update docstrings to remove references to removed function

expandSpansForward is no more, replaced by expandFloatSpansAndBuckets
and expandIntSpansAndBuckets

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>

tsdb/chunkenc/float_histogram.go

@@ -343,7 +343,7 @@ func (a *FloatHistogramAppender) appendable(h *histogram.FloatHistogram) (
 // original deltas to a new set of deltas to match a new span layout that adds
 // buckets, we simply need to generate a list of inserts.
 //
-// Note: Within expandSpansForward we don't have to worry about the changes to the
+// Note: Within expandFloatSpansAndBuckets we don't have to worry about the changes to the
 // spans themselves, thanks to the iterators we get to work with the more useful
 // bucket indices (which of course directly correspond to the buckets we have to
 // adjust).

tsdb/chunkenc/float_histogram_test.go

@@ -195,7 +195,7 @@ func TestFloatHistogramChunkSameBuckets(t *testing.T) {
 	require.Equal(t, ValNone, it4.Seek(exp[len(exp)-1].t+1))
 }
 
-// Mimics the scenario described for expandSpansForward.
+// Mimics the scenario described for expandFloatSpansAndBuckets.
 func TestFloatHistogramChunkBucketChanges(t *testing.T) {
 	c := Chunk(NewFloatHistogramChunk())
 

tsdb/chunkenc/histogram.go

@@ -374,7 +374,7 @@ func (a *HistogramAppender) appendable(h *histogram.Histogram) (
 // original deltas to a new set of deltas to match a new span layout that adds
 // buckets, we simply need to generate a list of inserts.
 //
-// Note: Within expandSpansForward we don't have to worry about the changes to the
+// Note: Within expandIntSpansAndBuckets we don't have to worry about the changes to the
 // spans themselves, thanks to the iterators we get to work with the more useful
 // bucket indices (which of course directly correspond to the buckets we have to
 // adjust).

tsdb/chunkenc/histogram_meta.go

@@ -284,11 +284,12 @@ type Insert struct {
 	bucketIdx int
 }
 
-// expandSpansBothWays is similar to expandSpansForward, but now b may also
-// cover an entirely different set of buckets. The function returns the
-// “forward” inserts to expand 'a' to also cover all the buckets exclusively
-// covered by 'b', and it returns the “backward” inserts to expand 'b' to also
-// cover all the buckets exclusively covered by 'a'.
+// expandSpansBothWays is similar to expandFloatSpansAndBuckets and
+// expandIntSpansAndBuckets, but now b may also cover an entirely different set
+// of buckets and counter resets are ignored. The function returns the “forward”
+// inserts to expand 'a' to also cover all the buckets exclusively covered by
+// 'b', and it returns the “backward” inserts to expand 'b' to also cover all
+// the buckets exclusively covered by 'a'.
 func expandSpansBothWays(a, b []histogram.Span) (forward, backward []Insert, mergedSpans []histogram.Span) {
 	ai := newBucketIterator(a)
 	bi := newBucketIterator(b)

tsdb/chunkenc/histogram_meta_test.go

@@ -78,7 +78,7 @@ func TestBucketIterator(t *testing.T) {
 			},
 			idxs: []int{100, 101, 102, 103, 112, 113, 114, 115, 116, 117, 118, 119},
 		},
-		// The below 2 sets ore the ones described in expandSpansForward's comments.
+		// The below 2 sets ore the ones described in expandFloatSpansAndBuckets's comments.
 		{
 			spans: []histogram.Span{
 				{Offset: 0, Length: 2},

tsdb/chunkenc/histogram_test.go

@@ -206,7 +206,7 @@ func TestHistogramChunkSameBuckets(t *testing.T) {
 	require.Equal(t, ValNone, it4.Seek(exp[len(exp)-1].t+1))
 }
 
-// Mimics the scenario described for expandSpansForward.
+// Mimics the scenario described for expandIntSpansAndBuckets.
 func TestHistogramChunkBucketChanges(t *testing.T) {
 	c := Chunk(NewHistogramChunk())