Question { 15774 }

What is a critical section and how is it implemented?

Answer

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. A critical section will usually
terminate in fixed time, and a thread, task or process will
only have to wait a fixed time to enter it. Some
synchronization mechanism is required at the entry and exit
of the critical section to ensure exclusive use.
for example a printer, can only be accessed by one process
at a time.
Example Code For Critical Sections with Win32 API: -
#include
CRITICAL_SECTION cs; /* This is the critical section
object -- once initialized, it cannot
be moved in memory */
/* Initialize the critical section -- This must be done
before locking */
InitializeCriticalSection(&cs);

/* 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);

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

Is This Answer Correct ?

10 Yes

2 No

Question { 18381 }

What is subclassing?

Answer

Subclassing is a standard technique in Windows programming
for customizing the behavior of a window. MFC wrap
subclassing into virtual function overriding.