ACE_Mutex ::获取问题

Question

I have a mutex in my class with the following definition:

ACE_Mutex m_specsMutex;

When i use the acquire() method that takes no parameters everything works just fine. But when i use it with a time value (as follows) it just immediately returns with -1 value. I'm sure that this mutex hasn't been acquired anywhere else so it shouldn't return -1.

m_specsMutex.acquire(ACE_OS::gettimeofday() + ACE_Time_Value(30))

Am i doing anything wrong?

Answer 1

Browing through the doxygen docs for ACE_Mutex, I don't understand how your code could possibly compile. The time-out value (tv) is passed either by reference or a pointer so that acquire() can update the absolute time at which the mutex was acquired. You cannot pass an expression. Try it like this:

ACE_Time_Value time = ACE_OS::gettimeofday() + ACE_Time_Value(30);
m_specsMutex.acquire(&time);

Answer 2

I had the same problem on win32. I needed much time to find a solution and want to share it with you.

ACE_Mutex (=ACE_Thread_Mutex) is implemented using CRITICAL_SECTION for win32 environments. This is very fast but has no possibility to wait with a timeout.

Finally I used ACE_Process_Mutex instead of ACE_Mutex. This is implemented with a HANDLE -based mutex for win32 environments and can be used with timeout.

More information can be found here: http://flylib.com/books/en/3.19.1.83/1/#_/term_