// loadChunks loads a group of chunks of a timeseries by their index. The chunk
// with the earliest time will have index 0, the following ones will have
// incrementally larger indexes. The indexOffset denotes the offset to be added to
// each index in indexes. It is the caller's responsibility to not persist or
// drop anything for the same fingerprint concurrently.
func (p *persistence) loadChunks(fp model.Fingerprint, indexes []int, indexOffset int) ([]chunk.Chunk, error) {
f, err := p.openChunkFileForReading(fp)
if err != nil {
return nil, err
}
defer f.Close()
chunks := make([]chunk.Chunk, 0, len(indexes))
buf := p.bufPool.Get().([]byte)
defer func() {
// buf may change below. An unwrapped 'defer p.bufPool.Put(buf)'
// would only put back the original buf.
p.bufPool.Put(buf)
}()
for i := 0; i < len(indexes); i++ {
// This loads chunks in batches. A batch is a streak of
// consecutive chunks, read from disk in one go.
batchSize := 1
if _, err := f.Seek(offsetForChunkIndex(indexes[i]+indexOffset), os.SEEK_SET); err != nil {
return nil, err
}
for ; batchSize < chunkMaxBatchSize &&
i+1 < len(indexes) &&
indexes[i]+1 == indexes[i+1]; i, batchSize = i+1, batchSize+1 {
}
readSize := batchSize * chunkLenWithHeader
if cap(buf) < readSize {
buf = make([]byte, readSize)
}
buf = buf[:readSize]
if _, err := io.ReadFull(f, buf); err != nil {
return nil, err
}
for c := 0; c < batchSize; c++ {
chunk, err := chunk.NewForEncoding(chunk.Encoding(buf[c*chunkLenWithHeader+chunkHeaderTypeOffset]))
if err != nil {
return nil, err
}
if err := chunk.UnmarshalFromBuf(buf[c*chunkLenWithHeader+chunkHeaderLen:]); err != nil {
return nil, err
}
chunks = append(chunks, chunk)
}
}
chunk.Ops.WithLabelValues(chunk.Load).Add(float64(len(chunks)))
atomic.AddInt64(&chunk.NumMemChunks, int64(len(chunks)))
return chunks, nil
}
// scan works like bufio.Scanner.Scan.
func (hs *headsScanner) scan() bool {
if hs.seriesCurrent == hs.seriesTotal || hs.err != nil {
return false
}
var (
seriesFlags byte
fpAsInt uint64
metric codable.Metric
persistWatermark int64
modTimeNano int64
modTime time.Time
chunkDescsOffset int64
savedFirstTime int64
numChunkDescs int64
firstTime int64
lastTime int64
encoding byte
ch chunk.Chunk
lastTimeHead model.Time
)
if seriesFlags, hs.err = hs.r.ReadByte(); hs.err != nil {
return false
}
headChunkPersisted := seriesFlags&flagHeadChunkPersisted != 0
if fpAsInt, hs.err = codable.DecodeUint64(hs.r); hs.err != nil {
return false
}
hs.fp = model.Fingerprint(fpAsInt)
if hs.err = metric.UnmarshalFromReader(hs.r); hs.err != nil {
return false
}
if hs.version != headsFormatLegacyVersion {
// persistWatermark only present in v2.
persistWatermark, hs.err = binary.ReadVarint(hs.r)
if hs.err != nil {
return false
}
modTimeNano, hs.err = binary.ReadVarint(hs.r)
if hs.err != nil {
return false
}
if modTimeNano != -1 {
modTime = time.Unix(0, modTimeNano)
}
}
if chunkDescsOffset, hs.err = binary.ReadVarint(hs.r); hs.err != nil {
return false
}
if savedFirstTime, hs.err = binary.ReadVarint(hs.r); hs.err != nil {
return false
}
if numChunkDescs, hs.err = binary.ReadVarint(hs.r); hs.err != nil {
return false
}
chunkDescs := make([]*chunk.Desc, numChunkDescs)
if hs.version == headsFormatLegacyVersion {
if headChunkPersisted {
persistWatermark = numChunkDescs
} else {
persistWatermark = numChunkDescs - 1
}
}
headChunkClosed := true // Initial assumption.
for i := int64(0); i < numChunkDescs; i++ {
if i < persistWatermark {
if firstTime, hs.err = binary.ReadVarint(hs.r); hs.err != nil {
return false
}
if lastTime, hs.err = binary.ReadVarint(hs.r); hs.err != nil {
return false
}
chunkDescs[i] = &chunk.Desc{
ChunkFirstTime: model.Time(firstTime),
ChunkLastTime: model.Time(lastTime),
}
chunk.NumMemDescs.Inc()
} else {
// Non-persisted chunk.
// If there are non-persisted chunks at all, we consider
// the head chunk not to be closed yet.
headChunkClosed = false
if encoding, hs.err = hs.r.ReadByte(); hs.err != nil {
return false
}
if ch, hs.err = chunk.NewForEncoding(chunk.Encoding(encoding)); hs.err != nil {
return false
}
if hs.err = ch.Unmarshal(hs.r); hs.err != nil {
return false
}
cd := chunk.NewDesc(ch, ch.FirstTime())
if i < numChunkDescs-1 {
// This is NOT the head chunk. So it's a chunk
// to be persisted, and we need to populate lastTime.
hs.chunksToPersistTotal++
cd.MaybePopulateLastTime()
}
chunkDescs[i] = cd
}
}
if lastTimeHead, hs.err = chunkDescs[len(chunkDescs)-1].LastTime(); hs.err != nil {
return false
}
hs.series = &memorySeries{
metric: model.Metric(metric),
chunkDescs: chunkDescs,
persistWatermark: int(persistWatermark),
modTime: modTime,
chunkDescsOffset: int(chunkDescsOffset),
savedFirstTime: model.Time(savedFirstTime),
lastTime: lastTimeHead,
headChunkClosed: headChunkClosed,
}
hs.seriesCurrent++
return true
}