How do I protect a character string in shared memory between two processes?

Question

I have a piece of shared memory that contains a char string and an integer between two processes.

Process A writes to it and Process B reads it (and not vice versa)

What is the most efficient and effective way to make sure that Process A doesn't happen to update (write to it) that same time Process B is reading it? (Should I just use flags in the shared memory, use semaphores, critical section....)

If you could point me in the right direction, I would appreciate it.

Thanks.

Windows, C++

Answer 1

You cannot use a Critical Section because these can only be used for synchronization between threads within the same process. For inter process synchronization you need to use a Mutex or a Semaphore. The difference between these two is that the former allows only a single thread to own a resource, while the latter can allow up to a maximum number (specified during creation) to own the resource simultaneously.

In your case a Mutex seems appropriate.