若为访问实际函数压制宏定义(例如像 (atomic_fetch_add)(...) 这样加括号),或程序定义拥有泛型函数名的外部标识符,则行为未定义。 对于有符号整数类型,定义算术为使用补码表示。无未定义结果。对于指针类型,结果可能是未定义地址,但运算不会另有未定义行为。 参数obj - 指向要修改的原子对象的指针 arg - 要加到存储于原子
#include <iostream> #include <thread> #include <atomic> std::atomic<long long> data; void do_work() { data.fetch_add(1, std::memory_order_relaxed); } int main() { std::thread th1(do_work); std::thread th2(do_work); std::thread th3(do_work); std::thread th4(do_work); ...
T fetch_add(T arg,std::memory_orderorder= std::memory_order_seq_cst)noexcept; (1)(since C++11) T fetch_add(T arg,std::memory_orderorder= std::memory_order_seq_cst)volatilenoexcept; (2)(since C++11) member only ofatomic<T*>partial specialization ...
#include <atomic> std::atomic<int> value(0); value.fetch_add(1, std::memory_order_acq_rel)...
T fetch_add(T arg, std::memory_orderorder=std::memory_order_seq_cst)constnoexcept; (1)(since C++20) member only ofatomic_ref<T*>template specialization T*fetch_add(std::ptrdiff_targ, std::memory_orderorder=std::memory_order_seq_cst)constnoexcept; ...
atomic<size_t> shared_cnt{0}; atomic<size_t> weak_cnt{0}; voidadd_shared_cnt(){ shared_cnt.fetch_add(1); } voidsub_shared_cnt(){ shared_cnt.fetch_sub(1); } }; template<typenameT> structshared_ptr { T *obj_{nullptr}; ...
std::atomic_fetch_add_explicit(&fun, 0, std::memory_order_relaxed); } { std::atomic<void (*)(int)> fun; // expected-error-re@*:* {{{(static_assert|static assertion)}} failed due to requirement '!is_function<void (int)>::value'{{.*}}Pointer to function isn't allowed}} //...
execute([&counter] { std::this_thread::sleep_for(10ms); std::atomic_fetch_add(&counter, 1); counter.notify_all(); }); 51 52 REQUIRE(pool.numThreads() == 1); 52 - pool.execute([&counter] { std::this_thread::sleep_for(std::chrono::milliseconds(10)); std::atomic_fetch_...
:ignite() .mount("/", routes![index, count]) .manage(HitCount(AtomicUsize::new(0)...
2 add eax, 1 add eax, 1 3 store x, eax 4 store x, eax 我们会发现最终x的值会是1而不是2,因为Thread 1的结果被覆盖掉了。这种情况下我们就需要对x++这样的操作加锁(例如Pthread中的mutex)以保证同步,或者使用一些提供了atomic operations的库(例如Windows API中的atomic库,Linux内核中的atomic.h,Java...