Merge pull request #9048 from prometheus/beorn7/histogram2

Fix lint issues

tsdb/chunkenc/chunk.go

@@ -36,6 +36,7 @@ func (e Encoding) String() string {
 	return "<unknown>"
 }
 
+// IsValidEncoding returns true for supported encodings.
 func IsValidEncoding(e Encoding) bool {
 	switch e {
 	case EncXOR, EncSHS:

tsdb/chunkenc/histo.go

@@ -105,6 +105,7 @@ func (c *HistoChunk) Meta() (int32, []histogram.Span, []histogram.Span, error) {
 	return readHistoChunkMeta(&b)
 }
 
+// Compact implements the Chunk interface.
 func (c *HistoChunk) Compact() {
 	if l := len(c.b.stream); cap(c.b.stream) > l+chunkCompactCapacityThreshold {
 		buf := make([]byte, l)
@@ -192,6 +193,7 @@ func (c *HistoChunk) Iterator(it Iterator) Iterator {
 	return c.iterator(it)
 }
 
+// HistoAppender is an Appender implementation for sparse histograms.
 type HistoAppender struct {
 	b *bstream
 
@@ -199,10 +201,9 @@ type HistoAppender struct {
 	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
-	// Note that we expect to handle negative deltas (e.g. resets) by
+	// handle negative deltas (e.g. resets) by creating new chunks, we still
-	// creating new chunks, we still want to support it in general hence
+	// want to support it in general hence signed integer types.
-	// signed integer types.
 	t                           int64
 	cnt, zcnt                   uint64
 	tDelta, cntDelta, zcntDelta int64
@@ -230,6 +231,10 @@ func putUvarint(b *bstream, buf []byte, x uint64) {
 	}
 }
 
+// Append implements Appender. This implementation does nothing for now.
+// TODO(beorn7): Implement in a meaningful way, i.e. we need to support
+// appending of stale markers, but this should never be used for "real"
+// samples.
 func (a *HistoAppender) Append(int64, float64) {}
 
 // Appendable returns whether the chunk can be appended to, and if so
@@ -239,7 +244,7 @@ func (a *HistoAppender) Append(int64, float64) {}
 // * the schema has changed
 // * the zerobucket threshold has changed
 // * any buckets disappeared
-func (a *HistoAppender) Appendable(h histogram.SparseHistogram) ([]interjection, []interjection, bool) {
+func (a *HistoAppender) Appendable(h histogram.SparseHistogram) ([]Interjection, []Interjection, bool) {
 	// TODO zerothreshold
 	if h.Schema != a.schema {
 		return nil, nil, false
@@ -359,7 +364,7 @@ func (a *HistoAppender) AppendHistogram(t int64, h histogram.SparseHistogram) {
 // (positive and/or negative) buckets used, according to the provided interjections, resulting in
 // the honoring of the provided new posSpans and negSpans
 // note: the decode-recode can probably be done more efficiently, but that's for a future optimization
-func (a *HistoAppender) Recode(posInterjections, negInterjections []interjection, posSpans, negSpans []histogram.Span) (Chunk, Appender) {
+func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection, posSpans, negSpans []histogram.Span) (Chunk, Appender) {
 	it := newHistoIterator(a.b.bytes())
 	hc := NewHistoChunk()
 	app, err := hc.Appender()

tsdb/chunkenc/histo_meta.go

@@ -11,11 +11,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// The code in this file was largely written by Damian Gryski as part of
-// https://github.com/dgryski/go-tsz and published under the license below.
-// It was modified to accommodate reading from byte slices without modifying
-// the underlying bytes, which would panic when reading from mmap'd
-// read-only byte slices.
 package chunkenc
 
 import "github.com/prometheus/prometheus/pkg/histogram"
@@ -125,8 +120,8 @@ try:
 	return 0, false
 }
 
-// interjection describes that num new buckets are introduced before processing the pos'th delta from the original slice
+// Interjection describes that num new buckets are introduced before processing the pos'th delta from the original slice
-type interjection struct {
+type Interjection struct {
 	pos int
 	num int
 }
@@ -153,14 +148,14 @@ type interjection struct {
 // need to generate a list of interjections
 // note: within compareSpans 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)
-func compareSpans(a, b []histogram.Span) ([]interjection, bool) {
+func compareSpans(a, b []histogram.Span) ([]Interjection, bool) {
 	ai := newBucketIterator(a)
 	bi := newBucketIterator(b)
 
-	var interjections []interjection
+	var interjections []Interjection
 
 	// when inter.num becomes > 0, this becomes a valid interjection that should be yielded when we finish a streak of new buckets
-	var inter interjection
+	var inter Interjection
 
 	av, aok := ai.Next()
 	bv, bok := bi.Next()
@@ -205,7 +200,7 @@ func compareSpans(a, b []histogram.Span) ([]interjection, bool) {
 }
 
 // caller is responsible for making sure len(in) and len(out) are appropriate for the provided interjections!
-func interject(in, out []int64, interjections []interjection) []int64 {
+func interject(in, out []int64, interjections []Interjection) []int64 {
 	var j int      // position in out
 	var v int64    // the last value seen
 	var interj int // the next interjection to process

tsdb/chunkenc/histo_meta_test.go

@@ -122,7 +122,7 @@ func TestInterjection(t *testing.T) {
 		{Offset: 1, Length: 4},
 		{Offset: 3, Length: 3},
 	}
-	interj := []interjection{
+	interj := []Interjection{
 		{
 			pos: 2,
 			num: 1,
@@ -140,13 +140,13 @@ func TestInterjection(t *testing.T) {
 	testInterject(interj, t)
 }
 
-func testCompareSpans(a, b []histogram.Span, exp []interjection, t *testing.T) {
+func testCompareSpans(a, b []histogram.Span, exp []Interjection, t *testing.T) {
 	got, ok := compareSpans(a, b)
 	require.Equal(t, true, ok)
 	require.Equal(t, exp, got)
 }
 
-func testInterject(interjections []interjection, t *testing.T) {
+func testInterject(interjections []Interjection, t *testing.T) {
 	// this tests the scenario as described in compareSpans's comments
 	// original deltas that represent these counts        : 6, 3, 3, 2, 4, 5, 1
 	a := []int64{6, -3, 0, -1, 2, 1, -4}

tsdb/chunkenc/xor.go

@@ -81,6 +81,7 @@ func (c *XORChunk) NumSamples() int {
 	return int(binary.BigEndian.Uint16(c.Bytes()))
 }
 
+// Compact implements the Chunk interface.
 func (c *XORChunk) Compact() {
 	if l := len(c.b.stream); cap(c.b.stream) > l+chunkCompactCapacityThreshold {
 		buf := make([]byte, l)