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series_cursor.go
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/
series_cursor.go
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package storage
import (
"context"
"errors"
"sort"
"github.com/influxdata/influxdb/models"
"github.com/influxdata/influxdb/query"
"github.com/influxdata/influxdb/tsdb"
"github.com/influxdata/influxql"
"github.com/opentracing/opentracing-go"
)
const measurementKey = "_measurement"
var (
measurementKeyBytes = []byte(measurementKey)
fieldKeyBytes = []byte("_field")
)
type seriesCursor interface {
Close()
Next() *seriesRow
Err() error
}
type seriesRow struct {
sortKey []byte
name []byte // measurement name
stags models.Tags // unmodified series tags
field field
tags models.Tags
query tsdb.CursorIterators
valueCond influxql.Expr
}
type mapValuer map[string]string
var _ influxql.Valuer = mapValuer(nil)
func (vs mapValuer) Value(key string) (interface{}, bool) {
v, ok := vs[key]
return v, ok
}
type indexSeriesCursor struct {
sqry tsdb.SeriesCursor
fields measurementFields
nf []field
err error
tags models.Tags
cond influxql.Expr
measurementCond influxql.Expr
row seriesRow
eof bool
hasFieldExpr bool
hasValueExpr bool
}
func newIndexSeriesCursor(ctx context.Context, predicate *Predicate, shards []*tsdb.Shard) (*indexSeriesCursor, error) {
queries, err := tsdb.CreateCursorIterators(ctx, shards)
if err != nil {
return nil, err
}
if queries == nil {
return nil, nil
}
span := opentracing.SpanFromContext(ctx)
if span != nil {
span = opentracing.StartSpan("index_cursor.create", opentracing.ChildOf(span.Context()))
defer span.Finish()
}
opt := query.IteratorOptions{
Aux: []influxql.VarRef{{Val: "key"}},
Authorizer: query.OpenAuthorizer,
Ascending: true,
Ordered: true,
}
p := &indexSeriesCursor{row: seriesRow{query: queries}}
if root := predicate.GetRoot(); root != nil {
if p.cond, err = NodeToExpr(root, measurementRemap); err != nil {
return nil, err
}
p.hasFieldExpr, p.hasValueExpr = HasFieldKeyOrValue(p.cond)
if !(p.hasFieldExpr || p.hasValueExpr) {
p.measurementCond = p.cond
opt.Condition = p.cond
} else {
p.measurementCond = influxql.Reduce(RewriteExprRemoveFieldValue(influxql.CloneExpr(p.cond)), nil)
if isBooleanLiteral(p.measurementCond) {
p.measurementCond = nil
}
opt.Condition = influxql.Reduce(RewriteExprRemoveFieldKeyAndValue(influxql.CloneExpr(p.cond)), nil)
if isBooleanLiteral(opt.Condition) {
opt.Condition = nil
}
}
}
var mitr tsdb.MeasurementIterator
name, singleMeasurement := HasSingleMeasurementNoOR(p.measurementCond)
if singleMeasurement {
mitr = tsdb.NewMeasurementSliceIterator([][]byte{[]byte(name)})
}
sg := tsdb.Shards(shards)
p.sqry, err = sg.CreateSeriesCursor(ctx, tsdb.SeriesCursorRequest{Measurements: mitr}, opt.Condition)
if p.sqry != nil && err == nil {
// Optimisation to check if request is only interested in results for a
// single measurement. In this case we can efficiently produce all known
// field keys from the collection of shards without having to go via
// the query engine.
