std::mutex::unlock (3) - Linux Man Pages
void unlock(); (since C++11)
Unlocks the mutex.
The mutex must be locked by the current thread of execution, otherwise, the behavior is undefined.
This operation synchronizes-with (as defined in std::memory_order) any subsequent lock operation that obtains ownership of the same mutex.
unlock() is usually not called directly: std::unique_lock and std::lock_guard are used to manage exclusive locking.
This example shows how lock and unlock can be used to protect shared data.
// Run this code
lock (public member function)
try_lock (public member function)