Merge pull request #9439 from codesome/counterresetmeta

Add info about counter resets in chunk meta

tsdb/chunkenc/histo.go

@@ -77,7 +77,7 @@ type HistoChunk struct {
 
 // NewHistoChunk returns a new chunk with Histo encoding of the given size.
 func NewHistoChunk() *HistoChunk {
-	b := make([]byte, 2, 128)
+	b := make([]byte, 3, 128)
 	return &HistoChunk{b: bstream{stream: b, count: 0}}
 }
 
@@ -106,6 +106,32 @@ func (c *HistoChunk) Meta() (int32, float64, []histogram.Span, []histogram.Span,
 	return readHistoChunkMeta(&b)
 }
 
+// CounterResetHeader defines the first 2 bits of the chunk header.
+type CounterResetHeader byte
+
+const (
+	CounterReset        CounterResetHeader = 0b10000000
+	NotCounterReset     CounterResetHeader = 0b01000000
+	GaugeType           CounterResetHeader = 0b11000000
+	UnknownCounterReset CounterResetHeader = 0b00000000
+)
+
+// SetCounterResetHeader sets the counter reset header.
+func (c *HistoChunk) SetCounterResetHeader(h CounterResetHeader) {
+	switch h {
+	case CounterReset, NotCounterReset, GaugeType, UnknownCounterReset:
+		bytes := c.Bytes()
+		bytes[2] = (bytes[2] & 0b00111111) | byte(h)
+	default:
+		panic("invalid CounterResetHeader type")
+	}
+}
+
+// GetCounterResetHeader returns the info about the first 2 bits of the chunk header.
+func (c *HistoChunk) GetCounterResetHeader() CounterResetHeader {
+	return CounterResetHeader(c.Bytes()[2] & 0b11000000)
+}
+
 // Compact implements the Chunk interface.
 func (c *HistoChunk) Compact() {
 	if l := len(c.b.stream); cap(c.b.stream) > l+chunkCompactCapacityThreshold {
@@ -249,42 +275,56 @@ func (a *HistoAppender) Append(int64, float64) {}
 // * any buckets disappeared
 // * there was a counter reset in the count of observations or in any bucket, including the zero bucket
 // * the last sample in the chunk was stale while the current sample is not stale
+// It returns an additional boolean set to true if it is not appendable because of a counter reset.
 // If the given sample is stale, it will always return true.
-func (a *HistoAppender) Appendable(h histogram.SparseHistogram) ([]Interjection, []Interjection, bool) {
+// If counterReset is true, okToAppend MUST be false.
+func (a *HistoAppender) Appendable(h histogram.SparseHistogram) (posInterjections []Interjection, negInterjections []Interjection, okToAppend bool, counterReset bool) {
 	if value.IsStaleNaN(h.Sum) {
 		// This is a stale sample whose buckets and spans don't matter.
-		return nil, nil, true
+		okToAppend = true
+		return
 	}
 	if value.IsStaleNaN(a.sum) {
 		// If the last sample was stale, then we can only accept stale samples in this chunk.
-		return nil, nil, false
+		return
+	}
+
+	if h.Count < a.cnt {
+		// There has been a counter reset.
+		counterReset = true
+		return
 	}
 
 	if h.Schema != a.schema || h.ZeroThreshold != a.zeroThreshold {
-		return nil, nil, false
+		return
 	}
-	posInterjections, ok := compareSpans(a.posSpans, h.PositiveSpans)
+
+	if h.ZeroCount < a.zcnt {
+		// There has been a counter reset since ZeroThreshold didn't change.
+		counterReset = true
+		return
+	}
+
+	var ok bool
+	posInterjections, ok = compareSpans(a.posSpans, h.PositiveSpans)
 	if !ok {
-		return nil, nil, false
+		counterReset = true
+		return
 	}
-	negInterjections, ok := compareSpans(a.negSpans, h.NegativeSpans)
+	negInterjections, ok = compareSpans(a.negSpans, h.NegativeSpans)
 	if !ok {
-		return nil, nil, false
+		counterReset = true
+		return
 	}
 
