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result_iter.go
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/
result_iter.go
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// Copyright 2020 Zhizhesihai (Beijing) Technology Limited.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package tables
import (
"context"
"io"
"sync/atomic"
tspb "github.com/zhihu/zetta-proto/pkg/tablestore"
"github.com/zhihu/zetta/tablestore/table"
)
type resultIter struct {
columns []*tspb.ColumnMeta
rowChan chan *tspb.SliceCell
rowsCount int64
nextToken []byte
limit int64
lastErr error
quitCh chan struct{}
}
func NewResultIter(limit int64) *resultIter {
return &resultIter{
rowChan: make(chan *tspb.SliceCell, 32),
limit: limit,
quitCh: make(chan struct{}),
}
}
func (ri *resultIter) Columns() []*tspb.ColumnMeta {
return ri.columns
}
func (ri *resultIter) LastErr() error {
return ri.lastErr
}
func (ri *resultIter) Next(ctx context.Context) (interface{}, error) {
row, ok := <-ri.rowChan
if !ok {
return nil, io.EOF
}
return row, nil
}
func (ri *resultIter) NextToken() []byte {
return ri.nextToken
}
func (ri *resultIter) Close() error {
select {
case <-ri.quitCh:
return ri.lastErr
default:
close(ri.quitCh)
close(ri.rowChan)
}
return ri.lastErr
}
func (ri *resultIter) sendData(row *tspb.SliceCell) error {
defer func() {
if x := recover(); x != nil {
return
}
}()
if ri.limit > 0 && atomic.LoadInt64(&ri.rowsCount) > ri.limit {
return table.ErrResultSetUserLimitReached
}
select {
case <-ri.quitCh:
case ri.rowChan <- row:
atomic.AddInt64(&ri.rowsCount, 1)
}
return nil
}
func (ri *resultIter) clearup() {
}