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  1. #include <iostream>
  2. #include <thread>
  3. #include <vector>
  4. #include <mutex>
  5. #include <chrono>
  6. #include <queue>
  7.  
  8. class LockedQueue {
  9. 	std::queue<int> queue_;
  10. 	mutable std::mutex mutex_;
  11. public:
  12. 	LockedQueue() = default;
  13.  
  14. 	// these don't have to be deleted, but you'd have to decide whether or
  15. 	// not each operation needed to invoke a lock, and in the case of operator=
  16. 	// you have two mutexes to contend with.
  17. 	LockedQueue(const LockedQueue&) = delete;
  18. 	LockedQueue(LockedQueue&&) = delete;
  19. 	LockedQueue& operator=(const LockedQueue&) = delete;
  20. 	LockedQueue& operator=(LockedQueue&&) = delete;
  21.  
  22. 	void push(int value) {
  23. 		std::lock_guard<std::mutex> lock(mutex_);
  24. 		queue_.push(value);
  25. 	}
  26. 	int pop() {
  27. 		std::lock_guard<std::mutex> lock(mutex_);
  28. 		int value = queue_.front();
  29. 		queue_.pop();
  30. 		return value;
  31. 	}
  32. 	bool empty() const {
  33. 		std::lock_guard<std::mutex> lock(mutex_);
  34. 		return queue_.empty();
  35. 	}
  36. };
  37.  
  38. void func(LockedQueue& work, LockedQueue& results);
  39.  
  40. int main()
  41. {
  42. 	LockedQueue work, results;
  43.     std::vector<std::thread> threads;
  44.  
  45.     for (int i = 0; i < 4; i++)
  46.     {
  47.     	work.push(i);
  48.         threads.emplace_back(func, std::ref(work), std::ref(results));
  49.     }
  50.  
  51.     for (auto& thread : threads)
  52.         thread.join();
  53.  
  54. 	while (!results.empty()) {
  55. 		int i = results.pop();
  56. 		std::cout << i;
  57. 	}
  58. }
  59.  
  60. void func(LockedQueue& work, LockedQueue& results)
  61. {
  62. 	int index = work.pop();
  63. 	using namespace std::chrono_literals;
  64. 	std::this_thread::sleep_for(1s);
  65.     results.push(index);
  66. }
Success #stdin #stdout 0s 36248KB
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https://ideone.com/7G0JEO
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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