forked from influxdata/influxdb
/
measurement_block.go
600 lines (490 loc) · 15.1 KB
/
measurement_block.go
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package tsi1
import (
"bytes"
"encoding/binary"
"errors"
"io"
"sort"
"github.com/influxdata/influxdb/pkg/estimator"
"github.com/influxdata/influxdb/pkg/estimator/hll"
"github.com/influxdata/influxdb/pkg/rhh"
)
// MeasurementBlockVersion is the version of the measurement block.
const MeasurementBlockVersion = 1
// Measurement flag constants.
const (
MeasurementTombstoneFlag = 0x01
)
// Measurement field size constants.
const (
// 1 byte offset for the block to ensure non-zero offsets.
MeasurementFillSize = 1
// Measurement trailer fields
MeasurementTrailerSize = 0 +
2 + // version
8 + 8 + // data offset/size
8 + 8 + // hash index offset/size
8 + 8 + // measurement sketch offset/size
8 + 8 // tombstone measurement sketch offset/size
// Measurement key block fields.
MeasurementNSize = 8
MeasurementOffsetSize = 8
)
// Measurement errors.
var (
ErrUnsupportedMeasurementBlockVersion = errors.New("unsupported measurement block version")
ErrMeasurementBlockSizeMismatch = errors.New("measurement block size mismatch")
)
// MeasurementBlock represents a collection of all measurements in an index.
type MeasurementBlock struct {
data []byte
hashData []byte
// Series block sketch and tombstone sketch for cardinality estimation.
// While we have exact counts for the block, these sketches allow us to
// estimate cardinality across multiple blocks (which might contain
// duplicate series).
sketch, tSketch estimator.Sketch
version int // block version
}
// Version returns the encoding version parsed from the data.
// Only valid after UnmarshalBinary() has been successfully invoked.
func (blk *MeasurementBlock) Version() int { return blk.version }
// Elem returns an element for a measurement.
func (blk *MeasurementBlock) Elem(name []byte) (e MeasurementBlockElem, ok bool) {
n := int64(binary.BigEndian.Uint64(blk.hashData[:MeasurementNSize]))
hash := rhh.HashKey(name)
pos := hash % n
// Track current distance
var d int64
for {
// Find offset of measurement.
offset := binary.BigEndian.Uint64(blk.hashData[MeasurementNSize+(pos*MeasurementOffsetSize):])
if offset == 0 {
return MeasurementBlockElem{}, false
}
// Evaluate name if offset is not empty.
if offset > 0 {
// Parse into element.
var e MeasurementBlockElem
e.UnmarshalBinary(blk.data[offset:])
// Return if name match.
if bytes.Equal(e.name, name) {
return e, true
}
// Check if we've exceeded the probe distance.
if d > rhh.Dist(rhh.HashKey(e.name), pos, n) {
return MeasurementBlockElem{}, false
}
}
// Move position forward.
pos = (pos + 1) % n
d++
if d > n {
return MeasurementBlockElem{}, false
}
}
}
// UnmarshalBinary unpacks data into the block. Block is not copied so data
// should be retained and unchanged after being passed into this function.
func (blk *MeasurementBlock) UnmarshalBinary(data []byte) error {
// Read trailer.
t, err := ReadMeasurementBlockTrailer(data)
if err != nil {
return err
}
// Save data section.
blk.data = data[t.Data.Offset:]
blk.data = blk.data[:t.Data.Size]
// Save hash index block.
blk.hashData = data[t.HashIndex.Offset:]
blk.hashData = blk.hashData[:t.HashIndex.Size]
// Initialise sketches. We're currently using HLL+.
var s, ts = hll.NewDefaultPlus(), hll.NewDefaultPlus()
if err := s.UnmarshalBinary(data[t.Sketch.Offset:][:t.Sketch.Size]); err != nil {
return err
}
blk.sketch = s
if err := ts.UnmarshalBinary(data[t.TSketch.Offset:][:t.TSketch.Size]); err != nil {
return err
}
blk.tSketch = ts
return nil
}
// Iterator returns an iterator over all measurements.
func (blk *MeasurementBlock) Iterator() MeasurementIterator {
return &blockMeasurementIterator{data: blk.data[MeasurementFillSize:]}
}
// seriesIDIterator returns an iterator for all series ids in a measurement.
