mirror of
https://github.com/prometheus/prometheus.git
synced 2024-12-23 12:44:05 -08:00
Use more varbit in histogram chunks
This adds bit buckets for larger numbers to varbit encoding and also an unsigned version of varbit encoding. Then, varbit encoding is used for all the histogram chunk data instead of varint. Signed-off-by: beorn7 <beorn@grafana.com>
This commit is contained in:
beorn7
parent
7309c20e7e
commit
7093b089f2
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@ -153,8 +153,6 @@ func (c *HistogramChunk) Appender() (Appender, error) {
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sum: it.sum,
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leading: it.leading,
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trailing: it.trailing,
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buf64: make([]byte, binary.MaxVarintLen64),
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}
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if binary.BigEndian.Uint16(a.b.bytes()) == 0 {
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a.leading = 0xff
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@ -222,20 +220,6 @@ type HistogramAppender struct {
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sum float64
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leading uint8
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trailing uint8
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buf64 []byte // For working on varint64's.
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}
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func putVarint(b *bstream, buf []byte, x int64) {
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for _, byt := range buf[:binary.PutVarint(buf, x)] {
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b.writeByte(byt)
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}
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}
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func putUvarint(b *bstream, buf []byte, x uint64) {
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for _, byt := range buf[:binary.PutUvarint(buf, x)] {
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b.writeByte(byt)
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}
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}
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// Append implements Appender. This implementation panics because normal float
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@ -418,18 +402,21 @@ func (a *HistogramAppender) AppendHistogram(t int64, h histogram.Histogram) {
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a.nBucketsDelta = make([]int64, numNBuckets)
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// Now store the actual data.
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putVarint(a.b, a.buf64, t)
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putUvarint(a.b, a.buf64, h.Count) // TODO(beorn7): Use putVarbitInt?
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putUvarint(a.b, a.buf64, h.ZeroCount) // TODO(beorn7): Use putVarbitInt?
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putVarbitInt(a.b, t)
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putVarbitUint(a.b, h.Count)
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putVarbitUint(a.b, h.ZeroCount) //
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a.b.writeBits(math.Float64bits(h.Sum), 64)
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for _, buck := range h.PositiveBuckets {
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putVarint(a.b, a.buf64, buck) // TODO(beorn7): Use putVarbitInt?
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for _, b := range h.PositiveBuckets {
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putVarbitInt(a.b, b)
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}
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for _, buck := range h.NegativeBuckets {
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putVarint(a.b, a.buf64, buck) // TODO(beorn7): Use putVarbitInt?
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for _, b := range h.NegativeBuckets {
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putVarbitInt(a.b, b)
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}
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case 1:
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tDelta = t - a.t
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if tDelta < 0 {
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panic("out of order timestamp")
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}
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cntDelta = int64(h.Count) - int64(a.cnt)
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zCntDelta = int64(h.ZeroCount) - int64(a.zCnt)
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@ -437,20 +424,20 @@ func (a *HistogramAppender) AppendHistogram(t int64, h histogram.Histogram) {
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cntDelta, zCntDelta = 0, 0
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}
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putVarint(a.b, a.buf64, tDelta) // TODO(beorn7): This should probably be putUvarint.
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putVarint(a.b, a.buf64, cntDelta) // TODO(beorn7): Use putVarbitInt?
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putVarint(a.b, a.buf64, zCntDelta) // TODO(beorn7): Use putVarbitInt?
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putVarbitUint(a.b, uint64(tDelta))
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putVarbitInt(a.b, cntDelta)
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putVarbitInt(a.b, zCntDelta)
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a.writeSumDelta(h.Sum)
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for i, buck := range h.PositiveBuckets {
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delta := buck - a.pBuckets[i]
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putVarint(a.b, a.buf64, delta) // TODO(beorn7): Use putVarbitInt?
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for i, b := range h.PositiveBuckets {
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delta := b - a.pBuckets[i]
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putVarbitInt(a.b, delta)
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a.pBucketsDelta[i] = delta
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}
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for i, buck := range h.NegativeBuckets {
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delta := buck - a.nBuckets[i]
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putVarint(a.b, a.buf64, delta) // TODO(beorn7): Use putVarbitInt?