-	if h.Count < a.cnt || h.ZeroCount < a.zcnt {
+	if counterResetInAnyBucket(a.posbuckets, h.PositiveBuckets, a.posSpans, h.PositiveSpans) ||
-		// There has been a counter reset.
+		counterResetInAnyBucket(a.negbuckets, h.NegativeBuckets, a.negSpans, h.NegativeSpans) {
-		return nil, nil, false
+		counterReset, posInterjections, negInterjections = true, nil, nil
+		return
 	}
 
-	if counterResetInAnyBucket(a.posbuckets, h.PositiveBuckets, a.posSpans, h.PositiveSpans) {
+	okToAppend = true
-		return nil, nil, false
+	return
-	}
-	if counterResetInAnyBucket(a.negbuckets, h.NegativeBuckets, a.negSpans, h.NegativeSpans) {
-		return nil, nil, false
-	}
-
-	return posInterjections, negInterjections, ok
 }
 
 // counterResetInAnyBucket returns true if there was a counter reset for any bucket.
@@ -476,7 +516,8 @@ func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection
 	// it again with the new span layout. This can probably be done in-place
 	// by editing the chunk. But let's first see how expensive it is in the
 	// big picture.
-	it := newHistoIterator(a.b.bytes())
+	byts := a.b.bytes()
+	it := newHistoIterator(byts)
 	hc := NewHistoChunk()
 	app, err := hc.Appender()
 	if err != nil {
@@ -504,6 +545,9 @@ func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection
 		}
 		app.AppendHistogram(tOld, hOld)
 	}
+
+	// Set the flags.
+	hc.SetCounterResetHeader(CounterResetHeader(byts[2] & 0b11000000))
 	return hc, app
 }
 
@@ -643,6 +687,7 @@ func (it *histoIterator) Next() bool {
 	if it.numRead == 0 {
 
 		// first read is responsible for reading chunk metadata and initializing fields that depend on it
+		// We give counter reset info at chunk level, hence we discard it here.
 		schema, zeroThreshold, posSpans, negSpans, err := readHistoChunkMeta(&it.br)
 		if err != nil {
 			it.err = err

tsdb/chunkenc/histo_meta.go

@@ -32,29 +32,34 @@ func putHistoChunkMetaSpans(b *bstream, spans []histogram.Span) {
 	}
 }
 
-func readHistoChunkMeta(b *bstreamReader) (int32, float64, []histogram.Span, []histogram.Span, error) {
+func readHistoChunkMeta(b *bstreamReader) (schema int32, zeroThreshold float64, posSpans []histogram.Span, negSpans []histogram.Span, err error) {
+	_, err = b.ReadByte() // The header.
+	if err != nil {
+		return
+	}
+
 	v, err := readInt64VBBucket(b)
 	if err != nil {
-		return 0, 0, nil, nil, err
+		return
 	}
-	schema := int32(v)
+	schema = int32(v)
 
-	zeroThreshold, err := readFloat64VBBucket(b)
+	zeroThreshold, err = readFloat64VBBucket(b)
 	if err != nil {
-		return 0, 0, nil, nil, err
+		return
 	}
 
-	posSpans, err := readHistoChunkMetaSpans(b)
+	posSpans, err = readHistoChunkMetaSpans(b)
 	if err != nil {
-		return 0, 0, nil, nil, err
+		return
 	}
 
-	negSpans, err := readHistoChunkMetaSpans(b)
+	negSpans, err = readHistoChunkMetaSpans(b)
 	if err != nil {
-		return 0, 0, nil, nil, err
+		return
 	}
 
