From 5823fefb7ab4754577df13da7ba62cf01677c78d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Robert=20Edstr=C3=B6m?=
 <108799+Legogris@users.noreply.github.com>
Date: Wed, 20 Feb 2019 22:16:02 +0100
Subject: [PATCH] Group stackdriver requests to send one point per timeseries
 (#5407)

---
 plugins/outputs/stackdriver/stackdriver.go    | 87 ++++++++++++++-----
 .../outputs/stackdriver/stackdriver_test.go   | 83 ++++++++++++++++++
 2 files changed, 149 insertions(+), 21 deletions(-)

diff --git a/plugins/outputs/stackdriver/stackdriver.go b/plugins/outputs/stackdriver/stackdriver.go
index 10823c8ed..c7d9e45bc 100644
--- a/plugins/outputs/stackdriver/stackdriver.go
+++ b/plugins/outputs/stackdriver/stackdriver.go
@@ -3,6 +3,7 @@ package stackdriver
 import (
 	"context"
 	"fmt"
+	"hash/fnv"
 	"log"
 	"path"
 	"sort"
@@ -111,15 +112,34 @@ func sorted(metrics []telegraf.Metric) []telegraf.Metric {
 	return batch
 }
 
+type timeSeriesBuckets map[uint64][]*monitoringpb.TimeSeries
+
+func (tsb timeSeriesBuckets) Add(m telegraf.Metric, f *telegraf.Field, ts *monitoringpb.TimeSeries) {
+	h := fnv.New64a()
+	h.Write([]byte(m.Name()))
+	h.Write([]byte{'\n'})
+	h.Write([]byte(f.Key))
+	h.Write([]byte{'\n'})
+	for key, value := range m.Tags() {
+		h.Write([]byte(key))
+		h.Write([]byte{'\n'})
+		h.Write([]byte(value))
+		h.Write([]byte{'\n'})
+	}
+	k := h.Sum64()
+
+	s := tsb[k]
+	s = append(s, ts)
+	tsb[k] = s
+}
+
 // Write the metrics to Google Cloud Stackdriver.
 func (s *Stackdriver) Write(metrics []telegraf.Metric) error {
 	ctx := context.Background()
 
 	batch := sorted(metrics)
-
+	buckets := make(timeSeriesBuckets)
 	for _, m := range batch {
-		timeSeries := []*monitoringpb.TimeSeries{}
-
 		for _, f := range m.FieldList() {
 			value, err := getStackdriverTypedValue(f.Value)
 			if err != nil {
@@ -150,25 +170,50 @@ func (s *Stackdriver) Write(metrics []telegraf.Metric) error {
 			}
 
 			// Prepare time series.
-			timeSeries = append(timeSeries,
-				&monitoringpb.TimeSeries{
-					Metric: &metricpb.Metric{
-						Type:   path.Join("custom.googleapis.com", s.Namespace, m.Name(), f.Key),
-						Labels: getStackdriverLabels(m.TagList()),
-					},
-					MetricKind: metricKind,
-					Resource: &monitoredrespb.MonitoredResource{
-						Type:   s.ResourceType,
-						Labels: s.ResourceLabels,
-					},
-					Points: []*monitoringpb.Point{
-						dataPoint,
-					},
-				})
-		}
+			timeSeries := &monitoringpb.TimeSeries{
+				Metric: &metricpb.Metric{
+					Type:   path.Join("custom.googleapis.com", s.Namespace, m.Name(), f.Key),
+					Labels: getStackdriverLabels(m.TagList()),
+				},
+				MetricKind: metricKind,
+				Resource: &monitoredrespb.MonitoredResource{
+					Type:   s.ResourceType,
+					Labels: s.ResourceLabels,
+				},
+				Points: []*monitoringpb.Point{
+					dataPoint,
+				},
+			}
 