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for i, b := range h.NegativeBuckets {
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delta := b - a.nBuckets[i]
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putVarbitInt(a.b, delta)
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a.nBucketsDelta[i] = delta
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}
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@ -721,21 +708,21 @@ func (it *histogramIterator) Next() bool {
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}
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// Now read the actual data.
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t, err := binary.ReadVarint(&it.br)
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t, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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}
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it.t = t
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cnt, err := binary.ReadUvarint(&it.br)
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cnt, err := readVarbitUint(&it.br)
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if err != nil {
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it.err = err
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return false
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}
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it.cnt = cnt
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zcnt, err := binary.ReadUvarint(&it.br)
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zcnt, err := readVarbitUint(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -750,7 +737,7 @@ func (it *histogramIterator) Next() bool {
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it.sum = math.Float64frombits(sum)
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for i := range it.pBuckets {
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v, err := binary.ReadVarint(&it.br)
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v, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -758,7 +745,7 @@ func (it *histogramIterator) Next() bool {
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it.pBuckets[i] = v
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}
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for i := range it.nBuckets {
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v, err := binary.ReadVarint(&it.br)
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v, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -771,15 +758,15 @@ func (it *histogramIterator) Next() bool {
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}
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if it.numRead == 1 {
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tDelta, err := binary.ReadVarint(&it.br)
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tDelta, err := readVarbitUint(&it.br)
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if err != nil {
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it.err = err
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return false
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}
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it.tDelta = tDelta
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it.t += int64(it.tDelta)
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it.tDelta = int64(tDelta)
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it.t += it.tDelta
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cntDelta, err := binary.ReadVarint(&it.br)
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cntDelta, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -787,7 +774,7 @@ func (it *histogramIterator) Next() bool {
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it.cntDelta = cntDelta
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it.cnt = uint64(int64(it.cnt) + it.cntDelta)
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zcntDelta, err := binary.ReadVarint(&it.br)
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zcntDelta, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -806,7 +793,7 @@ func (it *histogramIterator) Next() bool {
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}
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for i := range it.pBuckets {
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delta, err := binary.ReadVarint(&it.br)
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delta, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -816,7 +803,7 @@ func (it *histogramIterator) Next() bool {
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}
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for i := range it.nBuckets {
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delta, err := binary.ReadVarint(&it.br)
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delta, err := readVarbitInt(&it.br)
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if err != nil {
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it.err = err
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return false
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@ -27,7 +27,7 @@ func writeHistogramChunkLayout(b *bstream, schema int32, zeroThreshold float64,
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func putHistogramChunkLayoutSpans(b *bstream, spans []histogram.Span) {
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putVarbitInt(b, int64(len(spans)))
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for _, s := range spans {
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putVarbitInt(b, int64(s.Length))
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putVarbitUint(b, uint64(s.Length))
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putVarbitInt(b, int64(s.Offset))
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}
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}
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@ -69,7 +69,7 @@ func readHistogramChunkLayoutSpans(b *bstreamReader) ([]histogram.Span, error) {
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}
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for i := 0; i < int(num); i++ {
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length, err := readVarbitInt(b)
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length, err := readVarbitUint(b)
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if err != nil {
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return nil, err
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}
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@ -15,6 +15,9 @@ package chunkenc
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import (
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"math"
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"math/bits"
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"github.com/pkg/errors"
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)
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// putVarbitFloat writes a float64 using varbit encoding. It does so by
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@ -53,7 +56,8 @@ func readVarbitFloat(b *bstreamReader) (float64, error) {
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}
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// putVarbitInt writes an int64 using varbit encoding with a bit bucketing
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// optimized for the dod's observed in histogram buckets.
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// optimized for the dod's observed in histogram buckets, plus a few additional
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// buckets for large numbers.
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//
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// TODO(Dieterbe): We could improve this further: Each branch doesn't need to
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// support any values of any of the prior branches. So we can expand the range
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@ -62,22 +66,31 @@ func readVarbitFloat(b *bstreamReader) (float64, error) {
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// center-piece we skip).
