安全C++代码pool
转自：编写安全C++代码杂谈
1 class noncopyable 2 { 3 public: 4 noncopyable(const noncopyable&) = delete; 5 void operator=(const noncopyable&) = delete; 6 7 protected: 8 noncopyable() = default; 9 ~noncopyable() = default; 10 }; 11 12 struct connection { 13 std::string id; 14 //...other fields 15 }; 16 17 template<typename _Tp , size_t N> 18 class object_pool final : public noncopyable { 19 public: 20 using DeleterType = std::function<void(_Tp*)>; 21 using value_u_ptr = std::unique_ptr<_Tp, DeleterType>; 22 23 static object_pool& instance() { 24 static object_pool<_Tp, N> pool; 25 return pool; 26 } 27 28 value_u_ptr acquire() { 29 std::lock_guard<std::mutex> lock(mtx_); 30 if (empty()) { 31 return nullptr; 32 } 33 34 value_u_ptr ptr(pool_.front().release(), [this](_Tp* t) { 35 pool_.push_back(std::unique_ptr<_Tp>(t)); 36 }); 37 38 pool_.pop_front(); 39 return ptr; 40 } 41 42 bool empty() const { 43 return pool_.empty(); 44 } 45 46 size_t size() const { 47 return pool_.size(); 48 } 49 private: 50 object_pool() { 51 static_assert(N < 500, "init size is out of range"); 52 for (size_t i = 0; i < N; i++) { 53 pool_.push_back(std::unique_ptr<_Tp>(new _Tp)); 54 } 55 } 56 57 private: 58 std::deque<std::unique_ptr<_Tp>> pool_; 59 std::mutex mtx_; 60 };
