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block_stream_writer.go
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/
block_stream_writer.go
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package storage
import (
"bytes"
"path/filepath"
"sync"
"sync/atomic"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
)
// blockStreamWriter represents block stream writer.
type blockStreamWriter struct {
compressLevel int
timestampsWriter filestream.WriteCloser
valuesWriter filestream.WriteCloser
indexWriter filestream.WriteCloser
metaindexWriter filestream.WriteCloser
mr metaindexRow
timestampsBlockOffset uint64
valuesBlockOffset uint64
indexBlockOffset uint64
indexData []byte
compressedIndexData []byte
metaindexData []byte
compressedMetaindexData []byte
// prevTimestamps* is used as an optimization for reducing disk space usage
// when serially written blocks have identical timestamps.
// This is usually the case when adjacent blocks contain metrics scraped from the same target,
// since such metrics have identical timestamps.
prevTimestampsData []byte
prevTimestampsBlockOffset uint64
}
// Init initializes bsw with the given writers.
func (bsw *blockStreamWriter) reset() {
bsw.compressLevel = 0
bsw.timestampsWriter = nil
bsw.valuesWriter = nil
bsw.indexWriter = nil
bsw.metaindexWriter = nil
bsw.mr.Reset()
bsw.timestampsBlockOffset = 0
bsw.valuesBlockOffset = 0
bsw.indexBlockOffset = 0
bsw.indexData = bsw.indexData[:0]
bsw.compressedIndexData = bsw.compressedIndexData[:0]
bsw.metaindexData = bsw.metaindexData[:0]
bsw.compressedMetaindexData = bsw.compressedMetaindexData[:0]
bsw.prevTimestampsData = bsw.prevTimestampsData[:0]
bsw.prevTimestampsBlockOffset = 0
}
// MustInitFromInmemoryPart initializes bsw from inmemory part.
func (bsw *blockStreamWriter) MustInitFromInmemoryPart(mp *inmemoryPart, compressLevel int) {
bsw.reset()
bsw.compressLevel = compressLevel
bsw.timestampsWriter = &mp.timestampsData
bsw.valuesWriter = &mp.valuesData
bsw.indexWriter = &mp.indexData
bsw.metaindexWriter = &mp.metaindexData
}
// MustInitFromFilePart initializes bsw from a file-based part on the given path.
//
// The bsw doesn't pollute OS page cache if nocache is set.
func (bsw *blockStreamWriter) MustInitFromFilePart(path string, nocache bool, compressLevel int) {
path = filepath.Clean(path)
// Create the directory
fs.MustMkdirFailIfExist(path)
// Create part files in the directory.
timestampsPath := filepath.Join(path, timestampsFilename)
timestampsFile := filestream.MustCreate(timestampsPath, nocache)
valuesPath := filepath.Join(path, valuesFilename)
valuesFile := filestream.MustCreate(valuesPath, nocache)
indexPath := filepath.Join(path, indexFilename)
indexFile := filestream.MustCreate(indexPath, nocache)
// Always cache metaindex file in OS page cache, since it is immediately
// read after the merge.
metaindexPath := filepath.Join(path, metaindexFilename)
metaindexFile := filestream.MustCreate(metaindexPath, false)
bsw.reset()
bsw.compressLevel = compressLevel
bsw.timestampsWriter = timestampsFile
bsw.valuesWriter = valuesFile
bsw.indexWriter = indexFile
bsw.metaindexWriter = metaindexFile
}
// MustClose closes the bsw.
