wlog

package
v0.45.2 Latest Latest
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 Go to latest Published: Dec 19, 2023 License: Apache-2.0 Imports: 25 Imported by: 22

Documentation

Index

Constants

View Source 
const (
	DefaultSegmentSize = 128 * 1024 * 1024 // 128 MB

	WblDirName = "wbl"
)

Variables

View Source 
var (
	ErrIgnorable = errors.New("ignore me")
)

Functions

func DeleteCheckpoints 

func DeleteCheckpoints(dir string, maxIndex int) error

DeleteCheckpoints deletes all checkpoints in a directory below a given index.

func LastCheckpoint 

func LastCheckpoint(dir string) (string, int, error)

LastCheckpoint returns the directory name and index of the most recent checkpoint. If dir does not contain any checkpoints, ErrNotFound is returned.

func NewSegmentBufReader 

func NewSegmentBufReader(segs ...*Segment) *segmentBufReader

nolint:revive // TODO: Consider exporting segmentBufReader

func NewSegmentBufReaderWithOffset 

func NewSegmentBufReaderWithOffset(offset int, segs ...*Segment) (sbr *segmentBufReader, err error)

nolint:revive

func NewSegmentsRangeReader 

func NewSegmentsRangeReader(sr ...SegmentRange) (io.ReadCloser, error)

NewSegmentsRangeReader returns a new reader over the given WAL segment ranges. If first or last are -1, the range is open on the respective end.

func NewSegmentsReader 

func NewSegmentsReader(dir string) (io.ReadCloser, error)

NewSegmentsReader returns a new reader over all segments in the directory.

func SegmentName 

func SegmentName(dir string, i int) string

SegmentName builds a segment name for the directory.

func Segments 

func Segments(wlDir string) (first, last int, err error)

Segments returns the range [first, n] of currently existing segments. If no segments are found, first and n are -1.

Types

type CheckpointStats 

type CheckpointStats struct {
	DroppedSeries     int
	DroppedSamples    int // Includes histograms.
	DroppedTombstones int
	DroppedExemplars  int
	DroppedMetadata   int
	TotalSeries       int // Processed series including dropped ones.
	TotalSamples      int // Processed float and histogram samples including dropped ones.
	TotalTombstones   int // Processed tombstones including dropped ones.
	TotalExemplars    int // Processed exemplars including dropped ones.
	TotalMetadata     int // Processed metadata including dropped ones.
}

CheckpointStats returns stats about a created checkpoint.

func Checkpoint 

func Checkpoint(logger log.Logger, w *WL, from, to int, keep func(id chunks.HeadSeriesRef) bool, mint int64) (*CheckpointStats, error)

Checkpoint creates a compacted checkpoint of segments in range [from, to] in the given WAL. It includes the most recent checkpoint if it exists. All series not satisfying keep, samples/tombstones/exemplars below mint and metadata that are not the latest are dropped.

The checkpoint is stored in a directory named checkpoint.N in the same segmented format as the original WAL itself. This makes it easy to read it through the WAL package and concatenate it with the original WAL.

type CorruptionErr 

type CorruptionErr struct {
	Dir     string
	Segment int
	Offset  int64
	Err     error
}

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

func (*CorruptionErr) Error 

func (e *CorruptionErr) Error() string

type LiveReader 

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

LiveReader reads WAL records from an io.Reader. It allows reading of WALs that are still in the process of being written, and returns records as soon as they can be read.

func NewLiveReader 

func NewLiveReader(logger log.Logger, metrics *LiveReaderMetrics, r io.Reader) *LiveReader

NewLiveReader returns a new live reader.

func (*LiveReader) Err 

func (r *LiveReader) Err() error

Err returns any errors encountered reading the WAL. io.EOFs are not terminal and Next can be tried again. Non-EOFs are terminal, and the reader should not be used again. It is up to the user to decide when to stop trying should io.EOF be returned.

