std::atomic_flag_test_and_set, std::atomic_flag_test_and_set_explicit

 

C++

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ユーティリティライブラリ

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アルゴリズムライブラリ

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入力/出力ライブラリ

ローカライゼーションライブラリ

正規表現ライブラリ (C++11)

アトミック操作ライブラリ (C++11)

スレッドのサポートライブラリ (C++11)

 

アトミック操作ライブラリ

タイプ 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)

機能します 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)

アトミックのフラグ 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)

初期化 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)

メモリは発注 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)

 

Defined in header <atomic>
bool atomic_flag_test_and_set( volatile std::atomic_flag* p );	(1)	(C + + 11以来)
bool atomic_flag_test_and_set( std::atomic_flag* p );	(2)	(C + + 11以来)
bool atomic_flag_test_and_set_explicit( volatile std::atomic_flag* p,                                         std::memory_order order );	(3)	(C + + 11以来)
bool atomic_flag_test_and_set_explicit( std::atomic_flag* p,                                         std::memory_order order );	(4)	(C + + 11以来)

アトミックに設定するstd::atomic_flag（p）が指すtrueの状態を変更し、それが前に保持されている値を返します。.

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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パラメータ

p	-	アクセスするstd::atomic_flagへのポインタ 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	-	この操作には、メモリーを同期順序 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.

値を返します

以前pが指すフラグが保持している値

Original:

The value previously held by the flag pointed to by p

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例外

noexcept specification:  

noexcept

  (C + + 11以来)

可能な実装

First version
bool atomic_flag_test_and_set(volatile std::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(volatile std::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); }

例

スピンロックmutexはatomic_flagを使用してユーザ空間で実装することができます

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 acquired
        std::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>...

も参照してください

atomic_flag (C++11)	ロックフリーブール原子型 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. (クラス)
atomic_flag_clear atomic_flag_clear_explicit (C++11) (C++11)	アトミックfalseにフラグの値が設定されます 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. (機能)
memory_order (C++11)	与えられたアトミック操作用のメモリ順序の制約を定義しています 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です)
C documentation for atomic_flag_test_and_set, atomic_flag_test_and_set_explicit