Hi,

I have not researched this area, but it strikes me as one that could be very 
delicate. It may be that in most code paths it is assumed that some other 
function is incrementing the reference count. Great care should be taken in 
modifying this otherwise it may lead to memory leaks. I am hoping others who 
are more knowledgeable will add to this discussion.

Can you give more insight into what problem led you here?

Dave

-----Original Message-----
From: Zhu, Wen-Jun <[email protected]> 
Sent: Tuesday, August 14, 2018 4:11 AM
To: [email protected]
Subject: refCount on ComDiagsArea

hi,

When setting a ComDiagsArea, I find the refCount did not increase, in function 
atp_struct::setDiagsArea of file core/sql/exp/ExpAtp.h:

inline void atp_struct::setDiagsArea(ComDiagsArea* diagsArea) {
  if (diagsArea_)
    diagsArea_->decrRefCount();

  diagsArea_ = diagsArea;
}

I guess this is a problem.

There are two solutions to fix this:

1.     Invoke incrRefCount for ComDiagsArea to increase, just after the 
assignment.

2.     Overload the operator= for ComDiagsArea, to increase within the 
operator=,
I find operator= is declared in ComDiags.h, but there is no implementation.

The 2nd solution may be better, as the both increment for the left-hand side 
ComDiagsArea and the decrement for the right-hand side ComDiagsAre can be 
handled within a single operator=, which is friendly to users, like shared_ptr 
in C++.

Regards,
Wenjun Zhu

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