Consolidate mem index into HeadBlock

db.go

@@ -227,13 +227,12 @@ func (s *Shard) appendBatch(samples []hashedSample) error {
 	s.mtx.Lock()
 	defer s.mtx.Unlock()
 
-	var merr MultiError
+	// TODO(fabxc): distinguish samples between concurrent heads for
+	// different time blocks. Those may occurr during transition to still
+	// allow late samples to arrive for a previous block.
+	err := s.head.appendBatch(samples)
 
-	for _, sm := range samples {
-		merr.Add(s.head.append(sm.hash, sm.labels, sm.t, sm.v))
-	}
-
-	// TODO(fabxc): randomize over time
+	// TODO(fabxc): randomize over time and use better scoring function.
 	if s.head.stats.SampleCount/(uint64(s.head.stats.ChunkCount)+1) > 400 {
 		select {
 		case s.persistCh <- struct{}{}:
@@ -246,7 +245,7 @@ func (s *Shard) appendBatch(samples []hashedSample) error {
 		}
 	}
 
-	return merr.Err()
+	return err
 }
 
 func intervalOverlap(amin, amax, bmin, bmax int64) bool {

head.go

@@ -12,9 +12,18 @@ import (
 
 // HeadBlock handles reads and writes of time series data within a time window.
 type HeadBlock struct {
-	mtx   sync.RWMutex
-	descs map[uint64][]*chunkDesc // labels hash to possible chunks descs
-	index *memIndex
+	mtx sync.RWMutex
+
+	// descs holds all chunk descs for the head block. Each chunk implicitly
+	// is assigned the index as its ID.
+	descs []*chunkDesc
+	// hashes contains a collision map of label set hashes of chunks
+	// to their position in the chunk desc slice.
+	hashes map[uint64][]int
+
+	symbols  []string             // all seen strings
+	values   map[string]stringset // label names to possible values
+	postings *memPostings         // postings lists for terms
 
 	stats BlockStats
 }
@@ -22,8 +31,10 @@ type HeadBlock struct {
 // NewHeadBlock creates a new empty head block.
 func NewHeadBlock(baseTime int64) *HeadBlock {
 	b := &HeadBlock{
-		descs: make(map[uint64][]*chunkDesc, 2048),
-		index: newMemIndex(),
+		descs:    []*chunkDesc{},
+		hashes:   map[uint64][]int{},
+		values:   map[string]stringset{},
+		postings: &memPostings{m: make(map[term][]uint32)},
 	}
 	b.stats.MinTime = baseTime
 
@@ -37,11 +48,10 @@ func (h *HeadBlock) Querier(mint, maxt int64) Querier {
 
 // Chunk returns the chunk for the reference number.
 func (h *HeadBlock) Chunk(ref uint32) (chunks.Chunk, error) {
-	c, ok := h.index.forward[ref]
-	if !ok {
+	if int(ref) >= len(h.descs) {
 		return nil, errNotFound
 	}
-	return c.chunk, nil
+	return h.descs[int(ref)].chunk, nil
 }
 
 func (h *HeadBlock) interval() (int64, int64) {
@@ -60,7 +70,7 @@ func (h *HeadBlock) LabelValues(names ...string) (StringTuples, error) {
 	}
 	var sl []string
 
-	for s := range h.index.values[names[0]] {
+	for s := range h.values[names[0]] {
 		sl = append(sl, s)
 	}
 	sort.Strings(sl)
@@ -74,15 +84,16 @@ func (h *HeadBlock) LabelValues(names ...string) (StringTuples, error) {
 
 // Postings returns the postings list iterator for the label pair.
 func (h *HeadBlock) Postings(name, value string) (Postings, error) {
-	return h.index.Postings(term{name, value}), nil
+	return h.postings.get(term{name: name, value: value}), nil
 }
 
 // Series returns the series for the given reference.
 func (h *HeadBlock) Series(ref uint32, mint, maxt int64) (Series, error) {
-	cd, ok := h.index.forward[ref]
-	if !ok {
+	if int(ref) >= len(h.descs) {
 		return nil, errNotFound
 	}
+	cd := h.descs[ref]
+
 	if !intervalOverlap(cd.firsTimestamp, cd.lastTimestamp, mint, maxt) {
 		return nil, nil
 	}
@@ -101,9 +112,10 @@ func (h *HeadBlock) Series(ref uint32, mint, maxt int64) (Series, error) {
 // get retrieves the chunk with the hash and label set and creates
 // a new one if it doesn't exist yet.
 func (h *HeadBlock) get(hash uint64, lset labels.Labels) *chunkDesc {
-	cds := h.descs[hash]
-	for _, cd := range cds {
-		if cd.lset.Equals(lset) {
+	refs := h.hashes[hash]
+
+	for _, ref := range refs {
+		if cd := h.descs[ref]; cd.lset.Equals(lset) {
 			return cd
 		}
 	}
@@ -112,16 +124,44 @@ func (h *HeadBlock) get(hash uint64, lset labels.Labels) *chunkDesc {
 		lset:  lset,
 		chunk: chunks.NewXORChunk(int(math.MaxInt64)),
 	}
-	h.index.add(cd)
+	// Index the new chunk.
+	ref := len(h.descs)
+
+	h.descs = append(h.descs, cd)
+	h.hashes[hash] = append(refs, ref)
+
+	// Add each label pair as a term to the inverted index.
+	terms := make([]term, 0, len(lset))
+
+	for _, l := range lset {
+		terms = append(terms, term{name: l.Name, value: l.Value})
+
+		valset, ok := h.values[l.Name]
+		if !ok {
+			valset = stringset{}
+			h.values[l.Name] = valset
+		}
+		valset.set(l.Value)
+	}
+	h.postings.add(uint32(ref), terms...)
 