func (blk *MeasurementBlock) seriesIDIterator(name []byte) seriesIDIterator {
// Find measurement element.
e, ok := blk.Elem(name)
if !ok {
return &rawSeriesIDIterator{}
}
return &rawSeriesIDIterator{n: e.series.n, data: e.series.data}
}
// blockMeasurementIterator iterates over a list measurements in a block.
type blockMeasurementIterator struct {
elem MeasurementBlockElem
data []byte
}
// Next returns the next measurement. Returns nil when iterator is complete.
func (itr *blockMeasurementIterator) Next() MeasurementElem {
// Return nil when we run out of data.
if len(itr.data) == 0 {
return nil
}
// Unmarshal the element at the current position.
itr.elem.UnmarshalBinary(itr.data)
// Move the data forward past the record.
itr.data = itr.data[itr.elem.size:]
return &itr.elem
}
// rawSeriesIterator iterates over a list of raw series data.
type rawSeriesIDIterator struct {
prev uint32
n uint32
data []byte
}
// next returns the next decoded series.
func (itr *rawSeriesIDIterator) next() uint32 {
if len(itr.data) == 0 {
return 0
}
delta, n := binary.Uvarint(itr.data)
itr.data = itr.data[n:]
seriesID := itr.prev + uint32(delta)
itr.prev = seriesID
return seriesID
}
// MeasurementBlockTrailer represents meta data at the end of a MeasurementBlock.
type MeasurementBlockTrailer struct {
Version int // Encoding version
// Offset & size of data section.
Data struct {
Offset int64
Size int64
}
// Offset & size of hash map section.
HashIndex struct {
Offset int64
Size int64
}
// Offset and size of cardinality sketch for measurements.
Sketch struct {
Offset int64
Size int64
}
// Offset and size of cardinality sketch for tombstoned measurements.
TSketch struct {
Offset int64
Size int64
}
}
// ReadMeasurementBlockTrailer returns the block trailer from data.
func ReadMeasurementBlockTrailer(data []byte) (MeasurementBlockTrailer, error) {
var t MeasurementBlockTrailer
// Read version (which is located in the last two bytes of the trailer).
t.Version = int(binary.BigEndian.Uint16(data[len(data)-2:]))
if t.Version != MeasurementBlockVersion {
return t, ErrUnsupportedIndexFileVersion
}
// Slice trailer data.
buf := data[len(data)-MeasurementTrailerSize:]
// Read data section info.
t.Data.Offset, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
t.Data.Size, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
// Read measurement block info.
t.HashIndex.Offset, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
t.HashIndex.Size, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
// Read measurment sketch info.
t.Sketch.Offset, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
t.Sketch.Size, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
// Read tombstone measurment sketch info.
t.TSketch.Offset, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
t.TSketch.Size, buf = int64(binary.BigEndian.Uint64(buf[0:8])), buf[8:]
return t, nil
}
// WriteTo writes the trailer to w.
func (t *MeasurementBlockTrailer) WriteTo(w io.Writer) (n int64, err error) {
// Write data section info.
if err := writeUint64To(w, uint64(t.Data.Offset), &n); err != nil {
return n, err
} else if err := writeUint64To(w, uint64(t.Data.Size), &n); err != nil {
return n, err
}
// Write hash index section info.
if err := writeUint64To(w, uint64(t.HashIndex.Offset), &n); err != nil {
return n, err
} else if err := writeUint64To(w, uint64(t.HashIndex.Size), &n); err != nil {
return n, err
}
// Write measurement sketch info.
if err := writeUint64To(w, uint64(t.Sketch.Offset), &n); err != nil {
return n, err
} else if err := writeUint64To(w, uint64(t.Sketch.Size), &n); err != nil {
return n, err
}
// Write tombstone measurement sketch info.
if err := writeUint64To(w, uint64(t.TSketch.Offset), &n); err != nil {
return n, err
} else if err := writeUint64To(w, uint64(t.TSketch.Size), &n); err != nil {
return n, err
}
// Write measurement block version.
if err := writeUint16To(w, MeasurementBlockVersion, &n); err != nil {
return n, err
}
return n, nil
}
// MeasurementBlockElem represents an internal measurement element.
