A strange statement in SSLEchoServer tutorial

Ho to all,
I seen the statement qDeleteAll(m_clients.begin(), m_clients.end()); at line 81 of SSLEchoServer.cpp file of SSEchoServer tutorial project
(Qt\Examples\Qt-5.5\websockets\sslechoserver\sslechoserver.cpp).

My dubt: why call an esplicitally delete all m_clients elements using qDeleteAll() if his destructor (m_clients's destructor) call itself?
Commenting this line I did not seen memory leaks closing application with alive connections.

Sorry for my English :).
Regards
Giorgio

Quote:

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Originally Posted by oop

My dubt: why call an esplicitally delete all m_clients elements using qDeleteAll() if his destructor (m_clients's destructor) call itself?

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The destructor of QList on a pointer type does not call delete on the pointers, so qDeleteAll() is needed if you want these objects to be deleted as well.

Quote:

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Originally Posted by oop

Commenting this line I did not seen memory leaks closing application with alive connections.

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If by "closing application" you mean that it exited, then the operating system will have reclaimed all resources associated with the process.

Cheers,
_

Hi,
yes you are right m_clients contains pointers to QWebSocket and they are handled and then destroyed by QWebSocketServer (I am supposing) not by m_clients (QList ) destructor.
But thus the line I mentioned above ( qDeleteAll(m_clients.begin(),m_clients.end());) is not helpful. I can comment that line, close the application naturally (calling quit()) without memory leaks with or not the qDeleteAll(m_clients.begin(),m_clients.end());.

Yes I think in this case, this line, is not helpful.
I ask for better understand.


Giorgio

Quote:

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Originally Posted by oop

yes you are right m_clients contains pointers to QWebSocket and they are handled and then destroyed by QWebSocketServer (I am supposing)

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First rule of programming: don't make assumptions.
Especially not ones that can be disproven by reading the documentation:

Quote:

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Originally Posted by QtDocs

QWebSocketServer does not take ownership of the returned QWebSocket object. It is up to the caller to delete the object explicitly

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Quote:

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Originally Posted by oop

But thus the line I mentioned above ( qDeleteAll(m_clients.begin(),m_clients.end());) is not helpful. I can comment that line, close the application naturally (calling quit()) without memory leaks with or not the qDeleteAll(m_clients.begin(),m_clients.end());.

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And how did you check that? Valgrind? Some other memory profiler?

Cheers,
_

Hi, yes assumptions are dangerous.
No I did read documentation, I simply seen that commenting that line no wrong behaviours happen in application execution also quitting it with alive connections.
No, I did check in depth because my focus is at the moment at other thinks, I seen only no memory leaks reported from Visual Studio.

At the moment I am testing and working without the above qDeleteAll() and it are working fine, though I keep in mind that line and keep ready to restore it if some problem or suspect happens.


Sorry for my English.

Cheers,
Giorgio

Quote:

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Originally Posted by oop

No I did read documentation, I simply seen that commenting that line no wrong behaviours happen in application execution also quitting it with alive connections.

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How do you know that the connections weren't closed to the application shutdown?

Quote:

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Originally Posted by oop

No, I did check in depth because my focus is at the moment at other thinks, I seen only no memory leaks reported from Visual Studio.

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If you haven't investigated if that leads to leaks, how did you arrive at that conclusion?

Quote:

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Originally Posted by oop

At the moment I am testing and working without the above qDeleteAll() and it are working fine, though I keep in mind that line and keep ready to restore it if some problem or suspect happens.

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Why not just keep it as intended?

Cheers,
_