c++ - 我可以在线程 A 中进入 CriticalSection(s)，然后在线程 B 中离开 CriticalSection(s)吗？

Question

所以我有 SEND_SLOT 结构:

struct SEND_SLOT
{
    SEND_BUFFER buffer;
    uint16 index;
    CRITICAL_SECTION slotLock;
};

和一个连接结构:

struct connexion
{
    ...
    SEND_SLOT sendSlots[3];
    ...
}

在线程 A 中我做了:

if(TryEnterCriticalSection(&sendSlots[i]))
{  //Post send request...
   WSASend(...);
}

在线程 B 中我做了:

while(...)
{
   ...
   //request finished, data sent, and i get the index to the SEND_SLOT
   LeaveCriticalSection(&sendSlots[index]);
   ...
}

所以我试图在线程 A 中锁定 SEND_SLOT i，稍后我想解锁它，也许是从另一个线程，但它不起作用，每次我尝试发布新发送时它都会锁定第一个插槽，即使它哈希已经被锁定并且没有发出 LeaveCriticalSection。为什么？

Answer 1

不，这是不合法的。 documentation for LeaveCriticalSection解释了调用 EnterCriticalSection 的同一个线程也必须调用 LeaveCriticalSection:

A thread uses the EnterCriticalSection or TryEnterCriticalSection function to acquire ownership of a critical section object. To release its ownership, the thread must call LeaveCriticalSection once for each time that it entered the critical section.

If a thread calls LeaveCriticalSection when it does not have ownership of the specified critical section object, an error occurs that may cause another thread using EnterCriticalSection to wait indefinitely.

同样的限制适用于互斥量。对于您的情况，信号量会更合适。 MSDN说

only the thread that owns a mutex can successfully call the ReleaseMutex function, though any thread can use ReleaseSemaphore to increase the count of a semaphore object.