Critical Section

/*
In concurrent programming, a critical section is a piece of code that accesses a shared resource (data structure or device) that must not be concurrently accessed by more than one thread of execution.[1] A critical section will usually terminate in fixed time, and a thread, task, or process will have to wait for a fixed time to enter it (aka bounded waiting). Some synchronization mechanism is required at the entry and exit of the critical section to ensure exclusive use, for example a semaphore.
*/
/* Sample C/C++, Windows, link to kernel32.dll */
#include <windows.h>

static CRITICAL_SECTION cs; /* This is the critical section object -- once initialized,
                               it cannot be moved in memory */
                            /* If you program in OOP, declare this as a non-static member in your class */
void f()
{
    /* Enter the critical section -- other threads are locked out */
    EnterCriticalSection(&cs);

    /* Do some thread-safe processing! */

    /* Leave the critical section -- other threads can now EnterCriticalSection() */
    LeaveCriticalSection(&cs);
}

int main()
{
    /* Initialize the critical section before entering multi-threaded context. */
    InitializeCriticalSection(&cs);

    f();

    /* Release system object when all finished -- usually at the end of the cleanup code */
    DeleteCriticalSection(&cs);
return 0;
}