John Torjo wrote:

Batov, Vladimir wrote:

...

class writer_lock : public boost::mutex::scoped_lock { typedef boost::mutex::scoped_lock super;

public:

writer_lock(rw_mutex& mutex) : super(mutex.mutex_),

mutex_(mutex)

...

{ ++mutex_.num_writers_; // Make new readers wait.

^^^^

just curios, shouldn't this be thread-safe?

I believe it is thread-safe as writer_lock currently inherits from scoped_lock and, consequently, we get inside the writer_lock constructor after its base-class scoped_lock constructor. The base-class constructor does the synchronization.