-	return schema, zeroThreshold, posSpans, negSpans, nil
+	return
 }
 
 func readHistoChunkMetaSpans(b *bstreamReader) ([]histogram.Span, error) {

tsdb/chunkenc/histo_test.go

@@ -163,10 +163,11 @@ func TestHistoChunkBucketChanges(t *testing.T) {
 
 	// This is how span changes will be handled.
 	histoApp, _ := app.(*HistoAppender)
-	posInterjections, negInterjections, ok := histoApp.Appendable(h2)
+	posInterjections, negInterjections, ok, cr := histoApp.Appendable(h2)
 	require.Greater(t, len(posInterjections), 0)
 	require.Equal(t, 0, len(negInterjections))
 	require.True(t, ok) // Only new buckets came in.
+	require.False(t, cr)
 	c, app = histoApp.Recode(posInterjections, negInterjections, h2.PositiveSpans, h2.NegativeSpans)
 	app.AppendHistogram(ts2, h2)
 
@@ -234,10 +235,11 @@ func TestHistoChunkAppendable(t *testing.T) {
 		h2.PositiveBuckets = []int64{7, -2, -4, 2, -2, -1, 2, 3, 0, -5, 1} // 7 5 1 3 1 0 2 5 5 0 1 (total 30)
 
 		histoApp, _ := app.(*HistoAppender)
-		posInterjections, negInterjections, ok := histoApp.Appendable(h2)
+		posInterjections, negInterjections, ok, cr := histoApp.Appendable(h2)
 		require.Greater(t, len(posInterjections), 0)
 		require.Equal(t, 0, len(negInterjections))
 		require.True(t, ok) // Only new buckets came in.
+		require.False(t, cr)
 	}
 
 	{ // New histogram that has a bucket missing.
@@ -252,10 +254,11 @@ func TestHistoChunkAppendable(t *testing.T) {
 		h2.PositiveBuckets = []int64{6, -3, -1, 2, 1, -4} // counts: 6, 3, 2, 4, 5, 1 (total 21)
 
 		histoApp, _ := app.(*HistoAppender)
-		posInterjections, negInterjections, ok := histoApp.Appendable(h2)
+		posInterjections, negInterjections, ok, cr := histoApp.Appendable(h2)
 		require.Equal(t, 0, len(posInterjections))
 		require.Equal(t, 0, len(negInterjections))
 		require.False(t, ok) // Need to cut a new chunk.
+		require.True(t, cr)
 	}
 
 	{ // New histogram that has a counter reset while buckets are same.
@@ -264,10 +267,11 @@ func TestHistoChunkAppendable(t *testing.T) {
 		h2.PositiveBuckets = []int64{6, -4, 1, -1, 2, 1, -4} // counts: 6, 2, 3, 2, 4, 5, 1 (total 23)
 
 		histoApp, _ := app.(*HistoAppender)
-		posInterjections, negInterjections, ok := histoApp.Appendable(h2)
+		posInterjections, negInterjections, ok, cr := histoApp.Appendable(h2)
 		require.Equal(t, 0, len(posInterjections))
 		require.Equal(t, 0, len(negInterjections))
 		require.False(t, ok) // Need to cut a new chunk.
+		require.True(t, cr)
 	}
 
 	{ // New histogram that has a counter reset while new buckets were added.
@@ -284,10 +288,11 @@ func TestHistoChunkAppendable(t *testing.T) {
 		h2.PositiveBuckets = []int64{7, -2, -4, 2, -2, -1, 2, 3, 0, -5, 0} // 7 5 1 3 1 0 2 5 5 0 0 (total 29)
 
 		histoApp, _ := app.(*HistoAppender)
-		posInterjections, negInterjections, ok := histoApp.Appendable(h2)
+		posInterjections, negInterjections, ok, cr := histoApp.Appendable(h2)
 		require.Equal(t, 0, len(posInterjections))
 		require.Equal(t, 0, len(negInterjections))
 		require.False(t, ok) // Need to cut a new chunk.
+		require.True(t, cr)
 	}
 