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func putVarbitInt(b *bstream, val int64) {
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switch {
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case val == 0:
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case val == 0: // Precisely 0, needs 1 bit.
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b.writeBit(zero)
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case bitRange(val, 3): // -3 <= val <= 4
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case bitRange(val, 3): // -3 <= val <= 4, needs 5 bits.
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b.writeBits(0b10, 2)
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b.writeBits(uint64(val), 3)
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case bitRange(val, 6): // -31 <= val <= 32
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case bitRange(val, 6): // -31 <= val <= 32, 9 bits.
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b.writeBits(0b110, 3)
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b.writeBits(uint64(val), 6)
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case bitRange(val, 9): // -255 <= val <= 256
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case bitRange(val, 9): // -255 <= val <= 256, 13 bits.
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b.writeBits(0b1110, 4)
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b.writeBits(uint64(val), 9)
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case bitRange(val, 12): // -2047 <= val <= 2048
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case bitRange(val, 12): // -2047 <= val <= 2048, 17 bits.
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b.writeBits(0b11110, 5)
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b.writeBits(uint64(val), 12)
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case bitRange(val, 18): // -131071 <= val <= 131072, 3 bytes.
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b.writeBits(0b111110, 6)
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b.writeBits(uint64(val), 18)
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case bitRange(val, 25): // -16777215 <= val <= 16777216, 4 bytes.
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b.writeBits(0b1111110, 7)
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b.writeBits(uint64(val), 25)
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case bitRange(val, 56): // -36028797018963967 <= val <= 36028797018963968, 8 bytes.
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b.writeBits(0b11111110, 8)
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b.writeBits(uint64(val), 56)
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default:
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b.writeBits(0b11111, 5)
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b.writeBits(0b11111111, 8) // Worst case, needs 9 bytes.
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b.writeBits(uint64(val), 64)
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}
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}
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@ -85,7 +98,7 @@ func putVarbitInt(b *bstream, val int64) {
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// readVarbitInt reads an int64 encoced with putVarbitInt.
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func readVarbitInt(b *bstreamReader) (int64, error) {
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var d byte
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for i := 0; i < 5; i++ {
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for i := 0; i < 8; i++ {
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d <<= 1
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bit, err := b.readBitFast()
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if err != nil {
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@ -114,7 +127,13 @@ func readVarbitInt(b *bstreamReader) (int64, error) {
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sz = 9
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case 0b11110:
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sz = 12
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case 0b11111:
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case 0b111110:
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sz = 18
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case 0b1111110:
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sz = 25
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case 0b11111110:
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sz = 56
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case 0b11111111:
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// Do not use fast because it's very unlikely it will succeed.
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bits, err := b.readBits(64)
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if err != nil {
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@ -122,6 +141,8 @@ func readVarbitInt(b *bstreamReader) (int64, error) {
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}
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val = int64(bits)
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default:
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return 0, errors.Errorf("invalid bit pattern %b", d)
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}
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if sz != 0 {
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@ -141,3 +162,104 @@ func readVarbitInt(b *bstreamReader) (int64, error) {
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return val, nil
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}
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func bitRangeUint(x uint64, nbits int) bool {
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return bits.LeadingZeros64(x) >= 64-nbits
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}
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// putVarbitUint writes a uint64 using varbit encoding. It uses the same bit
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// buckets as putVarbitInt.
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func putVarbitUint(b *bstream, val uint64) {
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switch {
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case val == 0: // Precisely 0, needs 1 bit.
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b.writeBit(zero)
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case bitRangeUint(val, 3): // val <= 7, needs 5 bits.
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b.writeBits(0b10, 2)
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b.writeBits(val, 3)
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case bitRangeUint(val, 6): // val <= 63, 9 bits.
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b.writeBits(0b110, 3)
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b.writeBits(val, 6)
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case bitRangeUint(val, 9): // val <= 511, 13 bits.
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b.writeBits(0b1110, 4)
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b.writeBits(val, 9)
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case bitRangeUint(val, 12): // val <= 4095, 17 bits.
