How to tighten the scope when using C++ lock_guard?

Question

In C++, lock_guard allows you to be RAII compliant when using locks. It calls lock() when constructing the lock_guard, and unlock() when destroying it once it goes out of scope.

Is it possible to tighten the scope of lock_guard such that it is destroyed sooner, to avoid keeping the lock for longer than necessary?

Answer 1

I'm not 100% sure what you mean, but you can introduce a block scope for the std::lock_guard with curly braces like this:

void foo()
{
    // do uncritical stuff

    { 
        // critical part starts here with construction
        std::lock_guard<std::mutex> myLock(someMutex);

        // do critical stuff
    } // critical parts end here with myLock going out of scope

    // do uncritical stuff
}