1. // 004_完成端口.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
    2. //
    3. #include <windows.h>
    4. #include <stdio.h>
    6. struct MyOverlapped : public OVERLAPPED {
    7.     MyOverlapped()
    8.     {
    9.         // 将OVERLAPPED部分填充为0
    10.         memset(this, 0, sizeof(OVERLAPPED));
    11.         pBuff = NULL;
    12.     }
    13.     char *pBuff;
    14.     ~MyOverlapped() {
    15.         if (pBuff) {
    16.             delete pBuff;
    17.         }
    18.     }
    19. };
    21. DWORD WINAPI threadProc(LPVOID pArg)
    22. {
    23.     HANDLE hIoComp = (HANDLE)pArg;
    24.     DWORD dwBytes = 0;
    25.     ULONG_PTR completionKey = 0;
    26.     MyOverlapped* pOv=NULL;
    27.     BOOL ret = 0;
    28.     while ( 1 )
    29.     {
    30.         ret = GetQueuedCompletionStatus(
    31.             hIoComp,
    32.             &dwBytes,/*实际完成的字节数*/
    33.             &completionKey,/*和文件设备关联在一起的完成键*/
    34.             (OVERLAPPED**)&pOv,/*通过ReadFile投递IO任务时传递重叠结构*/
    35.             -1/*超时时间*/);
    36.         if (ret == FALSE) {
    37.             continue;
    38.         }
    39.         printf("读取偏移:[%d]的IO任务完成, 实际读取到的字节数:%d"
    40.                "读取到的内容是:%s",
    41.                pOv->Offset,
    42.                pOv->InternalHigh,
    43.                pOv->pBuff);
    45.         delete pOv;
    46.     }
    47.     return 0;
    48. }
    52. int main()
    53. {
    54.     // 1. 创建异步IO方式的文件对象
    55.     HANDLE hFile = INVALID_HANDLE_VALUE;
    56.     hFile = CreateFile(
    57.         L"004_完成端口.cpp",
    58.         GENERIC_READ,/*读写方式:只读*/
    59.         FILE_SHARE_READ,/*共享方式: 共享读*/
    60.         NULL,/*安全描述符*/
    61.         OPEN_EXISTING,/*创建标志:存在时才打开*/
    62.         FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,/*文件属性和标志:正常属性|重叠IO标志 */
    63.         NULL);
    65.     // 2. 创建一个完成端口对象
    66.     SYSTEM_INFO si = { 0 };
    67.     GetSystemInfo(&si);
    68.     HANDLE hIoComp = CreateIoCompletionPort(
    69.         INVALID_HANDLE_VALUE,
    70.         NULL,
    71.         NULL,
    72.         si.dwNumberOfProcessors/*处理器个数*/);
    74.     // 3. 将完成端口和文件对象进行绑定
    75.     CreateIoCompletionPort(
    76.         hFile,/*要和完成端口进行绑定的文件句柄*/
    77.         hIoComp,/*绑定到哪个完成端口上*/
    78.         0,/*完成键, 和文件句柄关联的值*/
    79.         0);
    81.     // 4. 创建指定个数线程, 在线程监视完成端口 完成列表的状态
    82.     for (int i = 0; i < si.dwNumberOfProcessors; ++i) {
    83.         CreateThread(0, 0,&threadProc, hIoComp, 0, 0);
    84.     }
    86.     DWORD read = 0;
    87.     // 5. 发起异步IO任务.
    88.     for (int i = 0; i < 100; ++i) {
    89.         MyOverlapped* pOv = new MyOverlapped;
    90.         pOv->pBuff = new char[50];
    91.         memset(pOv->pBuff, 0, 50);
    92.         pOv->Offset = i * 40;
    93.         ReadFile(hFile, pOv->pBuff, 40, &read, pOv);
    94.     }
    96.     while ( 1 )
    97.     {
    98.         Sleep(1000);
    99.     }
    100. }