Properly track and write meta file

block.go

@@ -35,8 +35,11 @@ type Block interface {
 
 // BlockMeta provides meta information about a block.
 type BlockMeta struct {
-	MinTime int64 `json:"minTime,omitempty"`
-	MaxTime int64 `json:"maxTime,omitempty"`
+	// MinTime and MaxTime specify the time range all samples
+	// in the block must be in. If unset, samples can be appended
+	// freely until they are set.
+	MinTime *int64 `json:"minTime,omitempty"`
+	MaxTime *int64 `json:"maxTime,omitempty"`
 
 	Stats struct {
 		NumSamples uint64 `json:"numSamples,omitempty"`
@@ -61,12 +64,48 @@ type persistedBlock struct {
 }
 
 type blockMeta struct {
-	Version int       `json:"version"`
-	Meta    BlockMeta `json:",inline"`
+	*BlockMeta
+	Version int `json:"version"`
 }
 
 const metaFilename = "meta.json"
 
+func readMetaFile(dir string) (*BlockMeta, error) {
+	b, err := ioutil.ReadFile(filepath.Join(dir, metaFilename))
+	if err != nil {
+		return nil, err
+	}
+	var m blockMeta
+
+	if err := json.Unmarshal(b, &m); err != nil {
+		return nil, err
+	}
+	if m.Version != 1 {
+		return nil, errors.Errorf("unexpected meta file version %d", m.Version)
+	}
+
+	return m.BlockMeta, nil
+}
+
+func writeMetaFile(dir string, meta *BlockMeta) error {
+	f, err := os.Create(filepath.Join(dir, metaFilename))
+	if err != nil {
+		return err
+	}
+
+	enc := json.NewEncoder(f)
+	enc.SetIndent("", "\t")
+
+	if err := enc.Encode(&blockMeta{Version: 1, BlockMeta: meta}); err != nil {
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
 func newPersistedBlock(dir string) (*persistedBlock, error) {
 	// TODO(fabxc): validate match of name and stats time, validate magic.
 
@@ -89,22 +128,20 @@ func newPersistedBlock(dir string) (*persistedBlock, error) {
 		return nil, errors.Wrap(err, "create index reader")
 	}
 
+	meta, err := readMetaFile(dir)
+	if err != nil {
+		return nil, err
+	}
+
 	pb := &persistedBlock{
 		dir:     dir,
+		meta:    *meta,
 		chunksf: chunksf,
 		indexf:  indexf,
 		chunkr:  sr,
 		indexr:  ir,
 	}
 
-	b, err := ioutil.ReadFile(filepath.Join(dir, metaFilename))
-	if err != nil {
-		return nil, err
-	}
-	if err := json.Unmarshal(b, &pb.meta); err != nil {
-		return nil, err
-	}
-
 	return pb, nil
 }
 

compact.go

@@ -147,13 +147,10 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 		return errors.Wrap(err, "create index file")
 	}
 
-	indexw, err := newIndexWriter(indexf)
-	if err != nil {
-		return errors.Wrap(err, "open index writer")
-	}
+	indexw := newIndexWriter(indexf)
 	chunkw := newSeriesWriter(chunkf, indexw)
 
-	if err = c.write(blocks, indexw, chunkw); err != nil {
+	if err = c.write(dir, blocks, indexw, chunkw); err != nil {
 		return errors.Wrap(err, "write compaction")
 	}
 
@@ -178,7 +175,7 @@ func (c *compactor) compact(dir string, blocks ...Block) (err error) {
 	return nil
 }
 
-func (c *compactor) write(blocks []Block, indexw IndexWriter, chunkw SeriesWriter) error {
+func (c *compactor) write(dir string, blocks []Block, indexw IndexWriter, chunkw SeriesWriter) error {
 	var set compactionSet
 
 	for i, b := range blocks {
@@ -260,7 +257,8 @@ func (c *compactor) write(blocks []Block, indexw IndexWriter, chunkw SeriesWrite
 	if err := indexw.WritePostings("", "", newListPostings(all)); err != nil {
 		return err
 	}
-	return nil
+
+	return writeMetaFile(dir, &meta)
 }
 
 type compactionSet interface {

db.go

@@ -281,7 +281,7 @@ func (db *DB) initBlocks() error {
 
 	for _, dir := range dirs {
 		if fileutil.Exist(filepath.Join(dir, walFileName)) {
-			h, err := openHeadBlock(dir, db.logger, nil)
+			h, err := openHeadBlock(dir, db.logger)
 			if err != nil {
 				return err
 			}
@@ -365,7 +365,6 @@ func (a *dbAppender) Add(ref uint64, t int64, v float64) error {
 	if gen != a.gen {
 		return ErrNotFound
 	}
-	a.db.metrics.samplesAppended.Inc()
 
 	return a.head.Add(ref, t, v)
 }
@@ -426,13 +425,12 @@ func (db *DB) blocksForInterval(mint, maxt int64) []Block {
 
