Question

我想实时监控一个线程中几个目录的变化，所以我决定与GetQueuedCompletionStatus异步使用ReadDirectoryChangesW（）方法。这是我的代码：

static DWORD WINAPI Routine( LPVOID lParam )
{
    FileSystemWatcher* obj = (FileSystemWatcher*)lParam;

    obj->hDir[0] = CreateFile(
        obj->WatchedDir[0].c_str(),
        GENERIC_READ|GENERIC_WRITE,
        FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE,
        NULL,
        OPEN_EXISTING,
        FILE_FLAG_BACKUP_SEMANTICS|FILE_FLAG_OVERLAPPED,
        NULL
    );

    obj->hDir[1] = CreateFile(
   obj->WatchedDir[1].c_str(),
   GENERIC_READ|GENERIC_WRITE,
   FILE_SHARE_READ|FILE_SHARE_WRITE|FILE_SHARE_DELETE,
   NULL,
   OPEN_EXISTING,
   FILE_FLAG_BACKUP_SEMANTICS|FILE_FLAG_OVERLAPPED,
   NULL
    );

    if( INVALID_HANDLE_VALUE == obj->hDir[0] || INVALID_HANDLE_VALUE == obj->hDir     [1] ) 
{
    return false;
}

obj->IOCPHandle[0] = CreateIoCompletionPort(obj->hDir[0], NULL, 0, 1);
obj->IOCPHandle[1] = CreateIoCompletionPort(obj->hDir[1], NULL, 0, 1);

if (obj->IOCPHandle[0] == INVALID_HANDLE_VALUE || obj->IOCPHandle[1] ==  INVALID_HANDLE_VALUE)
{
    return false;
}

    char buf[ 2*(sizeof(FILE_NOTIFY_INFORMATION)+MAX_PATH) ];
    FILE_NOTIFY_INFORMATION* pNotify=(FILE_NOTIFY_INFORMATION *)buf;
    DWORD BytesReturned;
    LPOVERLAPPED overLap = NULL;

    m_pFileNotifyInfo = pNotify;
    dirEvents[0] = CreateEvent(NULL, TRUE, FALSE, NULL);
    dirEvents[1] = CreateEvent(NULL, TRUE, FALSE, NULL);*/

    while(true)
    {

    BOOL success = ReadDirectoryChangesW( obj->hDir[0],
    pNotify,
    sizeof(buf),
    true,
    FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_DIR_NAME,
    &BytesReturned,
    overLap,
    NULL );
    BOOL success1 = ReadDirectoryChangesW( obj->hDir[1],
    pNotify,
    sizeof(buf),
    true,
    FILE_NOTIFY_CHANGE_FILE_NAME|FILE_NOTIFY_CHANGE_DIR_NAME,
    &BytesReturned,
    overLap,    
                 NULL );

    LPOVERLAPPED theOverLap;
    PULONG_PTR lpCompKey = NULL;
    if (GetQueuedCompletionStatus(obj->IOCPHandle[0], &BytesReturned, lpCompKey, &overLap, 100))
    {
    cout<<"First Dir Changed"<<endl;
    }

    if (GetQueuedCompletionStatus(obj->IOCPHandle[1], &BytesReturned, lpCompKey, &overLap, 100))
    {
    cout<<"Second Dir Changed"<<endl;
    }

    cout<<"Nothing happened yet"<<endl;

       }

    return 0;
}

这里当我运行我的代码时，我的线程无缘无故地阻塞，无论我设置为GetQueuedCompletionStatus（）函数的最后一个参数是什么值。我不知道为什么遇到这个问题。有人能告诉我原因吗？非常感谢！

Answer 1

您必须为异步I / O指定有效的OVERLAPPED结构才能工作。您正在使用NULL（LPOVERLAPPED overLap = NULL;）。
并发I / O操作必须使用单独的OVERLAPPED结构，而不仅仅是一个。
您确定需要IOCP吗？我只需在OVERLAPPED结构中填写hEvent并对这些事件进行WaitForMultipleObjects。

异步使用ReadDirectoryChangesW时出现线程死锁

1 个答案: