C++11: Condition Variables

C++11 added Condition Variables. Here is an example:

#include <condition_variable>
#include <iostream>
#include <mutex>
#include <thread>

std::condition_variable gConditionVariable;
bool                    gEventIsTriggered = false;
std::mutex              gMutex;

struct FunctionClass
{
  void operator()()
  {
    std::cout << "ThreadWaiting:";
    std::unique_lock<std::mutex> lock(gMutex);
    gConditionVariable.wait(lock, []{return gEventIsTriggered;});
    std::cout << "ThreadExiting:";
  }
};

int main()
{
  std::thread t1{FunctionClass()};
  std::thread t2{FunctionClass()};

  std::cout << "MainRunning:";
  gEventIsTriggered = true;
  gConditionVariable.notify_one();
  gEventIsTriggered = true;
  gConditionVariable.notify_one();

  t1.join();
  t2.join();
  std::cout << std::endl;
  return 0;
}
// Output: ThreadWaiting:ThreadWaiting:MainRunning:ThreadExiting:ThreadExiting:

Reference: https://isocpp.org/wiki/faq/cpp11-library-concurrency#std-condition