 	for _, b := range db.persisted {
 		m := b.Meta()
-		if intervalOverlap(mint, maxt, m.MinTime, m.MaxTime) {
+		if intervalOverlap(mint, maxt, *m.MinTime, *m.MaxTime) {
 			bs = append(bs, b)
 		}
 	}
 	for _, b := range db.heads {
-		m := b.Meta()
-		if intervalOverlap(mint, maxt, m.MinTime, m.MaxTime) {
+		if intervalOverlap(mint, maxt, b.mint, b.maxt) {
 			bs = append(bs, b)
 		}
 	}
@@ -443,22 +441,33 @@ func (db *DB) blocksForInterval(mint, maxt int64) []Block {
 // cut starts a new head block to append to. The completed head block
 // will still be appendable for the configured grace period.
 func (db *DB) cut() (*headBlock, error) {
+	var mint *int64
+
+	// If a previous block exists, fix its max time and and take the
+	// timestamp after as the minimum for the new head.
+	if len(db.heads) > 0 {
+		cur := db.heads[len(db.heads)-1]
+
+		cur.metamtx.Lock()
+
+		if cur.meta.MinTime == nil {
+			mt := cur.mint
+			cur.meta.MinTime = &mt
+		}
+		cur.meta.MaxTime = new(int64)
+
+		mt := cur.maxt + 1
+		cur.meta.MaxTime = &mt
+		mint = &mt
+
+		cur.metamtx.Unlock()
+	}
+
 	dir, err := nextBlockDir(db.dir)
 	if err != nil {
 		return nil, err
 	}
-
-	// If its not the very first head block, all its samples must not be
-	// larger than
-	var minTime *int64
-
-	if len(db.heads) > 0 {
-		cb := db.heads[len(db.heads)-1]
-		minTime = new(int64)
-		*minTime = cb.Meta().MaxTime + 1
-	}
-
-	newHead, err := openHeadBlock(dir, db.logger, minTime)
+	newHead, err := createHeadBlock(dir, db.logger, mint)
 	if err != nil {
 		return nil, err
 	}

head.go

@@ -1,13 +1,10 @@
 package tsdb
 
 import (
-	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"math"
 	"math/rand"
 	"os"
-	"path/filepath"
 	"sort"
 	"sync"
 	"time"
@@ -40,10 +37,7 @@ var (
 type headBlock struct {
 	mtx sync.RWMutex
 	dir string
-
-	// Head blocks are initialized with a minimum timestamp if they were preceded
-	// by another block. Appended samples must not have a smaller timestamp than this.
-	minTime *int64
+	wal *WAL
 
 	// descs holds all chunk descs for the head block. Each chunk implicitly
 	// is assigned the index as its ID.
@@ -58,14 +52,24 @@ type headBlock struct {
 	values   map[string]stringset // label names to possible values
 	postings *memPostings         // postings lists for terms
 
-	wal *WAL
+	metamtx    sync.RWMutex
+	meta       BlockMeta
+	mint, maxt int64 // timestamp range of current samples
+}
 
-	metamtx sync.RWMutex
-	meta    BlockMeta
+func createHeadBlock(dir string, l log.Logger, minTime *int64) (*headBlock, error) {
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return nil, err
+	}
+
+	if err := writeMetaFile(dir, &BlockMeta{MinTime: minTime}); err != nil {
+		return nil, err
+	}
+	return openHeadBlock(dir, l)
 }
 
 // openHeadBlock creates a new empty head block.
-func openHeadBlock(dir string, l log.Logger, minTime *int64) (*headBlock, error) {
+func openHeadBlock(dir string, l log.Logger) (*headBlock, error) {
 	if err := os.MkdirAll(dir, 0755); err != nil {
 		return nil, err
 	}
@@ -74,24 +78,22 @@ func openHeadBlock(dir string, l log.Logger, minTime *int64) (*headBlock, error)
 	if err != nil {
 		return nil, err
 	}
+	meta, err := readMetaFile(dir)
+	if err != nil {
+		return nil, err
+	}
 
 	h := &headBlock{
 		dir:      dir,
-		minTime:  minTime,
+		wal:      wal,
 		series:   []*memSeries{},
 		hashes:   map[uint64][]*memSeries{},
 		values:   map[string]stringset{},
 		postings: &memPostings{m: make(map[term][]uint32)},
-		wal:      wal,
 		mapper:   newPositionMapper(nil),
-	}
-
-	b, err := ioutil.ReadFile(filepath.Join(dir, metaFilename))
-	if err != nil {
-		return nil, err
-	}
-	if err := json.Unmarshal(b, &h.meta); err != nil {
-		return nil, err
+		meta:     *meta,
+		mint:     math.MaxInt64,
+		maxt:     math.MinInt64,
 	}
 
