std::atomic_exchange, std::atomic_exchange_explicit

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Espressioni regolari (C++11)

Operazioni atomicche (C++11)

Multithreading (C++11)

 

Atomic operazioni di biblioteca

Tipi 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)

Funzioni 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)

Bandiere Atomic 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)

Inizializzazione 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)

Memoria di ordinazione 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>

Elemento definito nell'header <atomic>
template< class T > T atomic_exchange( std::atomic<T>* obj, T desr );	(1)	(dal C++11)
template< class T > T atomic_exchange( volatile std::atomic<T>* obj, T desr );	(2)	(dal C++11)
template< class T > T atomic_exchange_explicit( std::atomic<T>* obj, T desr, std::memory_order order );	(3)	(dal C++11)
template< class T > T atomic_exchange_explicit( volatile std::atomic<T>* obj, T desr, std::memory_order order );	(4)	(dal C++11)

1-2)

Sostituisce atomico il valore puntato da obj con il valore di desr e restituisce il valore obj precedentemente detenuta, come per 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)

Sostituisce atomico il valore puntato da obj con il valore di desr e restituisce il valore obj precedentemente detenuta, come per 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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Parametri

obj	-	puntatore all'oggetto atomica da modificare 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	-	il valore da memorizzare nell'oggetto atomica 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 memoria di ordinazione per questa operazione: tutti i valori sono consentiti . 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.

Valore di ritorno

Il valore contenuto in precedenza dall'oggetto atomico puntato da obj

Original:

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

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Eccezioni

noexcept specification:  

<tbody> </tbody>

noexcept

  (dal C++11)

Esempio

Un mutex spinlock può essere implementato in spazio utente tramite un'operazione atomica scambio, simile a 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();
    }
}

Output:

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

Vedi anche

exchange (C++11)	atomicamente sostituito il valore dell'oggetto atomico e ottiene il valore contenuto in precedenza 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. (metodo pubblico)
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)	confronta atomicamente il valore dell'oggetto atomica con non-atomica argomento ed esegue lo scambio atomico se il carico uguale o atomico in caso contrario 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. (funzione di modello)
std::atomic_exchange(std::shared_ptr) std::atomic_exchange_explicit(std::shared_ptr)	specializzata operazioni atomiche per 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. (funzione di modello)
C documentation for atomic_exchange, atomic_exchange_explicit