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std::future_status

Defined in header <future> 
enum class future_status {
    ready,
    timeout,
    deferred
};
 (since C++11)

Specifies state of a future as returned by wait_for and wait_until functions of std::future and std::shared_future.

Constant Explanation
deferred the shared state contains a deferred function, so the result will be computed only when explicitly requested
ready the shared state is ready
timeout the shared state did not become ready before specified timeout duration has passed

See also

waits for the result, returns if it is not available for the specified timeout duration
(public member function of std::future<T>)
waits for the result, returns if it is not available for the specified timeout duration
(public member function of std::shared_future<T>)
waits for the result, returns if it is not available until specified time point has been reached
(public member function of std::future<T>)
waits for the result, returns if it is not available until specified time point has been reached
(public member function of std::shared_future<T>)

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