if singleMeasurement {
fkeys := sg.FieldKeysByMeasurement([]byte(name))
if len(fkeys) == 0 {
goto CLEANUP
}
fields := make([]field, 0, len(fkeys))
for _, key := range fkeys {
fields = append(fields, field{n: key, nb: []byte(key)})
}
p.fields = map[string][]field{name: fields}
return p, nil
}
var (
itr query.Iterator
fi query.FloatIterator
)
if itr, err = sg.CreateIterator(ctx, &influxql.Measurement{SystemIterator: "_fieldKeys"}, opt); itr != nil && err == nil {
if fi, err = toFloatIterator(itr); err != nil {
goto CLEANUP
}
p.fields = extractFields(fi)
fi.Close()
return p, nil
}
}
CLEANUP:
p.Close()
return nil, err
}
func (c *indexSeriesCursor) Close() {
if !c.eof {
c.eof = true
if c.sqry != nil {
c.sqry.Close()
c.sqry = nil
}
}
}
func copyTags(dst, src models.Tags) models.Tags {
if cap(dst) < src.Len() {
dst = make(models.Tags, src.Len())
} else {
dst = dst[:src.Len()]
}
copy(dst, src)
return dst
}
func (c *indexSeriesCursor) Next() *seriesRow {
if c.eof {
return nil
}
RETRY:
if len(c.nf) == 0 {
// next series key
sr, err := c.sqry.Next()
if err != nil {
c.err = err
c.Close()
return nil
} else if sr == nil {
c.Close()
return nil
}
c.row.name = sr.Name
c.row.stags = sr.Tags
c.tags = copyTags(c.tags, sr.Tags)
c.tags.Set(measurementKeyBytes, sr.Name)
c.nf = c.fields[string(sr.Name)]
}
c.row.field, c.nf = c.nf[0], c.nf[1:]
if c.measurementCond != nil && !evalExprBool(c.measurementCond, c) {
goto RETRY
}
c.tags.Set(fieldKeyBytes, c.row.field.nb)
if c.cond != nil && c.hasValueExpr {
// TODO(sgc): lazily evaluate valueCond
c.row.valueCond = influxql.Reduce(c.cond, c)
if isBooleanLiteral(c.row.valueCond) {
// we've reduced the expression to "true"
c.row.valueCond = nil
}
}
c.row.tags = copyTags(c.row.tags, c.tags)
return &c.row
}
func (c *indexSeriesCursor) Value(key string) (interface{}, bool) {
switch key {
case "_name":
return c.row.name, true
case "_field":
return c.row.field.n, true
default:
res := c.row.stags.Get([]byte(key))
return res, res != nil
}
}
func (c *indexSeriesCursor) Err() error {
return c.err
}
type limitSeriesCursor struct {
seriesCursor
n, o, c int64
}
func newLimitSeriesCursor(ctx context.Context, cur seriesCursor, n, o int64) *limitSeriesCursor {
return &limitSeriesCursor{seriesCursor: cur, o: o, n: n}
}
func (c *limitSeriesCursor) Next() *seriesRow {
if c.o > 0 {
for i := int64(0); i < c.o; i++ {
if c.seriesCursor.Next() == nil {
break
}
}
c.o = 0
}
if c.c >= c.n {
return nil
}
c.c++
return c.seriesCursor.Next()
}
func isBooleanLiteral(expr influxql.Expr) bool {
_, ok := expr.(*influxql.BooleanLiteral)
return ok
}
func toFloatIterator(iter query.Iterator) (query.FloatIterator, error) {
sitr, ok := iter.(query.FloatIterator)
if !ok {
return nil, errors.New("expected FloatIterator")
}
return sitr, nil
}
type measurementFields map[string][]field
type field struct {
n string
nb []byte
}
func extractFields(itr query.FloatIterator) measurementFields {
mf := make(measurementFields)
for {
p, err := itr.Next()
if err != nil {
return nil
} else if p == nil {
break
}
// Aux is populated by `fieldKeysIterator#Next`
fields := append(mf[p.Name], field{
n: p.Aux[0].(string),
})
mf[p.Name] = fields
}
if len(mf) == 0 {
return nil
}
for k, fields := range mf {
sort.Slice(fields, func(i, j int) bool {
return fields[i].n < fields[j].n
})
// deduplicate
i := 1
fields[0].nb = []byte(fields[0].n)
for j := 1; j < len(fields); j++ {
if fields[j].n != fields[j-1].n {
fields[i] = fields[j]
fields[i].nb = []byte(fields[i].n)
i++
}
}
mf[k] = fields[:i]
}
return mf
}