[Nepomuk] Nepomuk Core - Questions & Patches

[Sebastian Trüg]

On 05/29/2010 03:34 PM, Vishesh Handa wrote:
> On Sat, May 29, 2010 at 5:46 PM, Sebastian Trüg <trueg at kde.org
> <mailto:trueg at kde.org>> wrote:
> 
>     Hehe, this does not help at all. Think about it: in my example there are
>     2 Resource instances involved. Thus: 2 mutexes which are locked
>     independent of each other. :)
>     The mutex is already there in ResourceData. It simply needs to be locked
>     in Resource instead of ResourceData::determineUri.
> 
> 
> Uhh I'm confused. Why don't you handle the multi-threading?

Sure, I can do that. :)

> I should really learn about multi-threading. If you have a couple of
> spare minutes could you explain why my method won't work?
> 
> My rationale -
> 
> Thread 1 :
> Resource r1("foo");
> r1.property( nao:numericRating )
> -> the mutex is locked
> -> performs whatever and determines the uri
> 
> Thread 2 :
> Resource r2("foo");
> r2.setProperty( whatever )
> -> the mutex can't get locked so it waits till it does
> -> mutex now locked. Thread 1 should have determined the uri by now
> -> perform operation

Simple: r1 and r2 have different mutex intances. Thus, locking one does
not prevent the other from being locked. The idea is that both threads
need to lock the same mutex. And that is only possible if the mutex is
stored in ResourceData.

Cheers,
Sebastian