WaitForSingleObject 的内部实现原理

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WaitForSingleObject 的内部实现原理

2013年09月01日 ⁄ 综合 ⁄ 共 1887字 ⁄ 字号小中大 ⁄ 评论关闭

WaitForSingleObject 是 kernel32.dll 的导出函数，WaitForSingleObject 调用了ntdll.dll 的 NtWaitForSingleObject.
NtWaitForSingleObject 又调用了 KeWaitForSingleObject

WaitForSingleObject -> NtWaitForSingleObject -> KeWaitForSingleObject

以下是KeWaitForSingleObject的部分实现代码。

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CODE:

do
{
      WaitStatus = CurrentThread->WaitStatus;
      CurrentThread->WaitBlockList = WaitBlock = &CurrentThread->WaitBlock[0];
      CurrentObject = (PDISPATCHER_HEADER)Object;

      if (KiIsObjectSignaled(CurrentObject, CurrentThread))
      {
            if (CurrentObject->SignalState != MINLONG)
            {
                     KiSatisfyObjectWait(CurrentObject, CurrentThread);
                     Status = STATUS_WAIT_0;
                     goto WaitDone;
            }
            else
            {
                     if (CurrentObject->Type == MutantObject)
                     {
                              KeReleaseDispatcherDatabaseLock(CurrentThread->WaitIrql);
                              ExRaiseStatus(STATUS_MUTANT_LIMIT_EXCEEDED);
                     }
            }
      }

      WaitBlock->Object = CurrentObject;
      WaitBlock->Thread = CurrentThread;
      WaitBlock->WaitKey = (USHORT)(STATUS_WAIT_0);
      WaitBlock->WaitType = WaitAny;
      WaitBlock->NextWaitBlock = NULL;

KiCheckAlertability(Alertable, CurrentThread, WaitMode, &Status);

CurrentThread->WaitStatus = Status;

      if (Timeout != NULL)
      {
            //略.有超时设置的情况
      }

InsertTailList(&CurrentObject->WaitListHead, &WaitBlock->WaitListEntry);

      if (CurrentThread->Queue)
      {
            DPRINT("Waking Queue/n");
            KiWakeQueue(CurrentThread->Queue);
      }

PsBlockThread(&Status, Alertable, WaitMode, (UCHAR)WaitReason);

      if (Status != STATUS_KERNEL_APC)
      {
            return Status;
      }

DPRINT("Looping Again/n");
CurrentThread->WaitIrql = KeAcquireDispatcherDatabaseLock();

}while (TRUE);

WaitDone:

转载自： http://www.vbgood.com/viewthread.php?tid=76711