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Add logic to marshal and unmarshal to/from binary #5

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159 changes: 159 additions & 0 deletions structure/exponential.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,9 @@
package structure // import "github.com/lightstep/go-expohisto/structure"

import (
"encoding/binary"
"fmt"
"math"

"github.com/lightstep/go-expohisto/mapping"
"github.com/lightstep/go-expohisto/mapping/exponent"
Expand Down Expand Up @@ -138,6 +140,12 @@ type (
countAt(pos uint32) uint64
// reset resets all buckets to zero count.
reset()
// appendBinary appends binary representation to a
// given slice.
appendBinary([]byte) []byte
// unmarshalBinary decodes the binary representation into
// the backing bucket.
unmarshalBinary([]byte) int
}

// highLow is used to establish the maximum range of bucket
Expand Down Expand Up @@ -165,6 +173,70 @@ func (h *Histogram[N]) Init(cfg Config) {
h.mapping = m
}

// AppendBinary implements the binary appender interface for aggregation.Histogram.
func (h *Histogram[N]) AppendBinary(buf []byte) []byte {
buf = binary.BigEndian.AppendUint32(buf, uint32(h.maxSize))
buf = binary.BigEndian.AppendUint64(buf, h.count)
buf = binary.BigEndian.AppendUint64(buf, h.zeroCount)
switch any(h.sum).(type) {
case int64:
buf = binary.BigEndian.AppendUint64(buf, uint64(h.sum))
buf = binary.BigEndian.AppendUint64(buf, uint64(h.min))
buf = binary.BigEndian.AppendUint64(buf, uint64(h.max))
case float64:
buf = binary.BigEndian.AppendUint64(buf, math.Float64bits(float64(h.sum)))
buf = binary.BigEndian.AppendUint64(buf, math.Float64bits(float64(h.min)))
buf = binary.BigEndian.AppendUint64(buf, math.Float64bits(float64(h.max)))
}
buf = binary.BigEndian.AppendUint32(buf, uint32(h.mapping.Scale()))
buf = h.positive.AppendBinary(buf)
buf = h.negative.AppendBinary(buf)
return buf
}

func (h *Histogram[N]) UnmarshalBinary(buf []byte) (err error) {
h.maxSize = int32(binary.BigEndian.Uint32(buf[:4]))
buf = buf[4:]

h.count = binary.BigEndian.Uint64(buf[:8])
buf = buf[8:]

h.zeroCount = binary.BigEndian.Uint64(buf[:8])
buf = buf[8:]

switch any(h.sum).(type) {
case int64:
h.sum = N(binary.BigEndian.Uint64(buf[:8]))
buf = buf[8:]

h.min = N(binary.BigEndian.Uint64(buf[:8]))
buf = buf[8:]

h.max = N(binary.BigEndian.Uint64(buf[:8]))
buf = buf[8:]
case float64:
h.sum = N(math.Float64frombits(binary.BigEndian.Uint64(buf[:8])))
buf = buf[8:]

h.min = N(math.Float64frombits(binary.BigEndian.Uint64(buf[:8])))
buf = buf[8:]

h.max = N(math.Float64frombits(binary.BigEndian.Uint64(buf[:8])))
buf = buf[8:]
}
scale := int32(binary.BigEndian.Uint32(buf[:4]))
buf = buf[4:]

h.mapping, err = newMapping(int32(scale))
if err != nil {
return fmt.Errorf("failed to create mapping for histogram: %w", err)
}

offset := h.positive.UnmarshalBinary(buf)
h.negative.UnmarshalBinary(buf[offset:])
return nil
}

