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lock.go
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lock.go
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package fileutil
import (
"errors"
"os"
"syscall"
)
var (
ErrLocked = errors.New("file already locked")
)
type Lock interface {
Name() string
TryLock() error
Lock() error
Unlock() error
Destroy() error
}
type lock struct {
fd int
file *os.File
}
func (l *lock) Name() string {
return l.file.Name()
}
// TryLock acquires exclusivity on the lock without blocking
func (l *lock) TryLock() error {
err := syscall.Flock(l.fd, syscall.LOCK_EX|syscall.LOCK_NB)
if err != nil && err == syscall.EWOULDBLOCK {
return ErrLocked
}
return err
}
// Lock acquires exclusivity on the lock without blocking
func (l *lock) Lock() error {
return syscall.Flock(l.fd, syscall.LOCK_EX)
}
// Unlock unlocks the lock
func (l *lock) Unlock() error {
return syscall.Flock(l.fd, syscall.LOCK_UN)
}
func (l *lock) Destroy() error {
return l.file.Close()
}
func NewLock(file string) (Lock, error) {
f, err := os.Open(file)
if err != nil {
return nil, err
}
l := &lock{int(f.Fd()), f}
return l, nil
}