//
// It closes *Writer files passed to Init*.
func (bsw *blockStreamWriter) MustClose() {
// Flush remaining data.
bsw.flushIndexData()
// Write metaindex data.
bsw.compressedMetaindexData = encoding.CompressZSTDLevel(bsw.compressedMetaindexData[:0], bsw.metaindexData, bsw.compressLevel)
fs.MustWriteData(bsw.metaindexWriter, bsw.compressedMetaindexData)
// Close writers.
bsw.timestampsWriter.MustClose()
bsw.valuesWriter.MustClose()
bsw.indexWriter.MustClose()
bsw.metaindexWriter.MustClose()
bsw.reset()
}
// WriteExternalBlock writes b to bsw and updates ph and rowsMerged.
func (bsw *blockStreamWriter) WriteExternalBlock(b *Block, ph *partHeader, rowsMerged *atomic.Uint64) {
rowsMerged.Add(uint64(b.rowsCount()))
b.deduplicateSamplesDuringMerge()
headerData, timestampsData, valuesData := b.MarshalData(bsw.timestampsBlockOffset, bsw.valuesBlockOffset)
usePrevTimestamps := len(bsw.prevTimestampsData) > 0 && bytes.Equal(timestampsData, bsw.prevTimestampsData)
if usePrevTimestamps {
// The current timestamps block equals to the previous timestamps block.
// Update headerData so it points to the previous timestamps block. This saves disk space.
headerData, timestampsData, valuesData = b.MarshalData(bsw.prevTimestampsBlockOffset, bsw.valuesBlockOffset)
timestampsBlocksMerged.Add(1)
timestampsBytesSaved.Add(uint64(len(timestampsData)))
}
if len(bsw.indexData)+len(headerData) > maxBlockSize {
bsw.flushIndexData()
}
bsw.indexData = append(bsw.indexData, headerData...)
bsw.mr.RegisterBlockHeader(&b.bh)
if !usePrevTimestamps {
bsw.prevTimestampsData = append(bsw.prevTimestampsData[:0], timestampsData...)
bsw.prevTimestampsBlockOffset = bsw.timestampsBlockOffset
fs.MustWriteData(bsw.timestampsWriter, timestampsData)
bsw.timestampsBlockOffset += uint64(len(timestampsData))
}
fs.MustWriteData(bsw.valuesWriter, valuesData)
bsw.valuesBlockOffset += uint64(len(valuesData))
updatePartHeader(b, ph)
}
var (
timestampsBlocksMerged atomic.Uint64
timestampsBytesSaved atomic.Uint64
)
func updatePartHeader(b *Block, ph *partHeader) {
ph.BlocksCount++
ph.RowsCount += uint64(b.bh.RowsCount)
if b.bh.MinTimestamp < ph.MinTimestamp {
ph.MinTimestamp = b.bh.MinTimestamp
}
if b.bh.MaxTimestamp > ph.MaxTimestamp {
ph.MaxTimestamp = b.bh.MaxTimestamp
}
}
func (bsw *blockStreamWriter) flushIndexData() {
if len(bsw.indexData) == 0 {
return
}
// Write compressed index block to index data.
bsw.compressedIndexData = encoding.CompressZSTDLevel(bsw.compressedIndexData[:0], bsw.indexData, bsw.compressLevel)
indexBlockSize := len(bsw.compressedIndexData)
if uint64(indexBlockSize) >= 1<<32 {
logger.Panicf("BUG: indexBlock size must fit uint32; got %d", indexBlockSize)
}
fs.MustWriteData(bsw.indexWriter, bsw.compressedIndexData)
// Write metaindex row to metaindex data.
bsw.mr.IndexBlockOffset = bsw.indexBlockOffset
bsw.mr.IndexBlockSize = uint32(indexBlockSize)
bsw.metaindexData = bsw.mr.Marshal(bsw.metaindexData)
// Update offsets.
bsw.indexBlockOffset += uint64(indexBlockSize)
bsw.indexData = bsw.indexData[:0]
bsw.mr.Reset()
}
func getBlockStreamWriter() *blockStreamWriter {
v := bswPool.Get()
if v == nil {
return &blockStreamWriter{}
}
return v.(*blockStreamWriter)
}
func putBlockStreamWriter(bsw *blockStreamWriter) {
bsw.reset()
bswPool.Put(bsw)
}
var bswPool sync.Pool