gh-ost/vendor/github.com/siddontang/go-mysql/replication/binlogstreamer.go

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2016-06-16 09:15:56 +00:00
package replication
import (
"time"
"github.com/juju/errors"
)
var (
ErrGetEventTimeout = errors.New("Get event timeout, try get later")
ErrNeedSyncAgain = errors.New("Last sync error or closed, try sync and get event again")
ErrSyncClosed = errors.New("Sync was closed")
)
type BinlogStreamer struct {
ch chan *BinlogEvent
ech chan error
err error
}
func (s *BinlogStreamer) GetEvent() (*BinlogEvent, error) {
if s.err != nil {
return nil, ErrNeedSyncAgain
}
select {
case c := <-s.ch:
return c, nil
case s.err = <-s.ech:
return nil, s.err
}
}
// if timeout, ErrGetEventTimeout will returns
// timeout value won't be set too large, otherwise it may waste lots of memory
func (s *BinlogStreamer) GetEventTimeout(d time.Duration) (*BinlogEvent, error) {
if s.err != nil {
return nil, ErrNeedSyncAgain
}
select {
case c := <-s.ch:
return c, nil
case s.err = <-s.ech:
return nil, s.err
case <-time.After(d):
return nil, ErrGetEventTimeout
}
}
func (s *BinlogStreamer) close() {
s.closeWithError(ErrSyncClosed)
}
func (s *BinlogStreamer) closeWithError(err error) {
if err == nil {
err = ErrSyncClosed
}
select {
case s.ech <- err:
default:
}
}
func newBinlogStreamer() *BinlogStreamer {
s := new(BinlogStreamer)
s.ch = make(chan *BinlogEvent, 1024)
s.ech = make(chan error, 4)
return s
}