是否有效嵌套关键部分？ [英] Is it valid to nest a critical section?

问题描述

例如，这是否有效？

CRITICAL_SECTION cs;

::InitializeCriticalSection( &cs );

::EnterCriticalSection( &cs );      // First level
::EnterCriticalSection( &cs );        // Second level

/* do some stuff */

::LeaveCriticalSection( &cs );        // Second level
::LeaveCriticalSection( &cs );      // First level

::DeleteCriticalSection( &cs );

显然，我绝不会故意这样做，但如果这是因为函数调用，使得第一级被调用以锁定复杂（例如搜索）算法的对象，并且在该对象的访问器函数中调用第二级。

Obviously, I would never intentionally do this, but what if this were to come about as a result of function calls such that the "first level" gets called to lock an object for a complex (e.g. search) algorithm and the "second level" gets called in that object's accessor functions?

推荐答案

是的，它是有效的进入同一关键部分，而已经在它内部。从文档：

Yes it is valid to enter the same critical section while already inside it. From the docs:

在线程拥有临界区的所有权之后，它可以在不阻塞其执行的情况下对$ Enter $ Cr $ b额外调用EnterCriticalSection或TryEnterCriticalSection
。这防止线程从
死锁本身，同时等待它
已经拥有的关键部分。线程每次进入临界区
EnterCriticalSection和TryEnterCriticalSection成功。线程
每次进入
临界区时必须调用一次LeaveCriticalSection。

After a thread has ownership of a critical section, it can make additional calls to EnterCriticalSection or TryEnterCriticalSection without blocking its execution. This prevents a thread from deadlocking itself while waiting for a critical section that it already owns. The thread enters the critical section each time EnterCriticalSection and TryEnterCriticalSection succeed. A thread must call LeaveCriticalSection once for each time that it entered the critical section.

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