# std::shared_timed_mutex::try_lock_until

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< cpp‎ | thread‎ | shared timed mutex

template< class Clock, class Duration > bool try_lock_until( const std::chrono::time_point<Clock,Duration>& timeout_time ); |  | (since C++14)

Tries to lock the mutex. Blocks until specified `timeout_time` has been reached or the lock is acquired, whichever comes first. On successful lock acquisition returns true, otherwise returns false.

If `timeout_time` has already passed, this function behaves like try_lock().

`Clock` must meet the Clock requirements. The program is ill-formed if std::chrono::is_clock_v<Clock> is false (since C++20).

The standard recommends that the clock tied to `timeout_time` be used, in which case adjustments of the clock may be taken into account. Thus, the duration of the block might be more or less than timeout_time - Clock::now() at the time of the call, depending on the direction of the adjustment and whether it is honored by the implementation. The function also may block until after `timeout_time` has been reached due to process scheduling or resource contention delays.

As with try_lock(), this function is allowed to fail spuriously and return false even if the mutex was not locked by any other thread at some point before `timeout_time`.

Prior unlock() operation on the same mutex synchronizes-with (as defined in std::memory_order) this operation if it returns true.

If `try_lock_until` is called by a thread that already owns the `mutex` in any mode (shared or exclusive), the behavior is undefined.

### Parameters

timeout_time | - | maximum time point to block until

### Return value

true if the lock was acquired successfully, otherwise false.

### Exceptions

Any exception thrown by clock, time_point, or duration during the execution (clocks, time points, and durations provided by the standard library never throw)

### Example

This example shows a 10 seconds block

Run this code

    #include <thread>
    #include <iostream>
    #include <chrono>
    #include <mutex>

    std::shared_timed_mutex test_mutex;

    void f()
    {
        auto now=std::chrono::steady_clock::now();
        test_mutex.try_lock_until(now + std::chrono::seconds(10));
        std::cout << "hello world\n";
    }

    int main()
    {
        std::lock_guard<std::shared_timed_mutex> l(test_mutex);
        std::thread t(f);
        t.join();
    }

### See also

lock | locks the mutex, blocks if the mutex is not available (public member function)
try_lock | tries to lock the mutex, returns if the mutex is not available (public member function)
try_lock_for | tries to lock the mutex, returns if the mutex has been unavailable for the specified timeout duration (public member function)
unlock | unlocks the mutex (public member function)

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