c# - 是否可以通过 API 调用知道有多少未处理的已完成操作在 IOCP 上排队？

Question

我正在使用 C# 套接字（它使用 IOCP 进行回调）。我想要一种方法来确定我的处理逻辑落后的天气。是否有 API 调用可以为我提供尚未由回调处理的已完成操作的大小？

我考虑过使用诸如心跳操作之类的东西，我将其发布到队列中并确定我是否落后于其回调的经过时间，但如果可能的话，我更喜欢更直接的路线（另外我不容易访问到 .Net 内部控制的 IOCP 句柄）。

Answer 1

不是通过记录在案的 API，但你可以试试这个......

/*
GetIocpQueueCount

Description:
Returns the number of queued IOCP work and I/O completion items.

Remarks:
Microsoft declined to implement the NtQueryIoCompletion routine
for user mode. This function gets past that omission by calling
the NTDLL.DLL function dynamically.

Returns:
Number of items in the queue at the instant this function was
called, or -1 if an error occurred. Errors can be retrieved
by calling GetLastError.
*/
long GetIocpQueueCount()
{
   long lQueueDepth = -1;

   typedef DWORD (WINAPI *LPFNNTQUERYIOCOMPLETION)(HANDLE, int, PVOID, ULONG, PULONG);

   static LPFNNTQUERYIOCOMPLETION pfnNtQueryIoCompletion = NULL;

   if (MFTASKQUEUENOTCREATED != m_dwStatus)
   {
      DWORD rc = NO_ERROR;

      /* need to load dynamically */

      if (NULL == pfnNtQueryIoCompletion)
      {
         /* Now dynamically obtain the undocumented NtQueryIoCompletion
          * entry point from NTDLL.DLL
          */

         HMODULE hmodDll = ::GetModuleHandleW(L"ntdll.dll");

         // NTDLL is always loaded, just get its handle

         if (NULL != hmodDll)
         {
            pfnNtQueryIoCompletion = (LPFNNTQUERYIOCOMPLETION)::GetProcAddress(
               hmodDll,
               "NtQueryIoCompletion"); // NB: ANSI
         } 
      }

      if (NULL != pfnNtQueryIoCompletion)
      {
         rc = (pfnNtQueryIoCompletion)(
            m_hIOCP,
            0,
            (PVOID)&lQueueDepth,
            sizeof(lQueueDepth),
            NULL);
      }
      else
      {
         rc = ERROR_NOT_FOUND;
      }
      ::SetLastError(rc);
   }
   return lQueueDepth;
}