std::once_flag

 

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Defined in header <mutex>
class once_flag;		（C++11 起）

The class std::once_flag is a helper structure for std::call_once.

An object of type std::once_flag that is passed to multiple calls to std::call_once allows those calls to coordinate with eachother such that only one of the calls will actually run to completion.

std::once_flag is noncopyable.

。成员函数。

std::once_flag::once_flag

once_flag();

Constructs an once_flag object. The internal state is set to indicate that no function has been called yet.

Parameters

(none)

Exceptions

noexcept specification:  

noexcept

  （C++11 起）

。另请参阅。

call_once （C++11）	只有一次，即使从多个线程调用调用一个函数 Original: invokes a function only once even if called from multiple threads The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. （函数模板）