C++多线程（五）

女爷i 2022-08-14 00:43 259阅读 0赞

多线程之等待函数  
一 等待函数  
  
1）函数列举

<table style="width:640px; height:513px"> 
 <tbody> 
 <tr> 
 <th>Wait function</th> 
 <th>Description</th> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms684242.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">MsgWaitForMultipleObjects</a></td> 
 <td>Waits until one or all of the specified objects are in the signaled state or the time-out interval elapses. The objects can include input event objects.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms684245.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">MsgWaitForMultipleObjectsEx</a></td> 
 <td>Waits until one or all of the specified objects are in the signaled state, an I/O completion routine or asynchronous procedure call (APC) is queued to the thread, or the time-out interval elapses. The array of objects can include input event objects.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms685061.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">RegisterWaitForSingleObject</a></td> 
 <td>Directs a wait thread in the thread pool to wait on the object.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms686293.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">SignalObjectAndWait</a></td> 
 <td>Atomically signals one object and waits on another object.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms686870.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">UnregisterWait</a></td> 
 <td>Cancels a registered wait operation.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms686876.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">UnregisterWaitEx</a></td> 
 <td>Cancels a registered wait operation.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms687025.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">WaitForMultipleObjects</a></td> 
 <td>Waits until one or all of the specified objects are in the signaled state or the time-out interval elapses.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms687028.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">WaitForMultipleObjectsEx</a></td> 
 <td>Waits until one or all of the specified objects are in the signaled state, an I/O completion routine or asynchronous procedure call (APC) is queued to the thread, or the time-out interval elapses.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms687032.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">WaitForSingleObject</a></td> 
 <td>Waits until the specified object is in the signaled state or the time-out interval elapses.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms687036.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">WaitForSingleObjectEx</a></td> 
 <td>Waits until the specified object is in the signaled state, an I/O completion routine or asynchronous procedure call (APC) is queued to the thread, or the time-out interval elapses.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms687066.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">WaitOrTimerCallback</a></td> 
 <td>An application-defined function that serves as the starting address for a timer callback or a registered wait callback.</td> 
 </tr> 
 </tbody> 
</table>

<table style="width:597px; height:179px"> 
 <tbody> 
 <tr> 
 <th>Waitable-timer function</th> 
 <th>Description</th> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms681985.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">CancelWaitableTimer</a></td> 
 <td>Sets the specified waitable timer to the inactive state.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms682492.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">CreateWaitableTimer</a></td> 
 <td>Creates or opens a waitable timer object.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms682494.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">CreateWaitableTimerEx</a></td> 
 <td>Creates or opens a waitable timer object and returns a handle to the object.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms684337.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">OpenWaitableTimer</a></td> 
 <td>Opens an existing named waitable timer object.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms686289.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">SetWaitableTimer</a></td> 
 <td>Activates the specified waitable timer.</td> 
 </tr> 
 <tr> 
 <td><a href="http://msdn2.microsoft.com/en-us/library/ms686786.aspx" style="color:rgb(0,102,170); text-decoration:none" rel="nofollow">TimerAPCProc</a></td> 
 <td>Application-defined timer completion routine used with theSetWaitableTimer&nbsp;function.</td> 
 </tr> 
 </tbody> 
</table>

2）简单说明WaitForSingleObject  
  
DWORD WaitForSingleObject(HANDLE hObject,DWORD dwMilliseconds);

参数hObject：要等待的内核对象的句柄。  
参数dwMilliseconds： 设置的等待超时的时间，以毫秒为单位。可以设置为INGINIT。       
                                     顺便说一下，INFINITE已经定义为0xFFFFFFFF（或-1）。当然，传递INFINITE有些危险。如果对象永远不变为已  
                                     通知状态，那么调用线程永远不会被唤醒，它将永远处于死锁状态。  
返回值：WAIT\_OBJECT\_0表示要等待的对象已经变为已通知的状态。  
                 WAIT\_TIMEOUT表示设置的时间超时。  
                 WAIT\_FAILED表示失败，可能是传入的handle不正确或其他的问题。