// Sum implements aggregation.Histogram.
func (h *Histogram[N]) Sum() N {
return h.sum
Expand Down Expand Up @@ -209,6 +281,67 @@ func (h *Histogram[N]) Negative() *Buckets {
return &h.negative
}

func (b *Buckets) AppendBinary(buf []byte) []byte {
buf = binary.BigEndian.AppendUint32(buf, uint32(b.indexBase))
buf = binary.BigEndian.AppendUint32(buf, uint32(b.indexStart))
buf = binary.BigEndian.AppendUint32(buf, uint32(b.indexEnd))
// Append backing array width type
var widthType uint8
switch b.backing.(type) {
case *bucketsVarwidth[uint8]:
widthType = 1
case *bucketsVarwidth[uint16]:
widthType = 2
case *bucketsVarwidth[uint32]:
widthType = 3
case *bucketsVarwidth[uint64]:
widthType = 4
}
buf = append(buf, widthType)
if b.backing != nil {
buf = b.backing.appendBinary(buf)
}
return buf
}

func (b *Buckets) UnmarshalBinary(buf []byte) (offset int) {
origLen := len(buf)
b.indexBase = int32(binary.BigEndian.Uint32(buf[:4]))
buf = buf[4:]

b.indexStart = int32(binary.BigEndian.Uint32(buf[:4]))
buf = buf[4:]

b.indexEnd = int32(binary.BigEndian.Uint32(buf[:4]))
buf = buf[4:]
// Append backing array width type
widthType := uint8(buf[0])
buf = buf[1:]
switch widthType {
case 0:
// backing is nil
return origLen - len(buf)
case 1:
b.backing = &bucketsVarwidth[uint8]{
counts: []uint8{},
}
case 2:
b.backing = &bucketsVarwidth[uint16]{
counts: []uint16{},
}
case 3:
b.backing = &bucketsVarwidth[uint32]{
counts: []uint32{},
}
case 4:
b.backing = &bucketsVarwidth[uint64]{
counts: []uint64{},
}
}
buf = buf[b.backing.unmarshalBinary(buf):]
return origLen - len(buf)
}

// Offset implements aggregation.Bucket.
func (b *Buckets) Offset() int32 {
return b.indexStart
Expand Down Expand Up @@ -690,6 +823,32 @@ func (b *bucketsVarwidth[N]) tryIncrement(bucketIndex int32, incr uint64) bool {
return false
}

func (b *bucketsVarwidth[N]) appendBinary(buf []byte) []byte {
if b == nil {
return buf
}
buf = binary.BigEndian.AppendUint32(buf, uint32(b.size()))
for _, c := range b.counts {
buf = binary.BigEndian.AppendUint64(buf, uint64(c))
}
return buf
}

func (b *bucketsVarwidth[N]) unmarshalBinary(buf []byte) int {
if len(buf) == 0 {
return 0
}
originalLen := len(buf)
countsLen := int32(binary.BigEndian.Uint32(buf[:4]))
buf = buf[4:]
b.counts = make([]N, countsLen)
for i := range b.counts {
b.counts[i] = N(binary.BigEndian.Uint64(buf[:8]))
buf = buf[8:]
}
return originalLen - len(buf)
}

func widenBuckets[From, To bucketsCount](in *bucketsVarwidth[From]) *bucketsVarwidth[To] {
tmp := make([]To, len(in.counts))
for i := range in.counts {
Expand Down
17 changes: 17 additions & 0 deletions structure/exponential_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,23 @@ func TestAscendingSequence(t *testing.T) {
}
}

func TestCodec(t *testing.T) {
src := rand.NewSource(8584838584)
rnd := rand.New(src)
expected := NewFloat64(NewConfig(WithMaxSize(1024)))

totalCount := 512 + rand.Intn(512)
for i := 0; i < totalCount; i++ {
expected.Update(rnd.ExpFloat64())
expected.Update(-1 * rnd.ExpFloat64())
}

buf := expected.AppendBinary(nil)
actual := NewFloat64(NewConfig())
require.NoError(t, actual.UnmarshalBinary(buf))
requireEqual(t, expected, actual)
}

func testAscendingSequence(t *testing.T, maxSize, offset, initScale int32) {
for step := maxSize; step < 4*maxSize; step++ {
agg := NewFloat64(NewConfig(WithMaxSize(maxSize)))
Expand Down