What is the usage of mutex in C++?

In C++, mutex (mutual exclusion) is used to achieve thread synchronization in order to prevent race conditions between threads. Mutex ensures that only one thread can access shared resources at any given time.

1. Create and initialize a mutex.
2. Create a mutex object named mtx.
3. Locking and unlocking mutex.
4. Locking: Use the lock() function to lock the mutex. If the mutex has already been locked by another thread, the current thread will be blocked until the mutex is unlocked. mtx.lock(); // Lock the mutex
5. Unlock: Use the unlock() function to unlock the mutex. mtx.unlock(); // Unlock mutex
6. Automatically manage locking and unlocking mutexes:
   In order to ensure that mutexes are correctly unlocked in any situation, one can use the std::lock_guard class to automatically handle the locking and unlocking operations. The std::lock_guard automatically locks the mutex upon construction and automatically unlocks it at the end of its scope.
7. Automatically unlock the mutex at the end of the scope. Critical section code is executed within the scope and the mutex is unlocked automatically when the scope ends.
8. Attempt to lock a mutex lock:
   You can use the try_lock() function to attempt to lock a mutex lock. This function will try to lock the mutex, if the mutex is currently locked by another thread, the attempt to lock will fail and return false immediately; if the mutex is currently unlocked, the attempt to lock will succeed and return true.
9. If the mutex lock is successfully acquired, execute the critical section code and then unlock the mutex. Otherwise, if the mutex lock is not acquired, do nothing.

The above is the most common usage of mutex locks. Proper use of mutex locks can ensure safe access to shared resources in a multi-threaded environment.