chunks

package
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 Go to latest Published: Jun 20, 2022 License: Apache-2.0 Imports: 20 Imported by: 90

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Constants

View Source 
const (
	// MagicChunks is 4 bytes at the head of a series file.
	MagicChunks = 0x85BD40DD
	// MagicChunksSize is the size in bytes of MagicChunks.
	MagicChunksSize = 4

	ChunksFormatVersionSize = 1

	// SegmentHeaderSize defines the total size of the header part.
	SegmentHeaderSize = MagicChunksSize + ChunksFormatVersionSize + segmentHeaderPaddingSize
)

Segment header fields constants.

View Source 
const (
	// MaxChunkLengthFieldSize defines the maximum size of the data length part.
	MaxChunkLengthFieldSize = binary.MaxVarintLen32
	// ChunkEncodingSize defines the size of the chunk encoding part.
	ChunkEncodingSize = 1
)

Chunk fields constants.

View Source 
const (
	// MintMaxtSize is the size of the mint/maxt for head chunk file and chunks.
	MintMaxtSize = 8
	// SeriesRefSize is the size of series reference on disk.
	SeriesRefSize = 8
	// HeadChunkFileHeaderSize is the total size of the header for a head chunk file.
	HeadChunkFileHeaderSize = SegmentHeaderSize
	// MaxHeadChunkFileSize is the max size of a head chunk file.
	MaxHeadChunkFileSize = 128 * 1024 * 1024 // 128 MiB.
	// CRCSize is the size of crc32 sum on disk.
	CRCSize = 4
	// MaxHeadChunkMetaSize is the max size of an mmapped chunks minus the chunks data.
	// Max because the uvarint size can be smaller.
	MaxHeadChunkMetaSize = SeriesRefSize + 2*MintMaxtSize + ChunkEncodingSize + MaxChunkLengthFieldSize + CRCSize
	// MinWriteBufferSize is the minimum write buffer size allowed.
	MinWriteBufferSize = 64 * 1024 // 64KB.
	// MaxWriteBufferSize is the maximum write buffer size allowed.
	MaxWriteBufferSize = 8 * 1024 * 1024 // 8 MiB.
	// DefaultWriteBufferSize is the default write buffer size.
	DefaultWriteBufferSize = 4 * 1024 * 1024 // 4 MiB.
	// DefaultWriteQueueSize is the default size of the in-memory queue used before flushing chunks to the disk.
	// A value of 0 completely disables this feature.
	DefaultWriteQueueSize = 0
)
View Source 
const (
	// DefaultChunkSegmentSize is the default chunks segment size.
	DefaultChunkSegmentSize = 512 * 1024 * 1024
)
View Source 
const (
	// MagicHeadChunks is 4 bytes at the beginning of a head chunk file.
	MagicHeadChunks = 0x0130BC91
)

Head chunk file header fields constants.

Variables

View Source 
var ErrChunkDiskMapperClosed = errors.New("ChunkDiskMapper closed")

ErrChunkDiskMapperClosed returned by any method indicates that the ChunkDiskMapper was closed.

View Source 
var HeadChunkFilePreallocationSize int64 = MinWriteBufferSize * 2

HeadChunkFilePreallocationSize is the size to which the m-map file should be preallocated when a new file is cut. Windows needs pre-allocations while the other OS does not. But we observed that a 0 pre-allocation causes unit tests to flake. This small allocation for non-Windows OSes removes the flake.

Functions

This section is empty.

