Is my implementation of lock proper?

Question

Hi

I implemented singletone pattern for thread also.... Is portion related to thread safety correct ? I am getting only one thread id with this implementation , but the way thread safety is implemented is best or there is some chance of betterment?

https://code.sololearn.com/cnIb1K8RRQuL/?ref=app

Thanks in advance...!

Answer 1

You should try to avoid locking and unlocking a mutex yourself.
If new throws you'll have a dead lock. ( I know the chances are slim but still )

Instead use std::lock_guard:
https://en.cppreference.com/w/cpp/thread/lock_guard

They are similar to a unique_ptr.
Although do look out for the pitfall where you forget to name the lock_guard, because then your code will no longer be protected by it.

Note that since C++11 local static initialization is thread safe already.
As in
static A& getInstance()
{
static A instance;
return instance;
}
This only applies if the constructor itself is thread safe, though.

I'm not quite sure if it applies in your situation with a static member variable + new.

Also don't forget to mark your copy constructor and assignment operator as deleted.

Apart from that I don't see any other issues.