[PATCH 4 of 4 shelve-ext v4] shelve: make shelvestate use simplekeyvaluefile

[Kostia Balytskyi]

> -----Original Message-----
> From: Yuya Nishihara [mailto:youjah at gmail.com] On Behalf Of Yuya
> Nishihara
> Sent: Thursday, 11 May, 2017 14:48
> To: Kostia Balytskyi <ikostia at fb.com>
> Cc: mercurial-devel at mercurial-scm.org
> Subject: Re: [PATCH 4 of 4 shelve-ext v4] shelve: make shelvestate use
> simplekeyvaluefile
> 
> On Sun, 7 May 2017 06:07:06 -0700, Kostia Balytskyi wrote:
> > # HG changeset patch
> > # User Kostia Balytskyi <ikostia at fb.com> # Date 1494162279 25200
> > #      Sun May 07 06:04:39 2017 -0700
> > # Node ID 9f24868156f15473b08a418765411341c96e892b
> > # Parent  497904bddbaa75b9086c168ab2e03381dfaff165
> > shelve: make shelvestate use simplekeyvaluefile
> 
> This looks good to me.
> 
> > +    @classmethod
> > +    def _getversion(cls, repo):
> > +        """Read version information from shelvestate file"""
> > +        fp = repo.vfs(cls._filename)
> > +        try:
> > +            version = int(fp.readline().strip())
> > +        except ValueError as err:
> > +            raise error.CorruptedState(str(err))
> > +        finally:
> > +            fp.close()
> > +        return version
> > +
> > +    @classmethod
> > +    def _readold(cls, repo):
> > +        """Read the old position-based version of a shelvestate file"""
> > +        # Order is important, because old shelvestate file uses it
> > +        # to detemine values of fields (i.g. name is on the second line,
> > +        # originalwctx is on the third and so forth). Please do not change.
> > +        keys = ['version', 'name', 'originalwctx', 'pendingctx', 'parents',
> > +                'nodestoremove', 'branchtorestore', 'keep', 'activebook']
> > +        # this is executed only seldomly, so it is not a big deal
> > +        # that we open this file twice
> > +        fp = repo.vfs(cls._filename)
> > +        d = {}
> > +        try:
> > +            for key in keys:
> > +                d[key] = fp.readline().strip()
> > +        finally:
> > +            fp.close()
> > +        return d
> > +
> > +    @classmethod
> > +    def load(cls, repo):
> > +        version = cls._getversion(repo)
> > +        if version < cls._version:
> > +            d = cls._readold(repo)
> > +        elif version == cls._version:
> > +            d = scmutil.simplekeyvaluefile(repo.vfs, cls._filename)\
> > +                       .read(firstlinenonkeyval=True)
> 
> This is okay, but I really don't understand why the simplekeyvaluefile has to:
> 
>  - be a class instead of load/dump functions (like json)
>  - take a vfs instead of a file object
> 
> IMHO, these design decisions just make things complicated.

I like it being a class because it allows inheritance, which allows simplekeyvalue users
to add validation. Also, it can serve as a container for firstlinekey.
vfs vs a file object - I don't have an answer to this, maybe file object would've been better, but I'd prefer to not rewrite it.

> 
> > diff --git a/tests/test-shelve.t b/tests/test-shelve.t
> > --- a/tests/test-shelve.t
> > +++ b/tests/test-shelve.t
> > @@ -1578,7 +1578,7 @@ shelve on new branch, conflict with prev
> >    $ echo "ccc" >> a
> >    $ hg status
> >    M a
> > -  $ hg unshelve
> > +  $ hg unshelve --config shelve.oldstatefile=on
> 
> Maybe this has to be updated to use a pre-generated v1 state file?
> 
> >    unshelving change 'default'
> >    temporarily committing pending changes (restore with 'hg unshelve --
> abort')
> >    rebasing shelved changes
> > @@ -1591,9 +1591,8 @@ shelve on new branch, conflict with prev
> > Removing restore branch information from shelvedstate file(making it
> > looks like  in previous versions) and running unshelve --continue
> >
> > -  $ head -n 6 < .hg/shelvedstate > .hg/shelvedstate_oldformat
> > -  $ rm .hg/shelvedstate
> > -  $ mv .hg/shelvedstate_oldformat .hg/shelvedstate
> > +  $ cp .hg/shelvedstate .hg/shelvedstate_old  $ cat
> > + .hg/shelvedstate_old | grep -v 'branchtorestore' > .hg/shelvedstate