 	// Replay contents of the write ahead log.
@@ -99,23 +101,22 @@ func openHeadBlock(dir string, l log.Logger, minTime *int64) (*headBlock, error)
 		series: func(lset labels.Labels) error {
 			h.create(lset.Hash(), lset)
 			h.meta.Stats.NumSeries++
-
 			return nil
 		},
 		sample: func(s refdSample) error {
 			h.series[s.ref].append(s.t, s.v)
 
-			if h.minTime != nil && s.t < *h.minTime {
-				return errors.Errorf("sample earlier than minimum timestamp %d", *h.minTime)
+			if !h.inBounds(s.t) {
+				return ErrOutOfBounds
 			}
-			if s.t < h.meta.MinTime {
-				h.meta.MinTime = s.t
+
+			if s.t < h.mint {
+				h.mint = s.t
 			}
-			if s.t > h.meta.MaxTime {
-				h.meta.MaxTime = s.t
+			if s.t > h.maxt {
+				h.maxt = s.t
 			}
 			h.meta.Stats.NumSamples++
-
 			return nil
 		},
 	}); err != nil {
@@ -127,6 +128,12 @@ func openHeadBlock(dir string, l log.Logger, minTime *int64) (*headBlock, error)
 	return h, nil
 }
 
+// inBounds returns true if the given timestamp is within the valid
+// time bounds of the block.
+func (h *headBlock) inBounds(t int64) bool {
+	return h.meta.MinTime != nil && t < *h.meta.MinTime
+}
+
 // Close syncs all data and closes underlying resources of the head block.
 func (h *headBlock) Close() error {
 	return h.wal.Close()
@@ -294,12 +301,6 @@ func (a *headAppender) Commit() error {
 
 	a.createSeries()
 
-	var (
-		total = uint64(len(a.samples))
-		mint  = int64(math.MaxInt64)
-		maxt  = int64(math.MinInt64)
-	)
-
 	for i := range a.samples {
 		s := &a.samples[i]
 
@@ -315,10 +316,22 @@ func (a *headAppender) Commit() error {
 		return err
 	}
 
+	var (
+		total = uint64(len(a.samples))
+		mint  = int64(math.MaxInt64)
+		maxt  = int64(math.MinInt64)
+	)
+
 	for _, s := range a.samples {
 		if !a.series[s.ref].append(s.t, s.v) {
 			total--
 		}
+		if s.t < mint {
+			mint = s.t
+		}
+		if s.t > maxt {
+			maxt = s.t
+		}
 	}
 
 	a.mtx.RUnlock()
@@ -329,11 +342,11 @@ func (a *headAppender) Commit() error {
 	a.meta.Stats.NumSamples += total
 	a.meta.Stats.NumSeries += uint64(len(a.newSeries))
 
-	if mint < a.meta.MinTime {
-		a.meta.MinTime = mint
+	if mint < a.mint {
+		a.mint = mint
 	}
-	if maxt > a.meta.MaxTime {
-		a.meta.MaxTime = maxt
+	if maxt > a.maxt {
+		a.maxt = maxt
 	}
 
 	return nil

reader.go

@@ -178,14 +178,17 @@ func (r *indexReader) section(o uint32) (byte, []byte, error) {
 }
 
 func (r *indexReader) lookupSymbol(o uint32) (string, error) {
+	if int(o) > len(r.b) {
+		return "", errors.Errorf("invalid symbol offset %d", o)
+	}
 	l, n := binary.Uvarint(r.b[o:])
 	if n < 0 {
-		return "", fmt.Errorf("reading symbol length failed")
+		return "", errors.New("reading symbol length failed")
 	}
 
 	end := int(o) + n + int(l)
 	if end > len(r.b) {
-		return "", fmt.Errorf("invalid length")
+		return "", errors.New("invalid length")
 	}
 	b := r.b[int(o)+n : end]
 

writer.go

@@ -191,15 +191,14 @@ type indexWriter struct {
 	postings     []hashEntry       // postings lists offsets
 }
 
-func newIndexWriter(w io.Writer) (*indexWriter, error) {
-	ix := &indexWriter{
+func newIndexWriter(w io.Writer) *indexWriter {
+	return &indexWriter{
 		w:       ioutil.NewPageWriter(w, compactionPageBytes, 0),
 		ow:      w,
 		n:       0,
 		symbols: make(map[string]uint32, 4096),
 		series:  make(map[uint32]*indexWriterSeries, 4096),
 	}
-	return ix, ix.writeMeta()
 }
 
 func (w *indexWriter) write(wr io.Writer, b []byte) error {
@@ -336,6 +335,19 @@ func (w *indexWriter) writeSeries() error {
 }
 
 func (w *indexWriter) WriteLabelIndex(names []string, values []string) error {
+	if !w.started {
+		if err := w.writeMeta(); err != nil {
+			return err
+		}
+		if err := w.writeSymbols(); err != nil {
+			return err
+		}
+		if err := w.writeSeries(); err != nil {
+			return err
+		}
+		w.started = true
+	}
+
 	valt, err := newStringTuples(values, len(names))
 	if err != nil {
 		return err