forked from src-d/go-mysql-server
/
cross_join.go
151 lines (123 loc) · 2.73 KB
/
cross_join.go
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package plan
import (
"io"
"reflect"
opentracing "github.com/opentracing/opentracing-go"
"github.com/src-d/go-mysql-server/sql"
)
// CrossJoin is a cross join between two tables.
type CrossJoin struct {
BinaryNode
}
// NewCrossJoin creates a new cross join node from two tables.
func NewCrossJoin(left sql.Node, right sql.Node) *CrossJoin {
return &CrossJoin{
BinaryNode: BinaryNode{
Left: left,
Right: right,
},
}
}
// Schema implements the Node interface.
func (p *CrossJoin) Schema() sql.Schema {
return append(p.Left.Schema(), p.Right.Schema()...)
}
// Resolved implements the Resolvable interface.
func (p *CrossJoin) Resolved() bool {
return p.Left.Resolved() && p.Right.Resolved()
}
// RowIter implements the Node interface.
func (p *CrossJoin) RowIter(ctx *sql.Context) (sql.RowIter, error) {
var left, right string
if leftTable, ok := p.Left.(sql.Nameable); ok {
left = leftTable.Name()
} else {
left = reflect.TypeOf(p.Left).String()
}
if rightTable, ok := p.Right.(sql.Nameable); ok {
right = rightTable.Name()
} else {
right = reflect.TypeOf(p.Right).String()
}
span, ctx := ctx.Span("plan.CrossJoin", opentracing.Tags{
"left": left,
"right": right,
})
li, err := p.Left.RowIter(ctx)
if err != nil {
span.Finish()
return nil, err
}
return sql.NewSpanIter(span, &crossJoinIterator{
l: li,
rp: p.Right,
s: ctx,
}), nil
}
// WithChildren implements the Node interface.
func (p *CrossJoin) WithChildren(children ...sql.Node) (sql.Node, error) {
if len(children) != 2 {
return nil, sql.ErrInvalidChildrenNumber.New(p, len(children), 2)
}
return NewCrossJoin(children[0], children[1]), nil
}
func (p *CrossJoin) String() string {
pr := sql.NewTreePrinter()
_ = pr.WriteNode("CrossJoin")
_ = pr.WriteChildren(p.Left.String(), p.Right.String())
return pr.String()
}
type rowIterProvider interface {
RowIter(*sql.Context) (sql.RowIter, error)
}
type crossJoinIterator struct {
l sql.RowIter
rp rowIterProvider
r sql.RowIter
s *sql.Context
leftRow sql.Row
}
func (i *crossJoinIterator) Next() (sql.Row, error) {
for {
if i.leftRow == nil {
r, err := i.l.Next()
if err != nil {
return nil, err
}
i.leftRow = r
}
if i.r == nil {
iter, err := i.rp.RowIter(i.s)
if err != nil {
return nil, err
}
i.r = iter
}
rightRow, err := i.r.Next()
if err == io.EOF {
i.r = nil
i.leftRow = nil
continue
}
if err != nil {
return nil, err
}
var row sql.Row
row = append(row, i.leftRow...)
row = append(row, rightRow...)
return row, nil
}
}
func (i *crossJoinIterator) Close() (err error) {
if i.l != nil {
err = i.l.Close()
}
if i.r != nil {
if err == nil {
err = i.r.Close()
} else {
i.r.Close()
}
}
return err
}