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b.writeBits(0b11110, 5)
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b.writeBits(val, 12)
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case bitRangeUint(val, 18): // val <= 262143, 3 bytes.
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b.writeBits(0b111110, 6)
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b.writeBits(val, 18)
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case bitRangeUint(val, 25): // val <= 33554431, 4 bytes.
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b.writeBits(0b1111110, 7)
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b.writeBits(val, 25)
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case bitRangeUint(val, 56): // val <= 72057594037927935, 8 bytes.
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b.writeBits(0b11111110, 8)
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b.writeBits(val, 56)
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default:
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b.writeBits(0b11111111, 8) // Worst case, needs 9 bytes.
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b.writeBits(val, 64)
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}
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}
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// readVarbitUint reads a uint64 encoced with putVarbitUint.
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func readVarbitUint(b *bstreamReader) (uint64, error) {
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var d byte
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for i := 0; i < 8; i++ {
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d <<= 1
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bit, err := b.readBitFast()
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if err != nil {
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bit, err = b.readBit()
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}
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if err != nil {
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return 0, err
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}
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if bit == zero {
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break
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}
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d |= 1
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}
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var (
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bits uint64
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sz uint8
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err error
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)
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switch d {
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case 0b0:
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// val == 0
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case 0b10:
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sz = 3
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case 0b110:
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sz = 6
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case 0b1110:
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sz = 9
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case 0b11110:
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sz = 12
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case 0b111110:
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sz = 18
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case 0b1111110:
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sz = 25
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case 0b11111110:
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sz = 56
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case 0b11111111:
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// Do not use fast because it's very unlikely it will succeed.
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bits, err = b.readBits(64)
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if err != nil {
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return 0, err
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}
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default:
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return 0, errors.Errorf("invalid bit pattern %b", d)
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}
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if sz != 0 {
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bits, err = b.readBitsFast(sz)
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if err != nil {
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bits, err = b.readBits(sz)
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}
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if err != nil {
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return 0, err
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}
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}
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return bits, nil
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}
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85
tsdb/chunkenc/varbit_test.go
Normal file
85
tsdb/chunkenc/varbit_test.go
Normal file
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@ -0,0 +1,85 @@
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// Copyright 2021 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package chunkenc
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import (
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"math"
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"testing"
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"github.com/stretchr/testify/require"
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)
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func TestVarbitInt(t *testing.T) {
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numbers := []int64{
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math.MinInt64,
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-36028797018963968, -36028797018963967,
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-16777216, -16777215,
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-131072, -131071,
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-2048, -2047,
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-256, -255,
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-32, -31,
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-4, -3,
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-1, 0, 1,
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4, 5,
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32, 33,
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256, 257,
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2048, 2049,
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131072, 131073,
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16777216, 16777217,
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36028797018963968, 36028797018963969,
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math.MaxInt64,
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}
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bs := bstream{}
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||||
for _, n := range numbers {
|
||||
putVarbitInt(&bs, n)
|
||||
}
|
||||
|
||||
bsr := newBReader(bs.bytes())
|
||||
|
||||
for _, want := range numbers {
|
||||
got, err := readVarbitInt(&bsr)
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, want, got)
|
||||
}
|
||||
}
|
||||
|
||||
func TestVarbitUint(t *testing.T) {
|
||||
numbers := []uint64{
|
||||
0, 1,
|
||||
7, 8,
|
||||
63, 64,
|
||||
511, 512,
|
||||
4095, 4096,
|
||||
262143, 262144,
|
||||
33554431, 33554432,
|
||||
72057594037927935, 72057594037927936,
|
||||
math.MaxUint64,
|
||||
}
|
||||
|
||||
bs := bstream{}
|
||||
|
||||
for _, n := range numbers {
|
||||
putVarbitUint(&bs, n)
|
||||
}
|
||||
|
||||
bsr := newBReader(bs.bytes())
|
||||
|
||||
for _, want := range numbers {
|
||||
got, err := readVarbitUint(&bsr)
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, want, got)
|
||||
}
|
||||
}
|
||||
Loading…
Reference in a new issue