Add comment on SampleRingIterator

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

promql/engine.go

@@ -2114,15 +2114,10 @@ loop:
 				if floats == nil {
 					floats = getFPointSlice(16)
 				}
-				if n := len(floats); n < cap(floats) {
-					floats = floats[:n+1]
-					floats[n].T, floats[n].F = t, f
-				} else {
 				floats = append(floats, FPoint{T: t, F: f})
 			}
 		}
 	}
-	}
 	// The sought sample might also be in the range.
 	switch soughtValueType {
 	case chunkenc.ValFloatHistogram, chunkenc.ValHistogram:

storage/buffer.go

@@ -310,6 +310,8 @@ func (r *sampleRing) iterator() *SampleRingIterator {
 	return &r.it
 }
 
+// SampleRingIterator is returned by BufferedSeriesIterator.Buffer() and can be
+// used to iterate samples buffered in the lookback window.
 type SampleRingIterator struct {
 	r  *sampleRing
 	i  int
@@ -358,14 +360,6 @@ func (it *SampleRingIterator) Next() chunkenc.ValueType {
 	}
 }
 
-func (it *SampleRingIterator) Seek(int64) chunkenc.ValueType {
-	return chunkenc.ValNone
-}
-
-func (it *SampleRingIterator) Err() error {
-	return nil
-}
-
 func (it *SampleRingIterator) At() (int64, float64) {
 	return it.t, it.f
 }