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wip: test delta of delta to timestamp
Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
This commit is contained in:
György Krajcsovits
parent
4be3eaad85
commit
fed8ea58bd
1 changed files with 52 additions and 35 deletions
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@ -104,7 +104,7 @@ func (c *XorSTChunk) Appender() (Appender, error) {
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st: it.st,
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t: it.t,
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v: it.val,
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stDelta: it.stDelta,
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stDiff: it.stDiff,
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tDelta: it.tDelta,
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leading: it.leading,
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trailing: it.trailing,
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@ -141,7 +141,7 @@ type xorSTAppender struct {
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trailing uint8
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st, t int64
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v float64
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stDelta int64
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stDiff int64
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tDelta uint64
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}
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@ -170,9 +170,9 @@ type xorSTIterator struct {
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st, t int64
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val float64
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stDelta int64
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tDelta uint64
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err error
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stDiff int64
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tDelta uint64
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err error
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}
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func (it *xorSTIterator) Seek(t int64) ValueType {
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@ -223,15 +223,15 @@ func (it *xorSTIterator) Reset(b []byte) {
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it.val = 0
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it.leading = 0
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it.trailing = 0
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it.stDelta = 0
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it.stDiff = 0
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it.tDelta = 0
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it.err = nil
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}
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func (a *xorSTAppender) Append(st, t int64, v float64) {
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var (
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stDelta int64
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tDelta uint64
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stDiff int64
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tDelta uint64
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)
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switch a.numTotal {
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@ -248,11 +248,11 @@ func (a *xorSTAppender) Append(st, t int64, v float64) {
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a.b.writeBits(math.Float64bits(v), 64)
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case 1:
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buf := make([]byte, binary.MaxVarintLen64)
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stDelta = st - a.st
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if stDelta != 0 {
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if st != a.st {
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stDiff = a.t - st
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a.firstSTChangeOn = 1
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writeHeaderFirstSTChangeOn(a.b.bytes()[chunkHeaderSize:], 1)
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for _, b := range buf[:binary.PutVarint(buf, stDelta)] {
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for _, b := range buf[:binary.PutVarint(buf, stDiff)] {
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a.b.writeByte(b)
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}
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}
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@ -263,13 +263,40 @@ func (a *xorSTAppender) Append(st, t int64, v float64) {
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}
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a.writeVDelta(v)
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default:
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stDelta = st - a.st
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sdod := stDelta - a.stDelta
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if sdod != 0 {
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if a.firstSTChangeOn == 0 {
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if a.firstSTChangeOn == 0 {
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if st != a.st || a.numTotal == maxFirstSTChangeOn {
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stDiff = a.t - st
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a.firstSTChangeOn = a.numTotal
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writeHeaderFirstSTChangeOn(a.b.bytes()[chunkHeaderSize:], a.numTotal)
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sdod := stDiff
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// Gorilla has a max resolution of seconds, Prometheus milliseconds.
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// Thus we use higher value range steps with larger bit size.
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//
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// TODO(beorn7): This seems to needlessly jump to large bit
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// sizes even for very small deviations from zero. Timestamp
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// compression can probably benefit from some smaller bit
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// buckets. See also what was done for histogram encoding in
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// varbit.go.
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switch {
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case sdod == 0:
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a.b.writeBit(zero)
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case bitRange(sdod, 14):
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a.b.writeByte(0b10<<6 | (uint8(sdod>>8) & (1<<6 - 1))) // 0b10 size code combined with 6 bits of dod.
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a.b.writeByte(uint8(sdod)) // Bottom 8 bits of dod.
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case bitRange(sdod, 17):
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a.b.writeBits(0b110, 3)
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a.b.writeBits(uint64(sdod), 17)
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case bitRange(sdod, 20):
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a.b.writeBits(0b1110, 4)
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a.b.writeBits(uint64(sdod), 20)
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default:
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a.b.writeBits(0b1111, 4)
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a.b.writeBits(uint64(sdod), 64)
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}
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}
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} else {
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stDiff = a.t - st
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sdod := stDiff - a.stDiff
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// Gorilla has a max resolution of seconds, Prometheus milliseconds.
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// Thus we use higher value range steps with larger bit size.
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//
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@ -294,19 +321,6 @@ func (a *xorSTAppender) Append(st, t int64, v float64) {
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a.b.writeBits(0b1111, 4)
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a.b.writeBits(uint64(sdod), 64)
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}
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} else {
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if a.firstSTChangeOn == 0 {
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if a.numTotal == maxFirstSTChangeOn {
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// We are at the 127th sample. firstSTChangeOn can only fit
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// 7 bits due to a single byte header constrain, which is fine,
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// given typical 120 sample size.
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a.firstSTChangeOn = maxFirstSTChangeOn
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writeHeaderFirstSTChangeOn(a.b.bytes()[chunkHeaderSize:], maxFirstSTChangeOn)
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a.b.writeBit(zero)
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}
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} else {
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a.b.writeBit(zero)
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}
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}
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tDelta = uint64(t - a.t)
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@ -344,7 +358,7 @@ func (a *xorSTAppender) Append(st, t int64, v float64) {
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a.t = t
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a.v = v
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a.tDelta = tDelta
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a.stDelta = stDelta
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a.stDiff = stDiff
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a.numTotal++
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binary.BigEndian.PutUint16(a.b.bytes(), a.numTotal)
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@ -385,12 +399,12 @@ func (it *xorSTIterator) Next() ValueType {
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if it.numRead == 1 {
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// Optional ST delta read.
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if it.firstSTChangeOn == 1 {
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stDelta, err := binary.ReadVarint(&it.br)
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stDiff, err := binary.ReadVarint(&it.br)
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if err != nil {
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return it.retErr(err)
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}
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it.stDelta = stDelta
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it.st += it.stDelta
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it.stDiff = stDiff
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it.st = it.t - stDiff
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}
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tDelta, err := binary.ReadUvarint(&it.br)
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if err != nil {
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@ -456,9 +470,12 @@ func (it *xorSTIterator) Next() ValueType {
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}
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sdod = int64(bits)
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}
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it.stDelta += sdod
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it.st += it.stDelta
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if it.numRead == it.firstSTChangeOn {
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it.stDiff = sdod
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} else {
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it.stDiff += sdod
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}
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it.st = it.t - it.stDiff
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}
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var d byte
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