std::atomic_flag_test_and_set, std::atomic_flag_test_and_set_explicit

 

C++

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Libreria di Utilità

Stringhe

Contenitori

Algoritmi

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Libreria matematca

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Localizzazione

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)

 

Elemento definito nell'header <atomic>
bool atomic_flag_test_and_set(volatilestd::atomic_flag* p );	(1)	(dal C++11)
bool atomic_flag_test_and_set(std::atomic_flag* p );	(2)	(dal C++11)
bool atomic_flag_test_and_set_explicit(volatilestd::atomic_flag* p,                                         std::memory_order order );	(3)	(dal C++11)
bool atomic_flag_test_and_set_explicit(std::atomic_flag* p,                                         std::memory_order order );	(4)	(dal C++11)

Atomico cambia lo stato di un std::atomic_flag puntato da p per impostare (true) e restituisce il valore di essa deteneva prima.

Original:

Atomically changes the state of a std::atomic_flag pointed to by p to set (true) and returns the value it held before.

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Parametri

p	-	puntatore a std::atomic_flag per accedere Original: pointer to std::atomic_flag to access The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
order	-	la sincronizzazione fine memoria per questa operazione Original: the memory synchronization order for this operation 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 precedentemente detenuta dalla bandiera a cui punta p

Original:

The value previously held by the flag pointed to by p

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Eccezioni

noexcept specification:  

noexcept

  (dal C++11)

Possibile implementazione

First version
bool atomic_flag_test_and_set(volatilestd::atomic_flag* p){return p->test_and_set();}
Second version
bool atomic_flag_test_and_set(std::atomic_flag* p){return p->test_and_set();}
Third version
bool atomic_flag_test_and_set_explicit(volatilestd::atomic_flag* p, std::memory_order order){return p->test_and_set(order);}
Fourth version
bool atomic_flag_test_and_set_explicit(std::atomic_flag* p, std::memory_order order){return p->test_and_set(order);}

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(std::atomic_flag_test_and_set_explicit(&lock, std::memory_order_acquire));// spin until the lock is acquiredstd::cout<<"Output from thread "<< n <<'\n'; std::atomic_flag_clear_explicit(&lock, 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

atomic_flag (C++11)	il blocco privo di tipo booleano atomica Original: the lock-free boolean atomic type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (classe)
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)
memory_order (C++11)	definisce i limiti di memoria di ordinazione per il data operazione atomica Original: defines memory ordering constraints for the given atomic operation The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (typedef)
C documentation for atomic_flag_test_and_set, atomic_flag_test_and_set_explicit