[Amarok] 7bca886: debug: use elapsed timer

[Dan Meltzer]

On Tue, Nov 9, 2010 at 7:05 AM, Rick W. Chen <stuffcorpse at archlinux.us> wrote:
> 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?

Theres a performance graphing script in one of the top level
directories, with a readme as well.  It ties into the PERF_LOG macro
in debug.h

Dan,
>
> --
>    Rick
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