std::shared_mutex::try_lock_shared

bool try_lock_shared();

(since C++17)

Tries to lock the mutex in shared mode. Returns immediately. On successful lock acquisition returns true, otherwise returns false.

This function is allowed to fail spuriously and return false even if the mutex is not currenly exclusively locked by any other thread.

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

The behavior is undefined if the calling thread already owns the mutex in any mode.

(none).

true if the lock was acquired successfully, otherwise false.

(none).

lock	locks the mutex, blocks if the mutex is not available (public member function)
try_lock_shared	tries to lock the mutex for shared ownership, returns if the mutex is not available (public member function)
unlock_shared	unlocks the mutex (shared ownership) (public member function)