type MeasurementBlockElem struct {
flag byte // flag
name []byte // measurement name
tagBlock struct {
offset int64
size int64
}
series struct {
n uint32 // series count
data []byte // serialized series data
}
// size in bytes, set after unmarshaling.
size int
}
// Name returns the measurement name.
func (e *MeasurementBlockElem) Name() []byte { return e.name }
// Deleted returns true if the tombstone flag is set.
func (e *MeasurementBlockElem) Deleted() bool {
return (e.flag & MeasurementTombstoneFlag) != 0
}
// TagBlockOffset returns the offset of the measurement's tag block.
func (e *MeasurementBlockElem) TagBlockOffset() int64 { return e.tagBlock.offset }
// TagBlockSize returns the size of the measurement's tag block.
func (e *MeasurementBlockElem) TagBlockSize() int64 { return e.tagBlock.size }
// SeriesData returns the raw series data.
func (e *MeasurementBlockElem) SeriesData() []byte { return e.series.data }
// SeriesN returns the number of series associated with the measurement.
func (e *MeasurementBlockElem) SeriesN() uint32 { return e.series.n }
// SeriesID returns series ID at an index.
func (e *MeasurementBlockElem) SeriesID(i int) uint32 {
return binary.BigEndian.Uint32(e.series.data[i*SeriesIDSize:])
}
// SeriesIDs returns a list of decoded series ids.
//
// NOTE: This should be used for testing and diagnostics purposes only.
// It requires loading the entire list of series in-memory.
func (e *MeasurementBlockElem) SeriesIDs() []uint32 {
a := make([]uint32, 0, e.series.n)
var prev uint32
for data := e.series.data; len(data) > 0; {
delta, n := binary.Uvarint(data)
data = data[n:]
seriesID := prev + uint32(delta)
a = append(a, seriesID)
prev = seriesID
}
return a
}
// Size returns the size of the element.
func (e *MeasurementBlockElem) Size() int { return e.size }
// UnmarshalBinary unmarshals data into e.
func (e *MeasurementBlockElem) UnmarshalBinary(data []byte) error {
start := len(data)
// Parse flag data.
e.flag, data = data[0], data[1:]
// Parse tag block offset.
e.tagBlock.offset, data = int64(binary.BigEndian.Uint64(data)), data[8:]
e.tagBlock.size, data = int64(binary.BigEndian.Uint64(data)), data[8:]
// Parse name.
sz, n := binary.Uvarint(data)
e.name, data = data[n:n+int(sz)], data[n+int(sz):]
// Parse series data.
v, n := binary.Uvarint(data)
e.series.n, data = uint32(v), data[n:]
sz, n = binary.Uvarint(data)
data = data[n:]
e.series.data, data = data[:sz], data[sz:]
// Save length of elem.
e.size = start - len(data)
return nil
}
// MeasurementBlockWriter writes a measurement block.
type MeasurementBlockWriter struct {
buf bytes.Buffer
mms map[string]measurement
// Measurement sketch and tombstoned measurement sketch.
sketch, tSketch estimator.Sketch
}
// NewMeasurementBlockWriter returns a new MeasurementBlockWriter.
func NewMeasurementBlockWriter() *MeasurementBlockWriter {
return &MeasurementBlockWriter{
mms: make(map[string]measurement),
sketch: hll.NewDefaultPlus(),
tSketch: hll.NewDefaultPlus(),
}
}
// Add adds a measurement with series and tag set offset/size.
func (mw *MeasurementBlockWriter) Add(name []byte, deleted bool, offset, size int64, seriesIDs []uint32) {
mm := mw.mms[string(name)]
mm.deleted = deleted
mm.tagBlock.offset = offset
mm.tagBlock.size = size
mm.seriesIDs = seriesIDs
mw.mms[string(name)] = mm
if deleted {
mw.tSketch.Add(name)
} else {
mw.sketch.Add(name)
}
}
// WriteTo encodes the measurements to w.
func (mw *MeasurementBlockWriter) WriteTo(w io.Writer) (n int64, err error) {
var t MeasurementBlockTrailer
// The sketches must be set before calling WriteTo.
