mirror of
https://github.com/golang/go
synced 2024-11-19 06:04:39 -07:00
106 lines
2.6 KiB
Go
106 lines
2.6 KiB
Go
|
// 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()
|
||
|
|
}
|