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Move index values cache to bucket level to prevent race condition #306

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Move index values cache to bucket level to prevent race condition #306

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31 changes: 6 additions & 25 deletions pkg/block/indexheader/binary_reader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -418,8 +418,6 @@ type postingOffset struct {
tableOff int
}

const valueSymbolsCacheSize = 1024

type BinaryReader struct {
b index.ByteSlice
toc *BinaryTOC
Expand All @@ -438,12 +436,6 @@ type BinaryReader struct {
// Cache of the label name symbol lookups,
// as there are not many and they are half of all lookups.
nameSymbols map[uint32]string
// Direct cache of values. This is much faster than an LRU cache and still provides
// a reasonable cache hit ratio.
valueSymbols [valueSymbolsCacheSize]struct {
index uint32
symbol string
}

dec *index.Decoder

Expand Down Expand Up @@ -646,12 +638,12 @@ func newBinaryTOCFromByteSlice(bs index.ByteSlice) (*BinaryTOC, error) {
}, nil
}

func (r BinaryReader) IndexVersion() (int, error) {
func (r *BinaryReader) IndexVersion() (int, error) {
return r.indexVersion, nil
}

// TODO(bwplotka): Get advantage of multi value offset fetch.
func (r BinaryReader) PostingsOffset(name string, value string) (index.Range, error) {
func (r *BinaryReader) PostingsOffset(name string, value string) (index.Range, error) {
rngs, err := r.postingsOffset(name, value)
if err != nil {
return index.Range{}, err
Expand All @@ -674,7 +666,7 @@ func skipNAndName(d *encoding.Decbuf, buf *int) {
}
d.Skip(*buf)
}
func (r BinaryReader) postingsOffset(name string, values ...string) ([]index.Range, error) {
func (r *BinaryReader) postingsOffset(name string, values ...string) ([]index.Range, error) {
rngs := make([]index.Range, 0, len(values))
if r.indexVersion == index.FormatV1 {
e, ok := r.postingsV1[name]
Expand Down Expand Up @@ -811,11 +803,6 @@ func (r BinaryReader) postingsOffset(name string, values ...string) ([]index.Ran
}

func (r *BinaryReader) LookupSymbol(o uint32) (string, error) {
cacheIndex := o % valueSymbolsCacheSize
if cached := r.valueSymbols[cacheIndex]; cached.index == o && cached.symbol != "" {
return cached.symbol, nil
}

if s, ok := r.nameSymbols[o]; ok {
return s, nil
}
Expand All @@ -826,16 +813,10 @@ func (r *BinaryReader) LookupSymbol(o uint32) (string, error) {
o += headerLen - index.HeaderLen
}

s, err := r.symbols.Lookup(o)
if err != nil {
return s, err
}
r.valueSymbols[cacheIndex].index = o
r.valueSymbols[cacheIndex].symbol = s
return s, nil
return r.symbols.Lookup(o)
}

func (r BinaryReader) LabelValues(name string) ([]string, error) {
func (r *BinaryReader) LabelValues(name string) ([]string, error) {
if r.indexVersion == index.FormatV1 {
e, ok := r.postingsV1[name]
if !ok {
Expand Down Expand Up @@ -891,7 +872,7 @@ func yoloString(b []byte) string {
return *((*string)(unsafe.Pointer(&b)))
}

func (r BinaryReader) LabelNames() ([]string, error) {
func (r *BinaryReader) LabelNames() ([]string, error) {
allPostingsKeyName, _ := index.AllPostingsKey()
labelNames := make([]string, 0, len(r.postings))
for name := range r.postings {
Expand Down
41 changes: 38 additions & 3 deletions pkg/store/bucket.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1365,6 +1365,15 @@ func (s *bucketBlockSet) labelMatchers(matchers ...*labels.Matcher) ([]*labels.M
return res, true
}

const valueSymbolsCacheSize = 1024

var zeroIndexSymbol = indexSymbol{index: 0, symbol: ""}

type indexSymbol struct {
index uint32
symbol string
}

// bucketBlock represents a block that is located in a bucket. It holds intermediate
// state for the block on local disk.
type bucketBlock struct {
Expand All @@ -1388,6 +1397,9 @@ type bucketBlock struct {
// Block's labels used by block-level matchers to filter blocks to query. These are used to select blocks using
// request hints' BlockMatchers.
relabelLabels labels.Labels

valuesMutex sync.RWMutex
valueSymbols [valueSymbolsCacheSize]indexSymbol
}

func newBucketBlock(
Expand Down Expand Up @@ -1535,6 +1547,7 @@ type bucketIndexReader struct {

mtx sync.Mutex
loadedSeries map[uint64][]byte
valueSymbols [valueSymbolsCacheSize]indexSymbol
}

func newBucketIndexReader(ctx context.Context, block *bucketBlock) *bucketIndexReader {
Expand All @@ -1547,6 +1560,11 @@ func newBucketIndexReader(ctx context.Context, block *bucketBlock) *bucketIndexR
stats: &queryStats{},
loadedSeries: map[uint64][]byte{},
}
block.valuesMutex.RLock()
for k, v := range block.valueSymbols {
r.valueSymbols[k] = v
}
block.valuesMutex.RUnlock()
return r
}

Expand Down Expand Up @@ -2104,6 +2122,15 @@ func (r *bucketIndexReader) LoadSeriesForTime(ref uint64, lset *[]symbolizedLabe
// Close released the underlying resources of the reader.
func (r *bucketIndexReader) Close() error {
r.block.pendingReaders.Done()

r.block.valuesMutex.Lock()
for k, v := range r.valueSymbols {
// Only update the cache if the block cache entry is not set.
if v != zeroIndexSymbol && r.block.valueSymbols[k] == zeroIndexSymbol {
r.block.valueSymbols[k] = v
}
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This might be a problem. Not sure which way is better. Overwrite the entry every time?

}
r.block.valuesMutex.Unlock()
return nil
}

Expand All @@ -2115,9 +2142,17 @@ func (r *bucketIndexReader) LookupLabelsSymbols(symbolized []symbolizedLabel, lb
if err != nil {
return errors.Wrap(err, "lookup label name")
}
lv, err := r.dec.LookupSymbol(s.value)
if err != nil {
return errors.Wrap(err, "lookup label value")
var lv string
cacheIndex := s.value % valueSymbolsCacheSize
if cached := r.valueSymbols[cacheIndex]; cached.index == s.value && cached.symbol != "" {
lv = cached.symbol
} else {
lv, err = r.dec.LookupSymbol(s.value)
if err != nil {
return errors.Wrap(err, "lookup label value")
}
r.valueSymbols[cacheIndex].index = s.value
r.valueSymbols[cacheIndex].symbol = lv
}
*lbls = append(*lbls, labels.Label{Name: ln, Value: lv})
}
Expand Down