#include <mutex> #include <condition_variable> #include "semaphore.h" void semaphore::down() { // This locks the mutex until it is destroyed at method exit. std::unique_lock<std::mutex> lck(m_mux); // Check the mutex value, and wait if need be. if(--m_value < 0) { // Make us wait. When we wait, the mutex is unlocked until the // wait ends. m_waitcond.wait(lck); } } /* Semaphore up operation. */ void semaphore::up() { // This locks the mutex until it is destroyed at method exit. std::unique_lock<std::mutex> lck(m_mux); // Start a waiting thread if required. if(++m_value <= 0) m_waitcond.notify_one(); }