2/2 Extend receiverhelper scraper functions to simplify the scrape function interface

receiver/receiverhelper/receiver.go

@@ -22,6 +22,7 @@ import (
 	"go.opentelemetry.io/collector/component/componenterror"
 	"go.opentelemetry.io/collector/config/configmodels"
 	"go.opentelemetry.io/collector/consumer"
+	"go.opentelemetry.io/collector/consumer/pdata"
 )
 
 // Start specifies the function invoked when the receiver is being started.
@@ -103,15 +104,27 @@ func WithDefaultCollectionInterval(defaultCollectionInterval time.Duration) Metr
 	}
 }
 
-// AddScraper configures the provided scrape function to be called with
-// the specified options, and at the specified collection interval (one
-// minute by default).
+// AddMetricsScraper configures the provided scrape function to be called
+// with the specified options, and at the specified collection interval
+// (one minute by default).
 //
 // Observability information will be reported, and the scraped metrics
 // will be passed to the next consumer.
-func AddScraper(cfg ScraperConfig, scrape Scrape, options ...ScraperOption) MetricOption {
+func AddMetricsScraper(cfg ScraperConfig, scrape ScrapeMetrics, options ...ScraperOption) MetricOption {
 	return func(o *metricsReceiver) {
-		o.scrapers = append(o.scrapers, newScraper(cfg, scrape, options...))
+		o.metricScrapers = append(o.metricScrapers, newMetricsScraper(cfg, scrape, options...))
+	}
+}
+
+// AddResourceMetricsScraper configures the provided scrape function to
+// be called with the specified options, and at the specified collection
+// interval (one minute by default).
+//
+// Observability information will be reported, and the scraped resource
+// metrics will be passed to the next consumer.
+func AddResourceMetricsScraper(cfg ScraperConfig, scrape ScrapeResourceMetrics, options ...ScraperOption) MetricOption {
+	return func(o *metricsReceiver) {
+		o.resourceMetricScrapers = append(o.resourceMetricScrapers, newResourceMetricsScraper(cfg, scrape, options...))
 	}
 }
 
@@ -120,8 +133,9 @@ type metricsReceiver struct {
 	defaultCollectionInterval time.Duration
 	nextConsumer              consumer.MetricsConsumer
 
-	scrapers []*scraper
-	done     chan struct{}
+	metricScrapers         []*metricsScraper
+	resourceMetricScrapers []*resourceMetricsScraper
+	done                   chan struct{}
 }
 
 // NewMetricReceiver creates a Receiver with the configured options.
@@ -185,7 +199,7 @@ func NewMetricReceiver(config configmodels.Receiver, nextConsumer consumer.Metri
 
 // initializeScrapers initializes all the scrapers
 func (mr *metricsReceiver) initializeScrapers(ctx context.Context) error {
-	for _, scraper := range mr.scrapers {
+	for _, scraper := range mr.allBaseScrapers() {
 		if scraper.initialize == nil {
 			continue
 		}
@@ -201,14 +215,15 @@ func (mr *metricsReceiver) initializeScrapers(ctx context.Context) error {
 // startScraping initiates a ticker that calls Scrape based on the configured
 // collection interval.
 func (mr *metricsReceiver) startScraping() {
-	// TODO1: use one ticker for each set of scrapers that have the same collection interval.
-	// TODO2: consider allowing different "Scrape" functions to be configured, i.e. functions
-	//        that return MetricsSlice or ResourceMetricsSlice (similar to the existing Scraper
-	//        & ResourceScraper interfaces in the host metrics receiver). That will allow data
-	//        from multiple scrapers (that have the same collection interval) to be batched.
-
-	for i := 0; i < len(mr.scrapers); i++ {
-		scraper := mr.scrapers[i]
+	// TODO: use one ticker for each set of scrapers that have the same collection interval.
+
+	mr.startScrapingMetrics()
+	mr.startScrapingResourceMetrics()
+}
+
+func (mr *metricsReceiver) startScrapingMetrics() {
+	for i := 0; i < len(mr.metricScrapers); i++ {
+		scraper := mr.metricScrapers[i]
 		go func() {
 			collectionInterval := mr.defaultCollectionInterval
 			if scraper.cfg.CollectionInterval() != 0 {
@@ -221,7 +236,7 @@ func (mr *metricsReceiver) startScraping() {
 			for {
 				select {
 				case <-ticker.C:
-					mr.scrapeAndReport(context.Background(), scraper)
+					mr.scrapeMetricsAndReport(context.Background(), scraper)
 				case <-mr.done:
 					return
 				}
@@ -230,16 +245,71 @@ func (mr *metricsReceiver) startScraping() {
 	}
 }
 