 	// For the head block there's exactly one chunk per series.
 	h.stats.ChunkCount++
 	h.stats.SeriesCount++
 
-	h.descs[hash] = append(cds, cd)
 	return cd
 }
 
+func (h *HeadBlock) appendBatch(samples []hashedSample) error {
+	var merr MultiError
+
+	for _, s := range samples {
+		merr.Add(h.append(s.hash, s.labels, s.t, s.v))
+	}
+
+	return merr.Err()
+}
+
 // append adds the sample to the headblock.
 func (h *HeadBlock) append(hash uint64, lset labels.Labels, ts int64, v float64) error {
 	if err := h.get(hash, lset).append(ts, v); err != nil {
@@ -153,8 +193,8 @@ func (h *HeadBlock) persist(p string) (int64, error) {
 	defer sw.Close()
 	defer iw.Close()
 
-	for ref, cd := range h.index.forward {
-		if err := sw.WriteSeries(ref, cd.lset, []*chunkDesc{cd}); err != nil {
+	for ref, cd := range h.descs {
+		if err := sw.WriteSeries(uint32(ref), cd.lset, []*chunkDesc{cd}); err != nil {
 			return 0, err
 		}
 	}
@@ -162,7 +202,7 @@ func (h *HeadBlock) persist(p string) (int64, error) {
 	if err := iw.WriteStats(h.stats); err != nil {
 		return 0, err
 	}
-	for n, v := range h.index.values {
+	for n, v := range h.values {
 		s := make([]string, 0, len(v))
 		for x := range v {
 			s = append(s, x)
@@ -173,8 +213,8 @@ func (h *HeadBlock) persist(p string) (int64, error) {
 		}
 	}
 
-	for t := range h.index.postings.m {
-		if err := iw.WritePostings(t.name, t.value, h.index.postings.get(t)); err != nil {
+	for t := range h.postings.m {
+		if err := iw.WritePostings(t.name, t.value, h.postings.get(t)); err != nil {
 			return 0, err
 		}
 	}

postings.go

@@ -5,64 +5,14 @@ import (
 	"strings"
 )
 
-type memIndex struct {
-	lastID uint32
-
-	forward  map[uint32]*chunkDesc // chunk ID to chunk desc
-	values   map[string]stringset  // label names to possible values
-	postings *memPostings          // postings lists for terms
-}
-
-// newMemIndex returns a new in-memory  index.
-func newMemIndex() *memIndex {
-	return &memIndex{
-		lastID:   0,
-		forward:  make(map[uint32]*chunkDesc),
-		values:   make(map[string]stringset),
-		postings: &memPostings{m: make(map[term][]uint32)},
-	}
-}
-
-func (ix *memIndex) numSeries() int {
-	return len(ix.forward)
-}
-
-func (ix *memIndex) Postings(t term) Postings {
-	return ix.postings.get(t)
+type memPostings struct {
+	m map[term][]uint32
 }
 
 type term struct {
 	name, value string
 }
 
-func (ix *memIndex) add(chkd *chunkDesc) {
-	// Add each label pair as a term to the inverted index.
-	terms := make([]term, 0, len(chkd.lset))
-
-	for _, l := range chkd.lset {
-		terms = append(terms, term{name: l.Name, value: l.Value})
-
-		// Add to label name to values index.
-		valset, ok := ix.values[l.Name]
-		if !ok {
-			valset = stringset{}
-			ix.values[l.Name] = valset
-		}
-		valset.set(l.Value)
-	}
-	ix.lastID++
-	id := ix.lastID
-
-	ix.postings.add(id, terms...)
-
-	// Store forward index for the returned ID.
-	ix.forward[id] = chkd
-}
-
-type memPostings struct {
-	m map[term][]uint32
-}
-
 // Postings returns an iterator over the postings list for s.
 func (p *memPostings) get(t term) Postings {
 	return &listPostings{list: p.m[t], idx: -1}