[Amarok] 7bca886: debug: use elapsed timer

[Rick W. Chen]

On 09 Nov 2010 11:47 +0100, Kevin Funk:
> Tuesday 09 November 2010, "Rick W.Chen" <stuffcorpse at archlinux.us>:
> > commit 7bca88681ee8248741d0b6daa966326512621bbd
> > branch master
> > Author: Rick W. Chen <stuffcorpse at archlinux.us>
> > Date:   Tue Nov 9 17:06:12 2010 +1300
> > 
> >     debug: use elapsed timer
> > 
> >     as kdelibs SVN commit 1194322
> > 
> 
> (snip)
> 
> > @@ -130,6 +129,8 @@ using Debug::fatal;
> >  /// Performance logging
> >  #define PERF_LOG( msg ) { Debug::perfLog( msg, __PRETTY_FUNCTION__ ); }
> > 
> > +class BlockPrivate;
> > +
> >  namespace Debug
> >  {
> >      /**
> > @@ -157,13 +158,11 @@ namespace Debug
> >      class Block
> >      {
> >      public:
> > -        AMAROK_CORE_EXPORT Block(const char* name);
> > +        AMAROK_CORE_EXPORT Block( const char *name );
> >          AMAROK_CORE_EXPORT ~Block();
> > 
> >      private:
> > -        QTime m_startTime;
> > -        const char *m_label;
> > -        int m_color;
> > +       BlockPrivate *const d;
> >      };
> > 
> >      /**
> > diff --git a/src/core/support/Debug_p.h b/src/core/support/Debug_p.h
> > index 20ea59a..43d0676 100644
> > --- a/src/core/support/Debug_p.h
> > +++ b/src/core/support/Debug_p.h
> > @@ -20,7 +20,12 @@
> >  #include "Debug.h"
> > 
> >  #include <QString>
> > -#include <QTime>
> > +
> > +#if QT_VERSION >= 0x040700
> > +# include <QElapsedTimer>
> > +#else
> > +# include <QTime>
> > +#endif
> > 
> >  class IndentPrivate
> > 
> >      : public QObject
> > 
> > @@ -37,11 +42,15 @@ public:
> >  class BlockPrivate
> >  {
> >  public:
> > -    BlockPrivate(const char* label);
> > -
> > -    QTime m_startTime;
> > -    const char *m_label;
> > -    int m_color;
> > +    BlockPrivate( const char *text );
> > +
> > +#if QT_VERSION >= 0x040700
> > +    QElapsedTimer startTime;
> > +#else
> > +    QTime startTime;
> > +#endif
> > +    const char *label;
> > +    int color;
> >  };
> > 
> >  #endif // DEBUGPRIVATE_H
> 
> Hey Rick,
> 
> there was a reason for not using the pimpl idiom in the Block class. I didn't 
> add a comment about this, though.
> 
> I have no performance benchmarks, but it could get notably slow if you're 
> operating on the heap for each ctor/dtor call of Block. We're already using 
> this in most parts of Amarok, this code is used extensively during Amarok 
> startup. Also this is still the case within release builds.
> 
> Please do some benchmarks with regards to this, just to be sure. Startup time 
> is important.

I noticed in Debug_p.h BlockPrivate was defined but not used, so I
thought it was intended to be used later. I've not noticed slower
startup times but yes not using the private ptr stuff could have an
improvement. This only matters if debug is turned on though.

What's a good way to benchmark this?

-- 
    Rick