blocks|key|1087607|text|WaitForSingleObject和CreateSemaphore？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1087608|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

WaitForSingleObject and CreateSemaphore?

blocks|key|2989683|text|为什么说信号量是有问题的？Linux/Windows都有信号量的最大计数，实际上可以用“无限制”来描述。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2989684|在Windows上使用James的建议-它会工作得很好。初始化。您的信号量计数为零。将一个任务添加到您的大(线程安全)容器中，然后向信号量发送信号。在线程中，等待信号量，然后从容器中获取任务并对其进行处理。如果您愿意，您可以将信号量实例传递给多个线程-这样也可以正常工作。|2989685|Rgds，Martin|2989686|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

Why do you say that semaphores are problematic? Linux/Windows both have semaphores with a maximum count that can be realistically be described as 'Unlimited'.

Use James' suggestion on Windows - it will work fine. Init. your semaphore with zero count. Add a task to your big (thread-safe), container, then signal the semaphore. In the thread, wait on the semaphore, then get a task from your container and process it. You can pass the semaphore instance to multiple threads if you wish - that will work OK as well. 

Rgds,
Martin

blocks|key|2704163|text|听起来你想要一个Win32内核事件。参见CreateEvent。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2704164|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/ms682396.aspx^0|K|B|K|B|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

Sounds like you want a Win32 kernel event. See <a href="http://msdn.microsoft.com/en-us/library/ms682396.aspx" rel="nofollow"><code>CreateEvent</code></a>.

blocks|key|2989725|text|谢谢大家，这就是我的结论：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2989726|void+ThreadPool::ThreadStartPoint(ThreadPool*+tp)
{
++++while+(1)
++++{++++
++++++++WaitForSingleObject(tp->m_taskCountSemaphore,INFINITE);+//+while+(num+of+tasks==0)+block;+decreament+num+of+tasks

++++++++BaseTask*+current_task+=+0;

++++++++//+get+top+priority+task
++++++++EnterCriticalSection+(&tp->m_mutex);
++++++++{+++
++++++++++++current_task+=+tp->m_tasksQue.top();
++++++++++++tp->m_tasksQue.pop();
++++++++}
++++++++LeaveCriticalSection+(&tp->m_mutex);

++++++++current_task->operator()();+//+this+is+not+critical+section
++++++++current_task->PostExec();
++++}
}

void+ThreadPool::AddTask(BaseTask&+_task)
{
++++EnterCriticalSection+(&m_mutex);
++++{
++++++++m_tasksQue.push(&_task);
++++++++_task.PrepareTask(m_mutex);
++++}
++++LeaveCriticalSection+(&m_mutex);

++++if+(!ReleaseSemaphore(m_taskCountSemaphore,
++++++++++++++++++++++++++1,++++//+increament+num+of+tasks+by+1
++++++++++++++++++++++++++NULL++//+don't+store+previuos+num+of+tasks+value
++++++++++++++++++++++++++))+
++++{//if+failed
++++++++throw+("semaphore+release+failed");
++++}
}|code-block|syntax|javascript|2989727|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Thanks all,
thats my conclusion:

<pre><code>void ThreadPool::ThreadStartPoint(ThreadPool* tp)
{
 while (1)
 { 
 WaitForSingleObject(tp-&gt;m_taskCountSemaphore,INFINITE); // while (num of tasks==0) block; decreament num of tasks

 BaseTask* current_task = 0;

 // get top priority task
 EnterCriticalSection (&amp;tp-&gt;m_mutex);
 { 
 current_task = tp-&gt;m_tasksQue.top();
 tp-&gt;m_tasksQue.pop();
 }
 LeaveCriticalSection (&amp;tp-&gt;m_mutex);

 current_task-&gt;operator()(); // this is not critical section
 current_task-&gt;PostExec();
 }
}

void ThreadPool::AddTask(BaseTask&amp; _task)
{
 EnterCriticalSection (&amp;m_mutex);
 {
 m_tasksQue.push(&amp;_task);
 _task.PrepareTask(m_mutex);
 }
 LeaveCriticalSection (&amp;m_mutex);

 if (!ReleaseSemaphore(m_taskCountSemaphore,
 1, // increament num of tasks by 1
 NULL // don't store previuos num of tasks value
 )) 
 {//if failed
 throw ("semaphore release failed");
 }
}
</code></pre>

I want to write a thread which runs tasks from an unlimited-size container of tasks.

While the task-list is empty the thread trying to get a task should be blocked.

Coming from Linux I wanted to use condition variable which will be signaled on task adding and will be waited while the list is empty.

I found that CONDITION_VARIABLE is available only from windows Vista, so this is out of question.
Semaphores are problematic too due to the unlimited-size restriction.

Is there any apropriate subtitution?

Thanks

Condition Variable alternatives (c/c++ on windows xp)

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我想写一个线程，它从一个无限大小的任务容器中运行任务。当任务列表为空时，尝试获取任务的线程应该被阻塞。我来自Linux，我想使用条件变量，它将在添加任务时发出信号，并在列表为空时等待。我发现CONDITION_VARIABLE只能在windows Vista上使用，所以这是毫无疑问的。由于没有大小限制，信号量也是有问题...

问条件变量备选方案( windows xp上的c/c++)
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