Handle empty series correctly (#86)

Behaviour of this changed in thanos-io/thanos#3010 -- this now generates an error, as it probably should, but we sent back a series with no datapoints in it previously.

pkg/store/store.go

@@ -248,6 +248,11 @@ func (store *OpenTSDBStore) Series(
  if err != nil {
  return err
  }
+ if res == nil {
+ // OpenTSDB can return a series with no datapoints, in Prometheus this
+ // is just not returned.
+ continue
+ }
  if err := server.Send(res); err != nil {
  return err
  }
@@ -650,10 +655,14 @@ func (store *OpenTSDBStore) convertOpenTSDBResultsToSeriesResponse(respI *opents
  }
  chunks = append(chunks, aggrChunk)
  }
- return storepb.NewSeriesResponse(&storepb.Series{
- Labels: seriesLabels,
- Chunks: chunks,
- }), len(dps), nil
+ var response *storepb.SeriesResponse
+ if len(chunks) > 0 {
+ response = storepb.NewSeriesResponse(&storepb.Series{
+ Labels: seriesLabels,
+ Chunks: chunks,
+ })
+ }
+ return response, len(dps), nil
 }
 
 func convertPromQLMatcherToFilter(matcher storepb.LabelMatcher) (opentsdb.Filter, error) {

pkg/store/store_test.go

@@ -979,23 +979,21 @@ func TestConvertOpenTSDBResultsToSeriesResponse(t *testing.T) {
  Tags: map[string]string{},
  Dps: newDps(map[string]interface{}{}),
  },
- expectedOutput: storepb.NewSeriesResponse(&storepb.Series{
- Labels: []storepb.Label{{Name: "__name__", Value: "metric"}},
- Chunks: []storepb.AggrChunk{},
- }),
- expectedChunkTypes: []storepb.Aggr{},
+ expectedOutput: nil,
  },
  {
  input: opentsdb.QueryRespItem{
  Metric: "metric.with.dot.and-dash",
  Tags: map[string]string{},
- Dps: newDps(map[string]interface{}{}),
+ Dps: newDps(map[string]interface{}{
+ "1": 1.0,
+ }),
  },
  expectedOutput: storepb.NewSeriesResponse(&storepb.Series{
  Labels: []storepb.Label{{Name: "__name__", Value: "metric:with:dot:and_dash"}},
- Chunks: []storepb.AggrChunk{},
+ Chunks: []storepb.AggrChunk{{MinTime: 1, MaxTime: 1}},
  }),
- expectedChunkTypes: []storepb.Aggr{},
+ expectedChunkTypes: []storepb.Aggr{storepb.Aggr_RAW},
  },
  {
  input: opentsdb.QueryRespItem{
@@ -1187,13 +1185,22 @@ func TestConvertOpenTSDBResultsToSeriesResponse(t *testing.T) {
  expectedChunkTypes: []storepb.Aggr{storepb.Aggr_RAW},
  },
  }
- for _, test := range testCases {
+ for i, test := range testCases {
  store := NewOpenTSDBStore(
  log.NewJSONLogger(&testLogger{t}), nil, nil, time.Duration(0), 1*time.Minute, test.storeLabels, nil, nil, false, true, "foo")
  converted, _, err := store.convertOpenTSDBResultsToSeriesResponse(&test.input)
  if err != nil {
  t.Errorf("unexpected error: %s", err.Error())
  }
+ if converted == nil && test.expectedOutput == nil {
+ continue // Expected nothing, got nothing.
+ }
+ if test.expectedOutput == nil {
+ t.Errorf("expected nil, got %v", converted)
+ }
+ if converted == nil {
+ t.Errorf("%d: expected response, got nil", i)
+ }
  if len(converted.GetSeries().Labels) == len(test.expectedOutput.GetSeries().Labels) {
  // Labels must be alphabetically sorted
  for i, label := range converted.GetSeries().Labels {
@@ -1206,7 +1213,7 @@ func TestConvertOpenTSDBResultsToSeriesResponse(t *testing.T) {
  t.Errorf("number of tags does not match")
  }
  if len(test.expectedOutput.GetSeries().Chunks) != len(converted.GetSeries().Chunks) {
- t.Error("number of chunks does not match")
+ t.Errorf("%d: number of chunks does not match", i)
  }
  for ci, chunk := range test.expectedOutput.GetSeries().Chunks {
  convertedChunk := converted.GetSeries().Chunks[ci]