What is the difference between unique_lock and lock_guard in C++?

What is the difference between unique_lock and lock_guard in C++?

The main difference is that unique_lock is more flexible than lock_guard. unique_lock can be locked and unlocked multiple times, while lock_guard locks the mutex upon creation and unlocks it when it goes out of scope.

When should I use unique_lock instead of lock_guard?

You should use unique_lock when you need to lock and unlock the mutex multiple times or when you need to transfer ownership of the lock. lock_guard is simpler and should be used when you only need a simple lock.

Are there any performance differences between them?

Yes, lock_guard is generally more efficient because it has less overhead. However, the performance difference is usually negligible unless you're in a performance-critical section of code.

Can you give an example of when to use each?

Sure! Use lock_guard for simple, scoped locking, like protecting a shared resource in a function. Use unique_lock when you need to conditionally lock or unlock a mutex, like in a loop or when using condition variables.