Golang influxql.RewriteExpr函數代碼示例

// NewTagValuesIterator returns a new instance of TagValuesIterator.
func NewTagValuesIterator(sh *Shard, opt influxql.IteratorOptions) (influxql.Iterator, error) {
	if opt.Condition == nil {
		return nil, errors.New("a condition is required")
	}

	mms, ok, err := sh.index.measurementsByExpr(opt.Condition)
	if err != nil {
		return nil, err
	} else if !ok {
		mms = sh.index.Measurements()
		sort.Sort(mms)
	}

	filterExpr := influxql.CloneExpr(opt.Condition)
	filterExpr = influxql.RewriteExpr(filterExpr, func(e influxql.Expr) influxql.Expr {
		switch e := e.(type) {
		case *influxql.BinaryExpr:
			switch e.Op {
			case influxql.EQ, influxql.NEQ, influxql.EQREGEX, influxql.NEQREGEX:
				tag, ok := e.LHS.(*influxql.VarRef)
				if !ok || tag.Val == "name" || strings.HasPrefix(tag.Val, "_") {
					return nil
				}
			}
		}
		return e
	})

	var series []*Series
	keys := newStringSet()
	for _, mm := range mms {
		ss, ok, err := mm.tagKeysByExpr(opt.Condition)
		if err != nil {
			return nil, err
		} else if !ok {
			keys.add(mm.TagKeys()...)
		} else {
			keys = keys.union(ss)
		}

		ids, err := mm.seriesIDsAllOrByExpr(filterExpr)
		if err != nil {
			return nil, err
		}

		for _, id := range ids {
			series = append(series, mm.SeriesByID(id))
		}
	}

	return &tagValuesIterator{
		series: series,
		keys:   keys.list(),
		fields: opt.Aux,
	}, nil
}

// Ensure an Expr can be rewritten handling nils.
func TestRewriteExpr(t *testing.T) {
	expr := MustParseExpr(`(time > 1 AND time < 10) OR foo = 2`)

	// Remove all time expressions.
	act := influxql.RewriteExpr(expr, func(e influxql.Expr) influxql.Expr {
		switch e := e.(type) {
		case *influxql.BinaryExpr:
			if lhs, ok := e.LHS.(*influxql.VarRef); ok && lhs.Val == "time" {
				return nil
			}
		}
		return e
	})

	// Verify that everything is flipped.
	if act := act.String(); act != `foo = 2` {
		t.Fatalf("unexpected result: %s", act)
	}
}

func (s *Store) TagValues(database string, cond influxql.Expr) ([]TagValues, error) {
	if cond == nil {
		return nil, errors.New("a condition is required")
	}

	dbi := s.DatabaseIndex(database)
	if dbi == nil {
		return nil, nil
	}

	measurementExpr := influxql.CloneExpr(cond)
	measurementExpr = influxql.Reduce(influxql.RewriteExpr(measurementExpr, func(e influxql.Expr) influxql.Expr {
		switch e := e.(type) {
		case *influxql.BinaryExpr:
			switch e.Op {
			case influxql.EQ, influxql.NEQ, influxql.EQREGEX, influxql.NEQREGEX:
				tag, ok := e.LHS.(*influxql.VarRef)
				if !ok || tag.Val != "_name" {
					return nil
				}
			}
		}
		return e
	}), nil)

	mms, ok, err := dbi.MeasurementsByExpr(measurementExpr)
	if err != nil {
		return nil, err
	} else if !ok {
		mms = dbi.Measurements()
		sort.Sort(mms)
	}

	// If there are no measurements, return immediately.
	if len(mms) == 0 {
		return nil, nil
	}

	filterExpr := influxql.CloneExpr(cond)
	filterExpr = influxql.Reduce(influxql.RewriteExpr(filterExpr, func(e influxql.Expr) influxql.Expr {
		switch e := e.(type) {
		case *influxql.BinaryExpr:
			switch e.Op {
			case influxql.EQ, influxql.NEQ, influxql.EQREGEX, influxql.NEQREGEX:
				tag, ok := e.LHS.(*influxql.VarRef)
				if !ok || strings.HasPrefix(tag.Val, "_") {
					return nil
				}
			}
		}
		return e
	}), nil)

	tagValues := make([]TagValues, len(mms))
	for i, mm := range mms {
		tagValues[i].Measurement = mm.Name

		ids, err := mm.SeriesIDsAllOrByExpr(filterExpr)
		if err != nil {
			return nil, err
		}
		ss := mm.SeriesByIDSlice(ids)

