std::atomic_exchange, std::atomic_exchange_explicit

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Bibliothèque pour les expressions régulières (C++11)

Bibliothèque pour les opérations atomiques (C++11)

Bibliothèque pour les processus légers (threads) (C++11)

 

Atomique opérations de la bibliothèque

Types 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)

Fonctions 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_store atomic_store_explicit (C++11) (C++11)

atomic_load atomic_load_explicit (C++11) (C++11)

atomic_exchange atomic_exchange_explicit (C++11) (C++11)

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)

atomic_fetch_add atomic_fetch_add_explicit (C++11) (C++11)

atomic_fetch_sub atomic_fetch_sub_explicit (C++11) (C++11)

atomic_fetch_and atomic_fetch_and_explicit (C++11) (C++11)

atomic_fetch_or atomic_fetch_or_explicit (C++11) (C++11)

atomic_fetch_xor atomic_fetch_xor_explicit (C++11) (C++11)

Drapeaux atomiques 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_set atomic_flag_test_and_set_explicit (C++11) (C++11)

atomic_flag_clear atomic_flag_clear_explicit (C++11) (C++11)

Initialisation 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)

Mémoire de la commande 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)

 

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Déclaré dans l'en-tête <atomic>
template< class T > T atomic_exchange( std::atomic<T>* obj, T desr );	(1)	(depuis C++11)
template< class T > T atomic_exchange( volatile std::atomic<T>* obj, T desr );	(2)	(depuis C++11)
template< class T > T atomic_exchange_explicit( std::atomic<T>* obj, T desr, std::memory_order order );	(3)	(depuis C++11)
template< class T > T atomic_exchange_explicit( volatile std::atomic<T>* obj, T desr, std::memory_order order );	(4)	(depuis C++11)

1-2)

Remplace atomiquement la valeur pointée par obj avec la valeur de desr et retourne la valeur obj lieu précédemment, comme par 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)

Remplace atomiquement la valeur pointée par obj avec la valeur de desr et retourne la valeur obj lieu précédemment, comme par 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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Paramètres

obj	-	pointeur vers l'objet à modifier atomique 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	-	la valeur à stocker dans l'objet atomique 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	-	sycnhronization la mémoire de commande pour cette opération: toutes les valeurs sont autorisées . 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.

Retourne la valeur

La valeur détenue précédemment par l'objet atomique pointée par obj

Original:

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

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Exceptions

noexcept specification:  

<tbody> </tbody>

noexcept

   (depuis C++11)

Exemple

Un mutex spinlock peut être mis en œuvre en espace utilisateur en utilisant une opération d'échange atomique, semblable à 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();
    }
}

Résultat :

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

Voir aussi

exchange (C++11)	atomiquement remplacé, la valeur de l'objet atomique et obtient la valeur détenue précédemment 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. (fonction membre publique de std::atomic)
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)	compare atomiquement la valeur de l'objet atomique non atomique avec l'argument, et réalise un échange atomique égal ou si la charge atomique sinon 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. (fonction générique)
std::atomic_exchange(std::shared_ptr) std::atomic_exchange_explicit(std::shared_ptr)	se spécialise opérations atomiques pour 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. (fonction générique)
C documentation for atomic_exchange, atomic_exchange_explicit