pkge/receive: trace TSDB ingestion (#2384)

This commit adds a tracing span around the writing of remote-write
requests into TSDB. This will help us differentiate between the
latencies in the forwarding of requests around the hashring and the
latencies of appending to the database.

This commit also removes the `thanos_` prefix from the forwarding span
to better align with the span naming in the rest of the project.

Signed-off-by: Lucas Servén Marín <[email protected]>

pkg/receive/handler.go

@@ -362,7 +362,11 @@ func (h *Handler) parallelizeRequests(ctx context.Context, tenant string, replic
  if h.writer == nil {
  err = errors.New("storage is not ready")
  } else {
- err = h.writer.Write(wreqs[endpoint])
+ // Create a span to track writing the request into TSDB.
+ tracing.DoInSpan(ctx, "receive_tsdb_write", func(ctx context.Context) {
+
+ err = h.writer.Write(wreqs[endpoint])
+ })
  // When a MultiError is added to another MultiError, the error slices are concatenated, not nested.
  // To avoid breaking the counting logic, we need to flatten the error.
  if errs, ok := err.(terrors.MultiError); ok {
@@ -402,7 +406,7 @@ func (h *Handler) parallelizeRequests(ctx context.Context, tenant string, replic
  return
  }
  // Create a span to track the request made to another receive node.
- tracing.DoInSpan(ctx, "thanos_receive_forward", func(ctx context.Context) {
+ tracing.DoInSpan(ctx, "receive_forward", func(ctx context.Context) {
  // Actually make the request against the endpoint
  // we determined should handle these time series.
  _, err = cl.RemoteWrite(ctx, &storepb.WriteRequest{

pkg/receive/writer.go

@@ -12,6 +12,7 @@ import (
  "github.com/prometheus/prometheus/pkg/labels"
  "github.com/prometheus/prometheus/storage"
  terrors "github.com/prometheus/prometheus/tsdb/errors"
+
  "github.com/thanos-io/thanos/pkg/store/storepb/prompb"
 )