kicad-developers team mailing list archive

[Maciej Sumiński <maciej.suminski@xxxxxxx>]

Hi Carl,

Thank you for putting efforts to boost the performance of the ratsnest.
The function is brought by an external library 
(http://www.sintef.no/Projectweb/Geometry-Toolkits/TTL/), I am not sure 
what is exactly inside. The expected output should be a Delaunay 
triangulation of all nodes that are taken into account while computing 
ratsnest.
The only issue I am aware of, is the function does not handle well empty 
containers, but it should not be the case right now.

Now, when I looked again to the source code, RN_DATA is derived after 
hed::Node class (include/ttl/halfedge/hetriang.h), which contains a 
static field. Another thing is (I believe this is the main source of 
troubles) static hed::Triangulation (include/ttl/halfedge/hetraits.h:73).
Sorry that I did not say about that before, but I have just discovered 
that it is done that way. I will try to change it, but unfortunately 
there are little chances that I manage to do that before Sunday.

Regards,
Orson


On 01/22/2014 06:08 PM, Carl Poirier wrote:
> Maciej,
>
> Can you summarize to me how the function "Triangulation::createDelaunay(
> nodes.begin(), nodes.end() )" works, and what are the data structures
> involved?
>
> I believe there are some dependencies in there.
>
>
> On Tue, Jan 21, 2014 at 4:05 PM, Cirilo Bernardo
> <cirilo_bernardo@xxxxxxxxx <mailto:cirilo_bernardo@xxxxxxxxx>> wrote:
>
>      >________________________________
>      > From: Carl Poirier <carl.poirier.2@xxxxxxxxx
>     <mailto:carl.poirier.2@xxxxxxxxx>>
>      >To: Marco Serantoni <marco.serantoni@xxxxxxxxx
>     <mailto:marco.serantoni@xxxxxxxxx>>
>      >Cc: Kicad Developers <kicad-developers@xxxxxxxxxxxxxxxxxxx
>     <mailto:kicad-developers@xxxxxxxxxxxxxxxxxxx>>
>      >Sent: Wednesday, January 22, 2014 3:51 AM
>      >Subject: Re: [Kicad-developers] Net names and net codes
>      >
>      >
>      >
>      >There are some things in the code that don't like being
>     multithreaded. If I parallelize the for loop in
>     RN_DATA::Recalculate( int aNet ), I get a segfault. It does not
>     happen if I put a lock to the call updateNet( i ), but obviously
>     there is no increase in performance. I'm trying to find out what's
>     the problem now.
>      >
>      >
>      >
>     This sounds to me like data is being altered by different threads
>     and possibly there is some memory reallocation happening (growing
>     arrays, etc). Locks are only needed when there is contention
>     somewhere and of course locks should only be held for as short as
>     needed. Another pitfall with threading is that some variables may
>     need to be declared 'volatile' if they can be altered in another
>     thread while one function is executing. For example, let's say the
>     variable 'bool someX' can be altered in 2 threads; something like
>     this can happen:
>
>     1. FunctionA starts, and runs a loop while(!someX) { ... }
>     2. FunctionB sets 'someX' to 'true'
>     3. FunctionA continues to run the loop, which is not the intended
>     behavior
>
>     Of course similar things can happen when using shared memory and
>     forked processes.
>
>     Threading has other problems to watch out for - for example, are
>     there any static variables in functions? If so then you simply
>     cannot thread those functions without locks.
>
>     - Cirilo
>
>
>
>
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