Re: [sqlite] in memory to void *data (and back)

[Gaspard Bucher]

Hi Jay,

Thanks for the reply. By looking at the code in demovfs:

http://www.sqlite.org/src/doc/trunk/src/test_demovfs.c  

It seems that by adapting "demovfs" to use a growing buffer (the *aBuffer 
field), I do not even need to use the backup stuff: I can just use this adapted 
"memory" database and pass the pointer to *aBuffer to save db content.

The use case is a VST audio plugin that should provide a data blob for plugin 
parameters save/restore operations. I am guaranteed by the VST specs that there 
is no code executed in the plugin until the host has finished copying the 
buffer data.

Gaspard Bucher


founder, coder
teti sàrl (http://teti.ch)



On Tuesday, 13 November 2012 at 18:16, Jay A. Kreibich wrote:

> On Tue, Nov 13, 2012 at 06:08:17PM +0100, Gaspard Bucher scratched on the 
> wall:
> > Hi there !  
> >  
> > I am trying to figure out how to dump an in-memory database to some data 
> > pointer and back (from a void*data chunk to in-memory). The simplest 
> > solution I can figure out right now is:
> >  
> > A. save to void*data
> > 1. backup to file
> > 2. read file ==> void*data
> > 3. remove file
> >  
> > B. load from void*data
> > 1. write to file
> > 2. open from file
> > 3. backup to memory
> > 4. remove file
> >  
> > Is there anything simpler that avoids the temp files ?  
>  
> Not simpler, but cleaner... write a VFS plugin that reads/writes to a
> memory block. Use the backup API to go straight in and out of that,
> rather then a file.
>  
> -j
>  
> --  
> Jay A. Kreibich < J A Y @ K R E I B I.C H >
>  
> "Intelligence is like underwear: it is important that you have it,
> but showing it to the wrong people has the tendency to make them
> feel uncomfortable." -- Angela Johnson
> ___
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> sqlite-users@sqlite.org (mailto:sqlite-users@sqlite.org)
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>  
>  


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Re: [sqlite] in memory to void *data (and back)

[Jay A. Kreibich]

On Tue, Nov 13, 2012 at 06:08:17PM +0100, Gaspard Bucher scratched on the wall:
> Hi there !  
> 
> I am trying to figure out how to dump an in-memory database to some data 
> pointer and back (from a void*data chunk to in-memory). The simplest solution 
> I can figure out right now is:
> 
> A. save to void*data
> 1. backup to file
> 2. read file ==> void*data
> 3. remove file
> 
> B. load from void*data
> 1. write to file
> 2. open from file
> 3. backup to memory
> 4. remove file
> 
> Is there anything simpler that avoids the temp files ?  

  Not simpler, but cleaner... write a VFS plugin that reads/writes to a
  memory block.  Use the backup API to go straight in and out of that,
  rather then a file.

-j

-- 
Jay A. Kreibich < J A Y  @  K R E I B I.C H >

"Intelligence is like underwear: it is important that you have it,
 but showing it to the wrong people has the tendency to make them
 feel uncomfortable." -- Angela Johnson
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[sqlite] in memory to void *data (and back)

[Gaspard Bucher]

Hi there !  

I am trying to figure out how to dump an in-memory database to some data 
pointer and back (from a void*data chunk to in-memory). The simplest solution I 
can figure out right now is:

A. save to void*data
1. backup to file
2. read file ==> void*data
3. remove file

B. load from void*data
1. write to file
2. open from file
3. backup to memory
4. remove file

Is there anything simpler that avoids the temp files ?  

Gaspard Bucher


founder, coder
teti sàrl (http://teti.ch)


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