/
filemutex_windows.go
105 lines (93 loc) · 2.55 KB
/
filemutex_windows.go
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
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
// 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.
package main
import (
"sync"
"syscall"
"unsafe"
)
var (
modkernel32 = syscall.NewLazyDLL("kernel32.dll")
procLockFileEx = modkernel32.NewProc("LockFileEx")
procUnlockFileEx = modkernel32.NewProc("UnlockFileEx")
)
const (
INVALID_FILE_HANDLE = ^syscall.Handle(0)
LOCKFILE_EXCLUSIVE_LOCK = 2
)
func lockFileEx(h syscall.Handle, flags, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
r1, _, e1 := syscall.Syscall6(procLockFileEx.Addr(), 6, uintptr(h), uintptr(flags), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)))
if r1 == 0 {
if e1 != 0 {
err = error(e1)
} else {
err = syscall.EINVAL
}
}
return
}
func unlockFileEx(h syscall.Handle, reserved, locklow, lockhigh uint32, ol *syscall.Overlapped) (err error) {
r1, _, e1 := syscall.Syscall6(procUnlockFileEx.Addr(), 5, uintptr(h), uintptr(reserved), uintptr(locklow), uintptr(lockhigh), uintptr(unsafe.Pointer(ol)), 0)
if r1 == 0 {
if e1 != 0 {
err = error(e1)
} else {
err = syscall.EINVAL
}
}
return
}
// FileMutex is similar to sync.RWMutex, but also synchronizes across processes.
// This implementation is based on flock syscall.
type FileMutex struct {
mu sync.RWMutex
fd syscall.Handle
}
func MakeFileMutex(filename string) *FileMutex {
if filename == "" {
return &FileMutex{fd: INVALID_FILE_HANDLE}
}
fd, err := syscall.CreateFile(&(syscall.StringToUTF16(filename)[0]), syscall.GENERIC_READ|syscall.GENERIC_WRITE,
syscall.FILE_SHARE_READ|syscall.FILE_SHARE_WRITE, nil, syscall.OPEN_ALWAYS, syscall.FILE_ATTRIBUTE_NORMAL, 0)
if err != nil {
panic(err)
}
return &FileMutex{fd: fd}
}
func (m *FileMutex) Lock() {
m.mu.Lock()
if m.fd != INVALID_FILE_HANDLE {
var ol syscall.Overlapped
if err := lockFileEx(m.fd, LOCKFILE_EXCLUSIVE_LOCK, 0, 1, 0, &ol); err != nil {
panic(err)
}
}
}
func (m *FileMutex) Unlock() {
if m.fd != INVALID_FILE_HANDLE {
var ol syscall.Overlapped
if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
panic(err)
}
}
m.mu.Unlock()
}
func (m *FileMutex) RLock() {
m.mu.RLock()
if m.fd != INVALID_FILE_HANDLE {
var ol syscall.Overlapped
if err := lockFileEx(m.fd, 0, 0, 1, 0, &ol); err != nil {
panic(err)
}
}
}
func (m *FileMutex) RUnlock() {
if m.fd != INVALID_FILE_HANDLE {
var ol syscall.Overlapped
if err := unlockFileEx(m.fd, 0, 1, 0, &ol); err != nil {
panic(err)
}
}
m.mu.RUnlock()
}