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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 arrjson
import (
"io"
"sync/atomic"
"github.com/apache/arrow-go/v18/arrow"
"github.com/apache/arrow-go/v18/arrow/arrio"
"github.com/apache/arrow-go/v18/arrow/internal/debug"
"github.com/apache/arrow-go/v18/arrow/internal/dictutils"
"github.com/apache/arrow-go/v18/internal/json"
)
type Reader struct {
refs int64
schema *arrow.Schema
recs []arrow.Record
memo *dictutils.Memo
irec int // current record index. used for the arrio.Reader interface.
}
func NewReader(r io.Reader, opts ...Option) (*Reader, error) {
dec := json.NewDecoder(r)
dec.UseNumber()
var raw rawJSON
err := dec.Decode(&raw)
if err != nil {
return nil, err
}
cfg := newConfig()
for _, opt := range opts {
opt(cfg)
}
memo := dictutils.NewMemo()
schema := schemaFromJSON(raw.Schema, &memo)
dictionariesFromJSON(cfg.alloc, raw.Dictionaries, &memo)
rr := &Reader{
refs: 1,
schema: schema,
recs: recordsFromJSON(cfg.alloc, schema, raw.Records, &memo),
memo: &memo,
}
return rr, nil
}
// Retain increases the reference count by 1.
// Retain may be called simultaneously from multiple goroutines.
func (r *Reader) Retain() {
atomic.AddInt64(&r.refs, 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 (r *Reader) Release() {
debug.Assert(atomic.LoadInt64(&r.refs) > 0, "too many releases")
if atomic.AddInt64(&r.refs, -1) == 0 {
for i, rec := range r.recs {
if r.recs[i] != nil {
rec.Release()
r.recs[i] = nil
}
}
r.memo.Clear()
r.memo = nil
}
}
func (r *Reader) Schema() *arrow.Schema { return r.schema }
func (r *Reader) NumRecords() int { return len(r.recs) }
func (r *Reader) Read() (arrow.Record, error) {
if r.irec == r.NumRecords() {
return nil, io.EOF
}
rec := r.recs[r.irec]
r.irec++
return rec, nil
}
func (r *Reader) ReadAt(index int) (arrow.Record, error) {
if index >= r.NumRecords() {
return nil, io.EOF
}
rec := r.recs[index]
return rec, nil
}
var (
_ arrio.Reader = (*Reader)(nil)
)
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