Shows issue relating to invoking boost::condition_variable::notify_all outside of mutex-protected scope

condition_variable_issue.cc

#include <condition_variable>
#include <thread>
#include "boost/thread/condition_variable.hpp"
#include "boost/thread/thread.hpp"


template<typename Thread, typename Lock, typename CondVar>
void Loop() {
  for (int i = 0; i < 10000; ++i) {
    CondVar condition_variable;
    Lock::mutex_type mutex;
    bool flag(false);
    Lock unique_lock(mutex);

    Thread thread([&condition_variable, &mutex, &flag] {
      {
        Lock lock(mutex);
        flag = true;
      }
      condition_variable.notify_all();
    });

    thread.detach();

    while (!flag) {
      printf("Wait %i\n", i);
      condition_variable.wait(unique_lock);
    }
  }
}


int main() {
  Loop<std::thread, std::unique_lock<std::mutex>, std::condition_variable>();
  Loop<boost::thread, boost::unique_lock<boost::mutex>, boost::condition_variable>();
  return 0;
}