Fix a few trivial style nits

Signed-off-by: beorn7 <beorn@grafana.com>

tsdb/chunkenc/histo.go

@@ -72,7 +72,6 @@ const ()
 // TODO zerothreshold
 // TODO: encode schema and spans metadata in the chunk
 // TODO: decode-recode chunk when new spans appear
-
 type HistoChunk struct {
 	b bstream
 }
@@ -193,12 +192,14 @@ func (c *HistoChunk) Iterator(it Iterator) Iterator {
 type histoAppender struct {
 	b *bstream
 
-	// Meta
+	// Metadata:
 	schema             int32
 	posSpans, negSpans []histogram.Span
 
-	// for the fields that are tracked as dod's
+	// For the fields that are tracked as dod's.
-	// note that we expect to handle negative deltas (e.g. resets) by creating new chunks, we still want to support it in general hence signed integer types
+	// Note that we expect to handle negative deltas (e.g. resets) by
+	// creating new chunks, we still want to support it in general hence
+	// signed integer types.
 	t                           int64
 	cnt, zcnt                   uint64
 	tDelta, cntDelta, zcntDelta int64
@@ -206,12 +207,12 @@ type histoAppender struct {
 	posbuckets, negbuckets           []int64
 	posbucketsDelta, negbucketsDelta []int64
 
-	// for the fields that are gorilla xor coded
+	// The sum is Gorilla xor encoded.
 	sum      float64
 	leading  uint8
 	trailing uint8
 
-	buf64 []byte // for working on varint64's
+	buf64 []byte // For working on varint64's.
 }
 
 func putVarint(b *bstream, buf []byte, x int64) {
@@ -227,16 +228,18 @@ func putUvarint(b *bstream, buf []byte, x uint64) {
 }
 
 func (a *histoAppender) Append(int64, float64) {
-	panic("cannot call histoAppender.Append().")
+	panic("cannot call histoAppender.Append()")
 }
 
-// AppendHistogram appends a SparseHistogram to the chunk
+// AppendHistogram appends a SparseHistogram to the chunk. We assume the
-// we assume the histogram is properly structured. E.g. that the number pos/neg buckets used corresponds to the number conveyed by the pos/neg span structures
+// histogram is properly structured. E.g. that the number of pos/neg buckets
+// used corresponds to the number conveyed by the pos/neg span structures.
 func (a *histoAppender) AppendHistogram(t int64, h histogram.SparseHistogram) {
 	var tDelta, cntDelta, zcntDelta int64
 	num := binary.BigEndian.Uint16(a.b.bytes())
 
-	if num == 0 {
+	switch num {
+	case 0:
 		// the first append gets the privilege to dictate the metadata
 		// but it's also responsible for encoding it into the chunk!
 
@@ -260,7 +263,7 @@ func (a *histoAppender) AppendHistogram(t int64, h histogram.SparseHistogram) {
 		for _, buck := range h.NegativeBuckets {
 			putVarint(a.b, a.buf64, buck)
 		}
-	} else if num == 1 {
+	case 1:
 		tDelta = t - a.t
 		cntDelta = int64(h.Count) - int64(a.cnt)
 		zcntDelta = int64(h.ZeroCount) - int64(a.zcnt)
@@ -281,7 +284,7 @@ func (a *histoAppender) AppendHistogram(t int64, h histogram.SparseHistogram) {
 			putVarint(a.b, a.buf64, delta)
 			a.negbucketsDelta[i] = delta
 		}
-	} else {
+	default:
 		tDelta = t - a.t
 		cntDelta = int64(h.Count) - int64(a.cnt)
 		zcntDelta = int64(h.ZeroCount) - int64(a.zcnt)

tsdb/chunkenc/varbit_buckets.go

@@ -43,8 +43,13 @@
 
 package chunkenc
 
-// putInt64VBBucket writes an int64 using varbit optimized for SHS buckets
+// putInt64VBBucket writes an int64 using varbit optimized for SHS buckets.
-// note: we could improve this further: each branch doesn't need to support any values of any of the prior branches, so we can expand the range of each branch. do more with fewer bits
+//
+// TODO(Dieterbe): We could improve this further: Each branch doesn't need to
+// support any values of any of the prior branches. So we can expand the range
+// of each branch. Do more with fewer bits. It comes at the price of more
+// expensive encoding and decoding (cutting out and later adding back that
+// center-piece we skip).
 func putInt64VBBucket(b *bstream, val int64) {
 	switch {
 	case val == 0: