prometheus/vendor/github.com/fabxc/tsdb/compact.go
2017-02-20 11:11:44 +01:00

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package tsdb
import (
"os"
"path/filepath"
"time"
"github.com/coreos/etcd/pkg/fileutil"
"github.com/fabxc/tsdb/labels"
"github.com/pkg/errors"
"github.com/prometheus/client_golang/prometheus"
)
type compactor struct {
metrics *compactorMetrics
opts *compactorOptions
}
type compactorMetrics struct {
ran prometheus.Counter
failed prometheus.Counter
duration prometheus.Histogram
}
func newCompactorMetrics(r prometheus.Registerer) *compactorMetrics {
m := &compactorMetrics{}
m.ran = prometheus.NewCounter(prometheus.CounterOpts{
Name: "tsdb_compactions_total",
Help: "Total number of compactions that were executed for the partition.",
})
m.failed = prometheus.NewCounter(prometheus.CounterOpts{
Name: "tsdb_compactions_failed_total",
Help: "Total number of compactions that failed for the partition.",
})
m.duration = prometheus.NewHistogram(prometheus.HistogramOpts{
Name: "tsdb_compaction_duration",
Help: "Duration of compaction runs.",
})
if r != nil {
r.MustRegister(
m.ran,
m.failed,
m.duration,
)
}
return m
}
type compactorOptions struct {
maxBlockRange uint64
}
func newCompactor(r prometheus.Registerer, opts *compactorOptions) *compactor {
return &compactor{
opts: opts,
metrics: newCompactorMetrics(r),
}
}
type compactionInfo struct {
generation int
mint, maxt int64
}
const compactionBlocksLen = 4
// pick returns a range [i, j) in the blocks that are suitable to be compacted
// into a single block at position i.
func (c *compactor) pick(bs []compactionInfo) (i, j int, ok bool) {
if len(bs) == 0 {
return 0, 0, false
}
// First, we always compact pending in-memory blocks oldest first.
for i, b := range bs {
if b.generation > 0 {
continue
}
// Directly compact into 2nd generation with previous generation 1 blocks.
if i+1 >= compactionBlocksLen {
match := true
for _, pb := range bs[i-compactionBlocksLen+1 : i] {
match = match && pb.generation == 1
}
if match {
return i - compactionBlocksLen + 1, i + 1, true
}
}
// If we have enough generation 0 blocks to directly move to the
// 2nd generation, skip generation 1.
if len(bs)-i >= compactionBlocksLen {
// Guard against the newly compacted block becoming larger than
// the previous one.
if i == 0 || bs[i-1].generation >= 2 {
return i, i + compactionBlocksLen, true
}
}
// No optimizations possible, naiively compact the new block.
return i, i + 1, true
}
// Then we care about compacting multiple blocks, starting with the oldest.
for i := 0; i < len(bs)-compactionBlocksLen; i += compactionBlocksLen {
if c.match(bs[i : i+2]) {
return i, i + compactionBlocksLen, true
}
}
return 0, 0, false
}
func (c *compactor) match(bs []compactionInfo) bool {
g := bs[0].generation
if g >= 5 {
return false
}
for _, b := range bs {
if b.generation == 0 {
continue
}
if b.generation != g {
return false
}
}
return uint64(bs[len(bs)-1].maxt-bs[0].mint) <= c.opts.maxBlockRange
}
func mergeBlockMetas(blocks ...Block) (res BlockMeta) {
m0 := blocks[0].Meta()
res.Sequence = m0.Sequence
res.MinTime = m0.MinTime
res.MaxTime = blocks[len(blocks)-1].Meta().MaxTime
g := m0.Compaction.Generation
if g == 0 && len(blocks) > 1 {
g++
}
res.Compaction.Generation = g + 1
for _, b := range blocks {
res.Stats.NumSamples += b.Meta().Stats.NumSamples
}
return res
}
func (c *compactor) compact(dir string, blocks ...Block) (err error) {
start := time.Now()
defer func() {
if err != nil {
c.metrics.failed.Inc()
}
c.metrics.duration.Observe(time.Since(start).Seconds())
}()
if err = os.RemoveAll(dir); err != nil {
return err
}
if err = os.MkdirAll(dir, 0777); err != nil {
return err
}
chunkf, err := os.OpenFile(chunksFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
return errors.Wrap(err, "create chunk file")
}
indexf, err := os.OpenFile(indexFileName(dir), os.O_WRONLY|os.O_CREATE, 0666)
if err != nil {
return errors.Wrap(err, "create index file")
}
indexw := newIndexWriter(indexf)
chunkw := newChunkWriter(chunkf)
if err = c.write(dir, blocks, indexw, chunkw); err != nil {
return errors.Wrap(err, "write compaction")
}
if err = chunkw.Close(); err != nil {
return errors.Wrap(err, "close chunk writer")
}
if err = indexw.Close(); err != nil {
return errors.Wrap(err, "close index writer")
}
if err = fileutil.Fsync(chunkf); err != nil {
return errors.Wrap(err, "fsync chunk file")
}
if err = fileutil.Fsync(indexf); err != nil {
return errors.Wrap(err, "fsync index file")
}
if err = chunkf.Close(); err != nil {
return errors.Wrap(err, "close chunk file")
}
if err = indexf.Close(); err != nil {
return errors.Wrap(err, "close index file")
}
return nil
}
func (c *compactor) write(dir string, blocks []Block, indexw IndexWriter, chunkw ChunkWriter) error {
var set compactionSet
for i, b := range blocks {
all, err := b.Index().Postings("", "")
if err != nil {
return err
}
// TODO(fabxc): find more transparent way of handling this.
if hb, ok := b.(*headBlock); ok {
all = hb.remapPostings(all)
}
s := newCompactionSeriesSet(b.Index(), b.Series(), all)
if i == 0 {
set = s
continue
}
set, err = newCompactionMerger(set, s)
if err != nil {
return err
}
}
// We fully rebuild the postings list index from merged series.
var (
postings = &memPostings{m: make(map[term][]uint32, 512)}
values = map[string]stringset{}
i = uint32(0)
meta = mergeBlockMetas(blocks...)
)
for set.Next() {
lset, chunks := set.At()
if err := chunkw.WriteChunks(chunks...); err != nil {
return err
}
indexw.AddSeries(i, lset, chunks...)
meta.Stats.NumChunks += uint64(len(chunks))
meta.Stats.NumSeries++
for _, l := range lset {
valset, ok := values[l.Name]
if !ok {
valset = stringset{}
values[l.Name] = valset
}
valset.set(l.Value)
postings.add(i, term{name: l.Name, value: l.Value})
}
i++
}
if set.Err() != nil {
return set.Err()
}
s := make([]string, 0, 256)
for n, v := range values {
s = s[:0]
for x := range v {
s = append(s, x)
}
if err := indexw.WriteLabelIndex([]string{n}, s); err != nil {
return err
}
}
for t := range postings.m {
if err := indexw.WritePostings(t.name, t.value, postings.get(t)); err != nil {
return err
}
}
// Write a postings list containing all series.
all := make([]uint32, i)
for i := range all {
all[i] = uint32(i)
}
if err := indexw.WritePostings("", "", newListPostings(all)); err != nil {
return err
}
return writeMetaFile(dir, &meta)
}
type compactionSet interface {
Next() bool
At() (labels.Labels, []ChunkMeta)
Err() error
}
type compactionSeriesSet struct {
p Postings
index IndexReader
series SeriesReader
l labels.Labels
c []ChunkMeta
err error
}
func newCompactionSeriesSet(i IndexReader, s SeriesReader, p Postings) *compactionSeriesSet {
return &compactionSeriesSet{
index: i,
series: s,
p: p,
}
}
func (c *compactionSeriesSet) Next() bool {
if !c.p.Next() {
return false
}
c.l, c.c, c.err = c.index.Series(c.p.At())
if c.err != nil {
return false
}
for i := range c.c {
chk := &c.c[i]
chk.Chunk, c.err = c.series.Chunk(chk.Ref)
if c.err != nil {
return false
}
}
return true
}
func (c *compactionSeriesSet) Err() error {
if c.err != nil {
return c.err
}
return c.p.Err()
}
func (c *compactionSeriesSet) At() (labels.Labels, []ChunkMeta) {
return c.l, c.c
}
type compactionMerger struct {
a, b compactionSet
aok, bok bool
l labels.Labels
c []ChunkMeta
}
type compactionSeries struct {
labels labels.Labels
chunks []ChunkMeta
}
func newCompactionMerger(a, b compactionSet) (*compactionMerger, error) {
c := &compactionMerger{
a: a,
b: b,
}
// Initialize first elements of both sets as Next() needs
// one element look-ahead.
c.aok = c.a.Next()
c.bok = c.b.Next()
return c, c.Err()
}
func (c *compactionMerger) compare() int {
if !c.aok {
return 1
}
if !c.bok {
return -1
}
a, _ := c.a.At()
b, _ := c.b.At()
return labels.Compare(a, b)
}
func (c *compactionMerger) Next() bool {
if !c.aok && !c.bok || c.Err() != nil {
return false
}
d := c.compare()
// Both sets contain the current series. Chain them into a single one.
if d > 0 {
c.l, c.c = c.b.At()
c.bok = c.b.Next()
} else if d < 0 {
c.l, c.c = c.a.At()
c.aok = c.a.Next()
} else {
l, ca := c.a.At()
_, cb := c.b.At()
c.l = l
c.c = append(ca, cb...)
c.aok = c.a.Next()
c.bok = c.b.Next()
}
return true
}
func (c *compactionMerger) Err() error {
if c.a.Err() != nil {
return c.a.Err()
}
return c.b.Err()
}
func (c *compactionMerger) At() (labels.Labels, []ChunkMeta) {
return c.l, c.c
}
func renameDir(from, to string) error {
if err := os.RemoveAll(to); err != nil {
return err
}
if err := os.Rename(from, to); err != nil {
return err
}
// Directory was renamed; sync parent dir to persist rename.
pdir, err := fileutil.OpenDir(filepath.Dir(to))
if err != nil {
return err
}
if err = fileutil.Fsync(pdir); err != nil {
return err
}
if err = pdir.Close(); err != nil {
return err
}
return nil
}