[GraphHopper] Package private methods in AbstractBidirAlgo

[Peter K]

Hey Lars,

your use case is nice to hear :) as we primarily opened up those methods
from 'private' to 'package protected' to serve the needs of our
GraphHopper matrix Add-on which does exactly that what you are looking
for (but is currently not Open Source). It indeed reduces 1000*1000
normal route calculations by a factor of 10 (even ~40 faster is possible
but also more complex and not yet done).

> by setting "instruction" and "calcPoints" to false, so maybe it only
takes 15 minutes now.

Nice to hear your numbers: either you have a very fast machine or a
small area :). For what area (in km^2) did you measure this?


> I guess for a better solution one would have to do some major
refactorings.

No major refactoring is necessary, you should only need to put your
class under com.graphhopper.routing (although not recommended as we can
break the API!). In the next version, when we are more confident of the
necessary methods, we'll probably make them accessible to everyone.

Regards,
Peter.

> Hey Peter,
>
> I have an application where I have to calculate the road distance
> between a
> number of points, let's say a thousand. Right now I'm doing 1000*1000
> point
> to point queries (with CH) to calculate that distance matrix. This
> takes about
> 30 minutes, even though I recently found out that you can accelerate this
> by setting "instruction" and "calcPoints" to false, so maybe it only
> takes 
> 15 minutes now. 
>
> Anyways, in
> http://algo2.iti.kit.edu/documents/routeplanning/geisberger_dipl.pdf
> section 4.1 is described how you can implement a many to many routing
> by doing
> 1000 forward searches and 1000 backward searches but omitting the
> abort criterion.
> Most of the code to do that is already there you just have to get rid
> of the abort
> criterion in "dijkstrabiCH":
>   return currFrom.weight >= bestPath.getWeight() && currTo.weight >=
> bestPath.getWeight();
> and make bestWeightMapFrom and bestWeightMapTo in
> DijkstraBidirectionRef accessible. 
>
> Unfortunately, "dijkstrabiCH" is an anonymous class inside of 
> PrepareContractionHierarchies.createAlgo(). So for my preliminary
> tests I just
> ripped lots of code out of PrepareContractionHierarchies and
> DijkstraBidirectionRef.
> That's obviously not a good long-term solution. I guess for a better
> solution one 
> would have to do some major refactorings. 
>
> So, that's my motivation. Any comments? :)
>
> Best regards,
> Lars 
>
>
> On Mon, May 19, 2014 at 8:15 AM, Peter K <peathal at yahoo.de
> <mailto:peathal at yahoo.de>> wrote:
>
>     Hey Lars,
>
>     the reason is simple: no one (except our own classes) should use those
>     methods, so that we can break this API at any time we want. Which
>     methods you need and why?
>
>     Regards,
>     Peter.
>
>     > Hey there,
>     >
>     > is there a reason why there are methods and fields in
>     > AbstractBidirAlgo that have default visibility (package private)?
>     > Now you can't inherit from AbstractBidirAlgo if the inheriting class
>     > resides in different package than  com.graphhopper.routing.
>     >
>     > Best regards,
>     > Lars
>     >
>
>
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