Types

type BlockChunkRef 

type BlockChunkRef uint64

BlockChunkRef refers to a chunk within a persisted block. The upper 4 bytes are for the segment index and the lower 4 bytes are for the segment offset where the data starts for this chunk.

func NewBlockChunkRef 

func NewBlockChunkRef(fileIndex, fileOffset uint64) BlockChunkRef

NewBlockChunkRef packs the file index and byte offset into a BlockChunkRef.

func (BlockChunkRef) Unpack 

func (b BlockChunkRef) Unpack() (int, int)

type ByteSlice 

type ByteSlice interface {
	Len() int
	Range(start, end int) []byte
}

ByteSlice abstracts a byte slice.

type ChunkDiskMapper 

type ChunkDiskMapper struct {
	// contains filtered or unexported fields
}

ChunkDiskMapper is for writing the Head block chunks to the disk and access chunks via mmapped file.

func NewChunkDiskMapper 

func NewChunkDiskMapper(reg prometheus.Registerer, dir string, pool chunkenc.Pool, writeBufferSize, writeQueueSize int) (*ChunkDiskMapper, error)

NewChunkDiskMapper returns a new ChunkDiskMapper against the given directory using the default head chunk file duration. NOTE: 'IterateAllChunks' method needs to be called at least once after creating ChunkDiskMapper to set the maxt of all the file.

func (*ChunkDiskMapper) Chunk 

func (cdm *ChunkDiskMapper) Chunk(ref ChunkDiskMapperRef) (chunkenc.Chunk, error)

Chunk returns a chunk from a given reference.

func (*ChunkDiskMapper) Close 

func (cdm *ChunkDiskMapper) Close() error

Close closes all the open files in ChunkDiskMapper. It is not longer safe to access chunks from this struct after calling Close.

func (*ChunkDiskMapper) CutNewFile 

func (cdm *ChunkDiskMapper) CutNewFile()

CutNewFile makes that a new file will be created the next time a chunk is written.

func (*ChunkDiskMapper) DeleteCorrupted 

func (cdm *ChunkDiskMapper) DeleteCorrupted(originalErr error) error

DeleteCorrupted deletes all the head chunk files after the one which had the corruption (including the corrupt file).

func (*ChunkDiskMapper) IsQueueEmpty 

func (cdm *ChunkDiskMapper) IsQueueEmpty() bool

func (*ChunkDiskMapper) IterateAllChunks 

func (cdm *ChunkDiskMapper) IterateAllChunks(f func(seriesRef HeadSeriesRef, chunkRef ChunkDiskMapperRef, mint, maxt int64, numSamples uint16) error) (err error)

IterateAllChunks iterates all mmappedChunkFiles (in order of head chunk file name/number) and all the chunks within it and runs the provided function with information about each chunk. It returns on the first error encountered. NOTE: This method needs to be called at least once after creating ChunkDiskMapper to set the maxt of all the file.

func (*ChunkDiskMapper) Size 

func (cdm *ChunkDiskMapper) Size() (int64, error)

Size returns the size of the chunk files.

func (*ChunkDiskMapper) Truncate 

func (cdm *ChunkDiskMapper) Truncate(mint int64) error

Truncate deletes the head chunk files which are strictly below the mint. mint should be in milliseconds.

func (*ChunkDiskMapper) WriteChunk 

func (cdm *ChunkDiskMapper) WriteChunk(seriesRef HeadSeriesRef, mint, maxt int64, chk chunkenc.Chunk, callback func(err error)) (chkRef ChunkDiskMapperRef)

WriteChunk writes the chunk to the disk. The returned chunk ref is the reference from where the chunk encoding starts for the chunk.

type ChunkDiskMapperRef 

type ChunkDiskMapperRef uint64

ChunkDiskMapperRef represents the location of a head chunk on disk. The upper 4 bytes hold the index of the head chunk file and the lower 4 bytes hold the byte offset in the head chunk file where the chunk starts.

func (ChunkDiskMapperRef) Unpack 

func (ref ChunkDiskMapperRef) Unpack() (seq, offset int)

type ChunkRef 

type ChunkRef uint64

ChunkRef is a generic reference for reading chunk data. In prometheus it is either a HeadChunkRef or BlockChunkRef, though other implementations may have their own reference types.

type CorruptionErr 

type CorruptionErr struct {
	Dir       string
	FileIndex int
	Err       error
}

CorruptionErr is an error that's returned when corruption is encountered.

func (*CorruptionErr) Error 

func (e *CorruptionErr) Error() string

type HeadChunkID 

type HeadChunkID uint64

HeadChunkID refers to a specific chunk in a series (memSeries) in the Head. Each memSeries has its own monotonically increasing number to refer to its chunks. If the HeadChunkID value is...