 	{ // New histogram that has a counter reset while new buckets were added before the first bucket and reset on first bucket.
@@ -307,9 +312,10 @@ func TestHistoChunkAppendable(t *testing.T) {
 		h2.PositiveBuckets = []int64{1, 1, 3, -2, 0, -1, 2, 1, -4} // counts: 1, 2, 5, 3, 3, 2, 4, 5, 1 (total 26)
 
 		histoApp, _ := app.(*HistoAppender)
-		posInterjections, negInterjections, ok := histoApp.Appendable(h2)
+		posInterjections, negInterjections, ok, cr := histoApp.Appendable(h2)
 		require.Equal(t, 0, len(posInterjections))
 		require.Equal(t, 0, len(negInterjections))
 		require.False(t, ok) // Need to cut a new chunk.
+		require.True(t, cr)
 	}
 }

tsdb/head_append.go

@@ -605,20 +605,29 @@ func (s *memSeries) append(t int64, v float64, appendID uint64, chunkDiskMapper
 // appendHistogram adds the sparse histogram.
 // It is unsafe to call this concurrently with s.iterator(...) without holding the series lock.
 func (s *memSeries) appendHistogram(t int64, sh histogram.SparseHistogram, appendID uint64, chunkDiskMapper *chunks.ChunkDiskMapper) (sampleInOrder, chunkCreated bool) {
+	// Head controls the execution of recoding, so that we own the proper chunk reference afterwards.
+	// We check for Appendable before appendPreprocessor because in case it ends up creating a new chunk,
+	// we need to know if there was also a counter reset or not to set the meta properly.
+	app, _ := s.app.(*chunkenc.HistoAppender)
+	var (
+		posInterjections, negInterjections []chunkenc.Interjection
+		okToAppend, counterReset           bool
+	)
+	if app != nil {
+		posInterjections, negInterjections, okToAppend, counterReset = app.Appendable(sh)
+	}
+
 	c, sampleInOrder, chunkCreated := s.appendPreprocessor(t, chunkenc.EncSHS, chunkDiskMapper)
 	if !sampleInOrder {
 		return sampleInOrder, chunkCreated
 	}
 
 	if !chunkCreated {
-		// Head controls the execution of recoding, so that we own the proper chunk reference afterwards
+		// We have 3 cases here
-		app, _ := s.app.(*chunkenc.HistoAppender)
+		// !okToAppend -> we need to cut a new chunk
-		posInterjections, negInterjections, ok := app.Appendable(sh)
+		// okToAppend but we have interjections -> existing chunk needs recoding before we can append our histogram
-		// we have 3 cases here
+		// okToAppend and no interjections -> chunk is ready to support our histogram
-		// !ok -> we need to cut a new chunk
+		if !okToAppend || counterReset {
-		// ok but we have interjections -> existing chunk needs recoding before we can append our histogram
-		// ok and no interjections -> chunk is ready to support our histogram
-		if !ok {
 			c = s.cutNewHeadChunk(t, chunkenc.EncSHS, chunkDiskMapper)
 			chunkCreated = true
 		} else if len(posInterjections) > 0 || len(negInterjections) > 0 {
@@ -633,6 +642,17 @@ func (s *memSeries) appendHistogram(t int64, sh histogram.SparseHistogram, appen
 		}
 	}
 
+	if chunkCreated {
+		hc := s.headChunk.chunk.(*chunkenc.HistoChunk)
+		header := chunkenc.UnknownCounterReset
+		if counterReset {
+			header = chunkenc.CounterReset
+		} else if okToAppend {
+			header = chunkenc.NotCounterReset
+		}
+		hc.SetCounterResetHeader(header)
+	}
+
 	s.app.AppendHistogram(t, sh)
 	s.sparseHistogramSeries = true
 

tsdb/querier.go

@@ -717,6 +717,9 @@ func (p *populateWithDelChunkSeriesIterator) Next() bool {
 		h histogram.SparseHistogram
 	)
 	if p.currDelIter.ChunkEncoding() == chunkenc.EncSHS {
+		if hc, ok := p.currChkMeta.Chunk.(*chunkenc.HistoChunk); ok {
+			newChunk.(*chunkenc.HistoChunk).SetCounterResetHeader(hc.GetCounterResetHeader())
+		}
 		t, h = p.currDelIter.AtHistogram()
 		p.curr.MinTime = t
 		app.AppendHistogram(t, h.Copy())