forked from thanos-io/thanos
/
streamed_block_writer.go
265 lines (223 loc) · 7.63 KB
/
streamed_block_writer.go
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package downsample
import (
"io"
"path/filepath"
"github.com/go-kit/kit/log"
"github.com/go-kit/kit/log/level"
"github.com/improbable-eng/thanos/pkg/block"
"github.com/improbable-eng/thanos/pkg/block/metadata"
"github.com/improbable-eng/thanos/pkg/runutil"
"github.com/pkg/errors"
"github.com/prometheus/tsdb"
"github.com/prometheus/tsdb/chunks"
"github.com/prometheus/tsdb/fileutil"
"github.com/prometheus/tsdb/index"
"github.com/prometheus/tsdb/labels"
)
type labelValues map[string]struct{}
func (lv labelValues) add(value string) {
lv[value] = struct{}{}
}
func (lv labelValues) get(set *[]string) {
for value := range lv {
*set = append(*set, value)
}
}
type labelsValues map[string]labelValues
func (lv labelsValues) add(labelSet labels.Labels) {
for _, label := range labelSet {
values, ok := lv[label.Name]
if !ok {
// Add new label.
values = labelValues{}
lv[label.Name] = values
}
values.add(label.Value)
}
}
// streamedBlockWriter writes downsampled blocks to a new data block. Implemented to save memory consumption
// by writing chunks data right into the files, omitting keeping them in-memory. Index and meta data should be
// sealed afterwards, when there aren't more series to process.
type streamedBlockWriter struct {
blockDir string
finalized bool // set to true, if Close was called
logger log.Logger
ignoreFinalize bool // if true Close does not finalize block due to internal error.
meta metadata.Meta
totalChunks uint64
totalSamples uint64
chunkWriter tsdb.ChunkWriter
indexWriter tsdb.IndexWriter
indexReader tsdb.IndexReader
closers []io.Closer
labelsValues labelsValues // labelsValues list of used label sets: name -> []values.
memPostings *index.MemPostings // memPostings contains references from label name:value -> postings.
postings uint64 // postings is a current posting position.
}
// NewStreamedBlockWriter returns streamedBlockWriter instance, it's not concurrency safe.
// Caller is responsible to Close all io.Closers by calling the Close when downsampling is done.
// In case if error happens outside of the StreamedBlockWriter during the processing,
// index and meta files will be written anyway, so the caller is always responsible for removing block directory with
// a garbage on error.
// This approach simplifies StreamedBlockWriter interface, which is a best trade-off taking into account the error is an
// exception, not a general case.
func NewStreamedBlockWriter(
blockDir string,
indexReader tsdb.IndexReader,
logger log.Logger,
originMeta metadata.Meta,
) (w *streamedBlockWriter, err error) {
closers := make([]io.Closer, 0, 2)
// We should close any opened Closer up to an error.
defer func() {
if err != nil {
var merr tsdb.MultiError
merr.Add(err)
for _, cl := range closers {
merr.Add(cl.Close())
}
err = merr.Err()
}
}()
chunkWriter, err := chunks.NewWriter(filepath.Join(blockDir, block.ChunksDirname))
if err != nil {
return nil, errors.Wrap(err, "create chunk writer in streamedBlockWriter")
}
closers = append(closers, chunkWriter)
indexWriter, err := index.NewWriter(filepath.Join(blockDir, block.IndexFilename))
if err != nil {
return nil, errors.Wrap(err, "open index writer in streamedBlockWriter")
}
closers = append(closers, indexWriter)
symbols, err := indexReader.Symbols()
if err != nil {
return nil, errors.Wrap(err, "read symbols")
}
err = indexWriter.AddSymbols(symbols)
if err != nil {
return nil, errors.Wrap(err, "add symbols")
}
return &streamedBlockWriter{
logger: logger,
blockDir: blockDir,
indexReader: indexReader,
indexWriter: indexWriter,
chunkWriter: chunkWriter,
meta: originMeta,
closers: closers,
labelsValues: make(labelsValues, 1024),
memPostings: index.NewUnorderedMemPostings(),
}, nil
}
// WriteSeries writes chunks data to the chunkWriter, writes lset and chunks Metas to indexWrites and adds label sets to
// labelsValues sets and memPostings to be written on the finalize state in the end of downsampling process.
