What are the differences between lock_guard and unique_lock in C++?

What are the differences between lock_guard and unique_lock in C++?

Both lock_guard and unique_lock are used for managing mutexes in C++, but they have some key differences. lock_guard is a simple RAII wrapper that locks a mutex when created and unlocks it when destroyed. It's lightweight and cannot be unlocked manually. On the other hand, unique_lock is more flexible; it can be locked and unlocked multiple times and can also be moved to another unique_lock instance.

When should I use unique_lock instead of lock_guard?

You should use unique_lock when you need more control over the locking mechanism, such as when you need to lock and unlock the mutex multiple times or when you need to transfer ownership of the lock. If you just need a simple lock that automatically unlocks when it goes out of scope, lock_guard is usually sufficient.

Are there any performance differences between them?

Yes, there can be performance differences. lock_guard is generally faster and has less overhead because it does not support the additional features of unique_lock. If you don't need the extra functionality, lock_guard is the better choice for performance.

Can you give an example of when to use each?

Sure! Use lock_guard in simple scenarios where you just need to protect a critical section. Use unique_lock in more complex scenarios, like condition variables or when you need to lock and unlock multiple times.