraf/selfstat"
+	"github.com/influxdata/telegraf/testutil"
+)
+
+// newListener is the minimal HTTPListener construction to serve writes.
+func newListener() *HTTPListener {
+	listener := &HTTPListener{
+		TimeFunc:  time.Now,
+		acc:       &testutil.NopAccumulator{},
+		BytesRecv: selfstat.Register("http_listener", "bytes_received", map[string]string{}),
+		handler:   influx.NewMetricHandler(),
+		pool:      NewPool(200, DEFAULT_MAX_LINE_SIZE),
+		MaxLineSize: internal.Size{
+			Size: DEFAULT_MAX_LINE_SIZE,
+		},
+		MaxBodySize: internal.Size{
+			Size: DEFAULT_MAX_BODY_SIZE,
+		},
+	}
+	listener.parser = influx.NewParser(listener.handler)
+	return listener
+}
+
+func BenchmarkHTTPListener_serveWrite(b *testing.B) {
+	res := httptest.NewRecorder()
+	addr := "http://localhost/write?db=mydb"
+
+	benchmarks := []struct {
+		name  string
+		lines string
+	}{
+		{
+			name:  "single line, tag, and field",
+			lines: lines(1, 1, 1),
+		},
+		{
+			name:  "single line, 10 tags and fields",
+			lines: lines(1, 10, 10),
+		},
+		{
+			name:  "single line, 100 tags and fields",
+			lines: lines(1, 100, 100),
+		},
+		{
+			name:  "1k lines, single tag and field",
+			lines: lines(1000, 1, 1),
+		},
+		{
+			name:  "1k lines, 10 tags and fields",
+			lines: lines(1000, 10, 10),
+		},
+		{
+			name:  "10k lines, 10 tags and fields",
+			lines: lines(10000, 10, 10),
+		},
+		{
+			name:  "100k lines, 10 tags and fields",
+			lines: lines(100000, 10, 10),
+		},
+	}
+
+	for _, bm := range benchmarks {
+		b.Run(bm.name, func(b *testing.B) {
+			listener := newListener()
+
+			b.ResetTimer()
+			for n := 0; n < b.N; n++ {
+				req, err := http.NewRequest("POST", addr, strings.NewReader(bm.lines))
+				if err != nil {
+					b.Error(err)
+				}
+				listener.serveWrite(res, req)
+				if res.Code != http.StatusNoContent {
+					b.Errorf("unexpected status %d", res.Code)
+				}
+			}
+		})
+	}
+}
+
+func lines(lines, numTags, numFields int) string {
+	lp := make([]string, lines)
+	for i := 0; i < lines; i++ {
+		tags := make([]string, numTags)
+		for j := 0; j < numTags; j++ {
+			tags[j] = fmt.Sprintf("t%d=v%d", j, j)
+		}
+
+		fields := make([]string, numFields)
+		for k := 0; k < numFields; k++ {
+			fields[k] = fmt.Sprintf("f%d=%d", k, k)
+		}
+
+		lp[i] = fmt.Sprintf("m%d,%s %s",
+			i,
+			strings.Join(tags, ","),
+			strings.Join(fields, ","),
+		)
+	}
+
+	return strings.Join(lp, "\n")
+}