Introduce average resampler support

Fixes #526

Entire-Checkpoint: 893a1de325b5

pkg/metricstore/api.go

@@ -51,14 +51,15 @@ type APIMetricData struct {
 //
 // The request can be customized with flags to include/exclude statistics, raw data, and padding.
 type APIQueryRequest struct {
-	Cluster     string     `json:"cluster"`
-	Queries     []APIQuery `json:"queries"`
-	ForAllNodes []string   `json:"for-all-nodes"`
-	From        int64      `json:"from"`
-	To          int64      `json:"to"`
-	WithStats   bool       `json:"with-stats"`
-	WithData    bool       `json:"with-data"`
-	WithPadding bool       `json:"with-padding"`
+	Cluster      string     `json:"cluster"`
+	Queries      []APIQuery `json:"queries"`
+	ForAllNodes  []string   `json:"for-all-nodes"`
+	From         int64      `json:"from"`
+	To           int64      `json:"to"`
+	WithStats    bool       `json:"with-stats"`
+	WithData     bool       `json:"with-data"`
+	WithPadding  bool       `json:"with-padding"`
+	ResampleAlgo string     `json:"resample-algo,omitempty"`
 }
 
 // APIQueryResponse represents the response to an APIQueryRequest.
@@ -279,7 +280,7 @@ func FetchData(req APIQueryRequest) (*APIQueryResponse, error) {
 		for _, sel := range sels {
 			data := APIMetricData{}
 
-			data.Data, data.From, data.To, data.Resolution, err = ms.Read(sel, query.Metric, req.From, req.To, query.Resolution)
+			data.Data, data.From, data.To, data.Resolution, err = ms.Read(sel, query.Metric, req.From, req.To, query.Resolution, req.ResampleAlgo)
 			if err != nil {
 				// Skip Error If Just Missing Host or Metric, Continue
 				// Empty Return For Metric Handled Gracefully By Frontend

pkg/metricstore/metricstore.go

@@ -679,7 +679,7 @@ func (m *MemoryStore) WriteToLevel(l *Level, selector []string, ts int64, metric
 // If the level does not hold the metric itself, the data will be aggregated recursively from the children.
 // The second and third return value are the actual from/to for the data. Those can be different from
 // the range asked for if no data was available.
-func (m *MemoryStore) Read(selector util.Selector, metric string, from, to, resolution int64) ([]schema.Float, int64, int64, int64, error) {
+func (m *MemoryStore) Read(selector util.Selector, metric string, from, to, resolution int64, resampleAlgo string) ([]schema.Float, int64, int64, int64, error) {
 	if from > to {
 		return nil, 0, 0, 0, errors.New("[METRICSTORE]> invalid time range")
 	}
@@ -737,7 +737,11 @@ func (m *MemoryStore) Read(selector util.Selector, metric string, from, to, reso
 		}
 	}
 
-	data, resolution, err = resampler.LargestTriangleThreeBucket(data, minfo.Frequency, resolution)
+	resampleFn, rfErr := resampler.GetResampler(resampleAlgo)
+	if rfErr != nil {
+		return nil, 0, 0, 0, rfErr
+	}
+	data, resolution, err = resampleFn(data, minfo.Frequency, resolution)
 	if err != nil {
 		return nil, 0, 0, 0, err
 	}

pkg/metricstore/query.go

@@ -621,6 +621,7 @@ func (ccms *InternalMetricStore) LoadNodeListData(
 	resolution int,
 	from, to time.Time,
 	ctx context.Context,
+	resampleAlgo string,
 ) (map[string]schema.JobData, error) {
 	// Note: Order of node data is not guaranteed after this point
 	queries, assignedScope, err := buildNodeQueries(cluster, subCluster, nodes, metrics, scopes, int64(resolution))
@@ -636,12 +637,13 @@ func (ccms *InternalMetricStore) LoadNodeListData(
 	}
 
 	req := APIQueryRequest{
-		Cluster:   cluster,
-		Queries:   queries,
-		From:      from.Unix(),
-		To:        to.Unix(),
-		WithStats: true,
-		WithData:  true,
+		Cluster:      cluster,
+		Queries:      queries,
+		From:         from.Unix(),
+		To:           to.Unix(),
+		WithStats:    true,
+		WithData:     true,
+		ResampleAlgo: resampleAlgo,
 	}
 
 	resBody, err := FetchData(req)