if mw.sketch == nil {
return 0, errors.New("measurement sketch not set")
} else if mw.tSketch == nil {
return 0, errors.New("measurement tombstone sketch not set")
}
// Sort names.
names := make([]string, 0, len(mw.mms))
for name := range mw.mms {
names = append(names, name)
}
sort.Strings(names)
// Begin data section.
t.Data.Offset = n
// Write padding byte so no offsets are zero.
if err := writeUint8To(w, 0, &n); err != nil {
return n, err
}
// Encode key list.
for _, name := range names {
// Retrieve measurement and save offset.
mm := mw.mms[name]
mm.offset = n
mw.mms[name] = mm
// Write measurement
if err := mw.writeMeasurementTo(w, []byte(name), &mm, &n); err != nil {
return n, err
}
}
t.Data.Size = n - t.Data.Offset
// Build key hash map
m := rhh.NewHashMap(rhh.Options{
Capacity: int64(len(names)),
LoadFactor: LoadFactor,
})
for name := range mw.mms {
mm := mw.mms[name]
m.Put([]byte(name), &mm)
}
t.HashIndex.Offset = n
// Encode hash map length.
if err := writeUint64To(w, uint64(m.Cap()), &n); err != nil {
return n, err
}
// Encode hash map offset entries.
for i := int64(0); i < m.Cap(); i++ {
_, v := m.Elem(i)
var offset int64
if mm, ok := v.(*measurement); ok {
offset = mm.offset
}
if err := writeUint64To(w, uint64(offset), &n); err != nil {
return n, err
}
}
t.HashIndex.Size = n - t.HashIndex.Offset
// Write the sketches out.
t.Sketch.Offset = n
if err := writeSketchTo(w, mw.sketch, &n); err != nil {
return n, err
}
t.Sketch.Size = n - t.Sketch.Offset
t.TSketch.Offset = n
if err := writeSketchTo(w, mw.tSketch, &n); err != nil {
return n, err
}
t.TSketch.Size = n - t.TSketch.Offset
// Write trailer.
nn, err := t.WriteTo(w)
n += nn
if err != nil {
return n, err
}
return n, nil
}
// writeMeasurementTo encodes a single measurement entry into w.
func (mw *MeasurementBlockWriter) writeMeasurementTo(w io.Writer, name []byte, mm *measurement, n *int64) error {
// Write flag & tag block offset.
if err := writeUint8To(w, mm.flag(), n); err != nil {
return err
}
if err := writeUint64To(w, uint64(mm.tagBlock.offset), n); err != nil {
return err
} else if err := writeUint64To(w, uint64(mm.tagBlock.size), n); err != nil {
return err
}
// Write measurement name.
if err := writeUvarintTo(w, uint64(len(name)), n); err != nil {
return err
}
if err := writeTo(w, name, n); err != nil {
return err
}
// Write series data to buffer.
mw.buf.Reset()
var prev uint32
for _, seriesID := range mm.seriesIDs {
delta := seriesID - prev
var buf [binary.MaxVarintLen32]byte
i := binary.PutUvarint(buf[:], uint64(delta))
if _, err := mw.buf.Write(buf[:i]); err != nil {
return err
}
prev = seriesID
}
// Write series count.
if err := writeUvarintTo(w, uint64(len(mm.seriesIDs)), n); err != nil {
return err
}
// Write data size & buffer.
if err := writeUvarintTo(w, uint64(mw.buf.Len()), n); err != nil {
return err
}
nn, err := mw.buf.WriteTo(w)
if *n += nn; err != nil {
return err
}
return nil
}
// writeSketchTo writes an estimator.Sketch into w, updating the number of bytes
// written via n.
func writeSketchTo(w io.Writer, s estimator.Sketch, n *int64) error {
// TODO(edd): implement io.WriterTo on sketches.
data, err := s.MarshalBinary()
if err != nil {
return err
}
nn, err := w.Write(data)
*n += int64(nn)
return err
}
type measurement struct {
deleted bool
tagBlock struct {
offset int64
size int64
}
seriesIDs []uint32
offset int64
}
func (mm measurement) flag() byte {
var flag byte
if mm.deleted {
flag |= MeasurementTombstoneFlag
}
return flag
}