bug#2756: move SCCS later in vc-handled-backends

bug#2756: move SCCS later in vc-handled-backends

[Dan Nicolaescu]

SCCS should be moved after later in the vc-handled-backends list, after
the modern VCs.  

Opening any file costs a call to vc-sccs-registered
vc-sccs-search-project-dir (and whatever they call).

SCCS is not really popular nowadays, and that should be reflected on the
vc-handled-backends list.

bug#2756: move SCCS later in vc-handled-backends

[Stefan Monnier]

> SCCS should be moved after later in the vc-handled-backends list, after
> the modern VCs.
> Opening any file costs a call to vc-sccs-registered
> vc-sccs-search-project-dir (and whatever they call).

No matter where SCCS is in the vc-handled-backends list, those functions
will be run for any file that is not version controlled, which is likely
to be a very common case.

> SCCS is not really popular nowadays,

Same thing for RCS, indeed.

> and that should be reflected on the vc-handled-backends list.

We could remove backends from the list based on the presence/absence of
the corresponding executable(s).


        Stefan

bug#2756: move SCCS later in vc-handled-backends

[Dan Nicolaescu]

Stefan Monnier <monnier@IRO.UMontreal.CA> writes:

  > > SCCS should be moved after later in the vc-handled-backends list, after
  > > the modern VCs.
  > > Opening any file costs a call to vc-sccs-registered
  > > vc-sccs-search-project-dir (and whatever they call).
  > 
  > No matter where SCCS is in the vc-handled-backends list, those functions
  > will be run for any file that is not version controlled, which is likely
  > to be a very common case.
  >
  > > SCCS is not really popular nowadays,
  > 
  > Same thing for RCS, indeed.
  > 
  > > and that should be reflected on the vc-handled-backends list.
  > 
  > We could remove backends from the list based on the presence/absence of
  > the corresponding executable(s).

Would that be acceptable for 23.1?
If not, let's go for fixing the easier problem: moving SCCS later in the
list of backends.

bug#2756: move SCCS later in vc-handled-backends

[Stefan Monnier]

>> > SCCS should be moved after later in the vc-handled-backends list, after
>> > the modern VCs.
>> > Opening any file costs a call to vc-sccs-registered
>> > vc-sccs-search-project-dir (and whatever they call).
>> 
>> No matter where SCCS is in the vc-handled-backends list, those functions
>> will be run for any file that is not version controlled, which is likely
>> to be a very common case.
>> 
>> > SCCS is not really popular nowadays,
>> 
>> Same thing for RCS, indeed.
>> 
>> > and that should be reflected on the vc-handled-backends list.
>> 
>> We could remove backends from the list based on the presence/absence of
>> the corresponding executable(s).

> Would that be acceptable for 23.1?

No.

> If not, let's go for fixing the easier problem: moving SCCS later in the
> list of backends.

What problem?  And in what way is it a fix for it?


        Stefan

bug#2756: move SCCS later in vc-handled-backends

[Dan Nicolaescu]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

  > What problem?  And in what way is it a fix for it?

The fact that SCCS generates unnecessary work for all files managed by
bzr, git, hg (which is a good number nowadays).

bug#2756: move SCCS later in vc-handled-backends

[Stefan Monnier]

>> What problem?  And in what way is it a fix for it?
> The fact that SCCS generates unnecessary work for all files managed by
> bzr, git, hg (which is a good number nowadays).

Unnecessary work is not a problem in and of itself.
And, if this unnecessary work is a problem for Bzr, Git, or Hg files,
it's even more problematic for all the non-revision controlled files
which additionally need to do unnecessary work to determine that they're
neither under Git, Bzr, nor Hg control.  So changing the order won't
make much of a difference, other than hide the problem in the particular
case where you're lucky enough to access a file under the right VCS.


        Stefan

bug#2756: move SCCS later in vc-handled-backends

[Dan Nicolaescu]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

  > >> What problem?  And in what way is it a fix for it?
  > > The fact that SCCS generates unnecessary work for all files managed by
  > > bzr, git, hg (which is a good number nowadays).
  > 
  > Unnecessary work is not a problem in and of itself.