func (*LiveReader) Next 

func (r *LiveReader) Next() bool

Next returns true if Record() will contain a full record. If Next returns false, you should always checked the contents of Error(). Return false guarantees there are no more records if the segment is closed and not corrupt, otherwise if Err() == io.EOF you should try again when more data has been written.

func (*LiveReader) Offset 

func (r *LiveReader) Offset() int64

Offset returns the number of bytes consumed from this segment.

func (*LiveReader) Record 

func (r *LiveReader) Record() []byte

Record returns the current record. The returned byte slice is only valid until the next call to Next.

type LiveReaderMetrics 

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

LiveReaderMetrics holds all metrics exposed by the LiveReader.

func NewLiveReaderMetrics 

func NewLiveReaderMetrics(reg prometheus.Registerer) *LiveReaderMetrics

NewLiveReaderMetrics instantiates, registers and returns metrics to be injected at LiveReader instantiation.

type Reader 

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

Reader reads WAL records from an io.Reader.

func NewReader 

func NewReader(r io.Reader) *Reader

NewReader returns a new reader.

func (*Reader) Err 

func (r *Reader) Err() error

Err returns the last encountered error wrapped in a corruption error. If the reader does not allow to infer a segment index and offset, a total offset in the reader stream will be provided.

func (*Reader) Next 

func (r *Reader) Next() bool

Next advances the reader to the next records and returns true if it exists. It must not be called again after it returned false.

func (*Reader) Offset 

func (r *Reader) Offset() int64

Offset returns the current position of the segment being read.

func (*Reader) Record 

func (r *Reader) Record() []byte

Record returns the current record. The returned byte slice is only valid until the next call to Next.

func (*Reader) Segment 

func (r *Reader) Segment() int

Segment returns the current segment being read.

type Segment 

type Segment struct {
	SegmentFile
	// contains filtered or unexported fields
}

Segment represents a segment file.

func CreateSegment 

func CreateSegment(dir string, k int) (*Segment, error)

CreateSegment creates a new segment k in dir.

func OpenReadSegment 

func OpenReadSegment(fn string) (*Segment, error)

OpenReadSegment opens the segment with the given filename.

func OpenWriteSegment 

func OpenWriteSegment(logger log.Logger, dir string, k int) (*Segment, error)

OpenWriteSegment opens segment k in dir. The returned segment is ready for new appends.

func (*Segment) Dir 

func (s *Segment) Dir() string

Dir returns the directory of the segment.

func (*Segment) Index 

func (s *Segment) Index() int

Index returns the index of the segment.

type SegmentFile 

type SegmentFile interface {
	Stat() (os.FileInfo, error)
	Sync() error
	io.Writer
	io.Reader
	io.Closer
}

SegmentFile represents the underlying file used to store a segment.

type SegmentRange 

type SegmentRange struct {
	Dir         string
	First, Last int
}

SegmentRange groups segments by the directory and the first and last index it includes.

type WL 

type WL struct {
	WriteNotified WriteNotified
	// contains filtered or unexported fields
}

WL is a write log that stores records in segment files. It must be read from start to end once before logging new data. If an error occurs during read, the repair procedure must be called before it's safe to do further writes.

Segments are written to in pages of 32KB, with records possibly split across page boundaries. Records are never split across segments to allow full segments to be safely truncated. It also ensures that torn writes never corrupt records beyond the most recent segment.

func New 

func New(logger log.Logger, reg prometheus.Registerer, dir string, compress bool) (*WL, error)

New returns a new WAL over the given directory.

func NewSize 

func NewSize(logger log.Logger, reg prometheus.Registerer, dir string, segmentSize int, compress bool) (*WL, error)

NewSize returns a new write log over the given directory. New segments are created with the specified size.

func Open 

func Open(logger log.Logger, dir string) (*WL, error)

Open an existing WAL.

func (*WL) Close 

func (w *WL) Close() (err error)

Close flushes all writes and closes active segment.

func (*WL) CompressionEnabled 

func (w *WL) CompressionEnabled() bool

CompressionEnabled returns if compression is enabled on this WAL.

