[gdal-dev] Understanding VSI caching

[Even Rouault]

On lundi 9 avril 2018 18:33:32 CEST Andrea Aime wrote:
> Hi,
> is there any document explaning how VSI caching works. E.g., memory vs disk
> caching, whether the disk cache
> is long lived or exists only for the duration of the process (and if so,
> what about long lived processes
> like mapserver fastcgi?) and so on?

Hi Andrea,

Are you speaking about the cache machanism enabled with the VSI_CACHE=YES env variable ?
If so that's described at
http://gdal.org/gdal_virtual_file_systems.html#gdal_virtual_file_systems_vsicache
I see it lacks a bit high level details, like specifying this is RAM only, and not disk cached.
I'm going to add some words about that

Otherwise, the full "documentation" :-) is at:
https://github.com/OSGeo/gdal/blob/master/gdal/port/cpl_vsil_cache.cpp

The /vsicurl/ and related network file systems have also their own RAM cache mechanism
described at
http://gdal.org/gdal_virtual_file_systems.html#gdal_virtual_file_systems_vsicurl

Even

> 
> Cheers
> Andrea
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