[gdal-dev] VSIReadDir() and GDALOpenInfo

[Frank Warmerdam]

Andrey Kiselev wrote:
> On Wed, Jan 30, 2008 at 12:00:16PM -0500, Frank Warmerdam wrote:
>> But I'm wondering if there is a fundamentally better approach to
>> scanning for the list of files in a directory, or if this is
>> inherently quite an expensive operation.  Thoughts?  Other experiences
>> on this?  Is this more of an issue with particular file systems?
> 
> Ulrich Drepper has some insights on the issue:
> 
>  http://udrepper.livejournal.com/18555.html
> 
> Based on his article I see few problems with our code:
> 
>  1. We are using readdir() instead of readdir64().

Andrey,

In the VSIReadDir() code we do not actually consult the file size so
I don't see any requirement to complicate things with the 64bit variant.

>  2. We are not checking the file type: do we really need to add
>     subdirectory names to the list?

Yes, the sibling list should contain all normal files, special files
and directories.

>  3. Directory entry names have a fixed length, so we can optimize a bit
>     by removing CPLStrdup() call.

Memory still needs to be dynamically allocated for the entry in the list
returned from ReadDir() so I don't see what you are getting at.

> Other than above it seems to be nothing to optimize in our code.

It was an informative article though I'm left with the same conclusion.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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