[PATCH 1 of 8 RFC] vfs: replace invocation of file APIs of os module by ones via vfs

[FUJIWARA Katsunori]

At Sun, 17 Jun 2012 01:16:01 -0500,
Matt Mackall wrote:
> 
> On Sat, 2012-06-16 at 03:00 +0900, FUJIWARA Katsunori wrote:
> > At Fri, 15 Jun 2012 10:31:45 -0500,
> > Matt Mackall wrote:

> > > Also, this patch is quite big. It took me a while to locate the only
> > > real interesting bit: the definition of vfs. I'd rather see:
> > > 
> > > 1. rename the object
> > > 2. add a couple methods
> > > 3. convert some users
> > > 4. add some methods
> > > 5. convert some users
> > > ...
> > 
> > I understand that both "add a couple methods" and "convert some users"
> > mean "don't replace whole of code at once", am I right ?
> 
> It means I want to see the "small, interesting implementation bits"
> separated from the "large, boring, trivial conversions".
> 
> > Would you like the steps below ?
> > 
> >     1. pick some code path up
> >     2. check direct file API invocations in the path
> >     3. add just "a couple of" methods to current "opener" to invoke
> >        such APIs, if needed
> >     4. make codes in the path use methods of "opener"
> >     5. repeat from (3) to (4) for the path
> >     6. repeat from (1) to (5) for all paths
> >     5. create patch for each pairs of (3) and (4)
> 
> Please do a small amount of initial work, stop, and send a few patches.
> Much smaller than the current batch.

OK, I'll send small patch series to confirm working direction.


> > BTW:
> > 
> > > "Rename opener to vfs"
> > 
> > Should I rename both name of class and referring variables of "opener"
> > to "vfs"?  or only name of class ?
> 
> Well, we'll probably want to do both eventually. I think since we'll be
> adding a bunch of new callers to repo.<foo>.<someop>, we want to do
> rename the variables first, so we don't have to go back and change even
> more things later.

Sorry, I can't understand below sentence because of my poor English.

> so we don't have to go back and change even more things later.

But, I imagine the way to minimize changes in transition period like
as below. How about this ?

    1. add "vfs" like field(s) to objects referring openers, and make
       them referring openers too, at first

    2. use (or replace) "vfs" field instead of "opener" field in each
       small patch works

    3. finally, remove "opener" fields, when all of referring to them
       are replaced by ones to "vfs"
       

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[FUJIWARA Katsunori]                             foozy at lares.dti.ne.jp