		// Determine a list of keys from condition.
		keySet, ok, err := mm.TagKeysByExpr(cond)
		if err != nil {
			return nil, err
		}

		// Loop over all keys for each series.
		m := make(map[KeyValue]struct{}, len(ss))
		for _, series := range ss {
			for key, value := range series.Tags {
				if !ok {
					// nop
				} else if _, exists := keySet[key]; !exists {
					continue
				}
				m[KeyValue{key, value}] = struct{}{}
			}
		}

		// Return an empty slice if there are no key/value matches.
		if len(m) == 0 {
			continue
		}

		// Sort key/value set.
		a := make([]KeyValue, 0, len(m))
		for kv := range m {
			a = append(a, kv)
		}
		sort.Sort(KeyValues(a))
		tagValues[i].Values = a
	}

	return tagValues, nil
}

func (e *StatementExecutor) executeShowTagValues(stmt *influxql.SelectStatement, ctx *influxql.ExecutionContext, store LocalTSDBStore) error {
	if stmt.Condition == nil {
		return errors.New("a condition is required")
	}

	source := stmt.Sources[0].(*influxql.Measurement)
	index := store.DatabaseIndex(source.Database)
	if index == nil {
		ctx.Results <- &influxql.Result{StatementID: ctx.StatementID, Series: make([]*models.Row, 0)}
		return nil
	}

	measurementExpr := influxql.CloneExpr(stmt.Condition)
	measurementExpr = influxql.Reduce(influxql.RewriteExpr(measurementExpr, func(e influxql.Expr) influxql.Expr {
		switch e := e.(type) {
		case *influxql.BinaryExpr:
			switch e.Op {
			case influxql.EQ, influxql.NEQ, influxql.EQREGEX, influxql.NEQREGEX:
				tag, ok := e.LHS.(*influxql.VarRef)
				if !ok || tag.Val != "_name" {
					return nil
				}
			}
		}
		return e
	}), nil)

	mms, ok, err := index.MeasurementsByExpr(measurementExpr)
	if err != nil {
		return err
	} else if !ok {
		mms = index.Measurements()
		sort.Sort(mms)
	}

	// If there are no measurements, return immediately.
	if len(mms) == 0 {
		ctx.Results <- &influxql.Result{StatementID: ctx.StatementID, Series: make([]*models.Row, 0)}
		return nil
	}

	filterExpr := influxql.CloneExpr(stmt.Condition)
	filterExpr = influxql.Reduce(influxql.RewriteExpr(filterExpr, func(e influxql.Expr) influxql.Expr {
		switch e := e.(type) {
		case *influxql.BinaryExpr:
			switch e.Op {
			case influxql.EQ, influxql.NEQ, influxql.EQREGEX, influxql.NEQREGEX:
				tag, ok := e.LHS.(*influxql.VarRef)
				if !ok || strings.HasPrefix(tag.Val, "_") {
					return nil
				}
			}
		}
		return e
	}), nil)

	var emitted bool
	columns := stmt.ColumnNames()
	for _, mm := range mms {
		ids, err := mm.SeriesIDsAllOrByExpr(filterExpr)
		if err != nil {
			return err
		}
		ss := mm.SeriesByIDSlice(ids)

		// Determine a list of keys from condition.
		keySet, ok, err := mm.TagKeysByExpr(stmt.Condition)
		if err != nil {
			return err
		}

		// Loop over all keys for each series.
		m := make(map[keyValue]struct{}, len(ss))
		for _, series := range ss {
			for key, value := range series.Tags {
				if !ok {
					// nop
				} else if _, exists := keySet[key]; !exists {
					continue
				}
				m[keyValue{key, value}] = struct{}{}
			}
		}

		// Move to next series if no key/values match.
		if len(m) == 0 {
			continue
		}

		// Sort key/value set.
		a := make([]keyValue, 0, len(m))
		for kv := range m {
			a = append(a, kv)
		}
		sort.Sort(keyValues(a))

		// Convert to result values.
		slab := make([]interface{}, len(a)*2)
		values := make([][]interface{}, len(a))
		for i, elem := range a {
//.........這裏部分代碼省略.........