Add option to control metrics bundling

ocagent.go

@@ -90,6 +90,10 @@ type Exporter struct {
 	// Please do not confuse it with metricsBundler!
 	viewDataBundler *bundler.Bundler
 
+	// Bundler configuration options managed by viewDataBundler
+	viewDataDelay       time.Duration
+	viewDataBundleCount int
+
 	clientTransportCredentials credentials.TransportCredentials
 
 	grpcDialOptions []grpc.DialOption
@@ -112,6 +116,8 @@ const spanDataBufferSize = 300
 
 func NewUnstartedExporter(opts ...ExporterOption) (*Exporter, error) {
 	e := new(Exporter)
+	e.viewDataDelay = 2 * time.Second
+	e.viewDataBundleCount = 500
 	for _, opt := range opts {
 		opt.withExporter(e)
 	}
@@ -125,8 +131,8 @@ func NewUnstartedExporter(opts ...ExporterOption) (*Exporter, error) {
 	viewDataBundler := bundler.NewBundler((*view.Data)(nil), func(bundle interface{}) {
 		e.uploadViewData(bundle.([]*view.Data))
 	})
-	viewDataBundler.DelayThreshold = 2 * time.Second
-	viewDataBundler.BundleCountThreshold = 500 // TODO: (@odeke-em) make this configurable.
+	viewDataBundler.DelayThreshold = e.viewDataDelay
+	viewDataBundler.BundleCountThreshold = e.viewDataBundleCount
 	e.viewDataBundler = viewDataBundler
 	e.nodeInfo = NodeWithStartTime(e.serviceName)
 	if e.resourceDetector != nil {

options.go

@@ -173,6 +173,27 @@ func WithMetricNamePrefix(prefix string) ExporterOption {
 	return metricNamePrefixSetter(prefix)
 }
 
+type dataBundlerOptions struct {
+	delay time.Duration
+	count int
+}
+
+var _ ExporterOption = (*dataBundlerOptions)(nil)
+
+func (b dataBundlerOptions) withExporter(e *Exporter) {
+	if b.delay > 0 {
+		e.viewDataDelay = b.delay
+	}
+	if b.count > 0 {
+		e.viewDataBundleCount = b.count
+	}
+}
+
+// WithDataBundlerOptions provides an option for the caller to configure the metrics data bundler.
+func WithDataBundlerOptions(delay time.Duration, count int) ExporterOption {
+	return dataBundlerOptions{delay, count}
+}
+
 func (spanConfig SpanConfig) withExporter(e *Exporter) {
 	e.spanConfig = spanConfig
 }