std::atomic_flag

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C++

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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)

 

std::atomic_flag

Membri funzioni Original: Member 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::atomic_flag

atomic_flag::operator=

atomic_flag::clear

atomic_flag::test_and_set

 

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Elemento definito nell'header <atomic>
class atomic_flag;		(dal C++11)

std::atomic_flag è un tipo atomico boolean. A differenza di tutte le specializzazioni di std::atomic, è garantita senza blocchi. A differenza di std::atomic<bool>, std::atomic_flag non fornisce le operazioni di carico o negozio.

Original:

std::atomic_flag is an atomic boolean type. Unlike all specializations of std::atomic, it is guaranteed to be lock-free. Unlike std::atomic<bool>, std::atomic_flag does not provide load or store operations.

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Membri funzioni

(costruttore)	costruisce un atomic_flag Original: constructs an atomic_flag The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)
operator=	l'operatore di assegnazione Original: the assignment operator The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)
clear	imposta atomicamente bandiera false Original: atomically sets flag to false The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)
test_and_set	imposta atomicamente il flag su true e ottiene il suo valore precedente Original: atomically sets the flag to true and obtains its previous value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (metodo pubblico)

Esempio

Un mutex spinlock può essere implementato in spazio utente utilizzando un atomic_flag

Original:

A spinlock mutex can be implemented in userspace using an atomic_flag

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

std::atomic_flag lock = ATOMIC_FLAG_INIT;

void f(int n)
{
    for(int cnt = 0; cnt < 100; ++cnt) {
        while(lock.test_and_set(std::memory_order_acquire))  // acquire lock
             ; // spin
        std::cout << "Output from thread " << n << '\n';
        lock.clear(std::memory_order_release);               // release lock
    }
}
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

atomic_flag_test_and_set atomic_flag_test_and_set_explicit (C++11) (C++11)	imposta atomicamente il flag su true e restituisce il suo valore precedente Original: atomically sets the flag to true and returns its previous value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione)
atomic_flag_clear atomic_flag_clear_explicit (C++11) (C++11)	imposta atomicamente il valore della bandiera false Original: atomically sets the value of the flag to false The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (funzione)
ATOMIC_FLAG_INIT (C++11)	initializes an std::atomic_flag to false (macro costante)
C documentation for atomic_flag