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Go的标准库中Windows下的网络是使用了IOCP的,参见go源码go/src/runtime/netpoll_windows.go
,标准库为了与Epoll、kqueue等不同平台的IO模式使用统一的API,进行了封装。
如果想直接使用Windows的IOCP API编程,比如想按照:Windows下的高效网络模型IOCP完整示例中的流程写,就需要自行封装IOCP相关的API,虽然标准库中封装了很多系统调用,但是不是很全,而且API的函数签名也有一些问题,比如:
// Deprecated: CreateIoCompletionPort has the wrong function signature. Use x/sys/windows.CreateIoCompletionPort.
func CreateIoCompletionPort(filehandle Handle, cphandle Handle, key uint32, threadcnt uint32) (Handle, error) {return createIoCompletionPort(filehandle, cphandle, uintptr(key), threadcnt)
}// Deprecated: GetQueuedCompletionStatus has the wrong function signature. Use x/sys/windows.GetQueuedCompletionStatus.
func GetQueuedCompletionStatus(cphandle Handle, qty *uint32, key *uint32, overlapped **Overlapped, timeout uint32) error {var ukey uintptrvar pukey *uintptrif key != nil {ukey = uintptr(*key)pukey = &ukey}err := getQueuedCompletionStatus(cphandle, qty, pukey, overlapped, timeout)if key != nil {*key = uint32(ukey)if uintptr(*key) != ukey && err == nil {err = errorspkg.New("GetQueuedCompletionStatus returned key overflow")}}return err
}// Deprecated: PostQueuedCompletionStatus has the wrong function signature. Use x/sys/windows.PostQueuedCompletionStatus.
func PostQueuedCompletionStatus(cphandle Handle, qty uint32, key uint32, overlapped *Overlapped) error {return postQueuedCompletionStatus(cphandle, qty, uintptr(key), overlapped)
}
看了一下,其实内部调用的函数签名是没问题的,可以使用Go的魔法指令go:linkname
来解决:
//go:linkname CreateIoCompletionPort syscall.createIoCompletionPort
func CreateIoCompletionPort(fileHandle syscall.Handle, cpHandle syscall.Handle, key uintptr, threadCnt uint32) (handle syscall.Handle, err error)//go:linkname GetQueuedCompletionStatus syscall.getQueuedCompletionStatus
func GetQueuedCompletionStatus(cpHandle syscall.Handle, qty *uint32, key *uintptr, overlapped **syscall.Overlapped, timeout uint32) (err error)//go:linkname PostQueuedCompletionStatus syscall.postQueuedCompletionStatus
func PostQueuedCompletionStatus(cphandle syscall.Handle, qty uint32, key uintptr, overlapped *syscall.Overlapped) (err error)
另外还需要使用到一些API,比如WSACreateEvent
、WSAWaitForMultipleEvents
、WSAResetEvent
、WSAGetOverlappedResult
,就需要自行从Ws2_32.dll
中装载了:
var (modws2_32 = syscall.NewLazyDLL("Ws2_32.dll")procWSACreateEvent = modws2_32.NewProc("WSACreateEvent")procWSAWaitForMultipleEvents = modws2_32.NewProc("WSAWaitForMultipleEvents")procWSAResetEvent = modws2_32.NewProc("WSAResetEvent")procWSAGetOverlappedResult = modws2_32.NewProc("WSAGetOverlappedResult")
)func WSACreateEvent() (Handle syscall.Handle, err error) {r1, _, e1 := syscall.SyscallN(procWSACreateEvent.Addr())if r1 == 0 {err = errnoErr(e1)}return syscall.Handle(r1), nil
}func WSAWaitForMultipleEvents(cEvents uint32, lpEvent *syscall.Handle, fWaitAll bool, dwTimeout uint32, fAlertable bool) (uint32, error) {var WaitAll, Alertable uint32if fWaitAll {WaitAll = 1}if fAlertable {Alertable = 1}r1, _, e1 := syscall.SyscallN(procWSAWaitForMultipleEvents.Addr(), uintptr(cEvents), uintptr(unsafe.Pointer(lpEvent)), uintptr(WaitAll), uintptr(dwTimeout), uintptr(Alertable))if r1 == syscall.WAIT_FAILED {return 0, errnoErr(e1)}return uint32(r1), nil
