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# Atomic operations library

From cppreference.com
< cpp

The atomic library provides components for fine-grained atomic operations allowing for lockless concurrent programming. Each atomic operation is indivisible with regards to any other atomic operation that involves the same object. Atomic objects are the only C++ objects free of data races; that is, if one thread writes to an atomic while another thread reads from it, the behavior is well-defined.

Defined in header `<atomic>`
##### Atomic types
atomic (C++11) | atomic class template and specializations for bool, integral, and pointer types (class template) [edit]
##### Operations on atomic types
atomic_is_lock_free (C++11) | checks if the atomic type's operations are lock-free (function template) [edit]
atomic_store atomic_store_explicit (C++11)(C++11) | atomically replaces the value of the atomic object with a non-atomic argument (function template) [edit]
atomic_load atomic_load_explicit (C++11)(C++11) | atomically obtains the value stored in an atomic object (function template) [edit]
atomic_exchange atomic_exchange_explicit (C++11)(C++11) | atomically replaces the value of the atomic object with non-atomic argument and returns the old value of the atomic (function template) [edit]
atomic_compare_exchange_weak atomic_compare_exchange_weak_explicit atomic_compare_exchange_strong atomic_compare_exchange_strong_explicit (C++11)(C++11)(C++11)(C++11) | atomically compares the value of the atomic object with non-atomic argument and performs atomic exchange if equal or atomic load if not (function template) [edit]
atomic_fetch_add atomic_fetch_add_explicit (C++11)(C++11) | adds a non-atomic value to an atomic object and obtains the previous value of the atomic (function template) [edit]
atomic_fetch_sub atomic_fetch_sub_explicit (C++11)(C++11) | subtracts a non-atomic value from an atomic object and obtains the previous value of the atomic (function template) [edit]
atomic_fetch_and atomic_fetch_and_explicit (C++11)(C++11) | replaces the atomic object with the result of logical AND with a non-atomic argument and obtains the previous value of the atomic (function template) [edit]
atomic_fetch_or atomic_fetch_or_explicit (C++11)(C++11) | replaces the atomic object with the result of logical OR with a non-atomic argument and obtains the previous value of the atomic (function template) [edit]
atomic_fetch_xor atomic_fetch_xor_explicit (C++11)(C++11) | replaces the atomic object with the result of logical XOR with a non-atomic argument and obtains the previous value of the atomic (function template) [edit]
##### Flag type and operations
atomic_flag (C++11) | the lock-free boolean atomic type (class) [edit]
atomic_flag_test_and_set atomic_flag_test_and_set_explicit (C++11)(C++11) | atomically sets the flag to true and returns its previous value (function) [edit]
atomic_flag_clear atomic_flag_clear_explicit (C++11)(C++11) | atomically sets the value of the flag to false (function) [edit]
##### Initialization
atomic_init (C++11) | non-atomic initialization of a default-constructed atomic object (function template) [edit]
ATOMIC_VAR_INIT (C++11) | constant initialization of an atomic variable of static storage duration (function macro) [edit]
ATOMIC_FLAG_INIT (C++11) | initializes an std::atomic_flag to false (macro constant) [edit]
##### Memory synchronization ordering
memory_order (C++11) | defines memory ordering constraints for the given atomic operation (typedef) [edit]
kill_dependency (C++11) | removes the specified object from the std::memory_order_consume dependency tree (function template) [edit]
atomic_thread_fence (C++11) | generic memory order-dependent fence synchronization primitive (function) [edit]
atomic_signal_fence (C++11) | fence between a thread and a signal handler executed in the same thread (function) [edit]

### [edit] See also

C documentation for Atomic operations library

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