Add a metric batcher which preallocates batch sizes. (#194)

* Add a metric batcher which preallocates batch sizes.

* Fix received/dropped logic.

* Fix comments and add a new method that returns num dropped timeseries

* Use recordDroppedTimeseries when possible

* Rename ExportMetricsProtoAndReturnDropped to PushMetricsProto

* Fix tests.

Author: bogdandrutu

equivalence_test.go

@@ -102,18 +102,22 @@ func TestStatsAndMetricsEquivalence(t *testing.T) {
 			Name:             fmt.Sprintf("projects/%s", se.o.ProjectID),
 			MetricDescriptor: sMD,
 		}
-		pMDR, err := se.protoMetricDescriptorToCreateMetricDescriptorRequest(ctx, metricPbs[i], nil)
+		inMD, err := se.protoToMonitoringMetricDescriptor(metricPbs[i], nil)
 		if err != nil {
 			t.Errorf("#%d: Stats.protoMetricDescriptorToMetricDescriptor: %v", i, err)
 		}
+		pMDR := &monitoringpb.CreateMetricDescriptorRequest{
+			Name:             fmt.Sprintf("projects/%s", se.o.ProjectID),
+			MetricDescriptor: inMD,
+		}
 		if diff := cmpMDReq(pMDR, sMDR); diff != "" {
 			t.Fatalf("MetricDescriptor Mismatch -FromMetricsPb +FromMetrics: %s", diff)
 		}
 
 		stss, _ := se.metricToMpbTs(ctx, metric)
 		sctreql := se.combineTimeSeriesToCreateTimeSeriesRequest(stss)
-		tsl, _ := se.protoMetricToTimeSeries(ctx, se.getResource(nil, metricPbs[i], seenResources), metricPbs[i], nil)
-		pctreql := se.combineTimeSeriesToCreateTimeSeriesRequest(tsl)
+		allTss, _ := protoMetricToTimeSeries(ctx, se, se.getResource(nil, metricPbs[i], seenResources), metricPbs[i])
+		pctreql := se.combineTimeSeriesToCreateTimeSeriesRequest(allTss)
 		if diff := cmpTSReqs(pctreql, sctreql); diff != "" {
 			t.Fatalf("TimeSeries Mismatch -FromMetricsPb +FromMetrics: %s", diff)
 		}
@@ -336,7 +340,7 @@ func TestEquivalenceStatsVsMetricsUploads(t *testing.T) {
 		})
 
 	// Export the proto Metrics to the Stackdriver backend.
-	se.ExportMetricsProto(context.Background(), nil, nil, metricPbs)
+	se.PushMetricsProto(context.Background(), nil, nil, metricPbs)
 	se.Flush()
 
 	var stackdriverTimeSeriesFromMetricsPb []*monitoringpb.CreateTimeSeriesRequest

metrics_batcher.go

@@ -0,0 +1,91 @@
+// Copyright 2019, OpenCensus Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stackdriver
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	monitoring "cloud.google.com/go/monitoring/apiv3"
+	monitoringpb "google.golang.org/genproto/googleapis/monitoring/v3"
+)
+
+type metricsBatcher struct {
+	projectID string
+	allReqs   []*monitoringpb.CreateTimeSeriesRequest
+	allTss    []*monitoringpb.TimeSeries
+	allErrs   []error
+	// Counts all dropped TimeSeries by this exporter.
+	droppedTimeSeries int
+}
+
+func newMetricsBatcher(projectID string) *metricsBatcher {
+	return &metricsBatcher{
+		projectID:         projectID,
+		allTss:            make([]*monitoringpb.TimeSeries, 0, maxTimeSeriesPerUpload),
+		droppedTimeSeries: 0,
+	}
+}
+
+func (mb *metricsBatcher) recordDroppedTimeseries(numTimeSeries int, err error) {
+	mb.droppedTimeSeries += numTimeSeries
+	mb.allErrs = append(mb.allErrs, err)
+}
+
+func (mb *metricsBatcher) addTimeSeries(ts *monitoringpb.TimeSeries) {
+	mb.allTss = append(mb.allTss, ts)
+	if len(mb.allTss) == maxTimeSeriesPerUpload {
+		mb.allReqs = append(mb.allReqs, &monitoringpb.CreateTimeSeriesRequest{
+			Name:       monitoring.MetricProjectPath(mb.projectID),
+			TimeSeries: mb.allTss,
+		})
+		mb.allTss = make([]*monitoringpb.TimeSeries, maxTimeSeriesPerUpload)
+	}
+}
+
+func (mb *metricsBatcher) export(ctx context.Context, mc *monitoring.MetricClient) {
+	// Last batch, if any.
+	if len(mb.allTss) > 0 {
+		mb.allReqs = append(mb.allReqs, &monitoringpb.CreateTimeSeriesRequest{
+			Name:       monitoring.MetricProjectPath(mb.projectID),
+			TimeSeries: mb.allTss,
+		})
+	}
+
+	// Send create time series requests to Stackdriver.
+	for _, req := range mb.allReqs {
+		if err := createTimeSeries(ctx, mc, req); err != nil {
+			mb.recordDroppedTimeseries(len(req.TimeSeries), err)
+		}
+	}
+}
+
+func (mb *metricsBatcher) finalError() error {
+	numErrors := len(mb.allErrs)
+	if numErrors == 0 {
+		return nil
+	}
+
+	if numErrors == 1 {
+		return mb.allErrs[0]
+	}
+
+	errMsgs := make([]string, 0, numErrors)
+	for _, err := range mb.allErrs {
+		errMsgs = append(errMsgs, err.Error())
+	}
+	return fmt.Errorf("[%s]", strings.Join(errMsgs, "; "))
+}