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csv.go
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csv.go
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// Copyright © 2016 Wei Shen <shenwei356@gmail.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package cmd
import (
"fmt"
"io"
"github.com/shenwei356/xopen"
"github.com/shenwei356/multicorecsv"
)
// CSVRecordsChunk is chunk of CSV records
type CSVRecordsChunk struct {
ID uint64
Data [][]string
Err error
}
// CSVReader is
type CSVReader struct {
Reader *multicorecsv.Reader
bufferSize int
chunkSize int
Ch chan CSVRecordsChunk
fh *xopen.Reader
}
// NewCSVReader is
func NewCSVReader(file string, bufferSize int, chunkSize int) (*CSVReader, error) {
if bufferSize < 1 {
return nil, fmt.Errorf("value of bufferSize should be greater than 0")
}
if chunkSize < 1 {
return nil, fmt.Errorf("value of chunkSize should be greater than 0")
}
fh, err := xopen.Ropen(file)
if err != nil {
return nil, err
}
reader := multicorecsv.NewReader(fh)
ch := make(chan CSVRecordsChunk, bufferSize)
csvReader := &CSVReader{
Reader: reader,
bufferSize: bufferSize,
chunkSize: chunkSize,
Ch: ch,
fh: fh,
}
return csvReader, nil
}
// Run begins to read
func (csvReader *CSVReader) Run() {
go func() {
defer func() {
csvReader.fh.Close()
csvReader.Reader.Close()
}()
chunkData := make([][]string, csvReader.chunkSize)
var id uint64
var i int
for {
record, err := csvReader.Reader.Read()
if err == io.EOF {
id++
csvReader.Ch <- CSVRecordsChunk{id, chunkData[0:i], nil}
break
}
if err != nil {
csvReader.Ch <- CSVRecordsChunk{id, chunkData[0:i], err}
break
}
if record == nil {
continue
}
chunkData[i] = record
i++
if i == csvReader.chunkSize {
id++
csvReader.Ch <- CSVRecordsChunk{id, chunkData, nil}
chunkData = make([][]string, csvReader.chunkSize)
i = 0
}
}
close(csvReader.Ch)
}()
}