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buffered.go
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buffered.go
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package table
import (
"sync/atomic"
"github.com/influxdata/flux"
"github.com/influxdata/flux/codes"
"github.com/influxdata/flux/internal/errors"
)
// BufferedTable represents a table of buffered column readers.
type BufferedTable struct {
used int32
empty bool
GroupKey flux.GroupKey
Columns []flux.ColMeta
Buffers []flux.ColReader
}
// FromBuffer constructs a flux.Table from a single flux.ColReader.
func FromBuffer(cr flux.ColReader) flux.Table {
return &BufferedTable{
GroupKey: cr.Key(),
Columns: cr.Cols(),
Buffers: []flux.ColReader{cr},
}
}
func (b *BufferedTable) Key() flux.GroupKey {
return b.GroupKey
}
func (b *BufferedTable) Cols() []flux.ColMeta {
return b.Columns
}
func (b *BufferedTable) Do(f func(flux.ColReader) error) error {
if !atomic.CompareAndSwapInt32(&b.used, 0, 1) {
return errors.New(codes.Internal, "table already read")
}
i := 0
defer func() {
for ; i < len(b.Buffers); i++ {
b.Buffers[i].Release()
}
}()
b.empty = true
for ; i < len(b.Buffers); i++ {
cr := b.Buffers[i]
if cr.Len() > 0 {
b.empty = false
}
if err := f(cr); err != nil {
return err
}
cr.Release()
}
return nil
}
func (b *BufferedTable) Done() {
if atomic.CompareAndSwapInt32(&b.used, 0, 1) {
b.empty = b.isEmpty()
for _, buf := range b.Buffers {
buf.Release()
}
b.Buffers = nil
}
}
func (b *BufferedTable) Empty() bool {
if atomic.LoadInt32(&b.used) != 0 {
return b.empty
}
return b.isEmpty()
}
func (b *BufferedTable) isEmpty() bool {
for _, buf := range b.Buffers {
if buf.Len() > 0 {
return false
}
}
return true
}