Fixes no profiles to merge error (#559)

* Fixes no profiles to merge error.

* Fixes tests comparing timestamp

pkg/model/profile.go

@@ -4,6 +4,7 @@ import (
 	"strings"
 
 	"github.com/gogo/status"
+	"github.com/google/pprof/profile"
 	"github.com/prometheus/prometheus/model/labels"
 	"google.golang.org/grpc/codes"
 
@@ -45,3 +46,18 @@ func SelectorFromProfileType(profileType *typesv1.ProfileType) *labels.Matcher {
 		Value: profileType.Name + ":" + profileType.SampleType + ":" + profileType.SampleUnit + ":" + profileType.PeriodType + ":" + profileType.PeriodUnit,
 	}
 }
+
+// SetProfileMetadata sets the metadata on the profile.
+func SetProfileMetadata(p *profile.Profile, ty *typesv1.ProfileType) {
+	p.SampleType = []*profile.ValueType{{Type: ty.SampleType, Unit: ty.SampleUnit}}
+	p.DefaultSampleType = ty.SampleType
+	p.PeriodType = &profile.ValueType{Type: ty.PeriodType, Unit: ty.PeriodUnit}
+	switch ty.Name {
+	case "process_cpu": // todo: this should support other types of cpu profiles
+		p.Period = 1000000000
+	case "memory":
+		p.Period = 512 * 1024
+	default:
+		p.Period = 1
+	}
+}

pkg/phlaredb/block_querier.go

@@ -706,19 +706,12 @@ func (q Queriers) MergeProfilesPprof(ctx context.Context, stream *connect.BidiSt
 	if err := g.Wait(); err != nil {
 		return err
 	}
+	if len(result) == 0 {
+		result = append(result, &profile.Profile{})
+	}
 	for _, p := range result {
-		p.SampleType = []*profile.ValueType{{Type: r.Request.Type.SampleType, Unit: r.Request.Type.SampleUnit}}
-		p.DefaultSampleType = r.Request.Type.SampleType
-		p.PeriodType = &profile.ValueType{Type: r.Request.Type.PeriodType, Unit: r.Request.Type.PeriodUnit}
-		p.TimeNanos = model.Time(r.Request.Start).UnixNano()
-		switch r.Request.Type.Name {
-		case "process_cpu":
-			p.Period = 1000000000
-		case "memory":
-			p.Period = 512 * 1024
-		default:
-			p.Period = 1
-		}
+		phlaremodel.SetProfileMetadata(p, request.Type)
+		p.TimeNanos = model.Time(r.Request.End).UnixNano()
 	}
 	p, err := profile.Merge(result)
 	if err != nil {

pkg/phlaredb/phlaredb_test.go

@@ -386,6 +386,22 @@ func TestMergeProfilesPprof(t *testing.T) {
 		}))
 		require.NoError(t, bidi.CloseRequest())
 	})
+
+	t.Run("timerange with no Profiles", func(t *testing.T) {
+		bidi := client.MergeProfilesPprof(ctx)
+		require.NoError(t, bidi.Send(&ingestv1.MergeProfilesPprofRequest{
+			Request: &ingestv1.SelectProfilesRequest{
+				LabelSelector: `{pod="my-pod"}`,
+				Type:          mustParseProfileSelector(t, "process_cpu:cpu:nanoseconds:cpu:nanoseconds"),
+				Start:         0,
+				End:           1,
+			},
+		}))
+		_, err := bidi.Receive()
+		require.NoError(t, err)
+		_, err = bidi.Receive()
+		require.NoError(t, err)
+	})
 }
 
 func TestFilterProfiles(t *testing.T) {

pkg/querier/querier.go

@@ -310,12 +310,12 @@ func (q *Querier) SelectMergeProfile(ctx context.Context, req *connect.Request[q
 	}
 
 	// merge all profiles
-	profile, err := selectMergePprofProfile(gCtx, responses)
+	profile, err := selectMergePprofProfile(gCtx, profileType, responses)
 	if err != nil {
 		return nil, err
 	}
 	profile.DurationNanos = model.Time(req.Msg.End).UnixNano() - model.Time(req.Msg.Start).UnixNano()
-
+	profile.TimeNanos = model.Time(req.Msg.End).UnixNano()
 	return connect.NewResponse(profile), nil
 }
 

pkg/querier/querier_test.go

@@ -358,6 +358,7 @@ func Test_SelectMergeProfile(t *testing.T) {
 
 	expected := pprofth.FooBarProfile.Copy()
 	expected.DurationNanos = model.Time(req.Msg.End).UnixNano() - model.Time(req.Msg.Start).UnixNano()
+	expected.TimeNanos = model.Time(req.Msg.End).UnixNano()
 	for _, s := range expected.Sample {
 		s.Value[0] = s.Value[0] * 2
 	}

pkg/querier/select_merge.go

@@ -348,7 +348,7 @@ func selectMergeStacktraces(ctx context.Context, responses []responseFromIngeste
 }
 
 // selectMergePprofProfile selects the  profile from each ingester by deduping them and request merges of stacktraces in the pprof format.
-func selectMergePprofProfile(ctx context.Context, responses []responseFromIngesters[clientpool.BidiClientMergeProfilesPprof]) (*googlev1.Profile, error) {
+func selectMergePprofProfile(ctx context.Context, ty *typesv1.ProfileType, responses []responseFromIngesters[clientpool.BidiClientMergeProfilesPprof]) (*googlev1.Profile, error) {
 	mergeResults := make([]MergeResult[[]byte], len(responses))
 	iters := make([]MergeIterator, len(responses))
 	for i, resp := range responses {
@@ -389,6 +389,12 @@ func selectMergePprofProfile(ctx context.Context, responses []responseFromIngest
 	if err := g.Wait(); err != nil {
 		return nil, err
 	}
+
+	if len(results) == 0 {
+		empty := &profile.Profile{}
+		phlaremodel.SetProfileMetadata(empty, ty)
+		return pprof.FromProfile(empty)
+	}
 	p, err := profile.Merge(results)
 	if err != nil {
 		return nil, err