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row_frame.go
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row_frame.go
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// Copyright 2020-2021 Dolthub, Inc.
//
// 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package sql
import (
"sync"
querypb "github.com/dolthub/vitess/go/vt/proto/query"
)
const (
valueArrSize = 64
fieldArrSize = 2048
)
// Row2 is a tuple of values.
type Row2 []Value
type Value struct {
Typ querypb.Type
Val []byte
}
type RowFrame struct {
// Values are the values this row.
Values []Value
// varr is used as the backing array for the |Values|
// slice when len(Values) <= valueArrSize
varr [valueArrSize]Value
// farr is used as the backing array for |Value.Val|
// slices when there is capacity
farr [fieldArrSize]byte
// off tracks the next available position in |farr|
off uint16
}
func NewRowFrame(vals ...Value) (f *RowFrame) {
f = framePool.Get().(*RowFrame)
f.Append(vals...)
return
}
var framePool = sync.Pool{New: makeRowFrame}
func makeRowFrame() interface{} {
return &RowFrame{}
}
func (f *RowFrame) Row2() Row2 {
return f.Values
}
func (f *RowFrame) Append(vals ...Value) {
for _, v := range vals {
f.append(v)
}
}
func (f *RowFrame) append(v Value) {
buf := f.getBuffer(v)
copy(buf, v.Val)
v.Val = buf
// if |f.Values| grows past |len(f.varr)|
// we'll allocate a new backing array here
f.Values = append(f.Values, v)
}
func (f *RowFrame) getBuffer(v Value) (buf []byte) {
if f.checkCapacity(v) {
start := f.off
f.off += uint16(len(v.Val))
stop := f.off
buf = f.farr[start:stop]
} else {
buf = make([]byte, len(v.Val))
}
return
}
func (f *RowFrame) checkCapacity(v Value) bool {
return len(v.Val) <= (len(f.farr) - int(f.off))
}