feat: Use appenderV2 in OTLP ingestion

Depends on https://github.com/prometheus/prometheus/pull/17104

Signed-off-by: bwplotka <bwplotka@gmail.com>

storage/remote/otlptranslator/prometheusremotewrite/combined_appender.go

@@ -31,30 +31,6 @@ import (
 	"github.com/prometheus/prometheus/storage"
 )
 
-// Metadata extends metadata.Metadata with the metric family name.
-// OTLP calculates the metric family name for all metrics and uses
-// it for generating summary, histogram series by adding the magic
-// suffixes. The metric family name is passed down to the appender
-// in case the storage needs it for metadata updates.
-// Known user is Mimir that implements /api/v1/metadata and uses
-// Remote-Write 1.0 for this. Might be removed later if no longer
-// needed by any downstream project.
-type Metadata struct {
-	metadata.Metadata
-	MetricFamilyName string
-}
-
-// CombinedAppender is similar to storage.Appender, but combines updates to
-// metadata, created timestamps, exemplars and samples into a single call.
-type CombinedAppender interface {
-	// AppendSample appends a sample and related exemplars, metadata, and
-	// created timestamp to the storage.
-	AppendSample(ls labels.Labels, meta Metadata, ct, t int64, v float64, es []exemplar.Exemplar) error
-	// AppendHistogram appends a histogram and related exemplars, metadata, and
-	// created timestamp to the storage.
-	AppendHistogram(ls labels.Labels, meta Metadata, ct, t int64, h *histogram.Histogram, es []exemplar.Exemplar) error
-}
-
 // CombinedAppenderMetrics is for the metrics observed by the
 // combinedAppender implementation.
 type CombinedAppenderMetrics struct {
@@ -82,11 +58,11 @@ func NewCombinedAppenderMetrics(reg prometheus.Registerer) CombinedAppenderMetri
 // NewCombinedAppender creates a combined appender that sets start times and
 // updates metadata for each series only once, and appends samples and
 // exemplars for each call.
-func NewCombinedAppender(app storage.Appender, logger *slog.Logger, ingestCTZeroSample bool, metrics CombinedAppenderMetrics) CombinedAppender {
+// TODO(bwplotka): Rename to OTLP specific appender
+func NewCombinedAppender(app storage.Appender, logger *slog.Logger, metrics CombinedAppenderMetrics) storage.AppenderV2 {
 	return &combinedAppender{
-		app:                            app,
+		Appender:                       app,
 		logger:                         logger,
-		ingestCTZeroSample:             ingestCTZeroSample,
 		refs:                           make(map[uint64]seriesRef),
 		samplesAppendedWithoutMetadata: metrics.samplesAppendedWithoutMetadata,
 		outOfOrderExemplars:            metrics.outOfOrderExemplars,
@@ -101,7 +77,9 @@ type seriesRef struct {
 }
 
 type combinedAppender struct {
-	app                            storage.Appender
+	storage.Appender
+
+	opts                           storage.AppendV2Options
 	logger                         *slog.Logger
 	samplesAppendedWithoutMetadata prometheus.Counter
 	outOfOrderExemplars            prometheus.Counter
@@ -112,23 +90,33 @@ type combinedAppender struct {
 	refs map[uint64]seriesRef
 }
 
-func (b *combinedAppender) AppendSample(ls labels.Labels, meta Metadata, ct, t int64, v float64, es []exemplar.Exemplar) (err error) {
+func (b *combinedAppender) SetOptions(opts *storage.AppendV2Options) {
+	b.opts = *opts
+}
+
+func (b *combinedAppender) AppendSample(_ storage.SeriesRef, ls labels.Labels, meta storage.Metadata, ct, t int64, v float64, es []exemplar.Exemplar) (_ storage.SeriesRef, err error) {
 	return b.appendFloatOrHistogram(ls, meta.Metadata, ct, t, v, nil, es)
 }
 
