template< class Rep, class Period >
bool try_lock_shared_for( const std::chrono::duration<Rep,Period>& timeout_duration );
(since C++14)

Tries to lock the mutex in shared mode. Blocks until specified timeout_duration has elapsed or the shared lock is acquired, whichever comes first. On successful lock acquisition returns true, otherwise returns false.

If timeout_duration is less or equal timeout_duration.zero(), the function behaves like try_lock_shared().

This function may block for longer than timeout_duration due to scheduling or resource contention delays.

The standard recommends that a steady clock is used to measure the duration. If an implementation uses a system clock instead, the wait time may also be sensitive to clock adjustments.

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

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

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


timeout_duration - maximum duration to block for

Return value

true if the lock was acquired successfully, otherwise false.


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


See also

tries to lock the mutex for shared ownership, returns if the mutex is not available
(public member function)
tries to lock the mutex for shared ownership, returns if the mutex has been
unavailable until specified time point has been reached
(public member function)
tries to lock the mutex, returns if the mutex has been
unavailable for the specified timeout duration
(public member function)

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