Question

I have a class that uses libxml2. It has static members which are used to hold context for a schema file and its parser. I m using valgrind, and it s complaining that memory is not deallocated in connection with the schema context. This is because you need to free that memory yourself. However, since these context variables are static, I can t free on destruction of the object. Is there a way to call the necessary free functions, or should I just ignore valgrind.

Answer 1

Declare another class within your XML-using class. In its destructor, clean up your static members. Now give the outer class another static member of the inner class type. By virtue of having a non-trivial destructor, it will get cleaned up as the program exits, and thus your other values will get cleaned up, too.

class UseLibXml {
  static int xmlvar;

  struct StaticCleanup {
    ~StaticCleanup() {
      CleanUpLibXmlVar(UseLibXml::xmlvar);
    }
  };

  static StaticCleanup static_cleanup;
};

Define UseLibXml::static_cleanup the same place you define the other static variables, in one of your .cpp files.

Answer 2

Set up an atexit handler and free there. Or ignore.

Answer 3

If the valgrind error is showing up when the process ends, then I wouldn t worry about it. Why are the context variables static though?

You can generate a suppressions file that will make valgrind ignore the errors associated with your static contexts. See this page in the valgrind manual: suppressing errors

Answer 4

I think you can ignore this warnings, since they are not memory leaks. They memory occupied by them will return to OS as soon as your application exit

Answer 5

I assume these static variables are pointers?

Assuming you have:

class X
{
     private:
        static Plop*   staicXData;  // Initialised in the code.
};

I would change it to:

Class X
{
    private:
        static Plop&  getStatoc()
        {
            static Plop  data;     // Auto created on first use.
                                   // Destroyed on program exit.
            return data;
        }
};

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