func (*WL) Dir 

func (w *WL) Dir() string

Dir returns the directory of the WAL.

func (*WL) LastSegmentAndOffset 

func (w *WL) LastSegmentAndOffset() (seg, offset int, err error)

LastSegmentAndOffset returns the last segment number of the WAL and the offset in that file upto which the segment has been filled.

func (*WL) Log 

func (w *WL) Log(recs ...[]byte) error

Log writes the records into the log. Multiple records can be passed at once to reduce writes and increase throughput.

func (*WL) NextSegment 

func (w *WL) NextSegment() (int, error)

NextSegment creates the next segment and closes the previous one asynchronously. It returns the file number of the new file.

func (*WL) NextSegmentSync 

func (w *WL) NextSegmentSync() (int, error)

NextSegmentSync creates the next segment and closes the previous one in sync. It returns the file number of the new file.

func (*WL) Repair 

func (w *WL) Repair(origErr error) error

Repair attempts to repair the WAL based on the error. It discards all data after the corruption.

func (*WL) SetWriteNotified added in v0.45.0 

func (w *WL) SetWriteNotified(wn WriteNotified)

func (*WL) Size 

func (w *WL) Size() (int64, error)

Size computes the size of the write log. We do this by adding the sizes of all the files under the WAL dir.

func (*WL) Sync 

func (w *WL) Sync() error

Sync forces a file sync on the current write log segment. This function is meant to be used only on tests due to different behaviour on Operating Systems like windows and linux

func (*WL) Truncate 

func (w *WL) Truncate(i int) (err error)

Truncate drops all segments before i.

type Watcher 

type Watcher struct {

	// For testing, stop when we hit this segment.
	MaxSegment int
	// contains filtered or unexported fields
}

Watcher watches the TSDB WAL for a given WriteTo.

func NewWatcher 

func NewWatcher(metrics *WatcherMetrics, readerMetrics *LiveReaderMetrics, logger log.Logger, name string, writer WriteTo, dir string, sendExemplars, sendHistograms bool) *Watcher

NewWatcher creates a new WAL watcher for a given WriteTo.

func (*Watcher) Notify added in v0.45.0 

func (w *Watcher) Notify()

func (*Watcher) Run 

func (w *Watcher) Run() error

Run the watcher, which will tail the WAL until the quit channel is closed or an error case is hit.

func (*Watcher) SetStartTime 

func (w *Watcher) SetStartTime(t time.Time)

func (*Watcher) Start 

func (w *Watcher) Start()

Start the Watcher.

func (*Watcher) Stop 

func (w *Watcher) Stop()

Stop the Watcher.

type WatcherMetrics 

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

func NewWatcherMetrics 

func NewWatcherMetrics(reg prometheus.Registerer) *WatcherMetrics

type WriteNotified added in v0.45.0 

type WriteNotified interface {
	Notify()
}

Used to notifier the watcher that data has been written so that it can read.

type WriteTo 

type WriteTo interface {
	// Append and AppendExemplar should block until the samples are fully accepted,
	// whether enqueued in memory or successfully written to it's final destination.
	// Once returned, the WAL Watcher will not attempt to pass that data again.
	Append([]record.RefSample) bool
	AppendExemplars([]record.RefExemplar) bool
	AppendHistograms([]record.RefHistogramSample) bool
	AppendFloatHistograms([]record.RefFloatHistogramSample) bool
	StoreSeries([]record.RefSeries, int)

	// Next two methods are intended for garbage-collection: first we call
	// UpdateSeriesSegment on all current series
	UpdateSeriesSegment([]record.RefSeries, int)
	// Then SeriesReset is called to allow the deletion
	// of all series created in a segment lower than the argument.
	SeriesReset(int)
}

WriteTo is an interface used by the Watcher to send the samples it's read from the WAL on to somewhere else. Functions will be called concurrently and it is left to the implementer to make sure they are safe.

Source Files

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