InstrumentDefinitionParser allocates/deallocates a lot of strings

[Martyn Gigg]

#9860 profiled the IDF loading.

In processing an IDF file we have to check many times whether a given XML document/element has a node or attribute. Most code currently looks like

pTypeElem->hasAttribute("outline");
...

The Poco hasAttribute method only accepts a std::string so each call like this requires an implicit allocation/deallocation of a temporary std::string object.

An improvement that would cut down on the number of these allocations would be to have the tags defined in a separate file within functions or static methods, e.g.

    /// Allocate a static string and return the appropriate tag
    inline const std::string IDFTags::component()
    {
      static const std::string tag = "component";
      return tag;
    }

The static keyword ensures that the allocation only happens once and only the first time the function is actually called.

To summarise, the suggestion is to create a new class, IDFTags, that only has static methods like the one above. This would then be used by the InstrumentDefinitionParser class. Another advantage of this is that we would have a single file where all of the tags are defined, rather than them scattered around the InstrumentDefinitionParser code.

[Stuart Campbell]

This ticket has been transferred to github issue ​10905