CIS: "Protecting" code in stead of data
The Windows API contains a synchronization primitive that is a mutual exclusion device, but is also a colossal misnomer. I mean, of course, the
The “critical section” describes a piece of code that accesses a shared resource – shared between threads or processes. While such code should be analyzed and well-understood, and is indeed critical in a sense, it’s the data that needs to be protected from concurrent access, if necessary.
Much confusion has arisen from the name
CRITICAL_SECTION: more than once, I’ve seen them being used to “protect” the code itself, rather than the data.
ScopedLock class, such as the following, does two things:
- the class’ name makes it clear that it’s a lock, so something needs locking
- it takes care of exception-safety and prevents lock leaks
(Of course, a POSIX version of the same class does the same thing, but the POSIX mutex is better named).
A more elaborate solution would be to create a
Mutex class to encapsulate the
CRITICAL_SECTION, allowing newbies to google for “mutex”…