blob: 2bb775206a77fca61f7f62876d2e59b794f905d2 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
|
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build darwin dragonfly freebsd linux netbsd openbsd
package filemutex
import (
"syscall"
)
const (
mkdirPerm = 0750
)
// FileMutex is similar to sync.RWMutex, but also synchronizes across processes.
// This implementation is based on flock syscall.
type FileMutex struct {
fd int
}
func New(filename string) (*FileMutex, error) {
fd, err := syscall.Open(filename, syscall.O_CREAT|syscall.O_RDONLY, mkdirPerm)
if err != nil {
return nil, err
}
return &FileMutex{fd: fd}, nil
}
func (m *FileMutex) Lock() error {
if err := syscall.Flock(m.fd, syscall.LOCK_EX); err != nil {
return err
}
return nil
}
func (m *FileMutex) Unlock() error {
if err := syscall.Flock(m.fd, syscall.LOCK_UN); err != nil {
return err
}
return nil
}
func (m *FileMutex) RLock() error {
if err := syscall.Flock(m.fd, syscall.LOCK_SH); err != nil {
return err
}
return nil
}
func (m *FileMutex) RUnlock() error {
if err := syscall.Flock(m.fd, syscall.LOCK_UN); err != nil {
return err
}
return nil
}
// Close does an Unlock() combined with closing and unlinking the associated
// lock file. You should create a New() FileMutex for every Lock() attempt if
// using Close().
func (m *FileMutex) Close() error {
if err := syscall.Flock(m.fd, syscall.LOCK_UN); err != nil {
return err
}
return syscall.Close(m.fd)
}
|