-		if len(timeSeries) < 1 {
-			continue
+			buckets.Add(m, f, timeSeries)
+		}
+	}
+
+	// process the buckets in order
+	keys := make([]uint64, 0, len(buckets))
+	for k := range buckets {
+		keys = append(keys, k)
+	}
+	sort.Slice(keys, func(i, j int) bool { return keys[i] < keys[j] })
+
+	for len(buckets) != 0 {
+		// can send up to 200 time series to stackdriver
+		timeSeries := make([]*monitoringpb.TimeSeries, 0, 200)
+		for i, k := range keys {
+			s := buckets[k]
+			timeSeries = append(timeSeries, s[0])
+			if len(s) == 1 {
+				delete(buckets, k)
+				keys = append(keys[:i], keys[i+1:]...)
+				continue
+			}
+
+			s = s[1:]
+			buckets[k] = s
+
+			if len(timeSeries) == cap(timeSeries) {
+				break
+			}
 		}
 
 		// Prepare time series request.
diff --git a/plugins/outputs/stackdriver/stackdriver_test.go b/plugins/outputs/stackdriver/stackdriver_test.go
index c60d72d36..151c84020 100644
--- a/plugins/outputs/stackdriver/stackdriver_test.go
+++ b/plugins/outputs/stackdriver/stackdriver_test.go
@@ -207,6 +207,89 @@ func TestWriteAscendingTime(t *testing.T) {
 	})
 }
 
+func TestWriteBatchable(t *testing.T) {
+	expectedResponse := &emptypb.Empty{}
+	mockMetric.err = nil
+	mockMetric.reqs = nil
+	mockMetric.resps = append(mockMetric.resps[:0], expectedResponse)
+
+	c, err := monitoring.NewMetricClient(context.Background(), clientOpt)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s := &Stackdriver{
+		Project:   fmt.Sprintf("projects/%s", "[PROJECT]"),
+		Namespace: "test",
+		client:    c,
+	}
+
+	// Metrics in descending order of timestamp
+	metrics := []telegraf.Metric{
+		testutil.MustMetric("cpu",
+			map[string]string{
+				"foo": "bar",
+			},
+			map[string]interface{}{
+				"value": 42,
+			},
+			time.Unix(2, 0),
+		),
+		testutil.MustMetric("cpu",
+			map[string]string{
+				"foo": "foo",
+			},
+			map[string]interface{}{
+				"value": 43,
+			},
+			time.Unix(3, 0),
+		),
+		testutil.MustMetric("cpu",
+			map[string]string{
+				"foo": "bar",
+			},
+			map[string]interface{}{
+				"value": 43,
+			},
+			time.Unix(1, 0),
+		),
+	}
+
+	err = s.Connect()
+	require.NoError(t, err)
+	err = s.Write(metrics)
+	require.NoError(t, err)
+
+	require.Len(t, mockMetric.reqs, 2)
+	request := mockMetric.reqs[0].(*monitoringpb.CreateTimeSeriesRequest)
+	require.Len(t, request.TimeSeries, 2)
+	ts := request.TimeSeries[0]
+	require.Len(t, ts.Points, 1)
+	require.Equal(t, ts.Points[0].Interval, &monitoringpb.TimeInterval{
+		EndTime: &googlepb.Timestamp{
+			Seconds: 3,
+		},
+	})
+	require.Equal(t, ts.Points[0].Value, &monitoringpb.TypedValue{
+		Value: &monitoringpb.TypedValue_Int64Value{
+			Int64Value: int64(43),
+		},
+	})
+
+	ts = request.TimeSeries[1]
+	require.Len(t, ts.Points, 1)
+	require.Equal(t, ts.Points[0].Interval, &monitoringpb.TimeInterval{
+		EndTime: &googlepb.Timestamp{
+			Seconds: 1,
+		},
+	})
+	require.Equal(t, ts.Points[0].Value, &monitoringpb.TypedValue{
+		Value: &monitoringpb.TypedValue_Int64Value{
+			Int64Value: int64(43),
+		},
+	})
+}
+
 func TestWriteIgnoredErrors(t *testing.T) {
 	tests := []struct {
 		name        string