prometheus/prom/util/flock/flock_unix.go

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// +build darwin dragonfly freebsd linux netbsd openbsd
package flock
import (
"os"
"syscall"
)
type unixLock struct {
f *os.File
}
func (l *unixLock) Release() error {
if err := l.set(false); err != nil {
return err
}
return l.f.Close()
}
func (l *unixLock) set(lock bool) error {
how := syscall.LOCK_UN
if lock {
how = syscall.LOCK_EX
}
return syscall.Flock(int(l.f.Fd()), how|syscall.LOCK_NB)
}
func newLock(fileName string) (Releaser, error) {
f, err := os.OpenFile(fileName, os.O_RDWR|os.O_CREATE, 0644)
if err != nil {
return nil, err
}
l := &unixLock{f}
err = l.set(true)
if err != nil {
f.Close()
return nil, err
}
return l, nil
}