std::atomic_load, std::atomic_load_explicit

定义于头文件 `<atomic>`
	(1)	(C++11 起)
template< class T > T atomic_load( const std::atomic<T>* obj ) noexcept;
template< class T > T atomic_load( const volatile std::atomic<T>* obj ) noexcept;
			(2)	(C++11 起)
template< class T > T atomic_load_explicit( const std::atomic<T>* obj, std::memory_order order ) noexcept;
template< class T > T atomic_load_explicit( const volatile std::atomic<T>* obj, std::memory_order order ) noexcept;

1) 如同用 obj->load() 原子地获得 obj 所指向的值。

2) 如同用 obj->load(order) 原子地获得 obj 所指向的值。

obj	-	指向要加载的原子对象的指针
order	-	此操作所用的内存同步顺序：只容许 std::memory_order_relaxed 、 std::memory_order_consume 、 std::memory_order_acquire 和 std::memory_order_seq_cst 。

obj 所指向的原子对象所保有的值。

load	原子地获得原子对象的值 (`std::atomic<T>` 的公开成员函数)
atomic_storeatomic_store_explicit (C++11)(C++11)	原子地以非原子实参替换原子对象的值 (函数模板)
memory_order (C++11)	为给定的原子操作定义内存顺序制约 (枚举)

(C++20 中弃用)

为 std::shared_ptr 特化原子操作
(函数模板)

类
atomic (C++11)
atomic_ref (C++20)
函数
atomic_storeatomic_store_explicit (C++11)(C++11)
atomic_loadatomic_load_explicit (C++11)(C++11)
atomic_exchangeatomic_exchange_explicit (C++11)(C++11)
atomic_compare_exchange_weakatomic_compare_exchange_weak_explicitatomic_compare_exchange_strongatomic_compare_exchange_strong_explicit (C++11)(C++11)(C++11)(C++11)
atomic_fetch_addatomic_fetch_add_explicit (C++11)(C++11)
atomic_fetch_subatomic_fetch_sub_explicit (C++11)(C++11)
atomic_fetch_andatomic_fetch_and_explicit (C++11)(C++11)
atomic_fetch_oratomic_fetch_or_explicit (C++11)(C++11)
atomic_fetch_xoratomic_fetch_xor_explicit (C++11)(C++11)
atomic_is_lock_free (C++11)
atomic_waitatomic_wait_explicit (C++20)(C++20)
atomic_notify_one (C++20)
atomic_notify_all (C++20)
原子标志
atomic_flag (C++11)
atomic_flag_test_and_setatomic_flag_test_and_set_explicit (C++11)(C++11)
atomic_flag_clearatomic_flag_clear_explicit (C++11)(C++11)
atomic_flag_testatomic_flag_test_explicit (C++20)(C++20)
atomic_flag_waitatomic_flag_wait_explicit (C++20)(C++20)
atomic_flag_notify_one (C++20)
atomic_flag_notify_all (C++20)
初始化
atomic_init (C++11)(C++20 中弃用)
ATOMIC_VAR_INIT (C++11)(C++20 中弃用)
ATOMIC_FLAG_INIT (C++11)(C++20 中弃用)
内存顺序
memory_order (C++11)
kill_dependency (C++11)
atomic_thread_fence (C++11)
atomic_signal_fence (C++11)

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