std::atomic_exchange, std::atomic_exchange_explicit

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C++

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Biblioteca operações atômica

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

atomic (C++11)

atomic_is_lock_free (C++11)

Funções 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_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)

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

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)

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

atomic_init (C++11)

ATOMIC_VAR_INIT (C++11)

ATOMIC_FLAG_INIT (C++11)

Memória de encomenda Original: Memory ordering The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

memory_order (C++11)

kill_dependency (C++11)

atomic_thread_fence (C++11)

atomic_signal_fence (C++11)

 

<tbody> </tbody>

Definido no cabeçalho <atomic>
template< class T > T atomic_exchange( std::atomic<T>* obj, T desr );	(1)	(desde C++11)
template< class T > T atomic_exchange( volatile std::atomic<T>* obj, T desr );	(2)	(desde C++11)
template< class T > T atomic_exchange_explicit( std::atomic<T>* obj, T desr, std::memory_order order );	(3)	(desde C++11)
template< class T > T atomic_exchange_explicit( volatile std::atomic<T>* obj, T desr, std::memory_order order );	(4)	(desde C++11)

1-2)

Atomicamente substitui o valor apontado por obj com o valor de desr e retorna o valor obj realizada anteriormente, como por obj->exhange(desr)

Original:

Atomically replaces the value pointed to by obj with the value of desr and returns the value obj held previously, as if by obj->exhange(desr)

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3-4)

Atomicamente substitui o valor apontado por obj com o valor de desr e retorna o valor obj realizada anteriormente, como por obj->exhange(desr, order)

Original:

Atomically replaces the value pointed to by obj with the value of desr and returns the value obj held previously, as if by obj->exhange(desr, order)

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Parâmetros

obj	-	ponteiro para o objeto atômico modificar Original: pointer to the atomic object to modify The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
desr	-	o valor para armazenar no objeto atômico Original: the value to store 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.
order	-	o sycnhronization memória de ordenação para esta operação: todos os valores são permitidos . Original: the memory sycnhronization ordering for this operation: 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.

Valor de retorno

O valor realizado anteriormente pelo objeto atômico apontado por obj

Original:

The value held previously by the atomic object pointed to by obj

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Exceções

noexcept specification:  

<tbody> </tbody>

noexcept

  (desde C++11)

Exemplo

Um mutex spinlock pode ser implementado no userspace usando uma operação de troca de atómica, semelhante ao atomic_flag_test_and_set

Original:

A spinlock mutex can be implemented in userspace using an atomic exchange operation, similar to atomic_flag_test_and_set

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#include <thread>
#include <vector>
#include <iostream>
#include <atomic>

std::atomic<bool> lock = ATOMIC_VAR_INIT(false);

void f(int n)
{
    for(int cnt = 0; cnt < 100; ++cnt) {
        while(std::atomic_exchange_explicit(&lock, true, std::memory_order_acquire))
             ; // spin until acquired
        std::cout << "Output from thread " << n << '\n';
        std::atomic_store_explicit(&lock, false, std::memory_order_release);
    }
}
int main()
{
    std::vector<std::thread> v;
    for (int n = 0; n < 10; ++n) {
        v.emplace_back(f, n);
    }
    for (auto& t : v) {
        t.join();
    }
}

Saída:

Output from thread 2
Output from thread 6
Output from thread 7
...<exactly 1000 lines>...

Veja também

exchange (C++11)	atomicamente substituiu o valor do objeto atômico e obtém o valor retido anteriormente Original: atomically replaced the value of the atomic object and obtains the value held previously The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (of std::atomic função pública membro)
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)	atomicamente compara o valor do objeto atômico com não atômica argumento e realiza troca atômica se carga igual ou atômica se não Original: atomically compares the value of the atomic object with non-atomic argument and performs atomic exchange if equal or atomic load if not The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função)
std::atomic_exchange(std::shared_ptr) std::atomic_exchange_explicit(std::shared_ptr)	especializada operações atômicas para std::shared_ptr Original: specializes atomic operations for std::shared_ptr The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de função)
Documentação C para atomic_exchange, atomic_exchange_explicit