No, but given that it's unnecessary, and that it will be unnecessary in
the future too, why not get rid of it?

  > And, if this unnecessary work is a problem for Bzr, Git, or Hg files,
  > it's even more problematic for all the non-revision controlled files
  > which additionally need to do unnecessary work to determine that they're
  > neither under Git, Bzr, nor Hg control.  So changing the order won't
  > make much of a difference, other than hide the problem in the particular
  > case where you're lucky enough to access a file under the right VCS.

Yes, the thing is, what you are talking about above is a separate problem
that cannot be solved at this point.  
Even more, the solution for that problem would not solve the problem or
unnecessary checking for SCCS for systems that have sccs installed by
default (i.e. about all commercial unixes and free ones that install
cssc).  So why not just move SCCS to the end of the list?

bug#2756: move SCCS later in vc-handled-backends

[Stefan Monnier]

>> >> What problem?  And in what way is it a fix for it?
>> > The fact that SCCS generates unnecessary work for all files managed by
>> > bzr, git, hg (which is a good number nowadays).
>> Unnecessary work is not a problem in and of itself.
> No, but given that it's unnecessary, and that it will be unnecessary in
> the future too, why not get rid of it?
>> And, if this unnecessary work is a problem for Bzr, Git, or Hg files,
>> it's even more problematic for all the non-revision controlled files
>> which additionally need to do unnecessary work to determine that they're
>> neither under Git, Bzr, nor Hg control.  So changing the order won't
>> make much of a difference, other than hide the problem in the particular
>> case where you're lucky enough to access a file under the right VCS.
> Yes, the thing is, what you are talking about above is a separate problem
> that cannot be solved at this point.  
> Even more, the solution for that problem would not solve the problem or
> unnecessary checking for SCCS for systems that have sccs installed by
> default (i.e. about all commercial unixes and free ones that install
> cssc).  So why not just move SCCS to the end of the list?

Because we're in prestest so we limit ourselves to bug-fixes.


        Stefan

bug#2756: marked as done (move SCCS later in vc-handled-backends)

[Emacs bug Tracking System]

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Your message dated Wed, 26 Aug 2009 11:34:43 -0700 (PDT)
with message-id <200908261834.n7QIYhVX023388@godzilla.ics.uci.edu>
and subject line Re: bug#2756: move SCCS later in vc-handled-backends
has caused the Emacs bug report #2756,
regarding move SCCS later in vc-handled-backends
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
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2756: http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=2756
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From: Dan Nicolaescu <dann@ics.uci.edu>
To: bug-gnu-emacs <bug-gnu-emacs@gnu.org>
Subject: move SCCS later in vc-handled-backends
Date: Mon, 23 Mar 2009 10:25:21 -0700 (PDT)
Message-ID: <200903231725.n2NHPLF1011557@godzilla.ics.uci.edu>


SCCS should be moved after later in the vc-handled-backends list, after
the modern VCs.  

Opening any file costs a call to vc-sccs-registered
vc-sccs-search-project-dir (and whatever they call).

SCCS is not really popular nowadays, and that should be reflected on the
vc-handled-backends list.




[-- Attachment #3: Type: message/rfc822, Size: 2325 bytes --]

From: Dan Nicolaescu <dann@ics.uci.edu>
To: 2756-done@emacsbugs.donarmstrong.com
Subject: Re: bug#2756: move SCCS later in vc-handled-backends
Date: Wed, 26 Aug 2009 11:34:43 -0700 (PDT)
Message-ID: <200908261834.n7QIYhVX023388@godzilla.ics.uci.edu>

Dan Nicolaescu <dann@ics.uci.edu> writes:

  > SCCS should be moved after later in the vc-handled-backends list, after
  > the modern VCs.  
  > 
  > Opening any file costs a call to vc-sccs-registered
  > vc-sccs-search-project-dir (and whatever they call).
  > 
  > SCCS is not really popular nowadays, and that should be reflected on the
  > vc-handled-backends list.

Closing, this request has been rejected.