  • memSeries.firstChunkID+len(memSeries.mmappedChunks), it's the head chunk.
  • less than the above, but >= memSeries.firstID, then it's memSeries.mmappedChunks[i] where i = HeadChunkID - memSeries.firstID.

Example: assume a memSeries.firstChunkID=7 and memSeries.mmappedChunks=[p5,p6,p7,p8,p9]. | HeadChunkID value | refers to ... | |-------------------|----------------------------------------------------------------------------------------| | 0-6 | chunks that have been compacted to blocks, these won't return data for queries in Head | | 7-11 | memSeries.mmappedChunks[i] where i is 0 to 4. | | 12 | memSeries.headChunk |

type HeadChunkRef 

type HeadChunkRef uint64

HeadChunkRef packs a HeadSeriesRef and a ChunkID into a global 8 Byte ID. The HeadSeriesRef and ChunkID may not exceed 5 and 3 bytes respectively.

func NewHeadChunkRef 

func NewHeadChunkRef(hsr HeadSeriesRef, chunkID HeadChunkID) HeadChunkRef

func (HeadChunkRef) Unpack 

func (p HeadChunkRef) Unpack() (HeadSeriesRef, HeadChunkID)

type HeadSeriesRef 

type HeadSeriesRef uint64

HeadSeriesRef refers to in-memory series.

type Iterator 

type Iterator interface {
	// At returns the current meta.
	// It depends on implementation if the chunk is populated or not.
	At() Meta
	// Next advances the iterator by one.
	Next() bool
	// Err returns optional error if Next is false.
	Err() error
}

Iterator iterates over the chunks of a single time series.

type Meta 

type Meta struct {
	// Ref and Chunk hold either a reference that can be used to retrieve
	// chunk data or the data itself.
	// If Chunk is nil, call ChunkReader.Chunk(Meta.Ref) to get the chunk and assign it to the Chunk field
	Ref   ChunkRef
	Chunk chunkenc.Chunk

	// Time range the data covers.
	// When MaxTime == math.MaxInt64 the chunk is still open and being appended to.
	MinTime, MaxTime int64
}

Meta holds information about a chunk of data.

func (*Meta) OverlapsClosedInterval 

func (cm *Meta) OverlapsClosedInterval(mint, maxt int64) bool

OverlapsClosedInterval Returns true if the chunk overlaps [mint, maxt].

type Reader 

type Reader struct {
	// contains filtered or unexported fields
}

Reader implements a ChunkReader for a serialized byte stream of series data.

func NewDirReader 

func NewDirReader(dir string, pool chunkenc.Pool) (*Reader, error)

NewDirReader returns a new Reader against sequentially numbered files in the given directory.

func (*Reader) Chunk 

func (s *Reader) Chunk(ref ChunkRef) (chunkenc.Chunk, error)

Chunk returns a chunk from a given reference.

func (*Reader) Close 

func (s *Reader) Close() error

func (*Reader) Size 

func (s *Reader) Size() int64

Size returns the size of the chunks.

type Writer 

type Writer struct {
	// contains filtered or unexported fields
}

Writer implements the ChunkWriter interface for the standard serialization format.

func NewWriter 

func NewWriter(dir string) (*Writer, error)

NewWriter returns a new writer against the given directory using the default segment size.

func NewWriterWithSegSize 

func NewWriterWithSegSize(dir string, segmentSize int64) (*Writer, error)

NewWriterWithSegSize returns a new writer against the given directory and allows setting a custom size for the segments.

func (*Writer) Close 

func (w *Writer) Close() error

func (*Writer) WriteChunks 

func (w *Writer) WriteChunks(chks ...Meta) error

WriteChunks writes as many chunks as possible to the current segment, cuts a new segment when the current segment is full and writes the rest of the chunks in the new segment.

Source Files

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