-func (b *combinedAppender) AppendHistogram(ls labels.Labels, meta Metadata, ct, t int64, h *histogram.Histogram, es []exemplar.Exemplar) (err error) {
+func (b *combinedAppender) AppendHistogram(_ storage.SeriesRef, ls labels.Labels, meta storage.Metadata, ct, t int64, h *histogram.Histogram, fh *histogram.FloatHistogram, es []exemplar.Exemplar) (_ storage.SeriesRef, err error) {
 	if h == nil {
 		// Sanity check, we should never get here with a nil histogram.
 		b.logger.Error("Received nil histogram in CombinedAppender.AppendHistogram", "series", ls.String())
-		return errors.New("internal error, attempted to append nil histogram")
+		return 0, errors.New("internal error, attempted to append nil histogram")
+	}
+	if fh != nil {
+		// Sanity check, we should never get here with a otlp appender.
+		b.logger.Error("Received not nil float histogram in CombinedAppender.AppendHistogram", "series", ls.String())
+		return 0, errors.New("internal error, attempted to append float histogram; works only for nil histograms")
 	}
 	return b.appendFloatOrHistogram(ls, meta.Metadata, ct, t, 0, h, es)
 }
 
-func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadata.Metadata, ct, t int64, v float64, h *histogram.Histogram, es []exemplar.Exemplar) (err error) {
+func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadata.Metadata, ct, t int64, v float64, h *histogram.Histogram, es []exemplar.Exemplar) (ref storage.SeriesRef, err error) {
+	// TODO: Use compatibility layer here and adopt this code benefits (checking collisions) or move to some pre-layer.
 	hash := ls.Hash()
 	series, exists := b.refs[hash]
-	ref := series.ref
+	ref = series.ref
 	if exists && !labels.Equal(series.ls, ls) {
 		// Hash collision. The series reference we stored is pointing to a
 		// different series so we cannot use it, we need to reset the
@@ -142,9 +130,9 @@ func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadat
 	if updateRefs && ct != 0 && b.ingestCTZeroSample {
 		var newRef storage.SeriesRef
 		if h != nil {
-			newRef, err = b.app.AppendHistogramCTZeroSample(ref, ls, t, ct, h, nil)
+			newRef, err = b.Appender.AppendHistogramCTZeroSample(ref, ls, t, ct, h, nil)
 		} else {
-			newRef, err = b.app.AppendCTZeroSample(ref, ls, t, ct)
+			newRef, err = b.Appender.AppendCTZeroSample(ref, ls, t, ct)
 		}
 		if err != nil {
 			if !errors.Is(err, storage.ErrOutOfOrderCT) {
@@ -162,9 +150,9 @@ func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadat
 	{
 		var newRef storage.SeriesRef
 		if h != nil {
-			newRef, err = b.app.AppendHistogram(ref, ls, t, h, nil)
+			newRef, err = b.Appender.AppendHistogram(ref, ls, t, h, nil)
 		} else {
-			newRef, err = b.app.Append(ref, ls, t, v)
+			newRef, err = b.Appender.Append(ref, ls, t, v)
 		}
 		if err != nil {
 			// Although Append does not currently return ErrDuplicateSampleForTimestamp there is
@@ -188,7 +176,7 @@ func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadat
 	if !exists || series.meta.Help != meta.Help || series.meta.Type != meta.Type || series.meta.Unit != meta.Unit {
 		updateRefs = true
 		// If this is the first time we see this series, set the metadata.
-		_, err := b.app.UpdateMetadata(ref, ls, meta)
+		_, err := b.Appender.UpdateMetadata(ref, ls, meta)
 		if err != nil {
 			b.samplesAppendedWithoutMetadata.Add(1)
 			b.logger.Warn("Error while updating metadata from OTLP", "err", err)
@@ -206,7 +194,7 @@ func (b *combinedAppender) appendFloatOrHistogram(ls labels.Labels, meta metadat
 
 	b.appendExemplars(ref, ls, es)
 
-	return
+	return ref, err // TODO(bwplotka): implement partial errors
 }
 
 func sampleType(h *histogram.Histogram) string {
@@ -219,7 +207,7 @@ func sampleType(h *histogram.Histogram) string {
 func (b *combinedAppender) appendExemplars(ref storage.SeriesRef, ls labels.Labels, es []exemplar.Exemplar) storage.SeriesRef {
 	var err error
 	for _, e := range es {
-		if ref, err = b.app.AppendExemplar(ref, ls, e); err != nil {
+		if ref, err = b.Appender.AppendExemplar(ref, ls, e); err != nil {
 			switch {
 			case errors.Is(err, storage.ErrOutOfOrderExemplar):
 				b.outOfOrderExemplars.Add(1)