Resampler implemented

internal/memorystore/memorystore.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/ClusterCockpit/cc-metric-store/internal/config"
 	"github.com/ClusterCockpit/cc-metric-store/internal/util"
+	"github.com/ClusterCockpit/cc-metric-store/pkg/resampler"
 )
 
 var (
@@ -178,17 +179,18 @@ 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 int64) ([]util.Float, int64, int64, error) {
+func (m *MemoryStore) Read(selector util.Selector, metric string, from, to, resolution int64) ([]util.Float, int64, int64, int64, error) {
 	if from > to {
-		return nil, 0, 0, errors.New("invalid time range")
+		return nil, 0, 0, 0, errors.New("invalid time range")
 	}
 
 	minfo, ok := m.Metrics[metric]
 	if !ok {
-		return nil, 0, 0, errors.New("unkown metric: " + metric)
+		return nil, 0, 0, 0, errors.New("unkown metric: " + metric)
 	}
 
 	n, data := 0, make([]util.Float, (to-from)/minfo.Frequency+1)
+
 	err := m.root.findBuffers(selector, minfo.Offset, func(b *buffer) error {
 		cdata, cfrom, cto, err := b.read(from, to, data)
 		if err != nil {
@@ -221,9 +223,9 @@ func (m *MemoryStore) Read(selector util.Selector, metric string, from, to int64
 	})
 
 	if err != nil {
-		return nil, 0, 0, err
+		return nil, 0, 0, 0, err
 	} else if n == 0 {
-		return nil, 0, 0, errors.New("metric or host not found")
+		return nil, 0, 0, 0, errors.New("metric or host not found")
 	} else if n > 1 {
 		if minfo.Aggregation == config.AvgAggregation {
 			normalize := 1. / util.Float(n)
@@ -231,11 +233,17 @@ func (m *MemoryStore) Read(selector util.Selector, metric string, from, to int64
 				data[i] *= normalize
 			}
 		} else if minfo.Aggregation != config.SumAggregation {
-			return nil, 0, 0, errors.New("invalid aggregation")
+			return nil, 0, 0, 0, errors.New("invalid aggregation")
 		}
 	}
 
-	return data, from, to, nil
+	data, resolution, err = resampler.LargestTriangleThreeBucket(data, minfo.Frequency, resolution)
+
+	if err != nil {
+		return nil, 0, 0, 0, err
+	}
+
+	return data, from, to, resolution, nil
 }
 
 // Release all buffers for the selected level and all its children that contain only