func (w *streamedBlockWriter) WriteSeries(lset labels.Labels, chunks []chunks.Meta) error {
if w.finalized || w.ignoreFinalize {
return errors.Errorf("series can't be added, writers has been closed or internal error happened")
}
if len(chunks) == 0 {
level.Warn(w.logger).Log("empty chunks happened, skip series", lset)
return nil
}
if err := w.chunkWriter.WriteChunks(chunks...); err != nil {
w.ignoreFinalize = true
return errors.Wrap(err, "add chunks")
}
if err := w.indexWriter.AddSeries(w.postings, lset, chunks...); err != nil {
w.ignoreFinalize = true
return errors.Wrap(err, "add series")
}
w.labelsValues.add(lset)
w.memPostings.Add(w.postings, lset)
w.postings++
w.totalChunks += uint64(len(chunks))
for i := range chunks {
w.totalSamples += uint64(chunks[i].Chunk.NumSamples())
}
return nil
}
// Close calls finalizer to complete index and meta files and closes all io.CLoser writers.
// Idempotent.
func (w *streamedBlockWriter) Close() error {
if w.finalized {
return nil
}
var merr tsdb.MultiError
w.finalized = true
// Finalise data block only if there wasn't any internal errors.
if !w.ignoreFinalize {
merr.Add(w.finalize())
}
for _, cl := range w.closers {
merr.Add(cl.Close())
}
return errors.Wrap(merr.Err(), "close closers")
}
// finalize saves prepared index and meta data to corresponding files.
// It is called on Close. Even if an error happened outside of StreamWriter, it will finalize the block anyway,
// so it's a caller's responsibility to remove the block's directory.
func (w *streamedBlockWriter) finalize() error {
if err := w.writeLabelSets(); err != nil {
return errors.Wrap(err, "write label sets")
}
if err := w.writeMemPostings(); err != nil {
return errors.Wrap(err, "write mem postings")
}
if err := w.writeMetaFile(); err != nil {
return errors.Wrap(err, "write meta meta")
}
if err := w.syncDir(); err != nil {
return errors.Wrap(err, "sync blockDir")
}
level.Info(w.logger).Log(
"msg", "write downsampled block",
"mint", w.meta.MinTime,
"maxt", w.meta.MaxTime,
"ulid", w.meta.ULID,
"resolution", w.meta.Thanos.Downsample.Resolution,
)
return nil
}
// syncDir syncs blockDir on disk.
func (w *streamedBlockWriter) syncDir() (err error) {
df, err := fileutil.OpenDir(w.blockDir)
if err != nil {
return errors.Wrap(err, "open temporary block blockDir")
}
defer runutil.CloseWithErrCapture(w.logger, &err, df, "close temporary block blockDir")
if err := fileutil.Fsync(df); err != nil {
return errors.Wrap(err, "sync temporary blockDir")
}
return nil
}
// writeLabelSets fills the index writer with label sets.
func (w *streamedBlockWriter) writeLabelSets() error {
s := make([]string, 0, 256)
for n, v := range w.labelsValues {
s = s[:0]
v.get(&s)
if err := w.indexWriter.WriteLabelIndex([]string{n}, s); err != nil {
return errors.Wrap(err, "write label index")
}
}
return nil
}
// writeMemPostings fills the index writer with mem postings.
func (w *streamedBlockWriter) writeMemPostings() error {
w.memPostings.EnsureOrder()
for _, l := range w.memPostings.SortedKeys() {
if err := w.indexWriter.WritePostings(l.Name, l.Value, w.memPostings.Get(l.Name, l.Value)); err != nil {
return errors.Wrap(err, "write postings")
}
}
return nil
}
// writeMetaFile writes meta file.
func (w *streamedBlockWriter) writeMetaFile() error {
w.meta.Version = metadata.MetaVersion1
w.meta.Thanos.Source = metadata.CompactorSource
w.meta.Stats.NumChunks = w.totalChunks
w.meta.Stats.NumSamples = w.totalSamples
w.meta.Stats.NumSeries = w.postings
return metadata.Write(w.logger, w.blockDir, &w.meta)
}