[GraphHopper] what is the use case of SynchedDAWrapper?

[John Zhao]

Hi Peter,

If we use RAM to extract graphhopper, then use MMapDataAccess to load
graphhopper data.
In other words, if we read only with MMapDataAccess on server side, is it
correct and thread-safe?

*Best Regards,*
*ZhiQiang ZHAO*

On Tue, Jun 30, 2015 at 10:53 PM, Peter <graphhopper at gmx.de> wrote:

>  Hi,
>
> this is for two reasons:
>  first, it allows you to use the MMap for server side
>  second, it allows us to use multi-threaded algorithms at some point in
> the future
>
> Regards,
> Peter
>
>
> On 01.07.2015 02:31, John Zhao wrote:
>
> Hi Peter,
>
>  This question is for you. :)
>
>  I guess MMapDataAccess is mainly designed for running Graphhopper on
> Android device, which you can't load all the data into the limited memory.
>
>  In the comment of MMapDataAccess:
> This is a data structure which uses the operating system to synchronize
> between disc and memory.
> Use SynchDAWrapper if you intent to use this from multiple threads!
>
>  why GH need a thread-safe one, somebody want to do the extract on
> Android device?
> just curious.
>
>  Thanks in advance.
>
>  *Best Regards,*
> *ZhiQiang ZHAO*
>
>
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