atomic_compare_exchange_weak, atomic_compare_exchange_strong, atomic_compare_exchange_weak_explicit, atomic_compare_exchange_strong_explicit

 

C

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线程的支持 （C11）

原子操作 （C11）

 

原子操作库

类型 Original: Types The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

memory_order

atomic_flag

宏 Original: Macros The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

ATOMIC_***_LOCK_FREE

ATOMIC_FLAG_INIT

ATOMIC_VAR_INIT

kill_dependency

功能 Original: Functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

atomic_flag_test_and_set

atomic_flag_clear

atomic_init

atomic_is_lock_free

atomic_store

atomic_load

atomic_exchange

atomic_compare_exchange

atomic_fetch_add

atomic_fetch_sub

atomic_fetch_or

atomic_fetch_xor

atomic_fetch_and

atomic_thread_fence

atomic_signal_fence

 

Defined in header <stdatomic.h>
_Bool atomic_compare_exchange_strong( volatile A* obj,                                       C* expected, C desired );	(1)	（C11 起）
_Bool atomic_compare_exchange_weak( volatile A *obj,                                     C* expected, C desired );	(2)	（C11 起）
_Bool atomic_compare_exchange_strong_explicit( volatile A* obj,                                                C* expected, C desired,                                                memory_order succ,                                                memory_order fail );	(3)	（C11 起）
_Bool atomic_compare_exchange_weak_explicit( volatile A *obj,                                              C* expected, C desired,                                              memory_order succ,                                              memory_order fail );	(4)	（C11 起）

原子的值进行比较，指出，obj指出，expected的价值，如果这些都是平等的，取代了以前的desired（执行读 - 修改 - 写操作）。否则，加载的实际值所指向的obj到*expected（执行负载操作）.

Original:

Atomically compares the value pointed to by obj with the value pointed to by expected, and if those are equal, replaces the former with desired (performs read-modify-write operation). Otherwise, loads the actual value pointed to by obj into *expected (performs load operation).

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内存模型的读 - 修改 - 写和加载操作succ和fail。 （1-2）版本默认情况下，使用memory_order_seq_cst.

Original:

The memory models for the read-modify-write and load operations are succ and fail respectively. The (1-2) versions use memory_order_seq_cst by default.

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的弱形式（（1）和（3））的功能允许意外失败，即，如果*obj != *expected作为即使它们是相等的。当比较和交换是在一个循环中，弱版本会带来更好的性能，在某些平台上。当一个弱的比较和交换，需要一个循环，一个强大的，强大的一个是最好的.

Original:

The weak forms ((1) and (3)) of the functions are allowed to fail spuriously, that is, act as if *obj != *expected even if they are equal. When a compare-and-exchange is in a loop, the weak version will yield better performance on some platforms. When a weak compare-and-exchange would require a loop and a strong one would not, the strong one is preferable.

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这是一个通用函数定义的所有原子的对象类型。 A是一个原子对象的类型，C非原子的类型，对应于A.

Original:

This is a 通用函数 defined for all atomic object types. A is the type of an atomic object, C is the non-atomic type corresponding to A.

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参数

obj	-	指针的原子对象测试和修改 Original: pointer to the atomic object to test and modify The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
expected	-	预期发现的原子对象中的值的指针 Original: pointer to the value expected to be found in the atomic object The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
desired	-	要存储的值的原子对象中，如果是如预期的那样 Original: the value to store in the atomic object if it is as expected The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
succ	-	内存同步的读 - 修改 - 写操作的顺序，如果比较成功。允许所有的值都. Original: the memory synchronization ordering for the read-modify-write operation if the comparison succeeds. All values are permitted. The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
fail	-	存储器同步的负载操作的顺序，如果比较失败。不能是memory_order_release或memory_order_ack_rel并且不能指定更强的顺序比succ Original: the memory synchronization ordering for the load operation if the comparison fails. Cannot be memory_order_release or memory_order_ack_rel and cannot specify stronger ordering than succ The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

返回值

的比较结果：true如果*obj等于*exp，false否则.

Original:

The result of the comparison: true if *obj was equal to *exp, false otherwise.

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另请参阅

atomic_exchange atomic_exchange_explicit （C11）	交换值与原子的对象的值 Original: swaps a value with the value of an atomic object The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数）
C++ documentation for atomic_compare_exchange_weak, atomic_compare_exchange_strong, atomic_compare_exchange_weak_explicit, atomic_compare_exchange_strong_explicit