-// scrapeAndReport calls the Scrape function of the provided Scraper, records
-// observability information, and passes the scraped metrics to the next component.
-func (mr *metricsReceiver) scrapeAndReport(ctx context.Context, scraper *scraper) {
+// scrapeMetricsAndReport calls the Scrape function of the provided Metrics Scraper,
+// records observability information, and passes the scraped metrics to the next
+// component.
+func (mr *metricsReceiver) scrapeMetricsAndReport(ctx context.Context, ms *metricsScraper) {
 	// TODO: Add observability metrics support
-	metrics, err := scraper.scrape(ctx)
+	metrics, err := ms.scrape(ctx)
 	if err != nil {
 		return
 	}
 
-	mr.nextConsumer.ConsumeMetrics(ctx, metrics)
+	mr.nextConsumer.ConsumeMetrics(ctx, metricSliceToMetricData(metrics))
+}
+
+func metricSliceToMetricData(metrics pdata.MetricSlice) pdata.Metrics {
+	rms := pdata.NewResourceMetricsSlice()
+	rms.Resize(1)
+	rm := rms.At(0)
+	ilms := rm.InstrumentationLibraryMetrics()
+	ilms.Resize(1)
+	ilm := ilms.At(0)
+	metrics.MoveAndAppendTo(ilm.Metrics())
+	return resourceMetricsSliceToMetricData(rms)
+}
+
+func (mr *metricsReceiver) startScrapingResourceMetrics() {
+	for i := 0; i < len(mr.resourceMetricScrapers); i++ {
+		scraper := mr.resourceMetricScrapers[i]
+		go func() {
+			collectionInterval := mr.defaultCollectionInterval
+			if scraper.cfg.CollectionInterval() != 0 {
+				collectionInterval = scraper.cfg.CollectionInterval()
+			}
+
+			ticker := time.NewTicker(collectionInterval)
+			defer ticker.Stop()
+
+			for {
+				select {
+				case <-ticker.C:
+					mr.scrapeResourceMetricsAndReport(context.Background(), scraper)
+				case <-mr.done:
+					return
+				}
+			}
+		}()
+	}
+}
+
+// scrapeResourceMetricsAndReport calls the Scrape function of the provided Resource
+// Metrics Scrapers, records observability information, and passes the scraped metrics
+// to the next component.
+func (mr *metricsReceiver) scrapeResourceMetricsAndReport(ctx context.Context, rms *resourceMetricsScraper) {
+	// TODO: Add observability metrics support
+	metrics, err := rms.scrape(ctx)
+	if err != nil {
+		return
+	}
+
+	mr.nextConsumer.ConsumeMetrics(ctx, resourceMetricsSliceToMetricData(metrics))
+}
+
+func resourceMetricsSliceToMetricData(resourceMetrics pdata.ResourceMetricsSlice) pdata.Metrics {
+	md := pdata.NewMetrics()
+	resourceMetrics.MoveAndAppendTo(md.ResourceMetrics())
+	return md
 }
 
 // stopScraping stops the ticker
@@ -251,7 +321,7 @@ func (mr *metricsReceiver) stopScraping() {
 func (mr *metricsReceiver) closeScrapers(ctx context.Context) error {
 	var errors []error
 
-	for _, scraper := range mr.scrapers {
+	for _, scraper := range mr.allBaseScrapers() {
 		if scraper.close == nil {
 			continue
 		}
@@ -263,3 +333,15 @@ func (mr *metricsReceiver) closeScrapers(ctx context.Context) error {
 
 	return componenterror.CombineErrors(errors)
 }
+
+func (mr *metricsReceiver) allBaseScrapers() []baseScraper {
+	scrapers := make([]baseScraper, len(mr.metricScrapers)+len(mr.resourceMetricScrapers))
+	for i, ms := range mr.metricScrapers {
+		scrapers[i] = ms.baseScraper
+	}
+	startIdx := len(mr.metricScrapers)
+	for i, rms := range mr.resourceMetricScrapers {
+		scrapers[startIdx+i] = rms.baseScraper
+	}
+	return scrapers
+}