}func WSAResetEvent(handle syscall.Handle) (err error) {r1, _, e1 := syscall.SyscallN(procWSAResetEvent.Addr(), uintptr(handle))if r1 == 0 {err = errnoErr(e1)}return
}func WSAGetOverlappedResult(socket syscall.Handle, overlapped *syscall.Overlapped, transferBytes *uint32, bWait bool, flag *uint32) (err error) {var wait uint32if bWait {wait = 1}r1, _, e1 := syscall.SyscallN(procWSAGetOverlappedResult.Addr(), uintptr(socket), uintptr(unsafe.Pointer(overlapped)),uintptr(unsafe.Pointer(transferBytes)), uintptr(wait), uintptr(unsafe.Pointer(flag)))if r1 == 0 {err = errnoErr(e1)}return
}
笔者尝试了下,完全可以,
直接附上源码:
package mainimport ("errors""fmt""os""runtime""syscall""unsafe"_ "unsafe"
)//go:linkname CreateIoCompletionPort syscall.createIoCompletionPort
func CreateIoCompletionPort(fileHandle syscall.Handle, cpHandle syscall.Handle, key uintptr, threadCnt uint32) (handle syscall.Handle, err error)//go:linkname GetQueuedCompletionStatus syscall.getQueuedCompletionStatus
func GetQueuedCompletionStatus(cpHandle syscall.Handle, qty *uint32, key *uintptr, overlapped **syscall.Overlapped, timeout uint32) (err error)//go:linkname PostQueuedCompletionStatus syscall.postQueuedCompletionStatus
func PostQueuedCompletionStatus(cphandle syscall.Handle, qty uint32, key uintptr, overlapped *syscall.Overlapped) (err error)//go:linkname errnoErr syscall.errnoErr
func errnoErr(e syscall.Errno) errorvar (modws2_32 = syscall.NewLazyDLL("Ws2_32.dll")procWSACreateEvent = modws2_32.NewProc("WSACreateEvent")procWSAWaitForMultipleEvents = modws2_32.NewProc("WSAWaitForMultipleEvents")procWSAResetEvent = modws2_32.NewProc("WSAResetEvent")procWSAGetOverlappedResult = modws2_32.NewProc("WSAGetOverlappedResult")
)func WSACreateEvent() (Handle syscall.Handle, err error) {r1, _, e1 := syscall.SyscallN(procWSACreateEvent.Addr())if r1 == 0 {err = errnoErr(e1)}return syscall.Handle(r1), nil
}func WSAWaitForMultipleEvents(cEvents uint32, lpEvent *syscall.Handle, fWaitAll bool, dwTimeout uint32, fAlertable bool) (uint32, error) {var WaitAll, Alertable uint32if fWaitAll {WaitAll = 1}if fAlertable {Alertable = 1}r1, _, e1 := syscall.SyscallN(procWSAWaitForMultipleEvents.Addr(), uintptr(cEvents), uintptr(unsafe.Pointer(lpEvent)), uintptr(WaitAll), uintptr(dwTimeout), uintptr(Alertable))if r1 == syscall.WAIT_FAILED {return 0, errnoErr(e1)}return uint32(r1), nil
}func WSAResetEvent(handle syscall.Handle) (err error) {r1, _, e1 := syscall.SyscallN(procWSAResetEvent.Addr(), uintptr(handle))if r1 == 0 {err = errnoErr(e1)}return
}func WSAGetOverlappedResult(socket syscall.Handle, overlapped *syscall.Overlapped, transferBytes *uint32, bWait bool, flag *uint32) (err error) {var wait uint32if bWait {wait = 1}r1, _, e1 := syscall.SyscallN(procWSAGetOverlappedResult.Addr(), uintptr(socket), uintptr(unsafe.Pointer(overlapped)),uintptr(unsafe.Pointer(transferBytes)), uintptr(wait), uintptr(unsafe.Pointer(flag)))if r1 == 0 {err = errnoErr(e1)}return
