通过重叠 IO 的异步命名 Windows 管道通信

Question

我正在使用重叠 IO 在 C 代码中同时读取和写入单个 Windows 管道。我想编写一个同步函数来从单独的线程读取和写入数据。如果您使用的是同步 IO，则无法同时读取和写入管道。我的客户端和服务器使用相同的 write/read 函数。我的客户端一次又一次地发送服务器从未接收到的数据。有谁知道这是怎么发生的？如果我在客户端中使用同步 IO，一切都会按预期工作。

服务器管道由以下命令打开：

CreateNamedPipe(pipeName, PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED, PIPE_TYPE_BYTE | PIPE_READMODE_BYTE | PIPE_WAIT,
                                      instances, PIPE_BUF_SIZE, PIPE_BUF_SIZE, 0, NULL);

客户端管道是这样打开的：

CreateFile(pipeName, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);

我正在使用这些读取功能：

int readBytesPipeCommChannel(PipeCommChannelData* comm, uint32_t* amount)
    OVERLAPPED osRead;
    memset(&osRead, 0, sizeof(osRead));  
    osRead.hEvent = comm->readAsyncIOEvent;

    int err = 0;
    if(!ReadFile(comm->pipeH, comm->receiveBuffer, sizeof(comm->receiveBuffer), amount, &osRead))
    {   
        err = GetLastError();     
        if (err == ERROR_IO_PENDING)
        {
            if(WaitForSingleObject(osRead.hEvent, INFINITE))
            {
                GetOverlappedResult(comm->pipeH, &osRead, amount, TRUE);
            }
            else
            {
                CancelIo(comm->pipeH);
                return PIPE_EVENT_ERROR;
            }
        }
        else if(err != ERROR_BROKEN_PIPE)
        {
            return PIPE_READ_ERROR;
        }
    }
    if(err == ERROR_BROKEN_PIPE)
        return PIPE_BROKEN_ERR;

    return PIPE_OK;
}

最后但并非最不重要的写入功能：

int sendBytesPipeCommChannel(PipeCommChannelData* comm, const uint8_t* bytes, uint32_t amount)
{
    OVERLAPPED osWrite;
    memset(&osWrite, 0, sizeof(osWrite));  
    osWrite.hEvent = comm->writeAsyncIOEvent;

    uint32_t bytesWritten = 0; 
    for(uint32_t curPos = 0; curPos < amount; curPos += bytesWritten)
    {
        if(!WriteFile(comm->pipeH, &bytes[curPos], (amount - curPos), &bytesWritten, &osWrite))
        {
            if (GetLastError() != ERROR_IO_PENDING)
                return PIPE_WRITE_ERR; 

            if(!WaitForSingleObject(osWrite.hEvent, INFINITE))
            {
                CancelIo(comm->pipeH);
                return PIPE_EVENT_ERROR;
            }
        }
    }
    return PIPE_OK;
}

Answer 1

ReadFile 的文档说：

If hFile was opened with FILE_FLAG_OVERLAPPED, the following conditions are in effect:

The lpNumberOfBytesRead parameter should be set to NULL. Use the GetOverlappedResult function to get the actual number of bytes read.

即使操作同步完成，这也适用。

通过重叠 IO 的异步命名 Windows 管道通信

Asynchronous named Windows pipe communication via overlapped IO

c

windows

client-server

ipc

pipe