/
writer.go
79 lines (73 loc) · 1.29 KB
/
writer.go
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package v3
import (
"bufio"
"hash/crc32"
"io"
)
type DataWriter struct {
bw *bufio.Writer
opts *Options
emptyPage page
}
func NewDataWriter(w io.Writer, opt *Options) *DataWriter {
checkOptions(opt)
return &DataWriter{
bw: bufio.NewWriterSize(w, opt.pageSize),
opts: opt,
}
}
func (d *DataWriter) writeHeader(p []byte) (int, error) {
var kind uint16
if len(p) == 0 || p == nil {
kind = kindInactive
}
// create header
h := &header{
magic: magicBytes,
kind: kind,
crc32: crc32.ChecksumIEEE(p),
size: uint64(len(p)),
}
// write header
n, err := h.WriteTo(d.bw)
if err != nil {
return int(n), err
}
return int(n), nil
}
func (d *DataWriter) Write(p []byte) (int, error) {
// write header
n, err := d.writeHeader(p)
if err != nil {
return n, err
}
var nn int
nn += n
// write body
n, err = d.bw.Write(p)
if err != nil {
return n + nn, err
}
nn += n
// check align rules
if d.opts.pageAlign {
off := d.bw.Size() - d.bw.Buffered()
n, err = d.bw.Write(d.emptyPage.data[:off])
if err != nil {
return n + nn, err
}
nn += n
}
// check auto flush
if d.opts.autoFlush {
err = d.bw.Flush()
if err != nil {
return nn, err
}
}
// return bytes written
return nn, nil
}
func (d *DataWriter) Flush() error {
return d.bw.Flush()
}