[rrd-developers] rrd file access code

[Bernhard Reutner-Fischer]

On Mon, Oct 13, 2008 at 05:41:41PM +0200, Tobias Oetiker wrote:
>Hi Daniel,
>
>Today Daniel.Pocock at barclayscapital.com wrote:
>
>>
>>
>> Hi,
>>
>> I've just been reviewing the file access code and starting to implement
>> a mechanism for striping multiple RRDs into one big file, to further
>> reduce IO load.
>>
>> There are various functions in rrd_open.c (e.g. rrd_read, rrd_write)
>> that can be abstracted to do what is required.
>>
>> However, I notice that some other files (e.g. rrd_create.c) also have
>> code which accesses files directly (e.g. calling open() to create a
>> file).
>
>
>> Is there some ongoing work to centralise the file access code?  Would it
>> be worthwhile for me to patch some of this code (e.g. rrd_create.c) to
>> go through the functions in rrd_open.c, or is there some other solution
>> coming?
>
>I think create is one of the few places where there is local code,
>you can try converting it, but there will be some generalisation
>issues which caused the conversion not to happen the first time
>around.

There were no technical issues but create is not performance critical as
opposed to e.g. update, fetch, etc. (at least in my POV) so it was not
initially converted. I would consider finishing the conversion of all
such spots a cleanup.

It should be straight forward to update rrd_create and eventual other
leftovers to the interface provided in rrc_open.c (it deliberately
mimics normal read/write semantics to ease conversion).

HTH,

>what you might want to keep in mind is that I intend to create a
>new platform independent file format. This will also have an impact
>on this ... so if you are looking closely at all this code, the
>fileformat work might be integrated ...
>
>what I have done so fahr is documented on
>http://oss.oetiker.ch/rrdtool-trac/wiki/PortableRrdFormat