mirror of
https://github.com/VictoriaMetrics/VictoriaMetrics.git
synced 2024-12-01 14:47:38 +00:00
cc2647d212
Change the return values for these functions - now they return the unmarshaled result plus the size of the unmarshaled result in bytes, so the caller could re-slice the src for further unmarshaling. This improves performance of these functions in hot loops of VictoriaLogs a bit.
125 lines
3.6 KiB
Go
125 lines
3.6 KiB
Go
package mergeset
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import (
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"fmt"
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"io"
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"sort"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/encoding"
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)
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// metaindexRow describes a block of blockHeaders aka index block.
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type metaindexRow struct {
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// First item in the first block.
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// It is used for fast lookup of the required index block.
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firstItem []byte
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// The number of blockHeaders the block contains.
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blockHeadersCount uint32
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// The offset of the block in the index file.
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indexBlockOffset uint64
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// The size of the block in the index file.
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indexBlockSize uint32
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}
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func (mr *metaindexRow) Reset() {
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mr.firstItem = mr.firstItem[:0]
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mr.blockHeadersCount = 0
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mr.indexBlockOffset = 0
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mr.indexBlockSize = 0
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}
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func (mr *metaindexRow) Marshal(dst []byte) []byte {
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dst = encoding.MarshalBytes(dst, mr.firstItem)
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dst = encoding.MarshalUint32(dst, mr.blockHeadersCount)
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dst = encoding.MarshalUint64(dst, mr.indexBlockOffset)
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dst = encoding.MarshalUint32(dst, mr.indexBlockSize)
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return dst
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}
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func (mr *metaindexRow) Unmarshal(src []byte) ([]byte, error) {
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// Unmarshal firstItem
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fi, nSize := encoding.UnmarshalBytes(src)
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if nSize <= 0 {
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return src, fmt.Errorf("cannot unmarshal firstItem")
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}
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src = src[nSize:]
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mr.firstItem = append(mr.firstItem[:0], fi...)
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// Unmarshal blockHeadersCount
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if len(src) < 4 {
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return src, fmt.Errorf("cannot unmarshal blockHeadersCount from %d bytes; need at least %d bytes", len(src), 4)
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}
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mr.blockHeadersCount = encoding.UnmarshalUint32(src)
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src = src[4:]
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// Unmarshal indexBlockOffset
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if len(src) < 8 {
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return src, fmt.Errorf("cannot unmarshal indexBlockOffset from %d bytes; need at least %d bytes", len(src), 8)
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}
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mr.indexBlockOffset = encoding.UnmarshalUint64(src)
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src = src[8:]
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// Unmarshal indexBlockSize
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if len(src) < 4 {
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return src, fmt.Errorf("cannot unmarshal indexBlockSize from %d bytes; need at least %d bytes", len(src), 4)
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}
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mr.indexBlockSize = encoding.UnmarshalUint32(src)
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src = src[4:]
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if mr.blockHeadersCount <= 0 {
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return src, fmt.Errorf("blockHeadersCount must be bigger than 0; got %d", mr.blockHeadersCount)
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}
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if mr.indexBlockSize > 4*maxIndexBlockSize {
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// The index block size can exceed maxIndexBlockSize by up to 4x,
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// since it can contain commonPrefix and firstItem at blockHeader
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// with the maximum length of maxIndexBlockSize per each field.
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return src, fmt.Errorf("too big indexBlockSize: %d; cannot exceed %d", mr.indexBlockSize, 4*maxIndexBlockSize)
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}
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return src, nil
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}
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func unmarshalMetaindexRows(dst []metaindexRow, r io.Reader) ([]metaindexRow, error) {
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// It is ok to read all the metaindex in memory,
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// since it is quite small.
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compressedData, err := io.ReadAll(r)
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if err != nil {
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return dst, fmt.Errorf("cannot read metaindex data: %w", err)
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}
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data, err := encoding.DecompressZSTD(nil, compressedData)
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if err != nil {
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return dst, fmt.Errorf("cannot decompress metaindex data: %w", err)
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}
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dstLen := len(dst)
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for len(data) > 0 {
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if len(dst) < cap(dst) {
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dst = dst[:len(dst)+1]
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} else {
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dst = append(dst, metaindexRow{})
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}
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mr := &dst[len(dst)-1]
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tail, err := mr.Unmarshal(data)
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if err != nil {
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return dst, fmt.Errorf("cannot unmarshal metaindexRow #%d from metaindex data: %w", len(dst)-dstLen, err)
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}
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data = tail
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}
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if dstLen == len(dst) {
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return dst, fmt.Errorf("expecting non-zero metaindex rows; got zero")
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}
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// Make sure metaindexRows are sorted by firstItem.
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tmp := dst[dstLen:]
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ok := sort.SliceIsSorted(tmp, func(i, j int) bool {
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return string(tmp[i].firstItem) < string(tmp[j].firstItem)
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})
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if !ok {
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return dst, fmt.Errorf("metaindex %d rows aren't sorted by firstItem", len(tmp))
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}
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return dst, nil
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}
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