![None.gif][]DWORD dw = WaitForSingleObject(hProcess, 5000);  
![None.gif][]switch(dw)  
![ExpandedBlockStart.gif][]\{  
![InBlock.gif][]   case WAIT\_OBJECT\_0:  
![InBlock.gif][]      // The process terminated.  
![InBlock.gif][]      break;  
![InBlock.gif][]  
![InBlock.gif][]   case WAIT\_TIMEOUT:  
![InBlock.gif][]      // The process did not terminate within 5000 milliseconds.  
![InBlock.gif][]      break;  
![InBlock.gif][]  
![InBlock.gif][]   case WAIT\_FAILED:  
![InBlock.gif][]      // Bad call to function (invalid handle?)  
![InBlock.gif][]      break;  
![ExpandedBlockEnd.gif][]\}

3)简单说明WaitForMultipleObjects

DWORD WaitForMultipleObjects(DWORD dwCount,CONST HANDLE\* phObjects,BOOL fWaitAll,DWORD dwMilliseconds);

参数dwCout：需要等待的内核对象的数量。  
参数phObjects：需要等待的内核对象的是数组的指针。  
参数fWaitAll：表示是否需要等待所有的内核对象。  
参数dwMilliseconds：设置等待超时的时间。（同上函数）

返回值：WAIT\_FAILED和WAIT\_TIMEOUT同上函数。  
 如果为fWaitAll参数传递TRUE，同时所有对象均变为已通知状态，那么返回值是WAIT\_OBJECT\_0。如果为fWaitAll传递FALSE       ，那么一旦任何一个对象变为已通知状态，该函数便返回。在这种情况下，你可能想要知道哪个对象变为已通知状态。返回值是WAIT\_OBJECT\_0与（WAIT\_OBJECT\_0+dwCount- 1）之间的一个值。

![None.gif][]HANDLE h\[3\];  
![None.gif][]h\[0\] = hProcess1;  
![None.gif][]h\[1\] = hProcess2;  
![None.gif][]h\[2\] = hProcess3;  
![None.gif][]DWORD dw = WaitForMultipleObjects(3, h, FALSE, 5000);  
![None.gif][]switch(dw)   
![ExpandedBlockStart.gif][]\{  
![InBlock.gif][]   case WAIT\_FAILED:  
![InBlock.gif][]      // Bad call to function (invalid handle?)  
![InBlock.gif][]      break;  
![InBlock.gif][]  
![InBlock.gif][]   case WAIT\_TIMEOUT:  
![InBlock.gif][]      // None of the objects became signaled within 5000 milliseconds.  
![InBlock.gif][]      break;  
![InBlock.gif][]  
![InBlock.gif][]   case WAIT\_OBJECT\_0 + 0:  
![InBlock.gif][]      // The process identified by h\[0\] (hProcess1) terminated.  
![InBlock.gif][]      break;  
![InBlock.gif][]  
![InBlock.gif][]   case WAIT\_OBJECT\_0 + 1:  
![InBlock.gif][]      // The process identified by h\[1\] (hProcess2) terminated.  
![InBlock.gif][]      break;  
![InBlock.gif][]  
![InBlock.gif][]   case WAIT\_OBJECT\_0 + 2:  
![InBlock.gif][]      // The process identified by h\[2\] (hProcess3) terminated.  
![InBlock.gif][]      break;  
![ExpandedBlockEnd.gif][]\}

二 参考msdn和windows核心编程。

[None.gif]: /images/20220810/a151579c28f045f3ada542b7d83aba9d.png
[ExpandedBlockStart.gif]: /images/20220810/7119223c9f9f4670bb490a5fb2cf3cc5.png
[InBlock.gif]: /images/20220810/7b15ddaeb13b44478fae0d11e52a7cb6.png
[ExpandedBlockEnd.gif]: /images/20220810/051d8c0a875e4eda9e6d75a6db846a00.png