多個std :: condition_variable通知使用notify_one運行線程（）

Question

我想從另一個線程（主線程）使用std :: condition_variable發送多個通知到正在運行的線程。發送一次，但第二次或多次都不起作用。這是我做了什麼（不實際事件的不必要的細節）：

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

bool keep_running=true; 
bool condition_reached=false; 
std::mutex cond_mtx; 
std::condition_variable cond; 

void thread_waiting_to_be_notified(){ 
    while(keep_running){ 
     std::unique_lock<std::mutex> lk(cond_mtx); 
     cond.wait(lk,[]()->bool{return condition_reached;}); 
     std::cout << "got notitication" << std::endl; 
     condition_reached=false; 
    } 
} 

void some_event(){ 
/*some event happens here*/ 
} 

void another_event(){ 
/*another event happens here*/ 
} 

int main(){ 
    std::thread thr(thread_waiting_to_be_notified); 

    some_event();//first event 
    std::cout << "some event happened" << std::endl; 
    condition_reached=true; 
    cond.notify_one(); 

    another_event();//second event 
    std::cout << "another event happened" << std::endl; 
    condition_reached=true; 
    cond.notify_one(); 
    keep_running=false; 
    thr.join(); 

    return 0; 
} 

---

和我

some event happened 
another event happened 
got notitication 

但是輸出，我期望

some event happened 
another event happened 
got notitication 
got notitication 

任何意見，將不勝感激。

Answer 1

嘗試後

condition_reached=false;