Question

boost::recursive_mutex m;
m.lock();

versus

boost::lock_guard<boost::recursive_mutex> lock( mutex_ );

Is there an advantage to use the first Form? Does the second form only provide RAII mecanism, or are there others advantages ?

Answer 1

The advantage of using lock_guard is that it will release the lock when it goes out of scope. This eliminates the need to manually release the lock and reduces the chance of forgetting to do so.

boost::recursive_mutex mylock;

{
    boost::lock_guard<boost::recursive_mutex> lock( mylock );

    // do something

    if(false == do_something())
    {
        return; // "lock" goes out of scope and unlocks 'mylock' from it's destructor.
    }

}
// "lock" has gone out of scope and unlocked 'mylock' from it's destructor.