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      std::atomic_flag_test_and_set, std::atomic_flag_test_and_set_explicit

      De cppreference.com
      < cpp‎ | atomic

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      C++
       
      Atomique opérations de la bibliothèque
      Types
      Original:
      Types
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      atomic (C++11)
      atomic_is_lock_free (C++11)
      Fonctions
      Original:
      Functions
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      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
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      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
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      atomic_init (C++11)
      ATOMIC_VAR_INIT (C++11)
      ATOMIC_FLAG_INIT (C++11)
      Mémoire de la commande
      Original:
      Memory ordering
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      memory_order (C++11)
      kill_dependency (C++11)
      atomic_thread_fence (C++11)
      atomic_signal_fence (C++11)
       
      Déclaré dans l'en-tête <atomic>
      bool atomic_flag_test_and_set(volatilestd::atomic_flag* p );
      		 (1) (depuis C++11)
      bool atomic_flag_test_and_set(std::atomic_flag* p );
      		 (2) (depuis C++11)
      bool atomic_flag_test_and_set_explicit(volatilestd::atomic_flag* p,
                                              std::memory_order order );
      		 (3) (depuis C++11)
      bool atomic_flag_test_and_set_explicit(std::atomic_flag* p,
                                              std::memory_order order );
      		 (4) (depuis C++11)
      Change atomiquement l'état d'un std::atomic_flag pointé par p à régler (true) et renvoie la valeur qu'elle détenait avant .
      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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      Sommaire

      [modifier]Paramètres

      p -
      pointeur vers std::atomic_flag d'accès
      Original:
      pointer to std::atomic_flag to access
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      order -
      la commande de synchronisation de mémoire pour cette opération
      Original:
      the memory synchronization order for this operation
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      [modifier]Retourne la valeur

      La valeur précédemment détenu par le drapeau pointé par p
      Original:
      The value previously held by the flag pointed to by p
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      [modifier]Exceptions

      noexcept specification:  
      noexcept
         (depuis C++11)

      [modifier]Mise en œuvre possible

      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);}

      [modifier]Exemple

      Un mutex spinlock peut être mis en œuvre dans l'espace utilisateur en utilisant 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();}}

      Résultat : 

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

      [modifier]Voir aussi

      (C++11)
      la serrure sans type booléen atomique
      Original:
      the lock-free boolean atomic type
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      (classe)[edit]
      (C++11)
      (C++11)
      définit atomiquement la valeur de l'indicateur de false
      Original:
      atomically sets the value of the flag to false
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      (fonction)[edit]
      (C++11)
      définit des contraintes de mémoire de commande pour l'opération donnée atomique
      Original:
      defines memory ordering constraints for the given atomic operation
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      (typedef)[edit]
      C documentation for atomic_flag_test_and_set, atomic_flag_test_and_set_explicit
      Récupérée de « https://fr.cppreference.com/mwiki/index.php?title=cpp/atomic/atomic_flag_test_and_set&oldid=47600 »
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