/
data.go
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/
data.go
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// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you 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 array
import (
"hash/maphash"
"math/bits"
"sync/atomic"
"unsafe"
"github.com/apache/arrow/go/v14/arrow"
"github.com/apache/arrow/go/v14/arrow/internal/debug"
"github.com/apache/arrow/go/v14/arrow/memory"
)
// Data represents the memory and metadata of an Arrow array.
type Data struct {
refCount int64
dtype arrow.DataType
nulls int
offset int
length int
// for dictionary arrays: buffers will be the null validity bitmap and the indexes that reference
// values in the dictionary member. childData would be empty in a dictionary array
buffers []*memory.Buffer // TODO(sgc): should this be an interface?
childData []arrow.ArrayData // TODO(sgc): managed by ListArray, StructArray and UnionArray types
dictionary *Data // only populated for dictionary arrays
}
// NewData creates a new Data.
func NewData(dtype arrow.DataType, length int, buffers []*memory.Buffer, childData []arrow.ArrayData, nulls, offset int) *Data {
for _, b := range buffers {
if b != nil {
b.Retain()
}
}
for _, child := range childData {
if child != nil {
child.Retain()
}
}
return &Data{
refCount: 1,
dtype: dtype,
nulls: nulls,
length: length,
offset: offset,
buffers: buffers,
childData: childData,
}
}
// NewDataWithDictionary creates a new data object, but also sets the provided dictionary into the data if it's not nil
func NewDataWithDictionary(dtype arrow.DataType, length int, buffers []*memory.Buffer, nulls, offset int, dict *Data) *Data {
data := NewData(dtype, length, buffers, nil, nulls, offset)
if dict != nil {
dict.Retain()
}
data.dictionary = dict
return data
}
func (d *Data) Copy() *Data {
// don't pass the slices directly, otherwise it retains the connection
// we need to make new slices and populate them with the same pointers
bufs := make([]*memory.Buffer, len(d.buffers))
copy(bufs, d.buffers)
children := make([]arrow.ArrayData, len(d.childData))
copy(children, d.childData)
data := NewData(d.dtype, d.length, bufs, children, d.nulls, d.offset)
data.SetDictionary(d.dictionary)
return data
}
// Reset sets the Data for re-use.
func (d *Data) Reset(dtype arrow.DataType, length int, buffers []*memory.Buffer, childData []arrow.ArrayData, nulls, offset int) {
// Retain new buffers before releasing existing buffers in-case they're the same ones to prevent accidental premature
// release.
for _, b := range buffers {
if b != nil {
b.Retain()
}
}
for _, b := range d.buffers {
if b != nil {
b.Release()
}
}
d.buffers = buffers
// Retain new children data before releasing existing children data in-case they're the same ones to prevent accidental
// premature release.
for _, d := range childData {
if d != nil {
d.Retain()
}
}
for _, d := range d.childData {
if d != nil {
d.Release()
}
}
d.childData = childData
d.dtype = dtype
d.length = length
d.nulls = nulls
d.offset = offset
}
// Retain increases the reference count by 1.
// Retain may be called simultaneously from multiple goroutines.
func (d *Data) Retain() {
atomic.AddInt64(&d.refCount, 1)
}
// Release decreases the reference count by 1.
// When the reference count goes to zero, the memory is freed.
// Release may be called simultaneously from multiple goroutines.
func (d *Data) Release() {
debug.Assert(atomic.LoadInt64(&d.refCount) > 0, "too many releases")
if atomic.AddInt64(&d.refCount, -1) == 0 {
for _, b := range d.buffers {
if b != nil {
b.Release()
}
}
for _, b := range d.childData {
b.Release()
}
if d.dictionary != nil {
d.dictionary.Release()
}
d.dictionary, d.buffers, d.childData = nil, nil, nil
}
}
// DataType returns the DataType of the data.
func (d *Data) DataType() arrow.DataType { return d.dtype }
func (d *Data) SetNullN(n int) { d.nulls = n }
// NullN returns the number of nulls.
func (d *Data) NullN() int { return d.nulls }
// Len returns the length.
func (d *Data) Len() int { return d.length }
// Offset returns the offset.
func (d *Data) Offset() int { return d.offset }
// Buffers returns the buffers.
func (d *Data) Buffers() []*memory.Buffer { return d.buffers }
func (d *Data) Children() []arrow.ArrayData { return d.childData }
// Dictionary returns the ArrayData object for the dictionary member, or nil
func (d *Data) Dictionary() arrow.ArrayData { return d.dictionary }
// SetDictionary allows replacing the dictionary for this particular Data object
func (d *Data) SetDictionary(dict arrow.ArrayData) {
if d.dictionary != nil {
d.dictionary.Release()
d.dictionary = nil
}
if dict.(*Data) != nil {
dict.Retain()
d.dictionary = dict.(*Data)
}
}
// NewSliceData returns a new slice that shares backing data with the input.
// The returned Data slice starts at i and extends j-i elements, such as:
// slice := data[i:j]
// The returned value must be Release'd after use.
//
// NewSliceData panics if the slice is outside the valid range of the input Data.
// NewSliceData panics if j < i.
func NewSliceData(data arrow.ArrayData, i, j int64) arrow.ArrayData {
if j > int64(data.Len()) || i > j || data.Offset()+int(i) > data.Offset()+data.Len() {
panic("arrow/array: index out of range")
}
for _, b := range data.Buffers() {
if b != nil {
b.Retain()
}
}
for _, child := range data.Children() {
if child != nil {
child.Retain()
}
}
if data.(*Data).dictionary != nil {
data.(*Data).dictionary.Retain()
}
o := &Data{
refCount: 1,
dtype: data.DataType(),
nulls: UnknownNullCount,
length: int(j - i),
offset: data.Offset() + int(i),
buffers: data.Buffers(),
childData: data.Children(),
dictionary: data.(*Data).dictionary,
}
if data.NullN() == 0 {
o.nulls = 0
}
return o
}
func Hash(h *maphash.Hash, data arrow.ArrayData) {
a := data.(*Data)
h.Write((*[bits.UintSize / 8]byte)(unsafe.Pointer(&a.length))[:])
h.Write((*[bits.UintSize / 8]byte)(unsafe.Pointer(&a.length))[:])
if len(a.buffers) > 0 && a.buffers[0] != nil {
h.Write(a.buffers[0].Bytes())
}
for _, c := range a.childData {
Hash(h, c)
}
}