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|
package dataset
import (
"bytes"
"context"
"io"
"os"
"runtime"
"sync/atomic"
"golang.org/x/sync/errgroup"
)
func countLinesAll(names []string, delimiter []byte) (int, error) {
g, ctx := errgroup.WithContext(context.Background())
g.SetLimit(runtime.NumCPU() - 1)
var total atomic.Int64
for _, name := range names {
g.Go(func() error {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
var file *os.File
if f, err := os.Open(name); err != nil {
return err
} else {
file = f
}
if n, err := countLines(file, delimiter); err != nil {
return err
} else {
total.Add(n)
}
return nil
})
}
if err := g.Wait(); err != nil {
return 0, err
}
return int(total.Load()), nil
}
func countLines(r io.Reader, delimiter []byte) (int64, error) {
if len(delimiter) == 0 {
panic("empty delimiter")
}
l := len(delimiter)
buf := make([]byte, 128*1024)
var total int64
carry := 0
for {
n, err := r.Read(buf[carry:])
active := carry + n
if active >= l {
total += int64(bytes.Count(buf[:active], delimiter))
carry = l - 1
copy(buf[:carry], buf[active-carry:])
} else {
carry = active
}
if err == io.EOF {
break
}
if err != nil {
return 0, err
}
}
return total, nil
}
|
