Export TSDB status structs (#10783)

We would like to implement the tsdb/status API in certain Thanos
components.

In order to match the Prometheus API and avoid duplicating code,
this commit makes the structs used in the status API public.

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>

web/api/v1/api.go

@@ -1317,8 +1317,8 @@ func (api *API) serveFlags(_ *http.Request) apiFuncResult {
 	return apiFuncResult{api.flagsMap, nil, nil, nil}
 }
 
-// stat holds the information about individual cardinality.
-type stat struct {
+// TSDBStat holds the information about individual cardinality.
+type TSDBStat struct {
 	Name  string `json:"name"`
 	Value uint64 `json:"value"`
 }
@@ -1332,26 +1332,27 @@ type HeadStats struct {
 	MaxTime       int64  `json:"maxTime"`
 }
 
-// tsdbStatus has information of cardinality statistics from postings.
-type tsdbStatus struct {
-	HeadStats                   HeadStats `json:"headStats"`
-	SeriesCountByMetricName     []stat    `json:"seriesCountByMetricName"`
-	LabelValueCountByLabelName  []stat    `json:"labelValueCountByLabelName"`
-	MemoryInBytesByLabelName    []stat    `json:"memoryInBytesByLabelName"`
-	SeriesCountByLabelValuePair []stat    `json:"seriesCountByLabelValuePair"`
+// TSDBStatus has information of cardinality statistics from postings.
+type TSDBStatus struct {
+	HeadStats                   HeadStats  `json:"headStats"`
+	SeriesCountByMetricName     []TSDBStat `json:"seriesCountByMetricName"`
+	LabelValueCountByLabelName  []TSDBStat `json:"labelValueCountByLabelName"`
+	MemoryInBytesByLabelName    []TSDBStat `json:"memoryInBytesByLabelName"`
+	SeriesCountByLabelValuePair []TSDBStat `json:"seriesCountByLabelValuePair"`
 }
 
-func convertStats(stats []index.Stat) []stat {
-	result := make([]stat, 0, len(stats))
+// TSDBStatsFromIndexStats converts a index.Stat slice to a TSDBStat slice.
+func TSDBStatsFromIndexStats(stats []index.Stat) []TSDBStat {
+	result := make([]TSDBStat, 0, len(stats))
 	for _, item := range stats {
-		item := stat{Name: item.Name, Value: item.Count}
+		item := TSDBStat{Name: item.Name, Value: item.Count}
 		result = append(result, item)
 	}
 	return result
 }
 
 func (api *API) serveTSDBStatus(*http.Request) apiFuncResult {
-	s, err := api.db.Stats("__name__")
+	s, err := api.db.Stats(labels.MetricName)
 	if err != nil {
 		return apiFuncResult{nil, &apiError{errorInternal, err}, nil, nil}
 	}
@@ -1369,7 +1370,7 @@ func (api *API) serveTSDBStatus(*http.Request) apiFuncResult {
 			}
 		}
 	}
-	return apiFuncResult{tsdbStatus{
+	return apiFuncResult{TSDBStatus{
 		HeadStats: HeadStats{
 			NumSeries:     s.NumSeries,
 			ChunkCount:    chunkCount,
@@ -1377,10 +1378,10 @@ func (api *API) serveTSDBStatus(*http.Request) apiFuncResult {
 			MaxTime:       s.MaxTime,
 			NumLabelPairs: s.IndexPostingStats.NumLabelPairs,
 		},
-		SeriesCountByMetricName:     convertStats(s.IndexPostingStats.CardinalityMetricsStats),
-		LabelValueCountByLabelName:  convertStats(s.IndexPostingStats.CardinalityLabelStats),
-		MemoryInBytesByLabelName:    convertStats(s.IndexPostingStats.LabelValueStats),
-		SeriesCountByLabelValuePair: convertStats(s.IndexPostingStats.LabelValuePairsStats),
+		SeriesCountByMetricName:     TSDBStatsFromIndexStats(s.IndexPostingStats.CardinalityMetricsStats),
+		LabelValueCountByLabelName:  TSDBStatsFromIndexStats(s.IndexPostingStats.CardinalityLabelStats),
+		MemoryInBytesByLabelName:    TSDBStatsFromIndexStats(s.IndexPostingStats.LabelValueStats),
+		SeriesCountByLabelValuePair: TSDBStatsFromIndexStats(s.IndexPostingStats.LabelValuePairsStats),
 	}, nil, nil, nil}
 }