}type IOData struct {Overlapped syscall.OverlappedWsaBuf syscall.WSABufNBytes uint32isRead boolcliSock syscall.Handle
}func main() {listenFd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)if err != nil {return}defer func() {syscall.Closesocket(listenFd)syscall.WSACleanup()}()v4 := &syscall.SockaddrInet4{Port: 6000,Addr: [4]byte{},}err = syscall.Bind(listenFd, v4)if err != nil {return}err = syscall.Listen(listenFd, 0)if err != nil {return}hIOCP, err := CreateIoCompletionPort(syscall.InvalidHandle, 0, 0, 0)if err != nil {return}count := runtime.NumCPU()for i := 0; i < count; i++ {go workThread(hIOCP)}defer PostQueuedCompletionStatus(hIOCP, 0, 0, nil)for {acceptFd, er := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP)if er != nil {return}b := make([]byte, 1024)recvD := uint32(0)data := &IOData{Overlapped: syscall.Overlapped{},WsaBuf: syscall.WSABuf{Len: 1024,Buf: &b[0],},NBytes: 1024,isRead: true,cliSock: acceptFd,}data.Overlapped.HEvent, er = WSACreateEvent()if er != nil {return}size := uint32(unsafe.Sizeof(&syscall.SockaddrInet4{}) + 16)er = syscall.AcceptEx(listenFd, acceptFd, data.WsaBuf.Buf, data.WsaBuf.Len-size*2, size, size, &recvD, &data.Overlapped)if er != nil && !errors.Is(er, syscall.ERROR_IO_PENDING) {er = os.NewSyscallError("AcceptEx", er)continue}_, er = WSAWaitForMultipleEvents(1, &data.Overlapped.HEvent, true, syscall.INFINITE, true)if er != nil {return}WSAResetEvent(data.Overlapped.HEvent)dwBytes := uint32(0)flag := uint32(0)WSAGetOverlappedResult(acceptFd, (*syscall.Overlapped)(unsafe.Pointer(&data)), &dwBytes, true, &flag)if dwBytes == 0 {continue}fmt.Printf("client %d connected\n", acceptFd)_, err = CreateIoCompletionPort(acceptFd, hIOCP, 0, 0)if err != nil {continue}postWrite(data)}
}func postWrite(data *IOData) (err error) {data.isRead = false// 这里输出一下data指针,让运行时不把data给GC掉,否则就会出问题fmt.Printf("%p cli:%d send %s\n", data, data.cliSock, unsafe.String(data.WsaBuf.Buf, data.WsaBuf.Len))err = syscall.WSASend(data.cliSock, &data.WsaBuf, 1, &data.NBytes, 0, &data.Overlapped, nil)if err != nil {fmt.Printf("cli:%d send failed: %s\n", data.cliSock, err)return err}return
}func postRead(data *IOData) (err error) {data.NBytes = data.WsaBuf.Lendata.isRead = trueflag := uint32(0)err = syscall.WSARecv(data.cliSock, &data.WsaBuf, 1, &data.NBytes, &flag, &data.Overlapped, nil)if err != nil && !errors.Is(err, syscall.ERROR_IO_PENDING) {fmt.Printf("cli:%d receive failed: %s\n", data.cliSock, err)return err}return
}func workThread(hIOCP syscall.Handle) {var pOverlapped *syscall.Overlappedvar ioSize uint32var key uintptrfor {err := GetQueuedCompletionStatus(hIOCP, &ioSize, &key, &pOverlapped, syscall.INFINITE)if err != nil {fmt.Printf("GetQueuedCompletionStatus failed: %s\n", err)return}if ioSize == 0 {break}ioData := (*IOData)(unsafe.Pointer(pOverlapped))if ioData.isRead {postWrite(ioData)} else {postRead(ioData)}}
}
源码只是一个示例,有资源泄漏的问题待处理。
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