Multiple-readers, single-writer locks in Boost

Question

I\'m trying to implement the following code in a multithreading scenario:

Get shared access to mutex
Read data structure
If necessary:
   Get exclusive acces         


        

Answer 1

Yes, you can do exactly what you want as shown in the accepted answer here. A call to upgrade to exclusive access will block until all readers are done.

boost::shared_mutex _access;
void reader()
{
  // get shared access
  boost::shared_lock lock(_access);

  // now we have shared access
}

void writer()
{
  // get upgradable access
  boost::upgrade_lock lock(_access);

  // get exclusive access
  boost::upgrade_to_unique_lock uniqueLock(lock);
  // now we have exclusive access
}