chore(influxdb): update the import path of influxdb lib to the new one

This also upgrades it to the latest version and adds a benchmark which
shows some less allocation:

name                       old time/op    new time/op    delta
Influxdb1Second-4            3.56ms ± 0%    3.56ms ± 1%     ~
(p=0.841 n=5+5)
Influxdb2Second-4            12.1ms ± 0%    12.1ms ± 0%     ~
(p=0.095 n=5+5)
Influxdb100Milliseconds-4     341µs ± 1%     333µs ± 1%   -2.34%
(p=0.008 n=5+5)

name                       old alloc/op   new alloc/op   delta
Influxdb1Second-4            19.1kB ± 0%    16.6kB ± 0%  -13.37%
(p=0.008 n=5+5)
Influxdb2Second-4            18.8kB ± 0%    16.2kB ± 0%  -13.63%
(p=0.016 n=5+4)
Influxdb100Milliseconds-4    18.7kB ± 0%    16.1kB ± 0%  -13.72%
(p=0.008 n=5+5)

name                       old allocs/op  new allocs/op  delta
Influxdb1Second-4               291 ± 0%       231 ± 0%  -20.62%
(p=0.008 n=5+5)
Influxdb2Second-4               291 ± 0%       231 ± 0%  -20.62%
(p=0.008 n=5+5)
Influxdb100Milliseconds-4       291 ± 0%       231 ± 0%  -20.62%
(p=0.008 n=5+5)

The same test as in fce3884 gets 6909 RPS with 2.5GB of memory usage so
a considerate bump in rps for small amount of memory.

stats/influxdb/bench_test.go

@@ -0,0 +1,59 @@
+package influxdb
+
+import (
+	"io"
+	"io/ioutil"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/loadimpact/k6/stats"
+)
+
+func benchmarkInfluxdb(b *testing.B, t time.Duration) {
+	testCollectorCycle(b, func(rw http.ResponseWriter, r *http.Request) {
+		for {
+			time.Sleep(t)
+			m, _ := io.CopyN(ioutil.Discard, r.Body, 1<<18) // read 1/4 mb a time
+			if m == 0 {
+				break
+			}
+		}
+		rw.WriteHeader(204)
+	}, func(tb testing.TB, c *Collector) {
+		b = tb.(*testing.B)
+		b.ResetTimer()
+
+		var samples = make(stats.Samples, 10)
+		for i := 0; i < len(samples); i++ {
+			samples[i] = stats.Sample{
+				Metric: stats.New("testGauge", stats.Gauge),
+				Time:   time.Now(),
+				Tags: stats.NewSampleTags(map[string]string{
+					"something": "else",
+					"VU":        "21",
+					"else":      "something",
+				}),
+				Value: 2.0,
+			}
+		}
+
+		b.ResetTimer()
+		for i := 0; i < b.N; i++ {
+			c.Collect([]stats.SampleContainer{samples})
+			time.Sleep(time.Nanosecond * 20)
+		}
+	})
+}
+
+func BenchmarkInfluxdb1Second(b *testing.B) {
+	benchmarkInfluxdb(b, time.Second)
+}
+
+func BenchmarkInfluxdb2Second(b *testing.B) {
+	benchmarkInfluxdb(b, 2*time.Second)
+}
+
+func BenchmarkInfluxdb100Milliseconds(b *testing.B) {
+	benchmarkInfluxdb(b, 100*time.Millisecond)
+}

stats/influxdb/collector.go

@@ -26,11 +26,10 @@ import (
 	"sync"
 	"time"
 
-	"github.com/influxdata/influxdb/client/v2"
-	"github.com/sirupsen/logrus"
-
+	client "github.com/influxdata/influxdb1-client/v2"
 	"github.com/loadimpact/k6/lib"
 	"github.com/loadimpact/k6/stats"
+	"github.com/sirupsen/logrus"
 )
 
 // Verify that Collector implements lib.Collector
@@ -116,6 +115,7 @@ func (c *Collector) commit() {
 		<-c.semaphoreCh
 	}()
 	logrus.Debug("InfluxDB: Committing...")
+	logrus.WithField("samples", len(samples)).Debug("InfluxDB: Writing...")
 
 	batch, err := c.batchFromSamples(samples)
 	if err != nil {

stats/influxdb/util.go

@@ -23,7 +23,7 @@ package influxdb
 import (
 	"strings"
 
-	client "github.com/influxdata/influxdb/client/v2"
+	client "github.com/influxdata/influxdb1-client/v2"
 	null "gopkg.in/guregu/null.v3"
 )
 

stats/influxdb/util_test.go

@@ -23,7 +23,7 @@ package influxdb
 import (
 	"testing"
 
-	client "github.com/influxdata/influxdb/client/v2"
+	client "github.com/influxdata/influxdb1-client/v2"
 	"github.com/stretchr/testify/assert"
 	null "gopkg.in/guregu/null.v3"
 )